diff mbox series

[v3,3/3] iio: adc: add ADC driver for the TI TSC2046 controller

Message ID 20210319144509.7627-4-o.rempel@pengutronix.de (mailing list archive)
State New
Headers show
Series mainline ti tsc2046 adc driver | expand

Commit Message

Oleksij Rempel March 19, 2021, 2:45 p.m. UTC
Basically the TI TSC2046 touchscreen controller is 8 channel ADC optimized for
the touchscreen use case. By implementing it as an IIO ADC device, we can
make use of resistive-adc-touch and iio-hwmon drivers.

So far, this driver was tested with a custom version of resistive-adc-touch driver,
since it needs to be extended to make use of Z1 and Z2 channels. The X/Y
are working without additional changes.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 MAINTAINERS                  |   8 +
 drivers/iio/adc/Kconfig      |  12 +
 drivers/iio/adc/Makefile     |   1 +
 drivers/iio/adc/ti-tsc2046.c | 728 +++++++++++++++++++++++++++++++++++
 4 files changed, 749 insertions(+)
 create mode 100644 drivers/iio/adc/ti-tsc2046.c

Comments

kernel test robot March 19, 2021, 4:35 p.m. UTC | #1
Hi Oleksij,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linux/master]
[also build test WARNING on linus/master v5.12-rc3 next-20210319]
[cannot apply to iio/togreg]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Oleksij-Rempel/mainline-ti-tsc2046-adc-driver/20210319-224746
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a74e6a014c9d4d4161061f770c9b4f98372ac778
config: ia64-allmodconfig (attached as .config)
compiler: ia64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/63e96b25ae609f5659a28132f77d353cc7ecbd84
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Oleksij-Rempel/mainline-ti-tsc2046-adc-driver/20210319-224746
        git checkout 63e96b25ae609f5659a28132f77d353cc7ecbd84
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from include/linux/device.h:15,
                    from include/linux/spi/spi.h:10,
                    from drivers/iio/adc/ti-tsc2046.c:11:
   drivers/iio/adc/ti-tsc2046.c: In function 'tsc2046_adc_probe':
>> drivers/iio/adc/ti-tsc2046.c:621:16: warning: format '%d' expects argument of type 'int', but argument 4 has type 'long unsigned int' [-Wformat=]
     621 |   dev_err(dev, "SPI max_speed_hz is too high: %d Hz. Max supported freq is %d Hz\n",
         |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/dev_printk.h:19:22: note: in definition of macro 'dev_fmt'
      19 | #define dev_fmt(fmt) fmt
         |                      ^~~
   drivers/iio/adc/ti-tsc2046.c:621:3: note: in expansion of macro 'dev_err'
     621 |   dev_err(dev, "SPI max_speed_hz is too high: %d Hz. Max supported freq is %d Hz\n",
         |   ^~~~~~~
   drivers/iio/adc/ti-tsc2046.c:621:77: note: format string is defined here
     621 |   dev_err(dev, "SPI max_speed_hz is too high: %d Hz. Max supported freq is %d Hz\n",
         |                                                                            ~^
         |                                                                             |
         |                                                                             int
         |                                                                            %ld

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for FRAME_POINTER
   Depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
   Selected by
   - FAULT_INJECTION_STACKTRACE_FILTER && FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT && !X86_64 && !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86


vim +621 drivers/iio/adc/ti-tsc2046.c

   609	
   610	static int tsc2046_adc_probe(struct spi_device *spi)
   611	{
   612		const struct tsc2046_adc_dcfg *dcfg;
   613		struct device *dev = &spi->dev;
   614		struct tsc2046_adc_priv *priv;
   615		struct iio_dev *indio_dev;
   616		struct iio_trigger *trig;
   617		const char *name;
   618		int ret;
   619	
   620		if (spi->max_speed_hz > TI_TSC2046_MAX_CLK_FREQ) {
 > 621			dev_err(dev, "SPI max_speed_hz is too high: %d Hz. Max supported freq is %d Hz\n",
   622				spi->max_speed_hz, TI_TSC2046_MAX_CLK_FREQ);
   623			return -EINVAL;
   624		}
   625	
   626		dcfg = device_get_match_data(dev);
   627		if (!dcfg)
   628			return -EINVAL;
   629	
   630		spi->bits_per_word = 8;
   631		spi->mode &= ~SPI_MODE_X_MASK;
   632		spi->mode |= SPI_MODE_0;
   633		ret = spi_setup(spi);
   634		if (ret < 0)
   635			return dev_err_probe(dev, ret, "Error in spi setup\n");
   636	
   637		indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
   638		if (!indio_dev)
   639			return -ENOMEM;
   640	
   641		priv = iio_priv(indio_dev);
   642		priv->dcfg = dcfg;
   643	
   644		spi_set_drvdata(spi, indio_dev);
   645	
   646		priv->spi = spi;
   647	
   648		name = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
   649				      TI_TSC2046_NAME, dev_name(dev));
   650	
   651		indio_dev->name = name;
   652		indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
   653		indio_dev->channels = dcfg->channels;
   654		indio_dev->num_channels = dcfg->num_channels;
   655		indio_dev->info = &tsc2046_adc_info;
   656	
   657		tsc2046_adc_parse_fwnode(priv);
   658	
   659		ret = tsc2046_adc_setup_spi_msg(priv);
   660		if (ret)
   661			return ret;
   662	
   663		mutex_init(&priv->slock);
   664	
   665		/* TODO: remove IRQ_NOAUTOEN after needed patches are mainline */
   666		irq_set_status_flags(spi->irq, IRQ_NOAUTOEN);
   667		ret = devm_request_irq(dev, spi->irq, &tsc2046_adc_irq,
   668				       0, name, indio_dev);
   669		if (ret)
   670			return ret;
   671	
   672		trig = devm_iio_trigger_alloc(dev, "touchscreen-%s", indio_dev->name);
   673		if (!trig)
   674			return -ENOMEM;
   675	
   676		priv->trig = trig;
   677		trig->dev.parent = indio_dev->dev.parent;
   678		iio_trigger_set_drvdata(trig, indio_dev);
   679		trig->ops = &tsc2046_adc_trigger_ops;
   680	
   681		spin_lock_init(&priv->trig_lock);
   682		hrtimer_init(&priv->trig_timer, CLOCK_MONOTONIC,
   683			     HRTIMER_MODE_REL_SOFT);
   684		priv->trig_timer.function = tsc2046_adc_trig_more;
   685	
   686		ret = devm_iio_trigger_register(dev, trig);
   687		if (ret) {
   688			dev_err(dev, "failed to register trigger\n");
   689			return ret;
   690		}
   691	
   692		ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
   693						      &tsc2046_adc_trigger_handler, NULL);
   694		if (ret) {
   695			dev_err(dev, "Failed to setup triggered buffer\n");
   696			return ret;
   697		}
   698	
   699		/* set default trigger */
   700		indio_dev->trig = iio_trigger_get(priv->trig);
   701	
   702		ret = devm_iio_device_register(dev, indio_dev);
   703		if (ret) {
   704			dev_err(dev, "Failed to register iio device\n");
   705			return ret;
   706		}
   707	
   708		return 0;
   709	}
   710	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Andy Shevchenko March 19, 2021, 5:42 p.m. UTC | #2
On Fri, Mar 19, 2021 at 4:45 PM Oleksij Rempel <o.rempel@pengutronix.de> wrote:
>
> Basically the TI TSC2046 touchscreen controller is 8 channel ADC optimized for
> the touchscreen use case. By implementing it as an IIO ADC device, we can
> make use of resistive-adc-touch and iio-hwmon drivers.
>
> So far, this driver was tested with a custom version of resistive-adc-touch driver,
> since it needs to be extended to make use of Z1 and Z2 channels. The X/Y
> are working without additional changes.

Since kbuild bot found some issues and it will be v4, some additional
comments from me below.

...

> +#define        TI_TSC2046_SAMPLE_BITS \
> +       (sizeof(struct tsc2046_adc_atom) * BITS_PER_BYTE)

Isn't it something like BITS_PER_TYPE(struct ...) ?

...

> +struct tsc2046_adc_atom {
> +       /*
> +        * Command transmitted to the controller. This filed is empty on the RX
> +        * buffer.
> +        */
> +       u8 cmd;
> +       /*
> +        * Data received from the controller. This filed is empty for the TX
> +        * buffer
> +        */
> +       __be16 data;
> +} __packed;

filed -> field in both cases above.

...

> +       /*
> +        * Lock to protect the layout and the spi transfer buffer.

SPI

> +        * tsc2046_adc_group_layout can be changed within update_scan_mode(),
> +        * in this case the l[] and tx/rx buffer will be out of sync to each
> +        * other.
> +        */

...

> +static unsigned int tsc2046_adc_time_to_count(struct tsc2046_adc_priv *priv,
> +                                             unsigned long time)
> +{
> +       unsigned int bit_count, sample_count;
> +
> +       bit_count = DIV_ROUND_UP(time * NSEC_PER_USEC, priv->time_per_bit_ns);

Does it survive 32-bit builds?

> +       sample_count = DIV_ROUND_UP(bit_count, TI_TSC2046_SAMPLE_BITS);
> +
> +       dev_dbg(&priv->spi->dev, "Effective speed %u, time per bit: %u, count bits: %u, count samples: %u\n",
> +               priv->effective_speed_hz, priv->time_per_bit_ns,
> +               bit_count, sample_count);
> +
> +       return sample_count;
> +}

...

> +       /*
> +        * if PD bits are 0, controller will automatically disable ADC, VREF and
> +        * enable IRQ.
> +        */
> +       if (keep_power)
> +               pd = TI_TSC2046_PD0_ADC_ON;
> +       else
> +               pd = 0;

Can be ternary on one line, but it's up to you.

...

> +static u16 tsc2046_adc_get_value(struct tsc2046_adc_atom *buf)
> +{
> +       /* Last 3 bits on the wire are empty */

Last?! You meant Least significant?
Also, don't we lose precision if a new compatible chip appears that
does fill those bits?

Perhaps define the constant and put a comment why it's like this.

> +       return get_unaligned_be16(&buf->data) >> 3;
> +}

...

> +static size_t tsc2046_adc_group_set_layout(struct tsc2046_adc_priv *priv,
> +                                          unsigned int group,
> +                                          unsigned int ch_idx)
> +{
> +       struct tsc2046_adc_ch_cfg *ch = &priv->ch_cfg[ch_idx];
> +       struct tsc2046_adc_group_layout *prev, *cur;
> +       unsigned int max_count, count_skip;
> +       unsigned int offset = 0;
> +
> +       if (group) {
> +               prev = &priv->l[group - 1];
> +               offset = prev->offset + prev->count;
> +       }

I guess you may easily refactor this by supplying a pointer to the
current layout + current size.

> +       cur = &priv->l[group];

Also, can you move it down closer to the (single?) caller.

> +}

...

> +static int tsc2046_adc_scan(struct iio_dev *indio_dev)
> +{
> +       struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
> +       struct device *dev = &priv->spi->dev;
> +       int group;
> +       int ret;
> +
> +       ret = spi_sync(priv->spi, &priv->msg);
> +       if (ret < 0) {

> +               dev_err_ratelimited(dev, "SPI transfer filed: %pe\n",
> +                                   ERR_PTR(ret));

One line?

> +               return ret;
> +       }

> +       ret = iio_push_to_buffers_with_timestamp(indio_dev, &priv->scan_buf,
> +                                                iio_get_time_ns(indio_dev));
> +       /* If consumer is kfifo, we may get a EBUSY here - ignore it. */

the consumer

> +       if (ret < 0 && ret != -EBUSY) {
> +               dev_err_ratelimited(dev, "Failed to push scan buffer %pe\n",
> +                                   ERR_PTR(ret));
> +
> +               return ret;
> +       }
> +
> +       return 0;
> +}


...

> +static enum hrtimer_restart tsc2046_adc_trig_more(struct hrtimer *hrtimer)
> +{
> +       struct tsc2046_adc_priv *priv = container_of(hrtimer,
> +                                                    struct tsc2046_adc_priv,
> +                                                    trig_timer);
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&priv->trig_lock, flags);
> +
> +       disable_irq_nosync(priv->spi->irq);

> +       atomic_inc(&priv->trig_more_count);

You already have a spin lock, do you need to use the atomic API?

> +       iio_trigger_poll(priv->trig);
> +
> +       spin_unlock_irqrestore(&priv->trig_lock, flags);
> +
> +       return HRTIMER_NORESTART;
> +}

...

> +       size_t size = 0;

Move the assignment closer to the actual use of the variable.

...

> +       /*
> +        * In case SPI controller do not report effective_speed_hz, use
> +        * configure value and hope it will match

Missed period.

> +        */
> +       if (!priv->effective_speed_hz)
> +               priv->effective_speed_hz = priv->spi->max_speed_hz;

Also can be ternary on one line, but it's up to you.

...

> +       name = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
> +                             TI_TSC2046_NAME, dev_name(dev));

No NULL check?
Should be added or justified.

...

> +       trig->dev.parent = indio_dev->dev.parent;

Don't we have this done by core (some recent patches in upstream)?

...

> +       ret = devm_iio_device_register(dev, indio_dev);
> +       if (ret) {
> +               dev_err(dev, "Failed to register iio device\n");

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

  return ret;
or even
  return devm_iio_device_register(dev, indio_dev);
Jonathan Cameron March 20, 2021, 3:46 p.m. UTC | #3
On Fri, 19 Mar 2021 15:45:09 +0100
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> Basically the TI TSC2046 touchscreen controller is 8 channel ADC optimized for
> the touchscreen use case. By implementing it as an IIO ADC device, we can
> make use of resistive-adc-touch and iio-hwmon drivers.
> 
> So far, this driver was tested with a custom version of resistive-adc-touch driver,
> since it needs to be extended to make use of Z1 and Z2 channels. The X/Y
> are working without additional changes.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Not a lot to add to Andy's review.  A few minor things inline.
Biggest one is I think we should call out that we expect to add single
channel polled reading + scales etc in future to enable the iio-hwmon
usecase.

Jonathan

> ---
>  MAINTAINERS                  |   8 +
>  drivers/iio/adc/Kconfig      |  12 +
>  drivers/iio/adc/Makefile     |   1 +
>  drivers/iio/adc/ti-tsc2046.c | 728 +++++++++++++++++++++++++++++++++++
>  4 files changed, 749 insertions(+)
>  create mode 100644 drivers/iio/adc/ti-tsc2046.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0455cfd5c76c..2ea85a5bb4dd 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -18002,6 +18002,14 @@ S:	Supported
>  F:	Documentation/devicetree/bindings/net/nfc/trf7970a.txt
>  F:	drivers/nfc/trf7970a.c
>  
> +TI TSC2046 ADC DRIVER
> +M:	Oleksij Rempel <o.rempel@pengutronix.de>
> +R:	kernel@pengutronix.de
> +L:	linux-iio@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/iio/adc/ti,tsc2046.yaml
> +F:	drivers/iio/adc/ti-tsc2046.c
> +
>  TI TWL4030 SERIES SOC CODEC DRIVER
>  M:	Peter Ujfalusi <peter.ujfalusi@gmail.com>
>  L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
...
> diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
> new file mode 100644
> index 000000000000..c8c0dd9087c5
> --- /dev/null
> +++ b/drivers/iio/adc/ti-tsc2046.c
> @@ -0,0 +1,728 @@
> +/*
> + * The PENIRQ of TSC2046 controller is implemented as level shifter attached to
> + * the X+ line. If voltage of the X+ line reaches a specific level the IRQ will
> + * be activated or deactivated.
> + * To make this kind of IRQ reusable as trigger following additions were
> + * implemented:
> + * - rate limiting:
> + *   For typical touchscreen use case, we need to trigger about each 10ms.
> + * - hrtimer:
> + *   Continue triggering at least once after the IRQ was deactivated. Then
> + *   deactivate this trigger to stop sampling in order to reduce power
> + *   consumption.
> + */

Good description :)

...


> +
> +struct tsc2046_adc_scan_buf {
> +	/* Scan data for each channel */
> +	u16 data[TI_TSC2046_MAX_CHAN];
> +	/* Timestamp */
> +	s64 ts __aligned(8);
> +};

...

> +struct tsc2046_adc_priv {
> +	struct spi_device *spi;
> +	const struct tsc2046_adc_dcfg *dcfg;
> +
> +	struct iio_trigger *trig;
> +	struct hrtimer trig_timer;
> +	spinlock_t trig_lock;
> +	atomic_t trig_more_count;
> +
> +	struct spi_transfer xfer;
> +	struct spi_message msg;
> +
> +	struct tsc2046_adc_scan_buf scan_buf;

Given the type tsc2046_adc_scan_buf is never used for anything else
you could make things more compact by using 
	struct {
	} scan_buf; 

> +	/*
> +	 * Lock to protect the layout and the spi transfer buffer.
> +	 * tsc2046_adc_group_layout can be changed within update_scan_mode(),
> +	 * in this case the l[] and tx/rx buffer will be out of sync to each
> +	 * other.
> +	 */
> +	struct mutex slock;
> +	struct tsc2046_adc_group_layout l[TI_TSC2046_MAX_CHAN];
> +	struct tsc2046_adc_atom *rx;
> +	struct tsc2046_adc_atom *tx;
> +
> +	struct tsc2046_adc_atom *rx_one;
> +	struct tsc2046_adc_atom *tx_one;
> +
> +	unsigned int count;
> +	unsigned int groups;
> +	u32 effective_speed_hz;
> +	u32 scan_interval_us;
> +	u32 time_per_scan_us;
> +	u32 time_per_bit_ns;
> +
> +	struct tsc2046_adc_ch_cfg ch_cfg[TI_TSC2046_MAX_CHAN];
> +};
> +
> +#define TI_TSC2046_V_CHAN(index, bits, name)			\
> +{								\
> +	.type = IIO_VOLTAGE,					\
> +	.indexed = 1,						\
> +	.channel = index,					\
> +	.datasheet_name = "#name",				\
> +	.scan_index = index,					\
> +	.scan_type = {						\
> +		.sign = 'u',					\
> +		.realbits = bits,				\
> +		.storagebits = 16,				\
> +		.endianness = IIO_CPU,				\
> +	},							\
> +}

I'd not noticed this before but you are exposing nothing to the
normal IIO interfaces.

That means for usecases like iio-hwmon there is no access
to polled readings, or information like channel scaling.

I suppose that could be added later, but perhaps you want to call this
out by mentioning it in the patch description.


> +
> +#define DECLARE_TI_TSC2046_8_CHANNELS(name, bits) \
> +const struct iio_chan_spec name ## _channels[] = { \
> +	TI_TSC2046_V_CHAN(0, bits, TEMP0), \
> +	TI_TSC2046_V_CHAN(1, bits, Y), \
> +	TI_TSC2046_V_CHAN(2, bits, VBAT), \
> +	TI_TSC2046_V_CHAN(3, bits, Z1), \
> +	TI_TSC2046_V_CHAN(4, bits, Z2), \
> +	TI_TSC2046_V_CHAN(5, bits, X), \
> +	TI_TSC2046_V_CHAN(6, bits, AUX), \
> +	TI_TSC2046_V_CHAN(7, bits, TEMP1), \
> +	IIO_CHAN_SOFT_TIMESTAMP(8), \
> +}
> +
> +static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12);
> +
> +static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = {
> +	.channels = tsc2046_adc_channels,
> +	.num_channels = ARRAY_SIZE(tsc2046_adc_channels),
> +};
> +

Hmm.  Flexibility that isn't yet used.  Normally I'm pretty resistant
to this going in, unless I'm reassured that there is support for additional
devices already in the pipeline.  Is that true here?  Otherwise
this is basically unneeded complexity.

...

Jonathan
Oleksij Rempel March 22, 2021, 10:30 a.m. UTC | #4
On Fri, Mar 19, 2021 at 07:42:41PM +0200, Andy Shevchenko wrote:
> On Fri, Mar 19, 2021 at 4:45 PM Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> >
> > Basically the TI TSC2046 touchscreen controller is 8 channel ADC optimized for
> > the touchscreen use case. By implementing it as an IIO ADC device, we can
> > make use of resistive-adc-touch and iio-hwmon drivers.
> >
> > So far, this driver was tested with a custom version of resistive-adc-touch driver,
> > since it needs to be extended to make use of Z1 and Z2 channels. The X/Y
> > are working without additional changes.
> 
> Since kbuild bot found some issues and it will be v4, some additional
> comments from me below.
> ...
> 
> > +#define        TI_TSC2046_SAMPLE_BITS \
> > +       (sizeof(struct tsc2046_adc_atom) * BITS_PER_BYTE)
> 
> Isn't it something like BITS_PER_TYPE(struct ...) ?

sounds good.

> ...
> 
> > +struct tsc2046_adc_atom {
> > +       /*
> > +        * Command transmitted to the controller. This filed is empty on the RX
> > +        * buffer.
> > +        */
> > +       u8 cmd;
> > +       /*
> > +        * Data received from the controller. This filed is empty for the TX
> > +        * buffer
> > +        */
> > +       __be16 data;
> > +} __packed;
> 
> filed -> field in both cases above.

done

> ...
> 
> > +       /*
> > +        * Lock to protect the layout and the spi transfer buffer.
> 
> SPI
> 
> > +        * tsc2046_adc_group_layout can be changed within update_scan_mode(),
> > +        * in this case the l[] and tx/rx buffer will be out of sync to each
> > +        * other.
> > +        */
> 
> ...
> 
> > +static unsigned int tsc2046_adc_time_to_count(struct tsc2046_adc_priv *priv,
> > +                                             unsigned long time)
> > +{
> > +       unsigned int bit_count, sample_count;
> > +
> > +       bit_count = DIV_ROUND_UP(time * NSEC_PER_USEC, priv->time_per_bit_ns);
> 
> Does it survive 32-bit builds?

ACK. I develop and test it on 32bit ARM

> > +       sample_count = DIV_ROUND_UP(bit_count, TI_TSC2046_SAMPLE_BITS);
> > +
> > +       dev_dbg(&priv->spi->dev, "Effective speed %u, time per bit: %u, count bits: %u, count samples: %u\n",
> > +               priv->effective_speed_hz, priv->time_per_bit_ns,
> > +               bit_count, sample_count);
> > +
> > +       return sample_count;
> > +}
> 
> ...
> 
> > +       /*
> > +        * if PD bits are 0, controller will automatically disable ADC, VREF and
> > +        * enable IRQ.
> > +        */
> > +       if (keep_power)
> > +               pd = TI_TSC2046_PD0_ADC_ON;
> > +       else
> > +               pd = 0;
> 
> Can be ternary on one line, but it's up to you.

ACK. I'll keep it

> ...
> 
> > +static u16 tsc2046_adc_get_value(struct tsc2046_adc_atom *buf)
> > +{
> > +       /* Last 3 bits on the wire are empty */
> 
> Last?! You meant Least significant?

ACK. LSB

> Also, don't we lose precision if a new compatible chip appears that
> does fill those bits?

ACK. All of controllers supported by this driver:
drivers/input/touchscreen/ads7846.c:
- ti,tsc2046
- ti,ads7843
- ti,ads7845
- ti,ads7846
- ti,ads7873 (hm, there is no ti,ads7873, is it actually analog devices AD7873?)

support 8- or 12-bit resolution. Only 12 bit mode is supported by this
driver. It is possible that some one can produce a resistive touchscreen
controller based on X > 12bit ADC, but this will probably not increase precision
of this construction (there is a lot of noise any ways...). With other
words, it is possible, but not probably that some one will really do it.

> Perhaps define the constant and put a comment why it's like this.
> 
> > +       return get_unaligned_be16(&buf->data) >> 3;
> > +}
> 
> ...
> 
> > +static size_t tsc2046_adc_group_set_layout(struct tsc2046_adc_priv *priv,
> > +                                          unsigned int group,
> > +                                          unsigned int ch_idx)
> > +{
> > +       struct tsc2046_adc_ch_cfg *ch = &priv->ch_cfg[ch_idx];
> > +       struct tsc2046_adc_group_layout *prev, *cur;
> > +       unsigned int max_count, count_skip;
> > +       unsigned int offset = 0;
> > +
> > +       if (group) {
> > +               prev = &priv->l[group - 1];
> > +               offset = prev->offset + prev->count;
> > +       }
> 
> I guess you may easily refactor this by supplying a pointer to the
> current layout + current size.

Sure, but this will not make code more readable and it will not affect
the performance. Are there any other reason to do it? Just to make one
line instead of two?

> 
> > +       cur = &priv->l[group];
> 
> Also, can you move it down closer to the (single?) caller.
> 
> > +}
> 
> ...
> 
> > +static int tsc2046_adc_scan(struct iio_dev *indio_dev)
> > +{
> > +       struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
> > +       struct device *dev = &priv->spi->dev;
> > +       int group;
> > +       int ret;
> > +
> > +       ret = spi_sync(priv->spi, &priv->msg);
> > +       if (ret < 0) {
> 
> > +               dev_err_ratelimited(dev, "SPI transfer filed: %pe\n",
> > +                                   ERR_PTR(ret));
> 
> One line?

it will exceed the 80 char rule

> > +               return ret;
> > +       }
> 
> > +       ret = iio_push_to_buffers_with_timestamp(indio_dev, &priv->scan_buf,
> > +                                                iio_get_time_ns(indio_dev));
> > +       /* If consumer is kfifo, we may get a EBUSY here - ignore it. */
> 
> the consumer
> 
> > +       if (ret < 0 && ret != -EBUSY) {
> > +               dev_err_ratelimited(dev, "Failed to push scan buffer %pe\n",
> > +                                   ERR_PTR(ret));
> > +
> > +               return ret;
> > +       }
> > +
> > +       return 0;
> > +}
> 
> 
> ...
> 
> > +static enum hrtimer_restart tsc2046_adc_trig_more(struct hrtimer *hrtimer)
> > +{
> > +       struct tsc2046_adc_priv *priv = container_of(hrtimer,
> > +                                                    struct tsc2046_adc_priv,
> > +                                                    trig_timer);
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&priv->trig_lock, flags);
> > +
> > +       disable_irq_nosync(priv->spi->irq);
> 
> > +       atomic_inc(&priv->trig_more_count);
> 
> You already have a spin lock, do you need to use the atomic API?

I can only pass review comment from my other driver:
Memory locations that are concurrently accessed needs to be
marked as such, otherwise the compiler is allowed to funky stuff:
https://lore.kernel.org/lkml/CAGzjT4ez+gWr3BFQsEr-wma+vs6UZNJ+mRARx_BWoAKEJSsN=w@mail.gmail.com/

And here is one more link:
https://lwn.net/Articles/793253/#How%20Real%20Is%20All%20This?

Starting with commit 62e8a3258bda atomic API is using READ/WRITE_ONCE,
so I assume, I do nothing wrong by using it. Correct?


> > +       iio_trigger_poll(priv->trig);
> > +
> > +       spin_unlock_irqrestore(&priv->trig_lock, flags);
> > +
> > +       return HRTIMER_NORESTART;
> > +}
> 
> ...
> 
> > +       size_t size = 0;
> 
> Move the assignment closer to the actual use of the variable.
> 
> ...
> 
> > +       /*
> > +        * In case SPI controller do not report effective_speed_hz, use
> > +        * configure value and hope it will match
> 
> Missed period.
> 
> > +        */
> > +       if (!priv->effective_speed_hz)
> > +               priv->effective_speed_hz = priv->spi->max_speed_hz;
> 
> Also can be ternary on one line, but it's up to you.

it is better readable for me.

> ...
> 
> > +       name = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
> > +                             TI_TSC2046_NAME, dev_name(dev));
> 
> No NULL check?
> Should be added or justified.

name is set not optionally  by the spi_add_device()->spi_dev_set_name() 

> ...
> 
> > +       trig->dev.parent = indio_dev->dev.parent;
> 
> Don't we have this done by core (some recent patches in upstream)?

can you please point to the code which is doing it?

> ...
> 
> > +       ret = devm_iio_device_register(dev, indio_dev);
> > +       if (ret) {
> > +               dev_err(dev, "Failed to register iio device\n");
> 
> > +               return ret;
> > +       }
> > +
> > +       return 0;
> 
>   return ret;
> or even
>   return devm_iio_device_register(dev, indio_dev);

good point,

regards,
Oleksij
Oleksij Rempel March 22, 2021, 11:56 a.m. UTC | #5
Hi,

On Sat, Mar 20, 2021 at 03:46:01PM +0000, Jonathan Cameron wrote:
> On Fri, 19 Mar 2021 15:45:09 +0100
> Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> 
> > Basically the TI TSC2046 touchscreen controller is 8 channel ADC optimized for
> > the touchscreen use case. By implementing it as an IIO ADC device, we can
> > make use of resistive-adc-touch and iio-hwmon drivers.
> > 
> > So far, this driver was tested with a custom version of resistive-adc-touch driver,
> > since it needs to be extended to make use of Z1 and Z2 channels. The X/Y
> > are working without additional changes.
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> Not a lot to add to Andy's review.  A few minor things inline.
> Biggest one is I think we should call out that we expect to add single
> channel polled reading + scales etc in future to enable the iio-hwmon
> usecase.
> 
> Jonathan
> 
> > ---
> >  MAINTAINERS                  |   8 +
> >  drivers/iio/adc/Kconfig      |  12 +
> >  drivers/iio/adc/Makefile     |   1 +
> >  drivers/iio/adc/ti-tsc2046.c | 728 +++++++++++++++++++++++++++++++++++
> >  4 files changed, 749 insertions(+)
> >  create mode 100644 drivers/iio/adc/ti-tsc2046.c
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 0455cfd5c76c..2ea85a5bb4dd 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -18002,6 +18002,14 @@ S:	Supported
> >  F:	Documentation/devicetree/bindings/net/nfc/trf7970a.txt
> >  F:	drivers/nfc/trf7970a.c
> >  
> > +TI TSC2046 ADC DRIVER
> > +M:	Oleksij Rempel <o.rempel@pengutronix.de>
> > +R:	kernel@pengutronix.de
> > +L:	linux-iio@vger.kernel.org
> > +S:	Maintained
> > +F:	Documentation/devicetree/bindings/iio/adc/ti,tsc2046.yaml
> > +F:	drivers/iio/adc/ti-tsc2046.c
> > +
> >  TI TWL4030 SERIES SOC CODEC DRIVER
> >  M:	Peter Ujfalusi <peter.ujfalusi@gmail.com>
> >  L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
> ...
> > diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
> > new file mode 100644
> > index 000000000000..c8c0dd9087c5
> > --- /dev/null
> > +++ b/drivers/iio/adc/ti-tsc2046.c
> > @@ -0,0 +1,728 @@
> > +/*
> > + * The PENIRQ of TSC2046 controller is implemented as level shifter attached to
> > + * the X+ line. If voltage of the X+ line reaches a specific level the IRQ will
> > + * be activated or deactivated.
> > + * To make this kind of IRQ reusable as trigger following additions were
> > + * implemented:
> > + * - rate limiting:
> > + *   For typical touchscreen use case, we need to trigger about each 10ms.
> > + * - hrtimer:
> > + *   Continue triggering at least once after the IRQ was deactivated. Then
> > + *   deactivate this trigger to stop sampling in order to reduce power
> > + *   consumption.
> > + */
> 
> Good description :)
> 
> ...
> 
> 
> > +
> > +struct tsc2046_adc_scan_buf {
> > +	/* Scan data for each channel */
> > +	u16 data[TI_TSC2046_MAX_CHAN];
> > +	/* Timestamp */
> > +	s64 ts __aligned(8);
> > +};
> 
> ...
> 
> > +struct tsc2046_adc_priv {
> > +	struct spi_device *spi;
> > +	const struct tsc2046_adc_dcfg *dcfg;
> > +
> > +	struct iio_trigger *trig;
> > +	struct hrtimer trig_timer;
> > +	spinlock_t trig_lock;
> > +	atomic_t trig_more_count;
> > +
> > +	struct spi_transfer xfer;
> > +	struct spi_message msg;
> > +
> > +	struct tsc2046_adc_scan_buf scan_buf;
> 
> Given the type tsc2046_adc_scan_buf is never used for anything else
> you could make things more compact by using 
> 	struct {
> 	} scan_buf; 
> 
> > +	/*
> > +	 * Lock to protect the layout and the spi transfer buffer.
> > +	 * tsc2046_adc_group_layout can be changed within update_scan_mode(),
> > +	 * in this case the l[] and tx/rx buffer will be out of sync to each
> > +	 * other.
> > +	 */
> > +	struct mutex slock;
> > +	struct tsc2046_adc_group_layout l[TI_TSC2046_MAX_CHAN];
> > +	struct tsc2046_adc_atom *rx;
> > +	struct tsc2046_adc_atom *tx;
> > +
> > +	struct tsc2046_adc_atom *rx_one;
> > +	struct tsc2046_adc_atom *tx_one;
> > +
> > +	unsigned int count;
> > +	unsigned int groups;
> > +	u32 effective_speed_hz;
> > +	u32 scan_interval_us;
> > +	u32 time_per_scan_us;
> > +	u32 time_per_bit_ns;
> > +
> > +	struct tsc2046_adc_ch_cfg ch_cfg[TI_TSC2046_MAX_CHAN];
> > +};
> > +
> > +#define TI_TSC2046_V_CHAN(index, bits, name)			\
> > +{								\
> > +	.type = IIO_VOLTAGE,					\
> > +	.indexed = 1,						\
> > +	.channel = index,					\
> > +	.datasheet_name = "#name",				\
> > +	.scan_index = index,					\
> > +	.scan_type = {						\
> > +		.sign = 'u',					\
> > +		.realbits = bits,				\
> > +		.storagebits = 16,				\
> > +		.endianness = IIO_CPU,				\
> > +	},							\
> > +}
> 
> I'd not noticed this before but you are exposing nothing to the
> normal IIO interfaces.
> 
> That means for usecases like iio-hwmon there is no access
> to polled readings, or information like channel scaling.
> 
> I suppose that could be added later, but perhaps you want to call this
> out by mentioning it in the patch description.

If it is ok for you, then I'll add some words about it in to the patch
description.

> > +
> > +#define DECLARE_TI_TSC2046_8_CHANNELS(name, bits) \
> > +const struct iio_chan_spec name ## _channels[] = { \
> > +	TI_TSC2046_V_CHAN(0, bits, TEMP0), \
> > +	TI_TSC2046_V_CHAN(1, bits, Y), \
> > +	TI_TSC2046_V_CHAN(2, bits, VBAT), \
> > +	TI_TSC2046_V_CHAN(3, bits, Z1), \
> > +	TI_TSC2046_V_CHAN(4, bits, Z2), \
> > +	TI_TSC2046_V_CHAN(5, bits, X), \
> > +	TI_TSC2046_V_CHAN(6, bits, AUX), \
> > +	TI_TSC2046_V_CHAN(7, bits, TEMP1), \
> > +	IIO_CHAN_SOFT_TIMESTAMP(8), \
> > +}
> > +
> > +static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12);
> > +
> > +static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = {
> > +	.channels = tsc2046_adc_channels,
> > +	.num_channels = ARRAY_SIZE(tsc2046_adc_channels),
> > +};
> > +
> 
> Hmm.  Flexibility that isn't yet used.  Normally I'm pretty resistant
> to this going in, unless I'm reassured that there is support for additional
> devices already in the pipeline.  Is that true here?  Otherwise
> this is basically unneeded complexity.

In the long term this driver should replace
drivers/input/touchscreen/ads7846.c

This driver supports ti,ads7843, ti,ads7845, ti,ads7846.. at least with
following number of supported channels:
ti,ads7843 - 4 channels: x, y, aux0, aux1
ti,ads7845 - 3 channels: x, y, aux0
ti,ads7846 - 8 channels...

Currently I don't have this HW for testing and there a subtle
differences that have to be taken care of and tested.
Andy Shevchenko March 22, 2021, 1:41 p.m. UTC | #6
On Mon, Mar 22, 2021 at 12:30 PM Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> On Fri, Mar 19, 2021 at 07:42:41PM +0200, Andy Shevchenko wrote:
> > On Fri, Mar 19, 2021 at 4:45 PM Oleksij Rempel <o.rempel@pengutronix.de> wrote:

...

> > > +static u16 tsc2046_adc_get_value(struct tsc2046_adc_atom *buf)
> > > +{
> > > +       /* Last 3 bits on the wire are empty */
> >
> > Last?! You meant Least significant?
>
> ACK. LSB
>
> > Also, don't we lose precision if a new compatible chip appears that
> > does fill those bits?
>
> ACK. All of controllers supported by this driver:
> drivers/input/touchscreen/ads7846.c:
> - ti,tsc2046
> - ti,ads7843
> - ti,ads7845
> - ti,ads7846
> - ti,ads7873 (hm, there is no ti,ads7873, is it actually analog devices AD7873?)
>
> support 8- or 12-bit resolution. Only 12 bit mode is supported by this
> driver. It is possible that some one can produce a resistive touchscreen
> controller based on X > 12bit ADC, but this will probably not increase precision
> of this construction (there is a lot of noise any ways...). With other
> words, it is possible, but not probably that some one will really do it.
>
> > Perhaps define the constant and put a comment why it's like this.

Okay, and what happens here is something like cutting LSBs, but it
sounds strange to me. If you get 16 bit values, the MSBs should not be
used?

So, a good comment is required to explain the logic behind.

> > > +       return get_unaligned_be16(&buf->data) >> 3;
> > > +}

...

> > > +static size_t tsc2046_adc_group_set_layout(struct tsc2046_adc_priv *priv,
> > > +                                          unsigned int group,
> > > +                                          unsigned int ch_idx)
> > > +{
> > > +       struct tsc2046_adc_ch_cfg *ch = &priv->ch_cfg[ch_idx];
> > > +       struct tsc2046_adc_group_layout *prev, *cur;
> > > +       unsigned int max_count, count_skip;
> > > +       unsigned int offset = 0;
> > > +
> > > +       if (group) {
> > > +               prev = &priv->l[group - 1];
> > > +               offset = prev->offset + prev->count;
> > > +       }
> >
> > I guess you may easily refactor this by supplying a pointer to the
> > current layout + current size.
>
> Sure, but this will not make code more readable and it will not affect
> the performance. Are there any other reason to do it? Just to make one
> line instead of two?

It's still N - 1 unneeded checks and code is slightly harder to read.

> > > +       cur = &priv->l[group];
> >
> > Also, can you move it down closer to the (single?) caller.
> >
> > > +}

...

> > > +               dev_err_ratelimited(dev, "SPI transfer filed: %pe\n",
> > > +                                   ERR_PTR(ret));
> >
> > One line?
>
> it will exceed the 80 char rule

It's fine here.

...

> > > +       spin_lock_irqsave(&priv->trig_lock, flags);
> > > +
> > > +       disable_irq_nosync(priv->spi->irq);
> >
> > > +       atomic_inc(&priv->trig_more_count);
> >
> > You already have a spin lock, do you need to use the atomic API?
>
> I can only pass review comment from my other driver:
> Memory locations that are concurrently accessed needs to be
> marked as such, otherwise the compiler is allowed to funky stuff:
> https://lore.kernel.org/lkml/CAGzjT4ez+gWr3BFQsEr-wma+vs6UZNJ+mRARx_BWoAKEJSsN=w@mail.gmail.com/
>
> And here is one more link:
> https://lwn.net/Articles/793253/#How%20Real%20Is%20All%20This?
>
> Starting with commit 62e8a3258bda atomic API is using READ/WRITE_ONCE,
> so I assume, I do nothing wrong by using it. Correct?

Hmm... What I don't understand here is why you need a second level of
atomicity. spin lock already makes this access atomic (at least I have
checked couple of places and in both the variable is being accessed
under spin lock).

> > > +       iio_trigger_poll(priv->trig);
> > > +
> > > +       spin_unlock_irqrestore(&priv->trig_lock, flags);

...

> > > +       name = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
> > > +                             TI_TSC2046_NAME, dev_name(dev));
> >
> > No NULL check?
> > Should be added or justified.
>
> name is set not optionally  by the spi_add_device()->spi_dev_set_name()

I didn't get it.
You allocate memory and haven't checked against NULL. Why?

If the name field is optional and having it's NULL is okay (non-fatal
error), put a comment.

...

> > > +       trig->dev.parent = indio_dev->dev.parent;
> >
> > Don't we have this done by core (some recent patches in upstream)?
>
> can you please point to the code which is doing it?

I believe it's this one:

commit 970108185a0be29d1dbb25202d8c12d798e1c3a5
Author: Gwendal Grignou <gwendal@chromium.org>
Date:   Tue Mar 9 11:36:13 2021 -0800

   iio: set default trig->dev.parent
Oleksij Rempel March 22, 2021, 2:08 p.m. UTC | #7
On Mon, Mar 22, 2021 at 03:41:22PM +0200, Andy Shevchenko wrote:
> On Mon, Mar 22, 2021 at 12:30 PM Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> > On Fri, Mar 19, 2021 at 07:42:41PM +0200, Andy Shevchenko wrote:
> > > On Fri, Mar 19, 2021 at 4:45 PM Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> 
> ...
> 
> > > > +static u16 tsc2046_adc_get_value(struct tsc2046_adc_atom *buf)
> > > > +{
> > > > +       /* Last 3 bits on the wire are empty */
> > >
> > > Last?! You meant Least significant?
> >
> > ACK. LSB
> >
> > > Also, don't we lose precision if a new compatible chip appears that
> > > does fill those bits?
> >
> > ACK. All of controllers supported by this driver:
> > drivers/input/touchscreen/ads7846.c:
> > - ti,tsc2046
> > - ti,ads7843
> > - ti,ads7845
> > - ti,ads7846
> > - ti,ads7873 (hm, there is no ti,ads7873, is it actually analog devices AD7873?)
> >
> > support 8- or 12-bit resolution. Only 12 bit mode is supported by this
> > driver. It is possible that some one can produce a resistive touchscreen
> > controller based on X > 12bit ADC, but this will probably not increase precision
> > of this construction (there is a lot of noise any ways...). With other
> > words, it is possible, but not probably that some one will really do it.
> >
> > > Perhaps define the constant and put a comment why it's like this.
> 
> Okay, and what happens here is something like cutting LSBs, but it
> sounds strange to me. If you get 16 bit values, the MSBs should not be
> used?
> 
> So, a good comment is required to explain the logic behind.
> 
> > > > +       return get_unaligned_be16(&buf->data) >> 3;
> > > > +}
> 
> ...
> 
> > > > +static size_t tsc2046_adc_group_set_layout(struct tsc2046_adc_priv *priv,
> > > > +                                          unsigned int group,
> > > > +                                          unsigned int ch_idx)
> > > > +{
> > > > +       struct tsc2046_adc_ch_cfg *ch = &priv->ch_cfg[ch_idx];
> > > > +       struct tsc2046_adc_group_layout *prev, *cur;
> > > > +       unsigned int max_count, count_skip;
> > > > +       unsigned int offset = 0;
> > > > +
> > > > +       if (group) {
> > > > +               prev = &priv->l[group - 1];
> > > > +               offset = prev->offset + prev->count;
> > > > +       }
> > >
> > > I guess you may easily refactor this by supplying a pointer to the
> > > current layout + current size.
> >
> > Sure, but this will not make code more readable and it will not affect
> > the performance. Are there any other reason to do it? Just to make one
> > line instead of two?
> 
> It's still N - 1 unneeded checks and code is slightly harder to read.

fixed

> > > > +       cur = &priv->l[group];
> > >
> > > Also, can you move it down closer to the (single?) caller.
> > >
> > > > +}
> 
> ...
> 
> > > > +               dev_err_ratelimited(dev, "SPI transfer filed: %pe\n",
> > > > +                                   ERR_PTR(ret));
> > >
> > > One line?
> >
> > it will exceed the 80 char rule
> 
> It's fine here.

fixed

> ...
> 
> > > > +       spin_lock_irqsave(&priv->trig_lock, flags);
> > > > +
> > > > +       disable_irq_nosync(priv->spi->irq);
> > >
> > > > +       atomic_inc(&priv->trig_more_count);
> > >
> > > You already have a spin lock, do you need to use the atomic API?
> >
> > I can only pass review comment from my other driver:
> > Memory locations that are concurrently accessed needs to be
> > marked as such, otherwise the compiler is allowed to funky stuff:
> > https://lore.kernel.org/lkml/CAGzjT4ez+gWr3BFQsEr-wma+vs6UZNJ+mRARx_BWoAKEJSsN=w@mail.gmail.com/
> >
> > And here is one more link:
> > https://lwn.net/Articles/793253/#How%20Real%20Is%20All%20This?
> >
> > Starting with commit 62e8a3258bda atomic API is using READ/WRITE_ONCE,
> > so I assume, I do nothing wrong by using it. Correct?
> 
> Hmm... What I don't understand here is why you need a second level of
> atomicity. spin lock already makes this access atomic (at least I have
> checked couple of places and in both the variable is being accessed
> under spin lock).

fixed

> > > > +       iio_trigger_poll(priv->trig);
> > > > +
> > > > +       spin_unlock_irqrestore(&priv->trig_lock, flags);
> 
> ...
> 
> > > > +       name = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
> > > > +                             TI_TSC2046_NAME, dev_name(dev));
> > >
> > > No NULL check?
> > > Should be added or justified.
> >
> > name is set not optionally  by the spi_add_device()->spi_dev_set_name()
> 
> I didn't get it.
> You allocate memory and haven't checked against NULL. Why?

> If the name field is optional and having it's NULL is okay (non-fatal
> error), put a comment.

ah... I missed the point. You was talking about name == NULL, i was
thinking about dev_name(dev) == NULL.

fixed

> ...
> 
> > > > +       trig->dev.parent = indio_dev->dev.parent;
> > >
> > > Don't we have this done by core (some recent patches in upstream)?
> >
> > can you please point to the code which is doing it?
> 
> I believe it's this one:
> 
> commit 970108185a0be29d1dbb25202d8c12d798e1c3a5
> Author: Gwendal Grignou <gwendal@chromium.org>
> Date:   Tue Mar 9 11:36:13 2021 -0800
> 
>    iio: set default trig->dev.parent

ok, found it on iio/testing and rebased against it..

fixed

Thank you,
Oleksij
Jonathan Cameron March 22, 2021, 2:27 p.m. UTC | #8
> >   
> > > +	/*
> > > +	 * Lock to protect the layout and the spi transfer buffer.
> > > +	 * tsc2046_adc_group_layout can be changed within update_scan_mode(),
> > > +	 * in this case the l[] and tx/rx buffer will be out of sync to each
> > > +	 * other.
> > > +	 */
> > > +	struct mutex slock;
> > > +	struct tsc2046_adc_group_layout l[TI_TSC2046_MAX_CHAN];
> > > +	struct tsc2046_adc_atom *rx;
> > > +	struct tsc2046_adc_atom *tx;
> > > +
> > > +	struct tsc2046_adc_atom *rx_one;
> > > +	struct tsc2046_adc_atom *tx_one;
> > > +
> > > +	unsigned int count;
> > > +	unsigned int groups;
> > > +	u32 effective_speed_hz;
> > > +	u32 scan_interval_us;
> > > +	u32 time_per_scan_us;
> > > +	u32 time_per_bit_ns;
> > > +
> > > +	struct tsc2046_adc_ch_cfg ch_cfg[TI_TSC2046_MAX_CHAN];
> > > +};
> > > +
> > > +#define TI_TSC2046_V_CHAN(index, bits, name)			\
> > > +{								\
> > > +	.type = IIO_VOLTAGE,					\
> > > +	.indexed = 1,						\
> > > +	.channel = index,					\
> > > +	.datasheet_name = "#name",				\
> > > +	.scan_index = index,					\
> > > +	.scan_type = {						\
> > > +		.sign = 'u',					\
> > > +		.realbits = bits,				\
> > > +		.storagebits = 16,				\
> > > +		.endianness = IIO_CPU,				\
> > > +	},							\
> > > +}  
> > 
> > I'd not noticed this before but you are exposing nothing to the
> > normal IIO interfaces.
> > 
> > That means for usecases like iio-hwmon there is no access
> > to polled readings, or information like channel scaling.
> > 
> > I suppose that could be added later, but perhaps you want to call this
> > out by mentioning it in the patch description.  
> 
> If it is ok for you, then I'll add some words about it in to the patch
> description.
Sure

> 
> > > +
> > > +#define DECLARE_TI_TSC2046_8_CHANNELS(name, bits) \
> > > +const struct iio_chan_spec name ## _channels[] = { \
> > > +	TI_TSC2046_V_CHAN(0, bits, TEMP0), \
> > > +	TI_TSC2046_V_CHAN(1, bits, Y), \
> > > +	TI_TSC2046_V_CHAN(2, bits, VBAT), \
> > > +	TI_TSC2046_V_CHAN(3, bits, Z1), \
> > > +	TI_TSC2046_V_CHAN(4, bits, Z2), \
> > > +	TI_TSC2046_V_CHAN(5, bits, X), \
> > > +	TI_TSC2046_V_CHAN(6, bits, AUX), \
> > > +	TI_TSC2046_V_CHAN(7, bits, TEMP1), \
> > > +	IIO_CHAN_SOFT_TIMESTAMP(8), \
> > > +}
> > > +
> > > +static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12);
> > > +
> > > +static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = {
> > > +	.channels = tsc2046_adc_channels,
> > > +	.num_channels = ARRAY_SIZE(tsc2046_adc_channels),
> > > +};
> > > +  
> > 
> > Hmm.  Flexibility that isn't yet used.  Normally I'm pretty resistant
> > to this going in, unless I'm reassured that there is support for additional
> > devices already in the pipeline.  Is that true here?  Otherwise
> > this is basically unneeded complexity.  
> 
> In the long term this driver should replace
> drivers/input/touchscreen/ads7846.c
> 
> This driver supports ti,ads7843, ti,ads7845, ti,ads7846.. at least with
> following number of supported channels:
> ti,ads7843 - 4 channels: x, y, aux0, aux1
> ti,ads7845 - 3 channels: x, y, aux0
> ti,ads7846 - 8 channels...
> 
> Currently I don't have this HW for testing and there a subtle
> differences that have to be taken care of and tested.
> 

Note that I'm only going to merge this driver with an explicit statement
from Dmitry as input maintainer that he is fine with this approach.

Jonathan
Oleksij Rempel March 29, 2021, 7:38 a.m. UTC | #9
On Mon, Mar 22, 2021 at 02:27:22PM +0000, Jonathan Cameron wrote:
> > > > +static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12);
> > > > +
> > > > +static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = {
> > > > +	.channels = tsc2046_adc_channels,
> > > > +	.num_channels = ARRAY_SIZE(tsc2046_adc_channels),
> > > > +};
> > > > +  
> > > 
> > > Hmm.  Flexibility that isn't yet used.  Normally I'm pretty resistant
> > > to this going in, unless I'm reassured that there is support for additional
> > > devices already in the pipeline.  Is that true here?  Otherwise
> > > this is basically unneeded complexity.  
> > 
> > In the long term this driver should replace
> > drivers/input/touchscreen/ads7846.c
> > 
> > This driver supports ti,ads7843, ti,ads7845, ti,ads7846.. at least with
> > following number of supported channels:
> > ti,ads7843 - 4 channels: x, y, aux0, aux1
> > ti,ads7845 - 3 channels: x, y, aux0
> > ti,ads7846 - 8 channels...
> > 
> > Currently I don't have this HW for testing and there a subtle
> > differences that have to be taken care of and tested.
> > 
> 
> Note that I'm only going to merge this driver with an explicit statement
> from Dmitry as input maintainer that he is fine with this approach.

Since there is still no Dmitry's feedback please take a look to the
ti,ads7843 datasheet:
https://www.ti.com/lit/ds/symlink/ads7843.pdf

On the page 1 you can see, that this device has two general purpose ADC
inputs IN3, IN4. If some one will decide to mainline support for this
pins, will end with IIO ADC driver any way :)

Regards,
Oleksij
Jonathan Cameron March 29, 2021, 10:23 a.m. UTC | #10
On Mon, 29 Mar 2021 09:38:38 +0200
Oleksij Rempel <o.rempel@pengutronix.de> wrote:

> On Mon, Mar 22, 2021 at 02:27:22PM +0000, Jonathan Cameron wrote:
> > > > > +static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12);
> > > > > +
> > > > > +static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = {
> > > > > +	.channels = tsc2046_adc_channels,
> > > > > +	.num_channels = ARRAY_SIZE(tsc2046_adc_channels),
> > > > > +};
> > > > > +    
> > > > 
> > > > Hmm.  Flexibility that isn't yet used.  Normally I'm pretty resistant
> > > > to this going in, unless I'm reassured that there is support for additional
> > > > devices already in the pipeline.  Is that true here?  Otherwise
> > > > this is basically unneeded complexity.    
> > > 
> > > In the long term this driver should replace
> > > drivers/input/touchscreen/ads7846.c
> > > 
> > > This driver supports ti,ads7843, ti,ads7845, ti,ads7846.. at least with
> > > following number of supported channels:
> > > ti,ads7843 - 4 channels: x, y, aux0, aux1
> > > ti,ads7845 - 3 channels: x, y, aux0
> > > ti,ads7846 - 8 channels...
> > > 
> > > Currently I don't have this HW for testing and there a subtle
> > > differences that have to be taken care of and tested.
> > >   
> > 
> > Note that I'm only going to merge this driver with an explicit statement
> > from Dmitry as input maintainer that he is fine with this approach.  
> 
> Since there is still no Dmitry's feedback please take a look to the
> ti,ads7843 datasheet:
> https://www.ti.com/lit/ds/symlink/ads7843.pdf
> 
> On the page 1 you can see, that this device has two general purpose ADC
> inputs IN3, IN4. If some one will decide to mainline support for this
> pins, will end with IIO ADC driver any way :)

Understood, but I'm still going to want Dmitry to give an opinion on
this.  That might take a little while though as he may well be busy!

Jonathan

> 
> Regards,
> Oleksij
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 0455cfd5c76c..2ea85a5bb4dd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18002,6 +18002,14 @@  S:	Supported
 F:	Documentation/devicetree/bindings/net/nfc/trf7970a.txt
 F:	drivers/nfc/trf7970a.c
 
+TI TSC2046 ADC DRIVER
+M:	Oleksij Rempel <o.rempel@pengutronix.de>
+R:	kernel@pengutronix.de
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/adc/ti,tsc2046.yaml
+F:	drivers/iio/adc/ti-tsc2046.c
+
 TI TWL4030 SERIES SOC CODEC DRIVER
 M:	Peter Ujfalusi <peter.ujfalusi@gmail.com>
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index bf7d22fa4be2..a2898108f418 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1175,6 +1175,18 @@  config TI_TLC4541
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-tlc4541.
 
+config TI_TSC2046
+	tristate "Texas Instruments TSC2046 ADC driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for ADC functionality of Texas
+	  Instruments TSC2046 touch screen controller.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ti-tsc2046.
+
 config TWL4030_MADC
 	tristate "TWL4030 MADC (Monitoring A/D Converter)"
 	depends on TWL4030_CORE
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 5fca90ada0ec..440e18ac6780 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -105,6 +105,7 @@  obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
 obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
 obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
 obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
+obj-$(CONFIG_TI_TSC2046) += ti-tsc2046.o
 obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
 obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
 obj-$(CONFIG_VF610_ADC) += vf610_adc.o
diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
new file mode 100644
index 000000000000..c8c0dd9087c5
--- /dev/null
+++ b/drivers/iio/adc/ti-tsc2046.c
@@ -0,0 +1,728 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Texas Instruments TSC2046 SPI ADC driver
+ *
+ * Copyright (c) 2021 Oleksij Rempel <kernel@pengutronix.de>, Pengutronix
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#include <asm/unaligned.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger.h>
+
+/*
+ * The PENIRQ of TSC2046 controller is implemented as level shifter attached to
+ * the X+ line. If voltage of the X+ line reaches a specific level the IRQ will
+ * be activated or deactivated.
+ * To make this kind of IRQ reusable as trigger following additions were
+ * implemented:
+ * - rate limiting:
+ *   For typical touchscreen use case, we need to trigger about each 10ms.
+ * - hrtimer:
+ *   Continue triggering at least once after the IRQ was deactivated. Then
+ *   deactivate this trigger to stop sampling in order to reduce power
+ *   consumption.
+ */
+
+#define TI_TSC2046_NAME				"tsc2046"
+
+/* This driver doesn't aim at the peak continuous sample rate */
+#define	TI_TSC2046_MAX_SAMPLE_RATE		125000
+#define	TI_TSC2046_SAMPLE_BITS \
+	(sizeof(struct tsc2046_adc_atom) * BITS_PER_BYTE)
+#define	TI_TSC2046_MAX_CLK_FREQ \
+	(TI_TSC2046_MAX_SAMPLE_RATE * TI_TSC2046_SAMPLE_BITS)
+
+#define TI_TSC2046_SAMPLE_INTERVAL_US		10000
+
+#define TI_TSC2046_START			BIT(7)
+#define TI_TSC2046_ADDR				GENMASK(6, 4)
+#define TI_TSC2046_ADDR_TEMP1			7
+#define TI_TSC2046_ADDR_AUX			6
+#define TI_TSC2046_ADDR_X			5
+#define TI_TSC2046_ADDR_Z2			4
+#define TI_TSC2046_ADDR_Z1			3
+#define TI_TSC2046_ADDR_VBAT			2
+#define TI_TSC2046_ADDR_Y			1
+#define TI_TSC2046_ADDR_TEMP0			0
+
+/*
+ * The mode bit sets the resolution of the ADC. With this bit low, the next
+ * conversion has 12-bit resolution, whereas with this bit high, the next
+ * conversion has 8-bit resolution. This driver is optimized for 12-bit mode.
+ * So, for this driver, this bit should stay zero.
+ */
+#define TI_TSC2046_8BIT_MODE			BIT(3)
+
+/*
+ * SER/DFR - The SER/DFR bit controls the reference mode, either single-ended
+ * (high) or differential (low).
+ */
+#define TI_TSC2046_SER				BIT(2)
+
+/*
+ * If VREF_ON and ADC_ON are both zero, then the chip operates in
+ * auto-wake/suspend mode. In most case this bits should stay zero.
+ */
+#define TI_TSC2046_PD1_VREF_ON			BIT(1)
+#define TI_TSC2046_PD0_ADC_ON			BIT(0)
+
+#define TI_TSC2046_MAX_CHAN			8
+
+/* Represents a HW sample */
+struct tsc2046_adc_atom {
+	/*
+	 * Command transmitted to the controller. This filed is empty on the RX
+	 * buffer.
+	 */
+	u8 cmd;
+	/*
+	 * Data received from the controller. This filed is empty for the TX
+	 * buffer
+	 */
+	__be16 data;
+} __packed;
+
+struct tsc2046_adc_scan_buf {
+	/* Scan data for each channel */
+	u16 data[TI_TSC2046_MAX_CHAN];
+	/* Timestamp */
+	s64 ts __aligned(8);
+};
+
+/* Layout of atomic buffers within big buffer */
+struct tsc2046_adc_group_layout {
+	/* Group offset within the SPI RX buffer */
+	unsigned int offset;
+	/*
+	 * Amount of tsc2046_adc_atom structs within the same command gathered
+	 * within same group.
+	 */
+	unsigned int count;
+	/*
+	 * Settling samples (tsc2046_adc_atom structs) which should be skipped
+	 * before good samples will start.
+	 */
+	unsigned int skip;
+};
+
+struct tsc2046_adc_dcfg {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+};
+
+struct tsc2046_adc_ch_cfg {
+	unsigned int settling_time_us;
+	unsigned int oversampling_ratio;
+};
+
+struct tsc2046_adc_priv {
+	struct spi_device *spi;
+	const struct tsc2046_adc_dcfg *dcfg;
+
+	struct iio_trigger *trig;
+	struct hrtimer trig_timer;
+	spinlock_t trig_lock;
+	atomic_t trig_more_count;
+
+	struct spi_transfer xfer;
+	struct spi_message msg;
+
+	struct tsc2046_adc_scan_buf scan_buf;
+	/*
+	 * Lock to protect the layout and the spi transfer buffer.
+	 * tsc2046_adc_group_layout can be changed within update_scan_mode(),
+	 * in this case the l[] and tx/rx buffer will be out of sync to each
+	 * other.
+	 */
+	struct mutex slock;
+	struct tsc2046_adc_group_layout l[TI_TSC2046_MAX_CHAN];
+	struct tsc2046_adc_atom *rx;
+	struct tsc2046_adc_atom *tx;
+
+	struct tsc2046_adc_atom *rx_one;
+	struct tsc2046_adc_atom *tx_one;
+
+	unsigned int count;
+	unsigned int groups;
+	u32 effective_speed_hz;
+	u32 scan_interval_us;
+	u32 time_per_scan_us;
+	u32 time_per_bit_ns;
+
+	struct tsc2046_adc_ch_cfg ch_cfg[TI_TSC2046_MAX_CHAN];
+};
+
+#define TI_TSC2046_V_CHAN(index, bits, name)			\
+{								\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.channel = index,					\
+	.datasheet_name = "#name",				\
+	.scan_index = index,					\
+	.scan_type = {						\
+		.sign = 'u',					\
+		.realbits = bits,				\
+		.storagebits = 16,				\
+		.endianness = IIO_CPU,				\
+	},							\
+}
+
+#define DECLARE_TI_TSC2046_8_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+	TI_TSC2046_V_CHAN(0, bits, TEMP0), \
+	TI_TSC2046_V_CHAN(1, bits, Y), \
+	TI_TSC2046_V_CHAN(2, bits, VBAT), \
+	TI_TSC2046_V_CHAN(3, bits, Z1), \
+	TI_TSC2046_V_CHAN(4, bits, Z2), \
+	TI_TSC2046_V_CHAN(5, bits, X), \
+	TI_TSC2046_V_CHAN(6, bits, AUX), \
+	TI_TSC2046_V_CHAN(7, bits, TEMP1), \
+	IIO_CHAN_SOFT_TIMESTAMP(8), \
+}
+
+static DECLARE_TI_TSC2046_8_CHANNELS(tsc2046_adc, 12);
+
+static const struct tsc2046_adc_dcfg tsc2046_adc_dcfg_tsc2046e = {
+	.channels = tsc2046_adc_channels,
+	.num_channels = ARRAY_SIZE(tsc2046_adc_channels),
+};
+
+/*
+ * Convert time to a number of samples which can be transferred within this
+ * time.
+ */
+static unsigned int tsc2046_adc_time_to_count(struct tsc2046_adc_priv *priv,
+					      unsigned long time)
+{
+	unsigned int bit_count, sample_count;
+
+	bit_count = DIV_ROUND_UP(time * NSEC_PER_USEC, priv->time_per_bit_ns);
+	sample_count = DIV_ROUND_UP(bit_count, TI_TSC2046_SAMPLE_BITS);
+
+	dev_dbg(&priv->spi->dev, "Effective speed %u, time per bit: %u, count bits: %u, count samples: %u\n",
+		priv->effective_speed_hz, priv->time_per_bit_ns,
+		bit_count, sample_count);
+
+	return sample_count;
+}
+
+static u8 tsc2046_adc_get_cmd(struct tsc2046_adc_priv *priv, int ch_idx,
+			      bool keep_power)
+{
+	u32 pd;
+
+	/*
+	 * if PD bits are 0, controller will automatically disable ADC, VREF and
+	 * enable IRQ.
+	 */
+	if (keep_power)
+		pd = TI_TSC2046_PD0_ADC_ON;
+	else
+		pd = 0;
+
+	return TI_TSC2046_START | FIELD_PREP(TI_TSC2046_ADDR, ch_idx) | pd;
+}
+
+static u16 tsc2046_adc_get_value(struct tsc2046_adc_atom *buf)
+{
+	/* Last 3 bits on the wire are empty */
+	return get_unaligned_be16(&buf->data) >> 3;
+}
+
+static int tsc2046_adc_read_one(struct tsc2046_adc_priv *priv, int ch_idx,
+				u32 *effective_speed_hz)
+{
+	struct spi_transfer xfer;
+	struct spi_message msg;
+	int ret;
+
+	memset(&xfer, 0, sizeof(xfer));
+	priv->tx_one->cmd = tsc2046_adc_get_cmd(priv, ch_idx, false);
+	priv->tx_one->data = 0;
+	xfer.tx_buf = priv->tx_one;
+	xfer.rx_buf = priv->rx_one;
+	xfer.len = sizeof(*priv->tx_one);
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	/*
+	 * We aren't using spi_write_then_read() because we need to be able
+	 * to get hold of the effective_speed_hz from the xfer
+	 */
+	ret = spi_sync(priv->spi, &msg);
+	if (ret) {
+		dev_err_ratelimited(&priv->spi->dev, "SPI transfer filed %pe\n",
+				    ERR_PTR(ret));
+		return ret;
+	}
+
+	if (effective_speed_hz)
+		*effective_speed_hz = xfer.effective_speed_hz;
+
+	return tsc2046_adc_get_value(priv->rx_one);
+}
+
+static size_t tsc2046_adc_group_set_layout(struct tsc2046_adc_priv *priv,
+					   unsigned int group,
+					   unsigned int ch_idx)
+{
+	struct tsc2046_adc_ch_cfg *ch = &priv->ch_cfg[ch_idx];
+	struct tsc2046_adc_group_layout *prev, *cur;
+	unsigned int max_count, count_skip;
+	unsigned int offset = 0;
+
+	if (group) {
+		prev = &priv->l[group - 1];
+		offset = prev->offset + prev->count;
+	}
+
+	cur = &priv->l[group];
+
+	count_skip = tsc2046_adc_time_to_count(priv, ch->settling_time_us);
+	max_count = count_skip + ch->oversampling_ratio;
+
+	cur->offset = offset;
+	cur->count = max_count;
+	cur->skip = count_skip;
+
+	return sizeof(*priv->tx) * max_count;
+}
+
+static void tsc2046_adc_group_set_cmd(struct tsc2046_adc_priv *priv,
+				      unsigned int group, int ch_idx)
+{
+	struct tsc2046_adc_group_layout *l = &priv->l[group];
+	unsigned int i;
+	u8 cmd;
+
+	/*
+	 * Do not enable automatic power down on working samples. Otherwise the
+	 * plates will never be completely charged.
+	 */
+	cmd = tsc2046_adc_get_cmd(priv, ch_idx, true);
+
+	for (i = 0; i < l->count - 1; i++)
+		priv->tx[l->offset + i].cmd = cmd;
+
+	/* automatically power down on last sample */
+	priv->tx[l->offset + i].cmd = tsc2046_adc_get_cmd(priv, ch_idx, false);
+}
+
+static u16 tsc2046_adc_get_val(struct tsc2046_adc_priv *priv, int group)
+{
+	struct tsc2046_adc_group_layout *l;
+	unsigned int val, val_normalized = 0;
+	int valid_count, i;
+
+	l = &priv->l[group];
+	valid_count = l->count - l->skip;
+
+	for (i = 0; i < valid_count; i++) {
+		val = tsc2046_adc_get_value(&priv->rx[l->offset + l->skip + i]);
+		val_normalized += val;
+	}
+
+	return DIV_ROUND_UP(val_normalized, valid_count);
+}
+
+static int tsc2046_adc_scan(struct iio_dev *indio_dev)
+{
+	struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+	struct device *dev = &priv->spi->dev;
+	int group;
+	int ret;
+
+	ret = spi_sync(priv->spi, &priv->msg);
+	if (ret < 0) {
+		dev_err_ratelimited(dev, "SPI transfer filed: %pe\n",
+				    ERR_PTR(ret));
+		return ret;
+	}
+
+	for (group = 0; group < priv->groups; group++)
+		priv->scan_buf.data[group] = tsc2046_adc_get_val(priv, group);
+
+	ret = iio_push_to_buffers_with_timestamp(indio_dev, &priv->scan_buf,
+						 iio_get_time_ns(indio_dev));
+	/* If consumer is kfifo, we may get a EBUSY here - ignore it. */
+	if (ret < 0 && ret != -EBUSY) {
+		dev_err_ratelimited(dev, "Failed to push scan buffer %pe\n",
+				    ERR_PTR(ret));
+
+		return ret;
+	}
+
+	return 0;
+}
+
+static irqreturn_t tsc2046_adc_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+
+	mutex_lock(&priv->slock);
+	tsc2046_adc_scan(indio_dev);
+	mutex_unlock(&priv->slock);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int tsc2046_adc_update_scan_mode(struct iio_dev *indio_dev,
+					const unsigned long *active_scan_mask)
+{
+	struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+	unsigned int ch_idx, group = 0;
+	size_t size = 0;
+
+	mutex_lock(&priv->slock);
+
+	for_each_set_bit(ch_idx, active_scan_mask, indio_dev->num_channels) {
+		size += tsc2046_adc_group_set_layout(priv, group, ch_idx);
+		tsc2046_adc_group_set_cmd(priv, group, ch_idx);
+		group++;
+	}
+
+	priv->groups = group;
+	priv->xfer.len = size;
+	priv->time_per_scan_us = size * 8 * priv->time_per_bit_ns / NSEC_PER_USEC;
+
+	if ((priv->scan_interval_us - priv->time_per_scan_us) < 0)
+		dev_warn(&priv->spi->dev, "The scan interval (%d) is less then calculated scan time (%d)\n",
+			 priv->scan_interval_us, priv->time_per_scan_us);
+
+	mutex_unlock(&priv->slock);
+
+	return 0;
+}
+
+static const struct iio_info tsc2046_adc_info = {
+	.update_scan_mode = tsc2046_adc_update_scan_mode,
+};
+
+static enum hrtimer_restart tsc2046_adc_trig_more(struct hrtimer *hrtimer)
+{
+	struct tsc2046_adc_priv *priv = container_of(hrtimer,
+						     struct tsc2046_adc_priv,
+						     trig_timer);
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->trig_lock, flags);
+
+	disable_irq_nosync(priv->spi->irq);
+
+	atomic_inc(&priv->trig_more_count);
+	iio_trigger_poll(priv->trig);
+
+	spin_unlock_irqrestore(&priv->trig_lock, flags);
+
+	return HRTIMER_NORESTART;
+}
+
+static irqreturn_t tsc2046_adc_irq(int irq, void *dev_id)
+{
+	struct iio_dev *indio_dev = dev_id;
+	struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+
+	spin_lock(&priv->trig_lock);
+
+	hrtimer_try_to_cancel(&priv->trig_timer);
+
+	atomic_set(&priv->trig_more_count, 0);
+	disable_irq_nosync(priv->spi->irq);
+	iio_trigger_poll(priv->trig);
+
+	spin_unlock(&priv->trig_lock);
+
+	return IRQ_HANDLED;
+}
+
+static void tsc2046_adc_reenable_trigger(struct iio_trigger *trig)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+	unsigned long flags;
+	int delta;
+
+	/*
+	 * We can sample it as fast as we can, but usually we do not need so
+	 * many samples. Reduce the sample rate for default (touchscreen) use
+	 * case.
+	 * Currently we do not need a highly precise sample rate. It is enough
+	 * to have calculated numbers.
+	 */
+	delta = priv->scan_interval_us - priv->time_per_scan_us;
+	if (delta > 0)
+		fsleep(delta);
+
+	spin_lock_irqsave(&priv->trig_lock, flags);
+
+	/*
+	 * We need to trigger at least one extra sample to detect state
+	 * difference on ADC side.
+	 */
+	if (atomic_read(&priv->trig_more_count) == 0) {
+		int timeout_ms = DIV_ROUND_UP(priv->scan_interval_us,
+					      USEC_PER_MSEC);
+
+		hrtimer_start(&priv->trig_timer, ms_to_ktime(timeout_ms),
+			      HRTIMER_MODE_REL_SOFT);
+	}
+
+	enable_irq(priv->spi->irq);
+
+	spin_unlock_irqrestore(&priv->trig_lock, flags);
+}
+
+static int tsc2046_adc_set_trigger_state(struct iio_trigger *trig, bool enable)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+
+	if (enable) {
+		enable_irq(priv->spi->irq);
+	} else {
+		disable_irq(priv->spi->irq);
+		hrtimer_try_to_cancel(&priv->trig_timer);
+	}
+
+	return 0;
+}
+
+static const struct iio_trigger_ops tsc2046_adc_trigger_ops = {
+	.set_trigger_state = tsc2046_adc_set_trigger_state,
+	.reenable = tsc2046_adc_reenable_trigger,
+};
+
+static int tsc2046_adc_setup_spi_msg(struct tsc2046_adc_priv *priv)
+{
+	unsigned int ch_idx;
+	size_t size = 0;
+	int ret;
+
+	priv->tx_one = devm_kzalloc(&priv->spi->dev, sizeof(*priv->tx_one),
+				    GFP_KERNEL);
+	if (!priv->tx_one)
+		return -ENOMEM;
+
+	priv->rx_one = devm_kzalloc(&priv->spi->dev, sizeof(*priv->rx_one),
+				    GFP_KERNEL);
+	if (!priv->rx_one)
+		return -ENOMEM;
+
+	/*
+	 * Make dummy read to set initial power state and get real SPI clock
+	 * freq. It seems to be not important which channel is used for this
+	 * case.
+	 */
+	ret = tsc2046_adc_read_one(priv, TI_TSC2046_ADDR_TEMP0,
+				   &priv->effective_speed_hz);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * In case SPI controller do not report effective_speed_hz, use
+	 * configure value and hope it will match
+	 */
+	if (!priv->effective_speed_hz)
+		priv->effective_speed_hz = priv->spi->max_speed_hz;
+
+
+	priv->scan_interval_us = TI_TSC2046_SAMPLE_INTERVAL_US;
+	priv->time_per_bit_ns = DIV_ROUND_UP(NSEC_PER_SEC,
+					     priv->effective_speed_hz);
+
+	/*
+	 * Calculate and allocate maximal size buffer if all channels are
+	 * enabled.
+	 */
+	for (ch_idx = 0; ch_idx < priv->dcfg->num_channels; ch_idx++)
+		size += tsc2046_adc_group_set_layout(priv, ch_idx, ch_idx);
+
+	priv->tx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL);
+	if (!priv->tx)
+		return -ENOMEM;
+
+	priv->rx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL);
+	if (!priv->rx)
+		return -ENOMEM;
+
+	spi_message_init(&priv->msg);
+	priv->msg.context = priv;
+
+	priv->xfer.tx_buf = priv->tx;
+	priv->xfer.rx_buf = priv->rx;
+	priv->xfer.len = size;
+	spi_message_add_tail(&priv->xfer, &priv->msg);
+
+	return 0;
+}
+
+static void tsc2046_adc_parse_fwnode(struct tsc2046_adc_priv *priv)
+{
+	struct fwnode_handle *child;
+	struct device *dev = &priv->spi->dev;
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(priv->ch_cfg); i++) {
+		priv->ch_cfg[i].settling_time_us = 1;
+		priv->ch_cfg[i].oversampling_ratio = 1;
+	}
+
+	device_for_each_child_node(dev, child) {
+		u32 stl, overs, reg;
+		int ret;
+
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret) {
+			dev_err(dev, "invalid reg on %pfw, err: %pe\n", child,
+				ERR_PTR(ret));
+			continue;
+		}
+
+		if (reg >= ARRAY_SIZE(priv->ch_cfg)) {
+			dev_err(dev, "%pfw: Unsupported reg value: %i, max supported is: %zu.\n",
+				child, reg, ARRAY_SIZE(priv->ch_cfg));
+			continue;
+		}
+
+		ret = fwnode_property_read_u32(child, "settling-time-us", &stl);
+		if (!ret)
+			priv->ch_cfg[reg].settling_time_us = stl;
+
+		ret = fwnode_property_read_u32(child, "oversampling-ratio",
+					       &overs);
+		if (!ret)
+			priv->ch_cfg[reg].oversampling_ratio = overs;
+	}
+}
+
+static int tsc2046_adc_probe(struct spi_device *spi)
+{
+	const struct tsc2046_adc_dcfg *dcfg;
+	struct device *dev = &spi->dev;
+	struct tsc2046_adc_priv *priv;
+	struct iio_dev *indio_dev;
+	struct iio_trigger *trig;
+	const char *name;
+	int ret;
+
+	if (spi->max_speed_hz > TI_TSC2046_MAX_CLK_FREQ) {
+		dev_err(dev, "SPI max_speed_hz is too high: %d Hz. Max supported freq is %d Hz\n",
+			spi->max_speed_hz, TI_TSC2046_MAX_CLK_FREQ);
+		return -EINVAL;
+	}
+
+	dcfg = device_get_match_data(dev);
+	if (!dcfg)
+		return -EINVAL;
+
+	spi->bits_per_word = 8;
+	spi->mode &= ~SPI_MODE_X_MASK;
+	spi->mode |= SPI_MODE_0;
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Error in spi setup\n");
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	priv = iio_priv(indio_dev);
+	priv->dcfg = dcfg;
+
+	spi_set_drvdata(spi, indio_dev);
+
+	priv->spi = spi;
+
+	name = devm_kasprintf(dev, GFP_KERNEL, "%s-%s",
+			      TI_TSC2046_NAME, dev_name(dev));
+
+	indio_dev->name = name;
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
+	indio_dev->channels = dcfg->channels;
+	indio_dev->num_channels = dcfg->num_channels;
+	indio_dev->info = &tsc2046_adc_info;
+
+	tsc2046_adc_parse_fwnode(priv);
+
+	ret = tsc2046_adc_setup_spi_msg(priv);
+	if (ret)
+		return ret;
+
+	mutex_init(&priv->slock);
+
+	/* TODO: remove IRQ_NOAUTOEN after needed patches are mainline */
+	irq_set_status_flags(spi->irq, IRQ_NOAUTOEN);
+	ret = devm_request_irq(dev, spi->irq, &tsc2046_adc_irq,
+			       0, name, indio_dev);
+	if (ret)
+		return ret;
+
+	trig = devm_iio_trigger_alloc(dev, "touchscreen-%s", indio_dev->name);
+	if (!trig)
+		return -ENOMEM;
+
+	priv->trig = trig;
+	trig->dev.parent = indio_dev->dev.parent;
+	iio_trigger_set_drvdata(trig, indio_dev);
+	trig->ops = &tsc2046_adc_trigger_ops;
+
+	spin_lock_init(&priv->trig_lock);
+	hrtimer_init(&priv->trig_timer, CLOCK_MONOTONIC,
+		     HRTIMER_MODE_REL_SOFT);
+	priv->trig_timer.function = tsc2046_adc_trig_more;
+
+	ret = devm_iio_trigger_register(dev, trig);
+	if (ret) {
+		dev_err(dev, "failed to register trigger\n");
+		return ret;
+	}
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
+					      &tsc2046_adc_trigger_handler, NULL);
+	if (ret) {
+		dev_err(dev, "Failed to setup triggered buffer\n");
+		return ret;
+	}
+
+	/* set default trigger */
+	indio_dev->trig = iio_trigger_get(priv->trig);
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret) {
+		dev_err(dev, "Failed to register iio device\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id ads7950_of_table[] = {
+	{ .compatible = "ti,tsc2046e-adc", .data = &tsc2046_adc_dcfg_tsc2046e },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ads7950_of_table);
+
+static struct spi_driver tsc2046_adc_driver = {
+	.driver = {
+		.name = "tsc2046",
+		.of_match_table = ads7950_of_table,
+	},
+	.probe = tsc2046_adc_probe,
+};
+module_spi_driver(tsc2046_adc_driver);
+
+MODULE_AUTHOR("Oleksij Rempel <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("TI TSC2046 ADC");
+MODULE_LICENSE("GPL v2");