diff mbox series

[v4,2/2] iio: adc: adding support for PAC193x

Message ID 20240122084712.11507-3-marius.cristea@microchip.com (mailing list archive)
State Handled Elsewhere
Headers show
Series adding support for Microchip PAC193X Power Monitor | expand

Commit Message

marius.cristea@microchip.com Jan. 22, 2024, 8:47 a.m. UTC
From: Marius Cristea <marius.cristea@microchip.com>

This is the iio driver for Microchip
PAC193X series of Power Monitor with Accumulator chip family.

Signed-off-by: Marius Cristea <marius.cristea@microchip.com>
---
 .../ABI/testing/sysfs-bus-iio-adc-pac1934     |    9 +
 MAINTAINERS                                   |    7 +
 drivers/iio/adc/Kconfig                       |   12 +
 drivers/iio/adc/Makefile                      |    1 +
 drivers/iio/adc/pac1934.c                     | 1646 +++++++++++++++++
 5 files changed, 1675 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934
 create mode 100644 drivers/iio/adc/pac1934.c

Comments

Petre Rodan Jan. 26, 2024, 10:58 a.m. UTC | #1
Hello Marius,

a quick static scan reported the following

On Mon, Jan 22, 2024 at 10:47:12AM +0200, marius.cristea@microchip.com wrote:
> From: Marius Cristea <marius.cristea@microchip.com>
> 
> This is the iio driver for Microchip
> PAC193X series of Power Monitor with Accumulator chip family.

[..]
> +	mutex_init(&info->lock);
> +	ret = devm_add_action_or_reset(&client->dev, pac1934_mutex_destroy,
> +				       &info->lock);
> +
> +	/*
> +	 * do now any chip specific initialization (e.g. read/write
> +	 * some registers), enable/disable certain channels, change the sampling
> +	 * rate to the requested value
> +	 */
> +	ret = pac1934_chip_configure(info);
> +	if (ret < 0)
> +		return ret;

the previous assignation of ret is never used, so either dead code or you might
have wanted to return early based on it's value.

cheers,
peter
Jonathan Cameron Jan. 27, 2024, 4:47 p.m. UTC | #2
On Mon, 22 Jan 2024 10:47:12 +0200
<marius.cristea@microchip.com> wrote:

> From: Marius Cristea <marius.cristea@microchip.com>
> 
> This is the iio driver for Microchip
> PAC193X series of Power Monitor with Accumulator chip family.
> 
> Signed-off-by: Marius Cristea <marius.cristea@microchip.com>
Hi Marius,

A few small things inline

Thanks,

Jonathan

> ---
>  .../ABI/testing/sysfs-bus-iio-adc-pac1934     |    9 +
>  MAINTAINERS                                   |    7 +
>  drivers/iio/adc/Kconfig                       |   12 +
>  drivers/iio/adc/Makefile                      |    1 +
>  drivers/iio/adc/pac1934.c                     | 1646 +++++++++++++++++
>  5 files changed, 1675 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934
>  create mode 100644 drivers/iio/adc/pac1934.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934 b/Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934
> new file mode 100644
> index 000000000000..28a2d4283938
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934
> @@ -0,0 +1,9 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/in_shunt_resistor_Y
For consistency with channels etc, I think
in_shunt_resistorY is more consistent.

> +KernelVersion:	6.7
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		The value of the shunt resistor may be known only at runtime
> +		and set by a client application. This attribute allows to
> +		set its value in micro-ohms. X is the IIO index of the device.
> +		Y is the channel number. The value is used to calculate
> +		current, power and accumulated energy.
...

> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 3b73c509bd68..5d2d3a45a7be 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -930,6 +930,18 @@ config NPCM_ADC
>  	  This driver can also be built as a module. If so, the module
>  	  will be called npcm_adc.
>  
> +config PAC1934
> +	tristate "Microchip Technology PAC1934 driver"
> +	depends on I2C
> +	depends on IIO

It's in the IIO menu under an if IIO, so this should not be needed.

> +	help
> +	  Say yes here to build support for Microchip Technology's PAC1931,
> +	  PAC1932, PAC1933, PAC1934 Single/Multi-Channel Power Monitor with
> +	  Accumulator.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called pac1934.

> diff --git a/drivers/iio/adc/pac1934.c b/drivers/iio/adc/pac1934.c
> new file mode 100644
> index 000000000000..b1a6f9f87817
> --- /dev/null
> +++ b/drivers/iio/adc/pac1934.c
> @@ -0,0 +1,1646 @@
...

> +
> +#include <linux/acpi.h>
> +#include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <asm/unaligned.h>
> +
> +#include <linux/device.h>
Why is this one not in the set above?
It's an unusual one to pull out of the main include block.

> +

> +
> +#define PAC1934_DEFAULT_CHIP_SAMP_SPEED		1024
Small thing, but if a name like this indicates units that is always helpful to the
reader _HZ maybe?

> +/*
> + * these indexes are exactly describing the element order within a single
> + * PAC1934 phys channel IIO channel descriptor; see the static const struct
> + * iio_chan_spec pac1934_single_channel[] declaration
> + */
> +enum pac1934_ch_idx {
> +	IIO_EN,
> +	IIO_POW,
> +	IIO_VOLT,
> +	IIO_CRT,
> +	IIO_VOLTAVG,
> +	IIO_CRTAVG
Don't use an IIO prefix for these as anyone seeing them being used inline will think they
are subsystem wise.
PAC1934_CH_ENERGY
etc. It's worth burning a few characters to make the code easier to understand.

> +};

> +
> +static int pac1934_match_samp_rate(struct pac1934_chip_info *info, u32 new_samp_rate)
> +{
> +	int cnt;
> +
> +	for (cnt = 0; cnt < ARRAY_SIZE(samp_rate_map_tbl); cnt++) {
> +		if (new_samp_rate == samp_rate_map_tbl[cnt]) {
> +			info->crt_samp_spd_bitfield = cnt;

Return this - don't hide away an internal state update inside a matching function.
It's not something a reader will expect to be happening so makes review harder

> +			return 0;
> +		}
> +	}
> +
> +	/* not a valid sample rate value */
> +	return -EINVAL;
> +}


...

> +
> +static int pac1934_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
> +			     int val, int val2, long mask)
> +{
> +	struct pac1934_chip_info *info = iio_priv(indio_dev);
> +	struct i2c_client *client = info->client;
> +	int ret = -EINVAL;
> +	s32 old_samp_rate;
> +	u8 ctrl_reg;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = pac1934_match_samp_rate(info, val);
> +		if (ret)
> +			return ret;
> +
> +		old_samp_rate = info->sample_rate_value;
> +		info->sample_rate_value = val;

Why not just update it after succeeding rather than update the cached value
with a chance of having to revert that.  Note that you shouldn't update
 the info->crt_samp_spd_bitfield value either until the write succeeds.
(if it has an purpose after that - if not don't have it in info).

> +
> +		/* write the new sampling value and trigger a snapshot(incl refresh) */
> +		scoped_guard(mutex, &info->lock) {
> +			ctrl_reg = FIELD_PREP(PAC1934_CRTL_SAMPLE_RATE_MASK,
> +					      info->crt_samp_spd_bitfield);
> +			ret = i2c_smbus_write_byte_data(client, PAC1934_CTRL_REG_ADDR, ctrl_reg);
> +			if (ret) {
> +				dev_err(&client->dev,
> +					"%s - can't update sample rate\n",
> +					__func__);
> +				info->sample_rate_value = old_samp_rate;
> +				return ret;
> +			}
> +		}
> +
> +		/*
> +		 * now, force a snapshot with refresh - call retrieve
> +		 * data in order to update the refresh timer
> +		 * alter the timestamp in order to force trigger a
> +		 * register snapshot and a timestamp update
> +		 */
> +		info->tstamp -= msecs_to_jiffies(PAC1934_MIN_POLLING_TIME_MS);
> +		ret = pac1934_retrieve_data(info, (1024 / old_samp_rate) * 1000);
> +		if (ret < 0) {
> +			dev_err(&client->dev,
> +				"%s - cannot snapshot ctrl and measurement regs\n",
> +				__func__);
> +			return ret;
> +		}
> +
> +		return 0;
> +	case IIO_CHAN_INFO_ENABLE:
> +		scoped_guard(mutex, &info->lock) {
> +			info->enable_energy[chan->channel - 1] = val ? true : false;
> +			info->chip_reg_data.energy_sec_acc[chan->channel - 1] = 0;
> +		}
> +
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
...

> +/*
> + * documentation related to the ACPI device definition
> + * https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ApplicationNotes/ApplicationNotes/PAC1934-Integration-Notes-for-Microsoft-Windows-10-and-Windows-11-Driver-Support-DS00002534.pdf
> + */
> +static bool pac1934_acpi_parse_channel_config(struct i2c_client *client,
> +					      struct pac1934_chip_info *info)
> +{
> +	acpi_handle handle;
> +	union acpi_object *rez;
> +	struct device *dev = &client->dev;
> +	unsigned short bi_dir_mask;
> +	int idx, i;
> +	guid_t guid;
> +	const struct acpi_device_id *id;
> +
> +	handle = ACPI_HANDLE(&client->dev);
> +
> +	id = acpi_match_device(dev->driver->acpi_match_table, dev);

I'd like to see a comment on why we might fail to match here.
(I think someone using PRP0001 is the only path I can think of).

> +	if (!id)
> +		return false;
> +
> +	guid_parse(PAC1934_DSM_UUID, &guid);
> +
> +	rez = acpi_evaluate_dsm(handle, &guid, 0, PAC1934_ACPI_GET_NAMES_AND_MOHMS_VALS, NULL);
> +	if (!rez)
> +		return false;
> +
> +	for (i = 0; i < rez->package.count; i += 2) {
> +		idx = i / 2;
> +		info->labels[idx] =
> +			devm_kmemdup(&client->dev, rez->package.elements[i].string.pointer,
> +				     (size_t)rez->package.elements[i].string.length + 1,
> +				     GFP_KERNEL);
> +		info->labels[idx][rez->package.elements[i].string.length] = '\0';
> +		info->shunts[idx] =
> +			rez->package.elements[i + 1].integer.value * 1000;
> +		info->active_channels[idx] = (info->shunts[idx] != 0);
> +	}
> +
> +	ACPI_FREE(rez);
> +
> +	rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_UOHMS_VALS, NULL);
> +	if (!rez) {
> +		/*
> +		 * initializing with default values
> +		 * we assume all channels are unidirectional(the mask is zero)
> +		 * and assign the default sampling rate
> +		 */
> +		info->sample_rate_value = PAC1934_DEFAULT_CHIP_SAMP_SPEED;
> +		return true;
> +	}
> +
> +	for (i = 0; i < rez->package.count; i++) {
> +		idx = i;
> +		info->shunts[idx] = rez->package.elements[i].integer.value;
> +		info->active_channels[idx] = (info->shunts[idx] != 0);
> +	}
> +
> +	ACPI_FREE(rez);
> +
> +	rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_BIPOLAR_SETTINGS, NULL);
> +	if (!rez)
> +		return false;
> +
> +	bi_dir_mask = rez->package.elements[0].integer.value;
> +	info->bi_dir[0] = ((bi_dir_mask & (1 << 3)) | (bi_dir_mask & (1 << 7))) != 0;
> +	info->bi_dir[1] = ((bi_dir_mask & (1 << 2)) | (bi_dir_mask & (1 << 6))) != 0;
> +	info->bi_dir[2] = ((bi_dir_mask & (1 << 1)) | (bi_dir_mask & (1 << 5))) != 0;
> +	info->bi_dir[3] = ((bi_dir_mask & (1 << 0)) | (bi_dir_mask & (1 << 4))) != 0;
> +
> +	ACPI_FREE(rez);
> +
> +	rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_SAMP, NULL);
> +	if (!rez)
> +		return false;
> +
> +	info->sample_rate_value = rez->package.elements[0].integer.value;
> +
> +	ACPI_FREE(rez);
> +
> +	return true;
> +}

> +
> +static int pac1934_chip_configure(struct pac1934_chip_info *info)
> +{
> +	int cnt, ret;
> +	struct i2c_client *client = info->client;
> +	u8 regs[PAC1934_CTRL_STATUS_INFO_LEN], idx, ctrl_reg;
> +	u32 wait_time;
> +
> +	info->chip_reg_data.num_enabled_channels = 0;
> +	for (cnt = 0;  cnt < info->phys_channels; cnt++) {
> +		if (info->active_channels[cnt])
> +			info->chip_reg_data.num_enabled_channels++;
> +	}
> +
> +	/*
> +	 * read whatever information was gathered before the driver was loaded
> +	 * establish which channels are enabled/disabled and then establish the
> +	 * information retrieval mode (using SKIP or no).
> +	 * Read the chip ID values
> +	 */
> +	ret = i2c_smbus_read_i2c_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
> +					    ARRAY_SIZE(regs),
> +					    (u8 *)regs);
> +	if (ret < 0) {
> +		dev_err_probe(&client->dev, ret,
> +			      "%s - cannot read regs from 0x%02X\n",
> +			      __func__, PAC1934_CTRL_STAT_REGS_ADDR);
> +		return ret;
> +	}
> +
> +	/* write the CHANNEL_DIS and the NEG_PWR registers */
> +	regs[PAC1934_CHANNEL_DIS_REG_OFF] =
> +		FIELD_PREP(PAC1934_CHAN_DIS_CH1_OFF_MASK, !(info->active_channels[0])) |
> +		FIELD_PREP(PAC1934_CHAN_DIS_CH2_OFF_MASK, !(info->active_channels[1])) |
> +		FIELD_PREP(PAC1934_CHAN_DIS_CH3_OFF_MASK, !(info->active_channels[2])) |
> +		FIELD_PREP(PAC1934_CHAN_DIS_CH4_OFF_MASK, !(info->active_channels[3])) |
> +		FIELD_PREP(PAC1934_SMBUS_TIMEOUT_MASK, 0) |
> +		FIELD_PREP(PAC1934_SMBUS_BYTECOUNT_MASK, 0) |
> +		FIELD_PREP(PAC1934_SMBUS_NO_SKIP_MASK, 0);
> +
> +	regs[PAC1934_NEG_PWR_REG_OFF] =
> +		FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDI_MASK, info->bi_dir[0]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDI_MASK, info->bi_dir[1]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDI_MASK, info->bi_dir[2]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDI_MASK, info->bi_dir[3]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDV_MASK, info->bi_dir[0]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDV_MASK, info->bi_dir[1]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDV_MASK, info->bi_dir[2]) |
> +		FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDV_MASK, info->bi_dir[3]);
> +
> +	/* no SLOW triggered REFRESH, clear POR */
> +	regs[PAC1934_SLOW_REG_OFF] = 0;
> +
> +	ret =  i2c_smbus_write_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
> +					  ARRAY_SIZE(regs), (u8 *)regs);
> +	if (ret)
> +		return ret;
> +
> +	ctrl_reg = FIELD_PREP(PAC1934_CRTL_SAMPLE_RATE_MASK, info->crt_samp_spd_bitfield);
> +
> +	ret = i2c_smbus_write_byte_data(client, PAC1934_CTRL_REG_ADDR, ctrl_reg);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * send a REFRESH to the chip, so the new settings take place
> +	 * as well as resetting the accumulators
> +	 */
> +	ret = i2c_smbus_write_byte(client, PAC1934_REFRESH_REG_ADDR);
> +	if (ret) {
> +		dev_err(&client->dev,
> +			"%s - cannot send 0x%02X\n",
> +			__func__, PAC1934_REFRESH_REG_ADDR);
> +		return ret;
> +	}
> +
> +	/*
> +	 * get the current(in the chip) sampling speed and compute the
> +	 * required timeout based on its value
> +	 * the timeout is 1/sampling_speed
> +	 */
> +	idx = regs[PAC1934_CTRL_ACT_REG_OFF] >> PAC1934_SAMPLE_RATE_SHIFT;
> +	wait_time = (1024 / samp_rate_map_tbl[idx]) * 1000;
> +
> +	/*
> +	 * wait the maximum amount of time to be on the safe side
> +	 * the maximum wait time is for 8sps
> +	 */
> +	usleep_range(wait_time, wait_time + 100);
> +
> +	INIT_DELAYED_WORK(&info->work_chip_rfsh, pac1934_work_periodic_rfsh);
> +	/* Setup the latest moment for reading the regs before saturation */
> +	schedule_delayed_work(&info->work_chip_rfsh,
> +			      msecs_to_jiffies(PAC1934_MAX_RFSH_LIMIT_MS));
> +
> +	devm_add_action_or_reset(&client->dev, pac1934_cancel_delayed_work,
> +				 &info->work_chip_rfsh);

Can fail.  Check the return value (it's very unlikely to fail but good practice
to check it anyway).

> +
> +	return 0;
> +}
> +
> +static int pac1934_prep_iio_channels(struct pac1934_chip_info *info, struct iio_dev *indio_dev)
> +{
> +	struct i2c_client *client;
> +	struct iio_chan_spec *ch_sp;
> +	int channel_size, attribute_count, cnt;
> +	void *dyn_ch_struct, *tmp_data;
> +
> +	client = info->client;

Only used to get to client->dev.  A struct device *dev = &info->client.dev;
would be more useful in making the code more readable.

> +
> +	/* find out dynamically how many IIO channels we need */
> +	attribute_count = 0;
> +	channel_size = 0;
> +	for (cnt = 0; cnt < info->phys_channels; cnt++) {
> +		if (!info->active_channels[cnt])
> +			continue;
> +
> +		/* add the size of the properties of one chip physical channel */
> +		channel_size += sizeof(pac1934_single_channel);
> +		/* count how many enabled channels we have */
> +		attribute_count += ARRAY_SIZE(pac1934_single_channel);
> +		dev_info(&client->dev, ":%s: Channel %d active\n",
> +			 __func__, cnt + 1);
> +	}
> +
> +	dyn_ch_struct = devm_kzalloc(&client->dev, channel_size, GFP_KERNEL);
> +	if (!dyn_ch_struct)
> +		return -EINVAL;
> +
> +	tmp_data = dyn_ch_struct;
> +
> +	/* populate the dynamic channels and make all the adjustments */
> +	for (cnt = 0; cnt < info->phys_channels; cnt++) {
> +		if (!info->active_channels[cnt])
> +			continue;
> +
> +		memcpy(tmp_data, pac1934_single_channel, sizeof(pac1934_single_channel));
> +		ch_sp = (struct iio_chan_spec *)tmp_data;
> +		ch_sp[IIO_EN].channel = cnt + 1;
> +		ch_sp[IIO_EN].scan_index = cnt;
> +		ch_sp[IIO_EN].address = cnt + PAC1934_VPOWER_ACC_1_ADDR;
> +		ch_sp[IIO_POW].channel = cnt + 1;
> +		ch_sp[IIO_POW].scan_index = cnt;
> +		ch_sp[IIO_POW].address = cnt + PAC1934_VPOWER_1_ADDR;
> +		ch_sp[IIO_VOLT].channel = cnt + 1;
> +		ch_sp[IIO_VOLT].scan_index = cnt;
> +		ch_sp[IIO_VOLT].address = cnt + PAC1934_VBUS_1_ADDR;
> +		ch_sp[IIO_CRT].channel = cnt + 1;
> +		ch_sp[IIO_CRT].scan_index = cnt;
> +		ch_sp[IIO_CRT].address = cnt + PAC1934_VSENSE_1_ADDR;
> +		/*
> +		 * In order to be able to use labels for IIO_VOLT and IIO_VOLTAVG,
> +		 * respectively IIO_CRT and IIO_CRTAVG we need to use different
> +		 * channel numbers. We will add  +5 (+1 to maximum PAC channels).
> +		 */
> +		ch_sp[IIO_VOLTAVG].channel = cnt + 5;
> +		ch_sp[IIO_VOLTAVG].scan_index = cnt;
> +		ch_sp[IIO_VOLTAVG].address = cnt + PAC1934_VBUS_AVG_1_ADDR;
> +		ch_sp[IIO_CRTAVG].channel = cnt + 5;
> +		ch_sp[IIO_CRTAVG].scan_index = cnt;
> +		ch_sp[IIO_CRTAVG].address = cnt + PAC1934_VSENSE_AVG_1_ADDR;
> +
> +		/*
> +		 * now modify the parameters in all channels if the
> +		 * whole chip rail(channel) is bi-directional
> +		 */
> +		if (info->bi_dir[cnt]) {
> +			ch_sp[IIO_EN].scan_type.sign = 's';
> +			ch_sp[IIO_EN].scan_type.realbits = 47;
> +			ch_sp[IIO_POW].scan_type.sign = 's';
> +			ch_sp[IIO_POW].scan_type.realbits = 27;
> +			ch_sp[IIO_VOLT].scan_type.sign = 's';
> +			ch_sp[IIO_VOLT].scan_type.realbits = 15;
> +			ch_sp[IIO_CRT].scan_type.sign = 's';
> +			ch_sp[IIO_CRT].scan_type.realbits = 15;
> +			ch_sp[IIO_VOLTAVG].scan_type.sign = 's';
> +			ch_sp[IIO_VOLTAVG].scan_type.realbits = 15;
> +			ch_sp[IIO_CRTAVG].scan_type.sign = 's';
> +			ch_sp[IIO_CRTAVG].scan_type.realbits = 15;
> +		}
> +		tmp_data += sizeof(pac1934_single_channel);
> +	}
> +
> +	/*
> +	 * send the updated dynamic channel structure information towards IIO
> +	 * prepare the required field for IIO class registration
> +	 */
> +	indio_dev->num_channels = attribute_count;
> +
> +	indio_dev->channels = (const struct iio_chan_spec *)dyn_ch_struct;
> +
> +	if (!indio_dev->channels)

How could this condition be hit?

> +		return -EINVAL;
> +
> +	return 0;
> +}

...

> +static void pac1934_mutex_destroy(void *data)
> +{
> +	struct mutex *lock = data;
> +
> +	mutex_destroy(lock);

I'm of the school of thought that it's not worth destroying mutexes if we aren't
dealing with a situation where we have complex lifetimes for the containing structure.

I don't feel that strongly about it and would like the devm_mutex_init() proposals
to finally go upstream but for now I'd just drop this.

> +}
> +
> +static int pac1934_probe(struct i2c_client *client)
> +{
> +	struct pac1934_chip_info *info;
> +	const struct pac1934_features *chip;
> +	struct iio_dev *indio_dev;
> +	int cnt, ret;
> +	bool match = false;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*info));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	info = iio_priv(indio_dev);
> +
> +	i2c_set_clientdata(client, indio_dev);

Why?  I don't think this is ever read back by your driver
(I might be missing something!)



> +	info->client = client;
> +
> +	/* always start with energy accumulation enabled */
> +	for (cnt = 0; cnt < PAC1934_MAX_NUM_CHANNELS; cnt++)
> +		info->enable_energy[cnt] = true;
> +
> +	info->crt_samp_spd_bitfield = PAC1934_SAMP_1024SPS;
> +
> +	ret = pac1934_chip_identify(info);
> +	if (ret < 0) {
> +		/*
> +		 * If failed to identify the hardware based on internal registers,
> +		 * try using fallback compatible in device tree to deal with some newer part number.

Overly long line and it won't hurt readability to break it.
Try to keep to 80 char limit unless there is a good reason to go longer.

> +		 */
> +		chip = i2c_get_match_data(client);
> +		if (!chip)
> +			return -EINVAL;
> +
> +		info->phys_channels = chip->phys_channels;
> +		indio_dev->name = chip->name;
> +	} else {
> +		info->phys_channels = pac1934_chip_config[ret].phys_channels;
> +		indio_dev->name = pac1934_chip_config[ret].name;
> +	}
> +
> +	if (ACPI_HANDLE(&client->dev))

This gets messy because of PRP0001.  In theory the of_parse routine might be
the right one even though we have an ACPI FW.  I guess that's unlikely enough
that we can just fail to probe if we do.

> +		match = pac1934_acpi_parse_channel_config(client, info);
> +	else
> +		match = pac1934_of_parse_channel_config(client, info);
> +
> +	if (!match) {
> +		dev_dbg(&client->dev, "parameter parsing returned an error\n");
> +		return -EINVAL;
I'd promote this to a
		return dev_err_probe(&client->dev, -EINVAL, "....)

> +	}
> +
> +	mutex_init(&info->lock);
> +	ret = devm_add_action_or_reset(&client->dev, pac1934_mutex_destroy,
> +				       &info->lock);
As already noted, check ret.

> +
> +	/*
> +	 * do now any chip specific initialization (e.g. read/write
> +	 * some registers), enable/disable certain channels, change the sampling
> +	 * rate to the requested value
> +	 */
> +	ret = pac1934_chip_configure(info);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* prepare the channel information */
> +	ret = pac1934_prep_iio_channels(info, indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = pac1934_prep_custom_attributes(info, indio_dev);
> +	if (ret < 0) {
> +		dev_err_probe(&client->dev, ret,
> +			      "Can't configure custom attributes for PAC1934 device\n");
> +		return ret;
		return dev_err_probe()

> +	}
> +
> +	info->iio_info.read_raw = pac1934_read_raw;
> +	info->iio_info.read_avail = pac1934_read_avail;
> +	info->iio_info.write_raw = pac1934_write_raw;
> +	info->iio_info.read_label = pac1934_read_label;

Looks const. If it is, then make it so (look at other drivers for this)

> +
> +	indio_dev->info = &info->iio_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	/*
> +	 * read whatever has been accumulated in the chip so far
> +	 * and reset the accumulators
> +	 */
> +	ret = pac1934_reg_snapshot(info, true, PAC1934_REFRESH_REG_ADDR,
> +				   PAC1934_MIN_UPDATE_WAIT_TIME_US);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = devm_iio_device_register(&client->dev, indio_dev);
> +	if (ret < 0)
> +		dev_err_probe(&client->dev, ret,
> +			      "Can't register IIO device\n");
Feels odd to not return this
		return dev_err_probe()

	return 0;
> +
> +	return ret;
> +}

> +
> +/* using MCHP1930 to be compatible with BIOS ACPI */

That is apparent from the table. Comment doesn't add anything.
If you have a particular bios to point at that might be useful to mention here.

> +static const struct acpi_device_id pac1934_acpi_match[] = {
> +	{ "MCHP1930", .driver_data = (kernel_ulong_t)&pac1934_chip_config[PAC1934] },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(acpi, pac1934_acpi_match);
> +
> +static struct i2c_driver pac1934_driver = {
> +	.driver	 = {
> +		.name = "pac1934",
> +		.of_match_table = pac1934_of_match,
> +		.acpi_match_table = pac1934_acpi_match
> +		},
Normal style is to align this with . above. E.g.
	},

> +	.probe = pac1934_probe,
> +	.id_table = pac1934_id,
> +};
kernel test robot Jan. 28, 2024, 12:06 p.m. UTC | #3
Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on b1a1eaf6183697b77f7243780a25f35c7c0c8bdf]

url:    https://github.com/intel-lab-lkp/linux/commits/marius-cristea-microchip-com/dt-bindings-iio-adc-adding-support-for-PAC193X/20240122-165539
base:   b1a1eaf6183697b77f7243780a25f35c7c0c8bdf
patch link:    https://lore.kernel.org/r/20240122084712.11507-3-marius.cristea%40microchip.com
patch subject: [PATCH v4 2/2] iio: adc: adding support for PAC193x
config: x86_64-randconfig-121-20240128 (https://download.01.org/0day-ci/archive/20240128/202401281913.alVFRURI-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240128/202401281913.alVFRURI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401281913.alVFRURI-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/iio/adc/pac1934.c:1265:17: sparse: sparse: dubious: x & !y
   drivers/iio/adc/pac1934.c:1266:17: sparse: sparse: dubious: x & !y
   drivers/iio/adc/pac1934.c:1267:17: sparse: sparse: dubious: x & !y
   drivers/iio/adc/pac1934.c:1268:17: sparse: sparse: dubious: x & !y

vim +1265 drivers/iio/adc/pac1934.c

  1233	
  1234	static int pac1934_chip_configure(struct pac1934_chip_info *info)
  1235	{
  1236		int cnt, ret;
  1237		struct i2c_client *client = info->client;
  1238		u8 regs[PAC1934_CTRL_STATUS_INFO_LEN], idx, ctrl_reg;
  1239		u32 wait_time;
  1240	
  1241		info->chip_reg_data.num_enabled_channels = 0;
  1242		for (cnt = 0;  cnt < info->phys_channels; cnt++) {
  1243			if (info->active_channels[cnt])
  1244				info->chip_reg_data.num_enabled_channels++;
  1245		}
  1246	
  1247		/*
  1248		 * read whatever information was gathered before the driver was loaded
  1249		 * establish which channels are enabled/disabled and then establish the
  1250		 * information retrieval mode (using SKIP or no).
  1251		 * Read the chip ID values
  1252		 */
  1253		ret = i2c_smbus_read_i2c_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
  1254						    ARRAY_SIZE(regs),
  1255						    (u8 *)regs);
  1256		if (ret < 0) {
  1257			dev_err_probe(&client->dev, ret,
  1258				      "%s - cannot read regs from 0x%02X\n",
  1259				      __func__, PAC1934_CTRL_STAT_REGS_ADDR);
  1260			return ret;
  1261		}
  1262	
  1263		/* write the CHANNEL_DIS and the NEG_PWR registers */
  1264		regs[PAC1934_CHANNEL_DIS_REG_OFF] =
> 1265			FIELD_PREP(PAC1934_CHAN_DIS_CH1_OFF_MASK, !(info->active_channels[0])) |
  1266			FIELD_PREP(PAC1934_CHAN_DIS_CH2_OFF_MASK, !(info->active_channels[1])) |
  1267			FIELD_PREP(PAC1934_CHAN_DIS_CH3_OFF_MASK, !(info->active_channels[2])) |
  1268			FIELD_PREP(PAC1934_CHAN_DIS_CH4_OFF_MASK, !(info->active_channels[3])) |
  1269			FIELD_PREP(PAC1934_SMBUS_TIMEOUT_MASK, 0) |
  1270			FIELD_PREP(PAC1934_SMBUS_BYTECOUNT_MASK, 0) |
  1271			FIELD_PREP(PAC1934_SMBUS_NO_SKIP_MASK, 0);
  1272	
  1273		regs[PAC1934_NEG_PWR_REG_OFF] =
  1274			FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDI_MASK, info->bi_dir[0]) |
  1275			FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDI_MASK, info->bi_dir[1]) |
  1276			FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDI_MASK, info->bi_dir[2]) |
  1277			FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDI_MASK, info->bi_dir[3]) |
  1278			FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDV_MASK, info->bi_dir[0]) |
  1279			FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDV_MASK, info->bi_dir[1]) |
  1280			FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDV_MASK, info->bi_dir[2]) |
  1281			FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDV_MASK, info->bi_dir[3]);
  1282	
  1283		/* no SLOW triggered REFRESH, clear POR */
  1284		regs[PAC1934_SLOW_REG_OFF] = 0;
  1285	
  1286		ret =  i2c_smbus_write_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
  1287						  ARRAY_SIZE(regs), (u8 *)regs);
  1288		if (ret)
  1289			return ret;
  1290	
  1291		ctrl_reg = FIELD_PREP(PAC1934_CRTL_SAMPLE_RATE_MASK, info->crt_samp_spd_bitfield);
  1292	
  1293		ret = i2c_smbus_write_byte_data(client, PAC1934_CTRL_REG_ADDR, ctrl_reg);
  1294		if (ret)
  1295			return ret;
  1296	
  1297		/*
  1298		 * send a REFRESH to the chip, so the new settings take place
  1299		 * as well as resetting the accumulators
  1300		 */
  1301		ret = i2c_smbus_write_byte(client, PAC1934_REFRESH_REG_ADDR);
  1302		if (ret) {
  1303			dev_err(&client->dev,
  1304				"%s - cannot send 0x%02X\n",
  1305				__func__, PAC1934_REFRESH_REG_ADDR);
  1306			return ret;
  1307		}
  1308	
  1309		/*
  1310		 * get the current(in the chip) sampling speed and compute the
  1311		 * required timeout based on its value
  1312		 * the timeout is 1/sampling_speed
  1313		 */
  1314		idx = regs[PAC1934_CTRL_ACT_REG_OFF] >> PAC1934_SAMPLE_RATE_SHIFT;
  1315		wait_time = (1024 / samp_rate_map_tbl[idx]) * 1000;
  1316	
  1317		/*
  1318		 * wait the maximum amount of time to be on the safe side
  1319		 * the maximum wait time is for 8sps
  1320		 */
  1321		usleep_range(wait_time, wait_time + 100);
  1322	
  1323		INIT_DELAYED_WORK(&info->work_chip_rfsh, pac1934_work_periodic_rfsh);
  1324		/* Setup the latest moment for reading the regs before saturation */
  1325		schedule_delayed_work(&info->work_chip_rfsh,
  1326				      msecs_to_jiffies(PAC1934_MAX_RFSH_LIMIT_MS));
  1327	
  1328		devm_add_action_or_reset(&client->dev, pac1934_cancel_delayed_work,
  1329					 &info->work_chip_rfsh);
  1330	
  1331		return 0;
  1332	}
  1333
diff mbox series

Patch

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934 b/Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934
new file mode 100644
index 000000000000..28a2d4283938
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-pac1934
@@ -0,0 +1,9 @@ 
+What:		/sys/bus/iio/devices/iio:deviceX/in_shunt_resistor_Y
+KernelVersion:	6.7
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The value of the shunt resistor may be known only at runtime
+		and set by a client application. This attribute allows to
+		set its value in micro-ohms. X is the IIO index of the device.
+		Y is the channel number. The value is used to calculate
+		current, power and accumulated energy.
diff --git a/MAINTAINERS b/MAINTAINERS
index 35147477e8e4..5eea1e98e0f2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14231,6 +14231,13 @@  F:	Documentation/devicetree/bindings/nvmem/microchip,sama7g5-otpc.yaml
 F:	drivers/nvmem/microchip-otpc.c
 F:	include/dt-bindings/nvmem/microchip,sama7g5-otpc.h
 
+MICROCHIP PAC1934 POWER/ENERGY MONITOR DRIVER
+M:	Marius Cristea <marius.cristea@microchip.com>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/iio/adc/microchip,pac1934.yaml
+F:	drivers/iio/adc/pac1934.c
+
 MICROCHIP PCI1XXXX GP DRIVER
 M:	Vaibhaav Ram T.L <vaibhaavram.tl@microchip.com>
 M:	Kumaravel Thiagarajan <kumaravel.thiagarajan@microchip.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 3b73c509bd68..5d2d3a45a7be 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -930,6 +930,18 @@  config NPCM_ADC
 	  This driver can also be built as a module. If so, the module
 	  will be called npcm_adc.
 
+config PAC1934
+	tristate "Microchip Technology PAC1934 driver"
+	depends on I2C
+	depends on IIO
+	help
+	  Say yes here to build support for Microchip Technology's PAC1931,
+	  PAC1932, PAC1933, PAC1934 Single/Multi-Channel Power Monitor with
+	  Accumulator.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called pac1934.
+
 config PALMAS_GPADC
 	tristate "TI Palmas General Purpose ADC"
 	depends on MFD_PALMAS
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index d2fda54a3259..bbf9613fc339 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -86,6 +86,7 @@  obj-$(CONFIG_MP2629_ADC) += mp2629_adc.o
 obj-$(CONFIG_MXS_LRADC_ADC) += mxs-lradc-adc.o
 obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_NPCM_ADC) += npcm_adc.o
+obj-$(CONFIG_PAC1934) += pac1934.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_ADC5) += qcom-spmi-adc5.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
diff --git a/drivers/iio/adc/pac1934.c b/drivers/iio/adc/pac1934.c
new file mode 100644
index 000000000000..b1a6f9f87817
--- /dev/null
+++ b/drivers/iio/adc/pac1934.c
@@ -0,0 +1,1646 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * IIO driver for PAC1934 Multi-Channel DC Power/Energy Monitor
+ *
+ * Copyright (C) 2017-2024 Microchip Technology Inc. and its subsidiaries
+ *
+ * Author: Bogdan Bolocan <bogdan.bolocan@microchip.com>
+ * Author: Victor Tudose
+ * Author: Marius Cristea <marius.cristea@microchip.com>
+ *
+ * Datasheet for PAC1931, PAC1932, PAC1933 and PAC1934 can be found here:
+ * https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/PAC1931-Family-Data-Sheet-DS20005850E.pdf
+ */
+
+#include <linux/acpi.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <asm/unaligned.h>
+
+#include <linux/device.h>
+
+/*
+ * maximum accumulation time should be (17 * 60 * 1000) around 17 minutes@1024 sps
+ * till PAC1934 accumulation registers starts to saturate
+ */
+#define PAC1934_MAX_RFSH_LIMIT_MS		60000
+/* 50msec is the timeout for validity of the cached registers */
+#define PAC1934_MIN_POLLING_TIME_MS		50
+/*
+ * 1000usec is the minimum wait time for normal conversions when sample
+ * rate doesn't change
+ */
+#define PAC1934_MIN_UPDATE_WAIT_TIME_US		1000
+
+/* 32000mV */
+#define PAC1934_VOLTAGE_MILLIVOLTS_MAX		32000
+/* voltage bits resolution when set for unsigned values */
+#define PAC1934_VOLTAGE_U_RES			16
+/* voltage bits resolution when set for signed values */
+#define PAC1934_VOLTAGE_S_RES			15
+
+/*
+ * max signed value that can be stored on 32 bits and 8 digits fractional value
+ * (2^31 - 1) * 10^8 + 99999999
+ */
+#define PAC_193X_MAX_POWER_ACC			214748364799999999LL
+/*
+ * min signed value that can be stored on 32 bits and 8 digits fractional value
+ * -(2^31) * 10^8 - 99999999
+ */
+#define PAC_193X_MIN_POWER_ACC			-214748364899999999LL
+
+#define PAC1934_MAX_NUM_CHANNELS		4
+
+#define PAC1934_MEAS_REG_LEN			76
+#define PAC1934_CTRL_REG_LEN			12
+
+#define PAC1934_DEFAULT_CHIP_SAMP_SPEED		1024
+
+/* I2C address map */
+#define PAC1934_REFRESH_REG_ADDR		0x00
+#define PAC1934_CTRL_REG_ADDR			0x01
+#define PAC1934_ACC_COUNT_REG_ADDR		0x02
+#define PAC1934_VPOWER_ACC_1_ADDR		0x03
+#define PAC1934_VPOWER_ACC_2_ADDR		0x04
+#define PAC1934_VPOWER_ACC_3_ADDR		0x05
+#define PAC1934_VPOWER_ACC_4_ADDR		0x06
+#define PAC1934_VBUS_1_ADDR			0x07
+#define PAC1934_VBUS_2_ADDR			0x08
+#define PAC1934_VBUS_3_ADDR			0x09
+#define PAC1934_VBUS_4_ADDR			0x0A
+#define PAC1934_VSENSE_1_ADDR			0x0B
+#define PAC1934_VSENSE_2_ADDR			0x0C
+#define PAC1934_VSENSE_3_ADDR			0x0D
+#define PAC1934_VSENSE_4_ADDR			0x0E
+#define PAC1934_VBUS_AVG_1_ADDR			0x0F
+#define PAC1934_VBUS_AVG_2_ADDR			0x10
+#define PAC1934_VBUS_AVG_3_ADDR			0x11
+#define PAC1934_VBUS_AVG_4_ADDR			0x12
+#define PAC1934_VSENSE_AVG_1_ADDR		0x13
+#define PAC1934_VSENSE_AVG_2_ADDR		0x14
+#define PAC1934_VSENSE_AVG_3_ADDR		0x15
+#define PAC1934_VSENSE_AVG_4_ADDR		0x16
+#define PAC1934_VPOWER_1_ADDR			0x17
+#define PAC1934_VPOWER_2_ADDR			0x18
+#define PAC1934_VPOWER_3_ADDR			0x19
+#define PAC1934_VPOWER_4_ADDR			0x1A
+#define PAC1934_REFRESH_V_REG_ADDR		0x1F
+#define PAC1934_CTRL_STAT_REGS_ADDR		0x1C
+#define PAC1934_PID_REG_ADDR			0xFD
+#define PAC1934_MID_REG_ADDR			0xFE
+#define PAC1934_RID_REG_ADDR			0xFF
+
+/* PRODUCT ID REGISTER + MANUFACTURER ID REGISTER + REVISION ID REGISTER */
+#define PAC1934_ID_REG_LEN			3
+#define PAC1934_PID_IDX				0
+#define PAC1934_MID_IDX				1
+#define PAC1934_RID_IDX				2
+
+#define PAC1934_ACPI_GET_NAMES_AND_MOHMS_VALS	1
+#define PAC1934_ACPI_GET_UOHMS_VALS		2
+#define PAC1934_ACPI_GET_BIPOLAR_SETTINGS	4
+#define PAC1934_ACPI_GET_SAMP			5
+
+#define PAC1934_SAMPLE_RATE_SHIFT		6
+
+#define PAC1934_VBUS_SENSE_REG_LEN		2
+#define PAC1934_ACC_REG_LEN			3
+#define PAC1934_VPOWER_REG_LEN			4
+#define PAC1934_VPOWER_ACC_REG_LEN		6
+#define PAC1934_MAX_REGISTER_LENGTH		6
+
+#define PAC1934_CUSTOM_ATTR_FOR_CHANNEL		1
+
+/*
+ * relative offsets when using multi-byte reads/writes even though these
+ * bytes are read one after the other, they are not at adjacent memory
+ * locations within the I2C memory map. The chip can skip some addresses
+ */
+#define PAC1934_CHANNEL_DIS_REG_OFF		0
+#define PAC1934_NEG_PWR_REG_OFF			1
+
+/*
+ * when reading/writing multiple bytes from offset PAC1934_CHANNEL_DIS_REG_OFF,
+ * the chip jumps over the 0x1E (REFRESH_G) and 0x1F (REFRESH_V) offsets
+ */
+#define PAC1934_SLOW_REG_OFF			2
+#define PAC1934_CTRL_ACT_REG_OFF		3
+#define PAC1934_CHANNEL_DIS_ACT_REG_OFF		4
+#define PAC1934_NEG_PWR_ACT_REG_OFF		5
+#define PAC1934_CTRL_LAT_REG_OFF		6
+#define PAC1934_CHANNEL_DIS_LAT_REG_OFF		7
+#define PAC1934_NEG_PWR_LAT_REG_OFF		8
+#define PAC1934_PID_REG_OFF			9
+#define PAC1934_MID_REG_OFF			10
+#define PAC1934_REV_REG_OFF			11
+#define PAC1934_CTRL_STATUS_INFO_LEN		12
+
+#define PAC1934_MID				0x5D
+#define PAC1931_PID				0x58
+#define PAC1932_PID				0x59
+#define PAC1933_PID				0x5A
+#define PAC1934_PID				0x5B
+
+/* Scale constant = (10^3 * 3.2 * 10^9 / 2^28) for mili Watt-second */
+#define PAC1934_SCALE_CONSTANT			11921
+
+#define PAC1934_MAX_VPOWER_RSHIFTED_BY_28B	11921
+#define PAC1934_MAX_VSENSE_RSHIFTED_BY_16B	1525
+
+#define PAC1934_DEV_ATTR(name) (&iio_dev_attr_##name.dev_attr.attr)
+
+#define PAC1934_CRTL_SAMPLE_RATE_MASK	GENMASK(7, 6)
+#define PAC1934_CHAN_SLEEP_MASK		BIT(5)
+#define PAC1934_CHAN_SLEEP_SET		BIT(5)
+#define PAC1934_CHAN_SINGLE_MASK	BIT(4)
+#define PAC1934_CHAN_SINGLE_SHOT_SET	BIT(4)
+#define PAC1934_CHAN_ALERT_MASK		BIT(3)
+#define PAC1934_CHAN_ALERT_EN		BIT(3)
+#define PAC1934_CHAN_ALERT_CC_MASK	BIT(2)
+#define PAC1934_CHAN_ALERT_CC_EN	BIT(2)
+#define PAC1934_CHAN_OVF_ALERT_MASK	BIT(1)
+#define PAC1934_CHAN_OVF_ALERT_EN	BIT(1)
+#define PAC1934_CHAN_OVF_MASK		BIT(0)
+
+#define PAC1934_CHAN_DIS_CH1_OFF_MASK	BIT(7)
+#define PAC1934_CHAN_DIS_CH2_OFF_MASK	BIT(6)
+#define PAC1934_CHAN_DIS_CH3_OFF_MASK	BIT(5)
+#define PAC1934_CHAN_DIS_CH4_OFF_MASK	BIT(4)
+#define PAC1934_SMBUS_TIMEOUT_MASK	BIT(3)
+#define PAC1934_SMBUS_BYTECOUNT_MASK	BIT(2)
+#define PAC1934_SMBUS_NO_SKIP_MASK	BIT(1)
+
+#define PAC1934_NEG_PWR_CH1_BIDI_MASK	BIT(7)
+#define PAC1934_NEG_PWR_CH2_BIDI_MASK	BIT(6)
+#define PAC1934_NEG_PWR_CH3_BIDI_MASK	BIT(5)
+#define PAC1934_NEG_PWR_CH4_BIDI_MASK	BIT(4)
+#define PAC1934_NEG_PWR_CH1_BIDV_MASK	BIT(3)
+#define PAC1934_NEG_PWR_CH2_BIDV_MASK	BIT(2)
+#define PAC1934_NEG_PWR_CH3_BIDV_MASK	BIT(1)
+#define PAC1934_NEG_PWR_CH4_BIDV_MASK	BIT(0)
+
+/*
+ * Universal Unique Identifier (UUID),
+ * 033771E0-1705-47B4-9535-D1BBE14D9A09,
+ * is reserved to Microchip for the PAC1934.
+ */
+#define PAC1934_DSM_UUID		"033771E0-1705-47B4-9535-D1BBE14D9A09"
+
+enum pac1934_ids {
+	PAC1931,
+	PAC1932,
+	PAC1933,
+	PAC1934
+};
+
+enum pac1934_samps {
+	PAC1934_SAMP_1024SPS,
+	PAC1934_SAMP_256SPS,
+	PAC1934_SAMP_64SPS,
+	PAC1934_SAMP_8SPS
+};
+
+/*
+ * these indexes are exactly describing the element order within a single
+ * PAC1934 phys channel IIO channel descriptor; see the static const struct
+ * iio_chan_spec pac1934_single_channel[] declaration
+ */
+enum pac1934_ch_idx {
+	IIO_EN,
+	IIO_POW,
+	IIO_VOLT,
+	IIO_CRT,
+	IIO_VOLTAVG,
+	IIO_CRTAVG
+};
+
+/**
+ * struct pac1934_features - features of a pac1934 instance
+ * @phys_channels:	number of physical channels supported by the chip
+ * @name:		chip's name
+ */
+struct pac1934_features {
+	u8		phys_channels;
+	const char	*name;
+};
+
+struct samp_rate_mapping {
+	u16 samp_rate;
+	u8 shift2value;
+};
+
+static const unsigned int samp_rate_map_tbl[] = {
+	[PAC1934_SAMP_1024SPS] = 1024,
+	[PAC1934_SAMP_256SPS] = 256,
+	[PAC1934_SAMP_64SPS] = 64,
+	[PAC1934_SAMP_8SPS] = 8,
+};
+
+static const struct pac1934_features pac1934_chip_config[] = {
+	[PAC1931] = {
+	    .phys_channels = 1,
+	    .name = "pac1931",
+	},
+	[PAC1932] = {
+	    .phys_channels = 2,
+	    .name = "pac1932",
+	},
+	[PAC1933] = {
+	    .phys_channels = 3,
+	    .name = "pac1933",
+	},
+	[PAC1934] = {
+	    .phys_channels = 4,
+	    .name = "pac1934",
+	},
+};
+
+/**
+ * struct reg_data - data from the registers
+ * @meas_regs:			snapshot of raw measurements registers
+ * @ctrl_regs:			snapshot of control registers
+ * @energy_sec_acc:		snapshot of energy values
+ * @vpower_acc:			accumulated vpower values
+ * @vpower:			snapshot of vpower registers
+ * @vbus:			snapshot of vbus registers
+ * @vbus_avg:			averages of vbus registers
+ * @vsense:			snapshot of vsense registers
+ * @vsense_avg:			averages of vsense registers
+ * @num_enabled_channels:	count of how many chip channels are currently enabled
+ */
+struct reg_data {
+	u8	meas_regs[PAC1934_MEAS_REG_LEN];
+	u8	ctrl_regs[PAC1934_CTRL_REG_LEN];
+	s64	energy_sec_acc[PAC1934_MAX_NUM_CHANNELS];
+	s64	vpower_acc[PAC1934_MAX_NUM_CHANNELS];
+	s32	vpower[PAC1934_MAX_NUM_CHANNELS];
+	s32	vbus[PAC1934_MAX_NUM_CHANNELS];
+	s32	vbus_avg[PAC1934_MAX_NUM_CHANNELS];
+	s32	vsense[PAC1934_MAX_NUM_CHANNELS];
+	s32	vsense_avg[PAC1934_MAX_NUM_CHANNELS];
+	u8	num_enabled_channels;
+};
+
+/**
+ * struct pac1934_chip_info - information about the chip
+ * @client:			the i2c-client attached to the device
+ * @lock:			synchronize access to driver's state members
+ * @work_chip_rfsh:		work queue used for refresh commands
+ * @phys_channels:		phys channels count
+ * @active_channels:		array of values, true means that channel is active
+ * @enable_energy:		array of values, true means that channel energy is measured
+ * @bi_dir:			array of bools, true means that channel is bidirectional
+ * @chip_variant:		chip variant
+ * @chip_revision:		chip revision
+ * @shunts:			shunts
+ * @chip_reg_data:		chip reg data
+ * @sample_rate_value:		sampling frequency
+ * @labels:			table with channels labels
+ * @iio_info:			iio_info
+ * @crt_samp_spd_bitfield:	the current sampling speed
+ * @tstamp:			chip's uptime
+ */
+struct pac1934_chip_info {
+	struct i2c_client	*client;
+	struct mutex		lock; /* synchronize access to driver's state members */
+	struct delayed_work	work_chip_rfsh;
+	u8			phys_channels;
+	bool			active_channels[PAC1934_MAX_NUM_CHANNELS];
+	bool			enable_energy[PAC1934_MAX_NUM_CHANNELS];
+	bool			bi_dir[PAC1934_MAX_NUM_CHANNELS];
+	u8			chip_variant;
+	u8			chip_revision;
+	u32			shunts[PAC1934_MAX_NUM_CHANNELS];
+	struct reg_data		chip_reg_data;
+	s32			sample_rate_value;
+	char			*labels[PAC1934_MAX_NUM_CHANNELS];
+	struct iio_info		iio_info;
+	u8			crt_samp_spd_bitfield;
+	unsigned long		tstamp;
+};
+
+#define TO_PAC1934_CHIP_INFO(d) container_of(d, struct pac1934_chip_info, work_chip_rfsh)
+
+#define PAC1934_VPOWER_ACC_CHANNEL(_index, _si, _address) {			\
+	.type = IIO_ENERGY,							\
+	.address = (_address),							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)	|			\
+			      BIT(IIO_CHAN_INFO_SCALE)	|			\
+			      BIT(IIO_CHAN_INFO_ENABLE),			\
+	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = (_si),							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 48,							\
+		.storagebits = 64,						\
+		.endianness = IIO_CPU,						\
+	}									\
+}
+
+#define PAC1934_VBUS_CHANNEL(_index, _si, _address) {				\
+	.type = IIO_VOLTAGE,							\
+	.address = (_address),							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)	|			\
+			      BIT(IIO_CHAN_INFO_SCALE),				\
+	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = (_si),							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 16,							\
+		.storagebits = 16,						\
+		.endianness = IIO_CPU,						\
+	}									\
+}
+
+#define PAC1934_VBUS_AVG_CHANNEL(_index, _si, _address) {			\
+	.type = IIO_VOLTAGE,							\
+	.address = (_address),							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_AVERAGE_RAW)	|		\
+			      BIT(IIO_CHAN_INFO_SCALE),				\
+	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = (_si),							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 16,							\
+		.storagebits = 16,						\
+		.endianness = IIO_CPU,						\
+	}									\
+}
+
+#define PAC1934_VSENSE_CHANNEL(_index, _si, _address) {				\
+	.type = IIO_CURRENT,							\
+	.address = (_address),							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)	|			\
+			      BIT(IIO_CHAN_INFO_SCALE),				\
+	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = (_si),							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 16,							\
+		.storagebits = 16,						\
+		.endianness = IIO_CPU,						\
+	}									\
+}
+
+#define PAC1934_VSENSE_AVG_CHANNEL(_index, _si, _address) {			\
+	.type = IIO_CURRENT,							\
+	.address = (_address),							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_AVERAGE_RAW)	|		\
+			      BIT(IIO_CHAN_INFO_SCALE),				\
+	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = (_si),							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 16,							\
+		.storagebits = 16,						\
+		.endianness = IIO_CPU,						\
+	}									\
+}
+
+#define PAC1934_VPOWER_CHANNEL(_index, _si, _address) {				\
+	.type = IIO_POWER,							\
+	.address = (_address),							\
+	.indexed = 1,								\
+	.channel = (_index),							\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)	|			\
+			      BIT(IIO_CHAN_INFO_SCALE),				\
+	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),		\
+	.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = (_si),							\
+	.scan_type = {								\
+		.sign = 'u',							\
+		.realbits = 28,							\
+		.storagebits = 32,						\
+		.shift = 4,							\
+		.endianness = IIO_CPU,						\
+	}									\
+}
+
+static const struct iio_chan_spec pac1934_single_channel[] = {
+	PAC1934_VPOWER_ACC_CHANNEL(0, 0, PAC1934_VPOWER_ACC_1_ADDR),
+	PAC1934_VPOWER_CHANNEL(0, 0, PAC1934_VPOWER_1_ADDR),
+	PAC1934_VBUS_CHANNEL(0, 0, PAC1934_VBUS_1_ADDR),
+	PAC1934_VSENSE_CHANNEL(0, 0, PAC1934_VSENSE_1_ADDR),
+	PAC1934_VBUS_AVG_CHANNEL(0, 0, PAC1934_VBUS_AVG_1_ADDR),
+	PAC1934_VSENSE_AVG_CHANNEL(0, 0, PAC1934_VSENSE_AVG_1_ADDR),
+};
+
+/* Low-level I2c functions used to transfer up to 76 bytes at once */
+static int pac1934_i2c_read(struct i2c_client *client, u8 reg_addr, void *databuf, u8 len)
+{
+	int ret;
+	struct i2c_msg msgs[2] = {
+		{
+			.addr = client->addr,
+			.len = 1,
+			.buf = (u8 *)&reg_addr,
+		},
+		{
+			.addr = client->addr,
+			.len = len,
+			.buf = databuf,
+			.flags = I2C_M_RD
+		}
+	};
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int pac1934_match_samp_rate(struct pac1934_chip_info *info, u32 new_samp_rate)
+{
+	int cnt;
+
+	for (cnt = 0; cnt < ARRAY_SIZE(samp_rate_map_tbl); cnt++) {
+		if (new_samp_rate == samp_rate_map_tbl[cnt]) {
+			info->crt_samp_spd_bitfield = cnt;
+			return 0;
+		}
+	}
+
+	/* not a valid sample rate value */
+	return -EINVAL;
+}
+
+static ssize_t shunt_value_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct pac1934_chip_info *info = iio_priv(indio_dev);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+
+	return sysfs_emit(buf, "%u\n", info->shunts[this_attr->address]);
+}
+
+static ssize_t shunt_value_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct pac1934_chip_info *info = iio_priv(indio_dev);
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	int sh_val;
+
+	if (kstrtouint(buf, 10, &sh_val)) {
+		dev_err(dev, "Shunt value is not valid\n");
+		return -EINVAL;
+	}
+
+	scoped_guard(mutex, &info->lock)
+		info->shunts[this_attr->address] = sh_val;
+
+	return count;
+}
+
+static int pac1934_read_avail(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *channel,
+			      const int **vals, int *type, int *length, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*type = IIO_VAL_INT;
+		*vals = samp_rate_map_tbl;
+		*length = ARRAY_SIZE(samp_rate_map_tbl);
+		return IIO_AVAIL_LIST;
+	}
+
+	return -EINVAL;
+}
+
+static int pac1934_send_refresh(struct pac1934_chip_info *info,
+				u8 refresh_cmd, u32 wait_time)
+{
+	/* this function only sends REFRESH or REFRESH_V */
+	struct i2c_client *client = info->client;
+	int ret;
+	u8 bidir_reg;
+	bool revision_bug = false;
+
+	if (info->chip_revision == 2 || info->chip_revision == 3) {
+		/*
+		 * chip rev 2 and 3 bug workaround
+		 * see: PAC1934 Family Data Sheet Errata DS80000836A.pdf
+		 */
+		revision_bug = true;
+
+		bidir_reg =
+			FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDI_MASK, info->bi_dir[0]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDI_MASK, info->bi_dir[1]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDI_MASK, info->bi_dir[2]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDI_MASK, info->bi_dir[3]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDV_MASK, info->bi_dir[0]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDV_MASK, info->bi_dir[1]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDV_MASK, info->bi_dir[2]) |
+			FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDV_MASK, info->bi_dir[3]);
+
+		ret = i2c_smbus_write_byte_data(client,
+						PAC1934_CTRL_STAT_REGS_ADDR +
+						PAC1934_NEG_PWR_REG_OFF,
+						bidir_reg);
+		if (ret)
+			return ret;
+	}
+
+	ret = i2c_smbus_write_byte(client, refresh_cmd);
+	if (ret) {
+		dev_err(&client->dev, "%s - cannot send 0x%02X\n",
+			__func__, refresh_cmd);
+		return ret;
+	}
+
+	if (revision_bug) {
+		/*
+		 * chip rev 2 and 3 bug workaround - write again the same register
+		 * write the updated registers back
+		 */
+		ret = i2c_smbus_write_byte_data(client,
+						PAC1934_CTRL_STAT_REGS_ADDR +
+						PAC1934_NEG_PWR_REG_OFF, bidir_reg);
+		if (ret)
+			return ret;
+	}
+
+	/* register data retrieval timestamp */
+	info->tstamp = jiffies;
+
+	/* wait till the data is available */
+	usleep_range(wait_time, wait_time + 100);
+
+	return ret;
+}
+
+static int pac1934_reg_snapshot(struct pac1934_chip_info *info,
+				bool do_refresh, u8 refresh_cmd, u32 wait_time)
+{
+	int ret;
+	struct i2c_client *client = info->client;
+	u8 samp_shift, ctrl_regs_tmp;
+	u8 *offset_reg_data_p;
+	u16 tmp_value;
+	u32 samp_rate, cnt, tmp;
+	s64 curr_energy, inc;
+	u64 tmp_energy;
+	struct reg_data *reg_data;
+
+	guard(mutex)(&info->lock);
+
+	if (do_refresh) {
+		ret = pac1934_send_refresh(info, refresh_cmd, wait_time);
+		if (ret < 0) {
+			dev_err(&client->dev,
+				"%s - cannot send refresh\n",
+				__func__);
+			return ret;
+		}
+	}
+
+	ret = i2c_smbus_read_i2c_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
+					    PAC1934_CTRL_REG_LEN,
+					    (u8 *)info->chip_reg_data.ctrl_regs);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"%s - cannot read ctrl/status registers\n",
+			__func__);
+		return ret;
+	}
+
+	reg_data = &info->chip_reg_data;
+
+	/* read the data registers */
+	ret = pac1934_i2c_read(client, PAC1934_ACC_COUNT_REG_ADDR,
+			       (u8 *)reg_data->meas_regs, PAC1934_MEAS_REG_LEN);
+	if (ret) {
+		dev_err(&client->dev,
+			"%s - cannot read ACC_COUNT register: %d:%d\n",
+			__func__, ret, PAC1934_MEAS_REG_LEN);
+		return ret;
+	}
+
+	/* see how much shift is required by the sample rate */
+	samp_rate = samp_rate_map_tbl[((reg_data->ctrl_regs[PAC1934_CTRL_LAT_REG_OFF]) >> 6)];
+	samp_shift = get_count_order(samp_rate);
+
+	ctrl_regs_tmp = reg_data->ctrl_regs[PAC1934_CHANNEL_DIS_LAT_REG_OFF];
+	offset_reg_data_p = &reg_data->meas_regs[PAC1934_ACC_REG_LEN];
+
+	/* start with VPOWER_ACC */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		/* check if the channel is active, skip all fields if disabled */
+		if ((ctrl_regs_tmp << cnt) & 0x80)
+			continue;
+
+		/* skip if the energy accumulation is disabled */
+		if (info->enable_energy[cnt]) {
+			curr_energy = info->chip_reg_data.energy_sec_acc[cnt];
+
+			tmp_energy = get_unaligned_be48(offset_reg_data_p);
+
+			if (info->bi_dir[cnt])
+				reg_data->vpower_acc[cnt] = sign_extend64(tmp_energy, 47);
+			else
+				reg_data->vpower_acc[cnt] = tmp_energy;
+
+			/*
+			 * compute the scaled to 1 second accumulated energy value;
+			 * energy accumulator scaled to 1sec = VPOWER_ACC/2^samp_shift
+			 * the chip's sampling rate is 2^samp_shift samples/sec
+			 */
+			inc = (reg_data->vpower_acc[cnt] >> samp_shift);
+
+			/* add the power_acc field */
+			curr_energy += inc;
+
+			clamp(curr_energy, PAC_193X_MIN_POWER_ACC, PAC_193X_MAX_POWER_ACC);
+
+			reg_data->energy_sec_acc[cnt] = curr_energy;
+		}
+
+		offset_reg_data_p += PAC1934_VPOWER_ACC_REG_LEN;
+	}
+
+	/* continue with VBUS */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if ((ctrl_regs_tmp << cnt) & 0x80)
+			continue;
+
+		tmp_value = get_unaligned_be16(offset_reg_data_p);
+
+		if (info->bi_dir[cnt])
+			reg_data->vbus[cnt] = sign_extend32((u32)(tmp_value), 15);
+		else
+			reg_data->vbus[cnt] = tmp_value;
+
+		offset_reg_data_p += PAC1934_VBUS_SENSE_REG_LEN;
+	}
+
+	/* VSENSE */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if ((ctrl_regs_tmp << cnt) & 0x80)
+			continue;
+
+		tmp_value = get_unaligned_be16(offset_reg_data_p);
+
+		if (info->bi_dir[cnt])
+			reg_data->vsense[cnt] = sign_extend32((u32)(tmp_value), 15);
+		else
+			reg_data->vsense[cnt] = tmp_value;
+
+		offset_reg_data_p += PAC1934_VBUS_SENSE_REG_LEN;
+	}
+
+	/* VBUS_AVG */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if ((ctrl_regs_tmp << cnt) & 0x80)
+			continue;
+
+		tmp_value = get_unaligned_be16(offset_reg_data_p);
+
+		if (info->bi_dir[cnt])
+			reg_data->vbus_avg[cnt] = sign_extend32((u32)(tmp_value), 15);
+		else
+			reg_data->vbus_avg[cnt] = tmp_value;
+
+		offset_reg_data_p += PAC1934_VBUS_SENSE_REG_LEN;
+	}
+
+	/* VSENSE_AVG */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if ((ctrl_regs_tmp << cnt) & 0x80)
+			continue;
+
+		tmp_value = get_unaligned_be16(offset_reg_data_p);
+
+		if (info->bi_dir[cnt])
+			reg_data->vsense_avg[cnt] = sign_extend32((u32)(tmp_value), 15);
+		else
+			reg_data->vsense_avg[cnt] = tmp_value;
+
+		offset_reg_data_p += PAC1934_VBUS_SENSE_REG_LEN;
+	}
+
+	/* VPOWER */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if ((ctrl_regs_tmp << cnt) & 0x80)
+			continue;
+
+		tmp = get_unaligned_be32(offset_reg_data_p) >> 4;
+
+		if (info->bi_dir[cnt])
+			reg_data->vpower[cnt] = sign_extend32(tmp, 27);
+		else
+			reg_data->vpower[cnt] = tmp;
+
+		offset_reg_data_p += PAC1934_VPOWER_REG_LEN;
+	}
+
+	return 0;
+}
+
+static int pac1934_retrieve_data(struct pac1934_chip_info *info,
+				 u32 wait_time)
+{
+	int ret = 0;
+
+	/*
+	 * check if the minimal elapsed time has passed and if so,
+	 * re-read the chip, otherwise the cached info is just fine
+	 */
+	if (time_after(jiffies, info->tstamp + msecs_to_jiffies(PAC1934_MIN_POLLING_TIME_MS))) {
+		ret = pac1934_reg_snapshot(info, true, PAC1934_REFRESH_REG_ADDR,
+					   wait_time);
+
+		/*
+		 * Re-schedule the work for the read registers on timeout
+		 * (to prevent chip registers saturation)
+		 */
+		mod_delayed_work(system_wq, &info->work_chip_rfsh,
+				 msecs_to_jiffies(PAC1934_MAX_RFSH_LIMIT_MS));
+	}
+
+	return ret;
+}
+
+static int pac1934_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	struct pac1934_chip_info *info = iio_priv(indio_dev);
+	s64 curr_energy;
+	int ret, channel = chan->channel - 1;
+
+	ret = pac1934_retrieve_data(info, PAC1934_MIN_UPDATE_WAIT_TIME_US);
+	if (ret < 0)
+		return ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			*val = info->chip_reg_data.vbus[channel];
+			return IIO_VAL_INT;
+		case IIO_CURRENT:
+			*val = info->chip_reg_data.vsense[channel];
+			return IIO_VAL_INT;
+		case IIO_POWER:
+			*val = info->chip_reg_data.vpower[channel];
+			return IIO_VAL_INT;
+		case IIO_ENERGY:
+			curr_energy = info->chip_reg_data.energy_sec_acc[channel];
+			*val = (u32)curr_energy;
+			*val2 = (u32)(curr_energy >> 32);
+			return IIO_VAL_INT_64;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_AVERAGE_RAW:
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			*val = info->chip_reg_data.vbus_avg[channel];
+			return IIO_VAL_INT;
+		case IIO_CURRENT:
+			*val = info->chip_reg_data.vsense_avg[channel];
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->address) {
+		/* Voltages - scale for millivolts */
+		case PAC1934_VBUS_1_ADDR:
+		case PAC1934_VBUS_2_ADDR:
+		case PAC1934_VBUS_3_ADDR:
+		case PAC1934_VBUS_4_ADDR:
+		case PAC1934_VBUS_AVG_1_ADDR:
+		case PAC1934_VBUS_AVG_2_ADDR:
+		case PAC1934_VBUS_AVG_3_ADDR:
+		case PAC1934_VBUS_AVG_4_ADDR:
+			*val = PAC1934_VOLTAGE_MILLIVOLTS_MAX;
+			if (chan->scan_type.sign == 'u')
+				*val2 = PAC1934_VOLTAGE_U_RES;
+			else
+				*val2 = PAC1934_VOLTAGE_S_RES;
+			return IIO_VAL_FRACTIONAL_LOG2;
+		/*
+		 * Currents - scale for mA - depends on the
+		 * channel's shunt value
+		 * (100mV * 1000000) / (2^16 * shunt(uohm))
+		 */
+		case PAC1934_VSENSE_1_ADDR:
+		case PAC1934_VSENSE_2_ADDR:
+		case PAC1934_VSENSE_3_ADDR:
+		case PAC1934_VSENSE_4_ADDR:
+		case PAC1934_VSENSE_AVG_1_ADDR:
+		case PAC1934_VSENSE_AVG_2_ADDR:
+		case PAC1934_VSENSE_AVG_3_ADDR:
+		case PAC1934_VSENSE_AVG_4_ADDR:
+			*val = PAC1934_MAX_VSENSE_RSHIFTED_BY_16B;
+			if (chan->scan_type.sign == 'u')
+				*val2 = info->shunts[channel];
+			else
+				*val2 = info->shunts[channel] >> 1;
+			return IIO_VAL_FRACTIONAL;
+		/*
+		 * Power - uW - it will use the combined scale
+		 * for current and voltage
+		 * current(mA) * voltage(mV) = power (uW)
+		 */
+		case PAC1934_VPOWER_1_ADDR:
+		case PAC1934_VPOWER_2_ADDR:
+		case PAC1934_VPOWER_3_ADDR:
+		case PAC1934_VPOWER_4_ADDR:
+			*val = PAC1934_MAX_VPOWER_RSHIFTED_BY_28B;
+			if (chan->scan_type.sign == 'u')
+				*val2 = info->shunts[channel];
+			else
+				*val2 = info->shunts[channel] >> 1;
+			return IIO_VAL_FRACTIONAL;
+		case PAC1934_VPOWER_ACC_1_ADDR:
+		case PAC1934_VPOWER_ACC_2_ADDR:
+		case PAC1934_VPOWER_ACC_3_ADDR:
+		case PAC1934_VPOWER_ACC_4_ADDR:
+			/*
+			 * expresses the 32 bit scale value
+			 * here compute the scale for energy (miliWatt-second or miliJoule)
+			 */
+			*val = PAC1934_SCALE_CONSTANT;
+
+			if (chan->scan_type.sign == 'u')
+				*val2 = info->shunts[channel];
+			else
+				*val2 = info->shunts[channel] >> 1;
+			return IIO_VAL_FRACTIONAL;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = info->sample_rate_value;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_ENABLE:
+		*val = info->enable_energy[channel];
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int pac1934_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct pac1934_chip_info *info = iio_priv(indio_dev);
+	struct i2c_client *client = info->client;
+	int ret = -EINVAL;
+	s32 old_samp_rate;
+	u8 ctrl_reg;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = pac1934_match_samp_rate(info, val);
+		if (ret)
+			return ret;
+
+		old_samp_rate = info->sample_rate_value;
+		info->sample_rate_value = val;
+
+		/* write the new sampling value and trigger a snapshot(incl refresh) */
+		scoped_guard(mutex, &info->lock) {
+			ctrl_reg = FIELD_PREP(PAC1934_CRTL_SAMPLE_RATE_MASK,
+					      info->crt_samp_spd_bitfield);
+			ret = i2c_smbus_write_byte_data(client, PAC1934_CTRL_REG_ADDR, ctrl_reg);
+			if (ret) {
+				dev_err(&client->dev,
+					"%s - can't update sample rate\n",
+					__func__);
+				info->sample_rate_value = old_samp_rate;
+				return ret;
+			}
+		}
+
+		/*
+		 * now, force a snapshot with refresh - call retrieve
+		 * data in order to update the refresh timer
+		 * alter the timestamp in order to force trigger a
+		 * register snapshot and a timestamp update
+		 */
+		info->tstamp -= msecs_to_jiffies(PAC1934_MIN_POLLING_TIME_MS);
+		ret = pac1934_retrieve_data(info, (1024 / old_samp_rate) * 1000);
+		if (ret < 0) {
+			dev_err(&client->dev,
+				"%s - cannot snapshot ctrl and measurement regs\n",
+				__func__);
+			return ret;
+		}
+
+		return 0;
+	case IIO_CHAN_INFO_ENABLE:
+		scoped_guard(mutex, &info->lock) {
+			info->enable_energy[chan->channel - 1] = val ? true : false;
+			info->chip_reg_data.energy_sec_acc[chan->channel - 1] = 0;
+		}
+
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int pac1934_read_label(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan, char *label)
+{
+	struct pac1934_chip_info *info = iio_priv(indio_dev);
+
+	switch (chan->address) {
+	case PAC1934_VBUS_1_ADDR:
+	case PAC1934_VBUS_2_ADDR:
+	case PAC1934_VBUS_3_ADDR:
+	case PAC1934_VBUS_4_ADDR:
+		return sysfs_emit(label, "%s_VBUS_%d\n",
+				  info->labels[chan->scan_index],
+				  chan->scan_index + 1);
+	case PAC1934_VBUS_AVG_1_ADDR:
+	case PAC1934_VBUS_AVG_2_ADDR:
+	case PAC1934_VBUS_AVG_3_ADDR:
+	case PAC1934_VBUS_AVG_4_ADDR:
+		return sysfs_emit(label, "%s_VBUS_AVG_%d\n",
+				  info->labels[chan->scan_index],
+				  chan->scan_index + 1);
+	case PAC1934_VSENSE_1_ADDR:
+	case PAC1934_VSENSE_2_ADDR:
+	case PAC1934_VSENSE_3_ADDR:
+	case PAC1934_VSENSE_4_ADDR:
+		return sysfs_emit(label, "%s_IBUS_%d\n",
+				  info->labels[chan->scan_index],
+				  chan->scan_index + 1);
+	case PAC1934_VSENSE_AVG_1_ADDR:
+	case PAC1934_VSENSE_AVG_2_ADDR:
+	case PAC1934_VSENSE_AVG_3_ADDR:
+	case PAC1934_VSENSE_AVG_4_ADDR:
+		return sysfs_emit(label, "%s_IBUS_AVG_%d\n",
+				  info->labels[chan->scan_index],
+				  chan->scan_index + 1);
+	case PAC1934_VPOWER_1_ADDR:
+	case PAC1934_VPOWER_2_ADDR:
+	case PAC1934_VPOWER_3_ADDR:
+	case PAC1934_VPOWER_4_ADDR:
+		return sysfs_emit(label, "%s_POWER_%d\n",
+				  info->labels[chan->scan_index],
+				  chan->scan_index + 1);
+	case PAC1934_VPOWER_ACC_1_ADDR:
+	case PAC1934_VPOWER_ACC_2_ADDR:
+	case PAC1934_VPOWER_ACC_3_ADDR:
+	case PAC1934_VPOWER_ACC_4_ADDR:
+		return sysfs_emit(label, "%s_ENERGY_%d\n",
+				  info->labels[chan->scan_index],
+				  chan->scan_index + 1);
+	}
+
+	return 0;
+}
+
+static void pac1934_work_periodic_rfsh(struct work_struct *work)
+{
+	struct pac1934_chip_info *info = TO_PAC1934_CHIP_INFO((struct delayed_work *)work);
+	struct i2c_client *client = info->client;
+
+	dev_dbg(&client->dev, "%s - Periodic refresh\n", __func__);
+
+	/* do a REFRESH, then read */
+	pac1934_reg_snapshot(info, true, PAC1934_REFRESH_REG_ADDR,
+			     PAC1934_MIN_UPDATE_WAIT_TIME_US);
+
+	schedule_delayed_work(&info->work_chip_rfsh,
+			      msecs_to_jiffies(PAC1934_MAX_RFSH_LIMIT_MS));
+}
+
+static int pac1934_read_revision(struct pac1934_chip_info *info, u8 *buf)
+{
+	int ret;
+	struct i2c_client *client = info->client;
+
+	ret = i2c_smbus_read_i2c_block_data(client, PAC1934_PID_REG_ADDR,
+					    PAC1934_ID_REG_LEN,
+					    buf);
+	if (ret < 0) {
+		dev_err(&client->dev, "cannot read revision\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int pac1934_chip_identify(struct pac1934_chip_info *info)
+{
+	u8 rev_info[PAC1934_ID_REG_LEN];
+	struct i2c_client *client = info->client;
+	int ret = 0;
+
+	ret = pac1934_read_revision(info, (u8 *)rev_info);
+	if (ret)
+		return ret;
+
+	info->chip_variant = rev_info[PAC1934_PID_IDX];
+	info->chip_revision = rev_info[PAC1934_RID_IDX];
+
+	dev_dbg(&client->dev, "Chip variant: 0x%02X\n", info->chip_variant);
+	dev_dbg(&client->dev, "Chip revision: 0x%02X\n", info->chip_revision);
+
+	switch (info->chip_variant) {
+	case PAC1934_PID:
+		return PAC1934;
+	case PAC1933_PID:
+		return PAC1933;
+	case PAC1932_PID:
+		return PAC1932;
+	case PAC1931_PID:
+		return PAC1931;
+	default:
+		return -EINVAL;
+	}
+}
+
+/*
+ * documentation related to the ACPI device definition
+ * https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ApplicationNotes/ApplicationNotes/PAC1934-Integration-Notes-for-Microsoft-Windows-10-and-Windows-11-Driver-Support-DS00002534.pdf
+ */
+static bool pac1934_acpi_parse_channel_config(struct i2c_client *client,
+					      struct pac1934_chip_info *info)
+{
+	acpi_handle handle;
+	union acpi_object *rez;
+	struct device *dev = &client->dev;
+	unsigned short bi_dir_mask;
+	int idx, i;
+	guid_t guid;
+	const struct acpi_device_id *id;
+
+	handle = ACPI_HANDLE(&client->dev);
+
+	id = acpi_match_device(dev->driver->acpi_match_table, dev);
+	if (!id)
+		return false;
+
+	guid_parse(PAC1934_DSM_UUID, &guid);
+
+	rez = acpi_evaluate_dsm(handle, &guid, 0, PAC1934_ACPI_GET_NAMES_AND_MOHMS_VALS, NULL);
+	if (!rez)
+		return false;
+
+	for (i = 0; i < rez->package.count; i += 2) {
+		idx = i / 2;
+		info->labels[idx] =
+			devm_kmemdup(&client->dev, rez->package.elements[i].string.pointer,
+				     (size_t)rez->package.elements[i].string.length + 1,
+				     GFP_KERNEL);
+		info->labels[idx][rez->package.elements[i].string.length] = '\0';
+		info->shunts[idx] =
+			rez->package.elements[i + 1].integer.value * 1000;
+		info->active_channels[idx] = (info->shunts[idx] != 0);
+	}
+
+	ACPI_FREE(rez);
+
+	rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_UOHMS_VALS, NULL);
+	if (!rez) {
+		/*
+		 * initializing with default values
+		 * we assume all channels are unidirectional(the mask is zero)
+		 * and assign the default sampling rate
+		 */
+		info->sample_rate_value = PAC1934_DEFAULT_CHIP_SAMP_SPEED;
+		return true;
+	}
+
+	for (i = 0; i < rez->package.count; i++) {
+		idx = i;
+		info->shunts[idx] = rez->package.elements[i].integer.value;
+		info->active_channels[idx] = (info->shunts[idx] != 0);
+	}
+
+	ACPI_FREE(rez);
+
+	rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_BIPOLAR_SETTINGS, NULL);
+	if (!rez)
+		return false;
+
+	bi_dir_mask = rez->package.elements[0].integer.value;
+	info->bi_dir[0] = ((bi_dir_mask & (1 << 3)) | (bi_dir_mask & (1 << 7))) != 0;
+	info->bi_dir[1] = ((bi_dir_mask & (1 << 2)) | (bi_dir_mask & (1 << 6))) != 0;
+	info->bi_dir[2] = ((bi_dir_mask & (1 << 1)) | (bi_dir_mask & (1 << 5))) != 0;
+	info->bi_dir[3] = ((bi_dir_mask & (1 << 0)) | (bi_dir_mask & (1 << 4))) != 0;
+
+	ACPI_FREE(rez);
+
+	rez = acpi_evaluate_dsm(handle, &guid, 1, PAC1934_ACPI_GET_SAMP, NULL);
+	if (!rez)
+		return false;
+
+	info->sample_rate_value = rez->package.elements[0].integer.value;
+
+	ACPI_FREE(rez);
+
+	return true;
+}
+
+static bool pac1934_of_parse_channel_config(struct i2c_client *client,
+					    struct pac1934_chip_info *info)
+{
+	struct fwnode_handle *node, *fwnode;
+	unsigned int current_channel;
+	int idx, ret;
+
+	info->sample_rate_value = 1024;
+	current_channel = 1;
+
+	fwnode = dev_fwnode(&client->dev);
+	fwnode_for_each_available_child_node(fwnode, node) {
+		ret = fwnode_property_read_u32(node, "reg", &idx);
+		if (ret) {
+			dev_err_probe(&client->dev, ret,
+				      "reading invalid channel index\n");
+			goto err_fwnode;
+		}
+		/* adjust idx to match channel index (1 to 4) from the datasheet */
+		idx--;
+
+		if (current_channel >= (info->phys_channels + 1) ||
+		    idx >= info->phys_channels || idx < 0) {
+			dev_err_probe(&client->dev, -EINVAL,
+				      "%s: invalid channel_index %d value\n",
+				      fwnode_get_name(node), idx);
+			goto err_fwnode;
+		}
+
+		/* enable channel */
+		info->active_channels[idx] = true;
+
+		ret = fwnode_property_read_u32(node, "shunt-resistor-micro-ohms",
+					       &info->shunts[idx]);
+		if (ret) {
+			dev_err_probe(&client->dev, ret,
+				      "%s: invalid shunt-resistor value: %d\n",
+				      fwnode_get_name(node), info->shunts[idx]);
+			goto err_fwnode;
+		}
+
+		if (fwnode_property_present(node, "label")) {
+			ret = fwnode_property_read_string(node, "label",
+							  (const char **)&info->labels[idx]);
+			if (ret) {
+				dev_err_probe(&client->dev, ret,
+					      "%s: invalid rail-name value\n",
+					      fwnode_get_name(node));
+				goto err_fwnode;
+			}
+		}
+
+		info->bi_dir[idx] = fwnode_property_read_bool(node, "bipolar");
+
+		current_channel++;
+	}
+
+	return true;
+
+err_fwnode:
+	fwnode_handle_put(node);
+
+	return false;
+}
+
+static void pac1934_cancel_delayed_work(void *dwork)
+{
+	cancel_delayed_work_sync(dwork);
+}
+
+static int pac1934_chip_configure(struct pac1934_chip_info *info)
+{
+	int cnt, ret;
+	struct i2c_client *client = info->client;
+	u8 regs[PAC1934_CTRL_STATUS_INFO_LEN], idx, ctrl_reg;
+	u32 wait_time;
+
+	info->chip_reg_data.num_enabled_channels = 0;
+	for (cnt = 0;  cnt < info->phys_channels; cnt++) {
+		if (info->active_channels[cnt])
+			info->chip_reg_data.num_enabled_channels++;
+	}
+
+	/*
+	 * read whatever information was gathered before the driver was loaded
+	 * establish which channels are enabled/disabled and then establish the
+	 * information retrieval mode (using SKIP or no).
+	 * Read the chip ID values
+	 */
+	ret = i2c_smbus_read_i2c_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
+					    ARRAY_SIZE(regs),
+					    (u8 *)regs);
+	if (ret < 0) {
+		dev_err_probe(&client->dev, ret,
+			      "%s - cannot read regs from 0x%02X\n",
+			      __func__, PAC1934_CTRL_STAT_REGS_ADDR);
+		return ret;
+	}
+
+	/* write the CHANNEL_DIS and the NEG_PWR registers */
+	regs[PAC1934_CHANNEL_DIS_REG_OFF] =
+		FIELD_PREP(PAC1934_CHAN_DIS_CH1_OFF_MASK, !(info->active_channels[0])) |
+		FIELD_PREP(PAC1934_CHAN_DIS_CH2_OFF_MASK, !(info->active_channels[1])) |
+		FIELD_PREP(PAC1934_CHAN_DIS_CH3_OFF_MASK, !(info->active_channels[2])) |
+		FIELD_PREP(PAC1934_CHAN_DIS_CH4_OFF_MASK, !(info->active_channels[3])) |
+		FIELD_PREP(PAC1934_SMBUS_TIMEOUT_MASK, 0) |
+		FIELD_PREP(PAC1934_SMBUS_BYTECOUNT_MASK, 0) |
+		FIELD_PREP(PAC1934_SMBUS_NO_SKIP_MASK, 0);
+
+	regs[PAC1934_NEG_PWR_REG_OFF] =
+		FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDI_MASK, info->bi_dir[0]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDI_MASK, info->bi_dir[1]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDI_MASK, info->bi_dir[2]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDI_MASK, info->bi_dir[3]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH1_BIDV_MASK, info->bi_dir[0]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH2_BIDV_MASK, info->bi_dir[1]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH3_BIDV_MASK, info->bi_dir[2]) |
+		FIELD_PREP(PAC1934_NEG_PWR_CH4_BIDV_MASK, info->bi_dir[3]);
+
+	/* no SLOW triggered REFRESH, clear POR */
+	regs[PAC1934_SLOW_REG_OFF] = 0;
+
+	ret =  i2c_smbus_write_block_data(client, PAC1934_CTRL_STAT_REGS_ADDR,
+					  ARRAY_SIZE(regs), (u8 *)regs);
+	if (ret)
+		return ret;
+
+	ctrl_reg = FIELD_PREP(PAC1934_CRTL_SAMPLE_RATE_MASK, info->crt_samp_spd_bitfield);
+
+	ret = i2c_smbus_write_byte_data(client, PAC1934_CTRL_REG_ADDR, ctrl_reg);
+	if (ret)
+		return ret;
+
+	/*
+	 * send a REFRESH to the chip, so the new settings take place
+	 * as well as resetting the accumulators
+	 */
+	ret = i2c_smbus_write_byte(client, PAC1934_REFRESH_REG_ADDR);
+	if (ret) {
+		dev_err(&client->dev,
+			"%s - cannot send 0x%02X\n",
+			__func__, PAC1934_REFRESH_REG_ADDR);
+		return ret;
+	}
+
+	/*
+	 * get the current(in the chip) sampling speed and compute the
+	 * required timeout based on its value
+	 * the timeout is 1/sampling_speed
+	 */
+	idx = regs[PAC1934_CTRL_ACT_REG_OFF] >> PAC1934_SAMPLE_RATE_SHIFT;
+	wait_time = (1024 / samp_rate_map_tbl[idx]) * 1000;
+
+	/*
+	 * wait the maximum amount of time to be on the safe side
+	 * the maximum wait time is for 8sps
+	 */
+	usleep_range(wait_time, wait_time + 100);
+
+	INIT_DELAYED_WORK(&info->work_chip_rfsh, pac1934_work_periodic_rfsh);
+	/* Setup the latest moment for reading the regs before saturation */
+	schedule_delayed_work(&info->work_chip_rfsh,
+			      msecs_to_jiffies(PAC1934_MAX_RFSH_LIMIT_MS));
+
+	devm_add_action_or_reset(&client->dev, pac1934_cancel_delayed_work,
+				 &info->work_chip_rfsh);
+
+	return 0;
+}
+
+static int pac1934_prep_iio_channels(struct pac1934_chip_info *info, struct iio_dev *indio_dev)
+{
+	struct i2c_client *client;
+	struct iio_chan_spec *ch_sp;
+	int channel_size, attribute_count, cnt;
+	void *dyn_ch_struct, *tmp_data;
+
+	client = info->client;
+
+	/* find out dynamically how many IIO channels we need */
+	attribute_count = 0;
+	channel_size = 0;
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if (!info->active_channels[cnt])
+			continue;
+
+		/* add the size of the properties of one chip physical channel */
+		channel_size += sizeof(pac1934_single_channel);
+		/* count how many enabled channels we have */
+		attribute_count += ARRAY_SIZE(pac1934_single_channel);
+		dev_info(&client->dev, ":%s: Channel %d active\n",
+			 __func__, cnt + 1);
+	}
+
+	dyn_ch_struct = devm_kzalloc(&client->dev, channel_size, GFP_KERNEL);
+	if (!dyn_ch_struct)
+		return -EINVAL;
+
+	tmp_data = dyn_ch_struct;
+
+	/* populate the dynamic channels and make all the adjustments */
+	for (cnt = 0; cnt < info->phys_channels; cnt++) {
+		if (!info->active_channels[cnt])
+			continue;
+
+		memcpy(tmp_data, pac1934_single_channel, sizeof(pac1934_single_channel));
+		ch_sp = (struct iio_chan_spec *)tmp_data;
+		ch_sp[IIO_EN].channel = cnt + 1;
+		ch_sp[IIO_EN].scan_index = cnt;
+		ch_sp[IIO_EN].address = cnt + PAC1934_VPOWER_ACC_1_ADDR;
+		ch_sp[IIO_POW].channel = cnt + 1;
+		ch_sp[IIO_POW].scan_index = cnt;
+		ch_sp[IIO_POW].address = cnt + PAC1934_VPOWER_1_ADDR;
+		ch_sp[IIO_VOLT].channel = cnt + 1;
+		ch_sp[IIO_VOLT].scan_index = cnt;
+		ch_sp[IIO_VOLT].address = cnt + PAC1934_VBUS_1_ADDR;
+		ch_sp[IIO_CRT].channel = cnt + 1;
+		ch_sp[IIO_CRT].scan_index = cnt;
+		ch_sp[IIO_CRT].address = cnt + PAC1934_VSENSE_1_ADDR;
+		/*
+		 * In order to be able to use labels for IIO_VOLT and IIO_VOLTAVG,
+		 * respectively IIO_CRT and IIO_CRTAVG we need to use different
+		 * channel numbers. We will add  +5 (+1 to maximum PAC channels).
+		 */
+		ch_sp[IIO_VOLTAVG].channel = cnt + 5;
+		ch_sp[IIO_VOLTAVG].scan_index = cnt;
+		ch_sp[IIO_VOLTAVG].address = cnt + PAC1934_VBUS_AVG_1_ADDR;
+		ch_sp[IIO_CRTAVG].channel = cnt + 5;
+		ch_sp[IIO_CRTAVG].scan_index = cnt;
+		ch_sp[IIO_CRTAVG].address = cnt + PAC1934_VSENSE_AVG_1_ADDR;
+
+		/*
+		 * now modify the parameters in all channels if the
+		 * whole chip rail(channel) is bi-directional
+		 */
+		if (info->bi_dir[cnt]) {
+			ch_sp[IIO_EN].scan_type.sign = 's';
+			ch_sp[IIO_EN].scan_type.realbits = 47;
+			ch_sp[IIO_POW].scan_type.sign = 's';
+			ch_sp[IIO_POW].scan_type.realbits = 27;
+			ch_sp[IIO_VOLT].scan_type.sign = 's';
+			ch_sp[IIO_VOLT].scan_type.realbits = 15;
+			ch_sp[IIO_CRT].scan_type.sign = 's';
+			ch_sp[IIO_CRT].scan_type.realbits = 15;
+			ch_sp[IIO_VOLTAVG].scan_type.sign = 's';
+			ch_sp[IIO_VOLTAVG].scan_type.realbits = 15;
+			ch_sp[IIO_CRTAVG].scan_type.sign = 's';
+			ch_sp[IIO_CRTAVG].scan_type.realbits = 15;
+		}
+		tmp_data += sizeof(pac1934_single_channel);
+	}
+
+	/*
+	 * send the updated dynamic channel structure information towards IIO
+	 * prepare the required field for IIO class registration
+	 */
+	indio_dev->num_channels = attribute_count;
+
+	indio_dev->channels = (const struct iio_chan_spec *)dyn_ch_struct;
+
+	if (!indio_dev->channels)
+		return -EINVAL;
+
+	return 0;
+}
+
+static IIO_DEVICE_ATTR(in_shunt_resistor_1, 0644, shunt_value_show, shunt_value_store, 0);
+static IIO_DEVICE_ATTR(in_shunt_resistor_2, 0644, shunt_value_show, shunt_value_store, 1);
+static IIO_DEVICE_ATTR(in_shunt_resistor_3, 0644, shunt_value_show, shunt_value_store, 2);
+static IIO_DEVICE_ATTR(in_shunt_resistor_4, 0644, shunt_value_show, shunt_value_store, 3);
+
+static int pac1934_prep_custom_attributes(struct pac1934_chip_info *info,
+					  struct iio_dev *indio_dev)
+{
+	int i, j, active_channels_count = 0;
+	struct attribute **pac1934_custom_attr;
+	struct attribute_group *pac1934_group;
+	struct i2c_client *client = info->client;
+
+	for (i = 0 ; i < info->phys_channels; i++)
+		if (info->active_channels[i])
+			active_channels_count++;
+
+	pac1934_group = devm_kzalloc(&client->dev, sizeof(*pac1934_group), GFP_KERNEL);
+	if (!pac1934_group)
+		return -ENOMEM;
+
+	pac1934_custom_attr = devm_kzalloc(&client->dev,
+					   (PAC1934_CUSTOM_ATTR_FOR_CHANNEL *
+					   active_channels_count)
+					   * sizeof(*pac1934_group) + 1,
+					   GFP_KERNEL);
+	if (!pac1934_custom_attr)
+		return -ENOMEM;
+
+	j = 0;
+	for (i = 0 ; i < info->phys_channels; i++) {
+		if (info->active_channels[i]) {
+			switch (i) {
+			case 0:
+				pac1934_custom_attr[j] = PAC1934_DEV_ATTR(in_shunt_resistor_1);
+				break;
+			case 1:
+				pac1934_custom_attr[j] = PAC1934_DEV_ATTR(in_shunt_resistor_2);
+				break;
+			case 2:
+				pac1934_custom_attr[j] = PAC1934_DEV_ATTR(in_shunt_resistor_3);
+				break;
+			case 3:
+				pac1934_custom_attr[j] = PAC1934_DEV_ATTR(in_shunt_resistor_4);
+				break;
+			}
+			j++;
+		}
+	}
+
+	pac1934_group->attrs = pac1934_custom_attr;
+	info->iio_info.attrs = pac1934_group;
+
+	return 0;
+}
+
+static void pac1934_mutex_destroy(void *data)
+{
+	struct mutex *lock = data;
+
+	mutex_destroy(lock);
+}
+
+static int pac1934_probe(struct i2c_client *client)
+{
+	struct pac1934_chip_info *info;
+	const struct pac1934_features *chip;
+	struct iio_dev *indio_dev;
+	int cnt, ret;
+	bool match = false;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*info));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	info = iio_priv(indio_dev);
+
+	i2c_set_clientdata(client, indio_dev);
+	info->client = client;
+
+	/* always start with energy accumulation enabled */
+	for (cnt = 0; cnt < PAC1934_MAX_NUM_CHANNELS; cnt++)
+		info->enable_energy[cnt] = true;
+
+	info->crt_samp_spd_bitfield = PAC1934_SAMP_1024SPS;
+
+	ret = pac1934_chip_identify(info);
+	if (ret < 0) {
+		/*
+		 * If failed to identify the hardware based on internal registers,
+		 * try using fallback compatible in device tree to deal with some newer part number.
+		 */
+		chip = i2c_get_match_data(client);
+		if (!chip)
+			return -EINVAL;
+
+		info->phys_channels = chip->phys_channels;
+		indio_dev->name = chip->name;
+	} else {
+		info->phys_channels = pac1934_chip_config[ret].phys_channels;
+		indio_dev->name = pac1934_chip_config[ret].name;
+	}
+
+	if (ACPI_HANDLE(&client->dev))
+		match = pac1934_acpi_parse_channel_config(client, info);
+	else
+		match = pac1934_of_parse_channel_config(client, info);
+
+	if (!match) {
+		dev_dbg(&client->dev, "parameter parsing returned an error\n");
+		return -EINVAL;
+	}
+
+	mutex_init(&info->lock);
+	ret = devm_add_action_or_reset(&client->dev, pac1934_mutex_destroy,
+				       &info->lock);
+
+	/*
+	 * do now any chip specific initialization (e.g. read/write
+	 * some registers), enable/disable certain channels, change the sampling
+	 * rate to the requested value
+	 */
+	ret = pac1934_chip_configure(info);
+	if (ret < 0)
+		return ret;
+
+	/* prepare the channel information */
+	ret = pac1934_prep_iio_channels(info, indio_dev);
+	if (ret < 0)
+		return ret;
+
+	ret = pac1934_prep_custom_attributes(info, indio_dev);
+	if (ret < 0) {
+		dev_err_probe(&client->dev, ret,
+			      "Can't configure custom attributes for PAC1934 device\n");
+		return ret;
+	}
+
+	info->iio_info.read_raw = pac1934_read_raw;
+	info->iio_info.read_avail = pac1934_read_avail;
+	info->iio_info.write_raw = pac1934_write_raw;
+	info->iio_info.read_label = pac1934_read_label;
+
+	indio_dev->info = &info->iio_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	/*
+	 * read whatever has been accumulated in the chip so far
+	 * and reset the accumulators
+	 */
+	ret = pac1934_reg_snapshot(info, true, PAC1934_REFRESH_REG_ADDR,
+				   PAC1934_MIN_UPDATE_WAIT_TIME_US);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret < 0)
+		dev_err_probe(&client->dev, ret,
+			      "Can't register IIO device\n");
+
+	return ret;
+}
+
+static const struct i2c_device_id pac1934_id[] = {
+	{ .name = "pac1931", .driver_data = (kernel_ulong_t)&pac1934_chip_config[PAC1931] },
+	{ .name = "pac1932", .driver_data = (kernel_ulong_t)&pac1934_chip_config[PAC1932] },
+	{ .name = "pac1933", .driver_data = (kernel_ulong_t)&pac1934_chip_config[PAC1933] },
+	{ .name = "pac1934", .driver_data = (kernel_ulong_t)&pac1934_chip_config[PAC1934] },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, pac1934_id);
+
+static const struct of_device_id pac1934_of_match[] = {
+	{
+		.compatible = "microchip,pac1931",
+		.data = &pac1934_chip_config[PAC1931]
+	},
+	{
+		.compatible = "microchip,pac1932",
+		.data = &pac1934_chip_config[PAC1932]
+	},
+	{
+		.compatible = "microchip,pac1933",
+		.data = &pac1934_chip_config[PAC1933]
+	},
+	{
+		.compatible = "microchip,pac1934",
+		.data = &pac1934_chip_config[PAC1934]
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, pac1934_of_match);
+
+/* using MCHP1930 to be compatible with BIOS ACPI */
+static const struct acpi_device_id pac1934_acpi_match[] = {
+	{ "MCHP1930", .driver_data = (kernel_ulong_t)&pac1934_chip_config[PAC1934] },
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, pac1934_acpi_match);
+
+static struct i2c_driver pac1934_driver = {
+	.driver	 = {
+		.name = "pac1934",
+		.of_match_table = pac1934_of_match,
+		.acpi_match_table = pac1934_acpi_match
+		},
+	.probe = pac1934_probe,
+	.id_table = pac1934_id,
+};
+
+module_i2c_driver(pac1934_driver);
+
+MODULE_AUTHOR("Bogdan Bolocan <bogdan.bolocan@microchip.com>");
+MODULE_AUTHOR("Victor Tudose");
+MODULE_AUTHOR("Marius Cristea <marius.cristea@microchip.com>");
+MODULE_DESCRIPTION("IIO driver for PAC1934 Multi-Channel DC Power/Energy Monitor");
+MODULE_LICENSE("GPL");