| Message ID | 20201123074532.3730-2-rentao.bupt@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | hwmon: (max127) Add Maxim MAX127 hardware monitoring | expand |
On Sun, Nov 22, 2020 at 11:45:31PM -0800, rentao.bupt@gmail.com wrote: > From: Tao Ren <rentao.bupt@gmail.com> > > Add hardware monitoring driver for the Maxim MAX127 chip. > > MAX127 min/max range handling code is inspired by the max197 driver. > > Signed-off-by: Tao Ren <rentao.bupt@gmail.com> > --- > Changes in v4: > - delete unnecessary "#include" lines. > - simplify i2c_transfer() error handling. > - add mutex to protect ctrl_byte in write_min|max() functions. > Changes in v3: > - no code change. xdp maintainers were removed from to/cc list. > Changes in v2: > - replace devm_hwmon_device_register_with_groups() with > devm_hwmon_device_register_with_info() API. > - divide min/max read and write methods to separate functions. > - fix raw-to-vin conversion logic. > - refine ctrl_byte handling so mutex is not needed to protect the > byte. > - improve i2c_transfer() error handling. > - a few other improvements (comments, variable naming, and etc.). > > drivers/hwmon/Kconfig | 9 ++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/max127.c | 346 +++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 356 insertions(+) > create mode 100644 drivers/hwmon/max127.c > > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 9d600e0c5584..716df51edc87 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -950,6 +950,15 @@ config SENSORS_MAX1111 > This driver can also be built as a module. If so, the module > will be called max1111. > > +config SENSORS_MAX127 > + tristate "Maxim MAX127 12-bit 8-channel Data Acquisition System" > + depends on I2C > + help > + Say y here to support Maxim's MAX127 DAS chips. > + > + This driver can also be built as a module. If so, the module > + will be called max127. > + > config SENSORS_MAX16065 > tristate "Maxim MAX16065 System Manager and compatibles" > depends on I2C > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index 1083bbfac779..01ca5d3fbad4 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -127,6 +127,7 @@ obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o > obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o > obj-$(CONFIG_SENSORS_LTQ_CPUTEMP) += ltq-cputemp.o > obj-$(CONFIG_SENSORS_MAX1111) += max1111.o > +obj-$(CONFIG_SENSORS_MAX127) += max127.o > obj-$(CONFIG_SENSORS_MAX16065) += max16065.o > obj-$(CONFIG_SENSORS_MAX1619) += max1619.o > obj-$(CONFIG_SENSORS_MAX1668) += max1668.o > diff --git a/drivers/hwmon/max127.c b/drivers/hwmon/max127.c > new file mode 100644 > index 000000000000..1c54146b6086 > --- /dev/null > +++ b/drivers/hwmon/max127.c > @@ -0,0 +1,346 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* > + * Hardware monitoring driver for MAX127. > + * > + * Copyright (c) 2020 Facebook Inc. > + */ > + > +#include <linux/err.h> > +#include <linux/hwmon.h> > +#include <linux/i2c.h> > +#include <linux/init.h> > +#include <linux/module.h> > + > +/* > + * MAX127 Control Byte. Refer to MAX127 datasheet, Table 1 "Control-Byte > + * Format" for details. > + */ > +#define MAX127_CTRL_START BIT(7) > +#define MAX127_CTRL_SEL_SHIFT 4 > +#define MAX127_CTRL_RNG BIT(3) > +#define MAX127_CTRL_BIP BIT(2) > +#define MAX127_CTRL_PD1 BIT(1) > +#define MAX127_CTRL_PD0 BIT(0) > + > +#define MAX127_NUM_CHANNELS 8 > +#define MAX127_SET_CHANNEL(ch) (((ch) & 7) << MAX127_CTRL_SEL_SHIFT) > + > +/* > + * MAX127 channel input ranges. Refer to MAX127 datasheet, Table 3 "Range > + * and Polarity Selection" for details. > + */ > +#define MAX127_FULL_RANGE 10000 /* 10V */ > +#define MAX127_HALF_RANGE 5000 /* 5V */ > + > +/* > + * MAX127 returns 2 bytes at read: > + * - the first byte contains data[11:4]. > + * - the second byte contains data[3:0] (MSB) and 4 dummy 0s (LSB). > + * Refer to MAX127 datasheet, "Read a Conversion (Read Cycle)" section > + * for details. > + */ > +#define MAX127_DATA_LEN 2 > +#define MAX127_DATA_SHIFT 4 > + > +#define MAX127_SIGN_BIT BIT(11) > + > +struct max127_data { > + struct mutex lock; > + struct i2c_client *client; > + u8 ctrl_byte[MAX127_NUM_CHANNELS]; > +}; > + > +static int max127_select_channel(struct i2c_client *client, u8 ctrl_byte) > +{ > + int status; > + struct i2c_msg msg = { > + .addr = client->addr, > + .flags = 0, > + .len = sizeof(ctrl_byte), > + .buf = &ctrl_byte, > + }; > + > + status = i2c_transfer(client->adapter, &msg, 1); > + > + return (status == 1) ? 0 : -EIO; This isn't what I said and asked for. It drops the unnecessary else, but now it overwrites an error value. Guenter > +} > + > +static int max127_read_channel(struct i2c_client *client, long *val) > +{ > + int status; > + u8 i2c_data[MAX127_DATA_LEN]; > + struct i2c_msg msg = { > + .addr = client->addr, > + .flags = I2C_M_RD, > + .len = sizeof(i2c_data), > + .buf = i2c_data, > + }; > + > + status = i2c_transfer(client->adapter, &msg, 1); > + if (status != 1) > + return -EIO; This isn't what I asked for. Guenter > + > + *val = (i2c_data[1] >> MAX127_DATA_SHIFT) | > + ((u16)i2c_data[0] << MAX127_DATA_SHIFT); > + return 0; > +} > + > +static long max127_process_raw(u8 ctrl_byte, long raw) > +{ > + long scale, weight; > + > + /* > + * MAX127's data coding is binary in unipolar mode with 1 LSB = > + * (Full-Scale/4096) and two’s complement binary in bipolar mode > + * with 1 LSB = [(2 x |FS|)/4096]. > + * Refer to MAX127 datasheet, "Transfer Function" section for > + * details. > + */ > + scale = (ctrl_byte & MAX127_CTRL_RNG) ? MAX127_FULL_RANGE : > + MAX127_HALF_RANGE; > + if (ctrl_byte & MAX127_CTRL_BIP) { > + weight = (raw & MAX127_SIGN_BIT); > + raw &= ~MAX127_SIGN_BIT; > + raw -= weight; > + raw *= 2; > + } > + > + return raw * scale / 4096; > +} > + > +static int max127_read_input(struct max127_data *data, int channel, long *val) > +{ > + long raw; > + int status; > + struct i2c_client *client = data->client; > + u8 ctrl_byte = data->ctrl_byte[channel]; > + > + mutex_lock(&data->lock); > + > + status = max127_select_channel(client, ctrl_byte); > + if (status) > + goto exit; > + > + status = max127_read_channel(client, &raw); > + if (status) > + goto exit; > + > + *val = max127_process_raw(ctrl_byte, raw); > + > +exit: > + mutex_unlock(&data->lock); > + return status; > +} > + > +static int max127_read_min(struct max127_data *data, int channel, long *val) > +{ > + u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3; > + static const int min_input_map[4] = { > + 0, /* RNG=0, BIP=0 */ > + -MAX127_HALF_RANGE, /* RNG=0, BIP=1 */ > + 0, /* RNG=1, BIP=0 */ > + -MAX127_FULL_RANGE, /* RNG=1, BIP=1 */ > + }; > + > + *val = min_input_map[rng_bip]; > + return 0; > +} > + > +static int max127_read_max(struct max127_data *data, int channel, long *val) > +{ > + u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3; > + static const int max_input_map[4] = { > + MAX127_HALF_RANGE, /* RNG=0, BIP=0 */ > + MAX127_HALF_RANGE, /* RNG=0, BIP=1 */ > + MAX127_FULL_RANGE, /* RNG=1, BIP=0 */ > + MAX127_FULL_RANGE, /* RNG=1, BIP=1 */ > + }; > + > + *val = max_input_map[rng_bip]; > + return 0; > +} > + > +static int max127_write_min(struct max127_data *data, int channel, long val) > +{ > + u8 ctrl; > + > + mutex_lock(&data->lock); > + > + ctrl = data->ctrl_byte[channel]; > + if (val <= -MAX127_FULL_RANGE) { > + ctrl |= (MAX127_CTRL_RNG | MAX127_CTRL_BIP); > + } else if (val < 0) { > + ctrl |= MAX127_CTRL_BIP; > + ctrl &= ~MAX127_CTRL_RNG; > + } else { > + ctrl &= ~MAX127_CTRL_BIP; > + } > + data->ctrl_byte[channel] = ctrl; > + > + mutex_unlock(&data->lock); > + > + return 0; > +} > + > +static int max127_write_max(struct max127_data *data, int channel, long val) > +{ > + mutex_lock(&data->lock); > + > + if (val >= MAX127_FULL_RANGE) > + data->ctrl_byte[channel] |= MAX127_CTRL_RNG; > + else > + data->ctrl_byte[channel] &= ~MAX127_CTRL_RNG; > + > + mutex_unlock(&data->lock); > + > + return 0; > +} > + > +static umode_t max127_is_visible(const void *_data, > + enum hwmon_sensor_types type, > + u32 attr, int channel) > +{ > + if (type == hwmon_in) { > + switch (attr) { > + case hwmon_in_input: > + return 0444; > + > + case hwmon_in_min: > + case hwmon_in_max: > + return 0644; > + > + default: > + break; > + } > + } > + > + return 0; > +} > + > +static int max127_read(struct device *dev, enum hwmon_sensor_types type, > + u32 attr, int channel, long *val) > +{ > + int status; > + struct max127_data *data = dev_get_drvdata(dev); > + > + if (type != hwmon_in) > + return -EOPNOTSUPP; > + > + switch (attr) { > + case hwmon_in_input: > + status = max127_read_input(data, channel, val); > + break; > + > + case hwmon_in_min: > + status = max127_read_min(data, channel, val); > + break; > + > + case hwmon_in_max: > + status = max127_read_max(data, channel, val); > + break; > + > + default: > + status = -EOPNOTSUPP; > + break; > + } > + > + return status; > +} > + > +static int max127_write(struct device *dev, enum hwmon_sensor_types type, > + u32 attr, int channel, long val) > +{ > + int status; > + struct max127_data *data = dev_get_drvdata(dev); > + > + if (type != hwmon_in) > + return -EOPNOTSUPP; > + > + switch (attr) { > + case hwmon_in_min: > + status = max127_write_min(data, channel, val); > + break; > + > + case hwmon_in_max: > + status = max127_write_max(data, channel, val); > + break; > + > + default: > + status = -EOPNOTSUPP; > + break; > + } > + > + return status; > +} > + > +static const struct hwmon_ops max127_hwmon_ops = { > + .is_visible = max127_is_visible, > + .read = max127_read, > + .write = max127_write, > +}; > + > +static const struct hwmon_channel_info *max127_info[] = { > + HWMON_CHANNEL_INFO(in, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, > + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX), > + NULL, > +}; > + > +static const struct hwmon_chip_info max127_chip_info = { > + .ops = &max127_hwmon_ops, > + .info = max127_info, > +}; > + > +static int max127_probe(struct i2c_client *client, > + const struct i2c_device_id *id) > +{ > + int i; > + struct device *hwmon_dev; > + struct max127_data *data; > + struct device *dev = &client->dev; > + > + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + data->client = client; > + mutex_init(&data->lock); > + for (i = 0; i < ARRAY_SIZE(data->ctrl_byte); i++) > + data->ctrl_byte[i] = (MAX127_CTRL_START | > + MAX127_SET_CHANNEL(i)); > + > + hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, > + data, > + &max127_chip_info, > + NULL); > + > + return PTR_ERR_OR_ZERO(hwmon_dev); > +} > + > +static const struct i2c_device_id max127_id[] = { > + { "max127", 0 }, > + { } > +}; > +MODULE_DEVICE_TABLE(i2c, max127_id); > + > +static struct i2c_driver max127_driver = { > + .class = I2C_CLASS_HWMON, > + .driver = { > + .name = "max127", > + }, > + .probe = max127_probe, > + .id_table = max127_id, > +}; > + > +module_i2c_driver(max127_driver); > + > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Mike Choi <mikechoi@fb.com>"); > +MODULE_AUTHOR("Tao Ren <rentao.bupt@gmail.com>"); > +MODULE_DESCRIPTION("MAX127 Hardware Monitoring driver"); > -- > 2.17.1 >
On Mon, Nov 23, 2020 at 05:18:32AM -0800, Guenter Roeck wrote: > On Sun, Nov 22, 2020 at 11:45:31PM -0800, rentao.bupt@gmail.com wrote: > > From: Tao Ren <rentao.bupt@gmail.com> > > > > Add hardware monitoring driver for the Maxim MAX127 chip. > > > > MAX127 min/max range handling code is inspired by the max197 driver. > > > > Signed-off-by: Tao Ren <rentao.bupt@gmail.com> > > --- > > Changes in v4: > > - delete unnecessary "#include" lines. > > - simplify i2c_transfer() error handling. > > - add mutex to protect ctrl_byte in write_min|max() functions. > > Changes in v3: > > - no code change. xdp maintainers were removed from to/cc list. > > Changes in v2: > > - replace devm_hwmon_device_register_with_groups() with > > devm_hwmon_device_register_with_info() API. > > - divide min/max read and write methods to separate functions. > > - fix raw-to-vin conversion logic. > > - refine ctrl_byte handling so mutex is not needed to protect the > > byte. > > - improve i2c_transfer() error handling. > > - a few other improvements (comments, variable naming, and etc.). > > > > drivers/hwmon/Kconfig | 9 ++ > > drivers/hwmon/Makefile | 1 + > > drivers/hwmon/max127.c | 346 +++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 356 insertions(+) > > create mode 100644 drivers/hwmon/max127.c > > > > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > > index 9d600e0c5584..716df51edc87 100644 > > --- a/drivers/hwmon/Kconfig > > +++ b/drivers/hwmon/Kconfig > > @@ -950,6 +950,15 @@ config SENSORS_MAX1111 > > This driver can also be built as a module. If so, the module > > will be called max1111. > > > > +config SENSORS_MAX127 > > + tristate "Maxim MAX127 12-bit 8-channel Data Acquisition System" > > + depends on I2C > > + help > > + Say y here to support Maxim's MAX127 DAS chips. > > + > > + This driver can also be built as a module. If so, the module > > + will be called max127. > > + > > config SENSORS_MAX16065 > > tristate "Maxim MAX16065 System Manager and compatibles" > > depends on I2C > > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > > index 1083bbfac779..01ca5d3fbad4 100644 > > --- a/drivers/hwmon/Makefile > > +++ b/drivers/hwmon/Makefile > > @@ -127,6 +127,7 @@ obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o > > obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o > > obj-$(CONFIG_SENSORS_LTQ_CPUTEMP) += ltq-cputemp.o > > obj-$(CONFIG_SENSORS_MAX1111) += max1111.o > > +obj-$(CONFIG_SENSORS_MAX127) += max127.o > > obj-$(CONFIG_SENSORS_MAX16065) += max16065.o > > obj-$(CONFIG_SENSORS_MAX1619) += max1619.o > > obj-$(CONFIG_SENSORS_MAX1668) += max1668.o > > diff --git a/drivers/hwmon/max127.c b/drivers/hwmon/max127.c > > new file mode 100644 > > index 000000000000..1c54146b6086 > > --- /dev/null > > +++ b/drivers/hwmon/max127.c > > @@ -0,0 +1,346 @@ > > +// SPDX-License-Identifier: GPL-2.0+ > > +/* > > + * Hardware monitoring driver for MAX127. > > + * > > + * Copyright (c) 2020 Facebook Inc. > > + */ > > + > > +#include <linux/err.h> > > +#include <linux/hwmon.h> > > +#include <linux/i2c.h> > > +#include <linux/init.h> > > +#include <linux/module.h> > > + > > +/* > > + * MAX127 Control Byte. Refer to MAX127 datasheet, Table 1 "Control-Byte > > + * Format" for details. > > + */ > > +#define MAX127_CTRL_START BIT(7) > > +#define MAX127_CTRL_SEL_SHIFT 4 > > +#define MAX127_CTRL_RNG BIT(3) > > +#define MAX127_CTRL_BIP BIT(2) > > +#define MAX127_CTRL_PD1 BIT(1) > > +#define MAX127_CTRL_PD0 BIT(0) > > + > > +#define MAX127_NUM_CHANNELS 8 > > +#define MAX127_SET_CHANNEL(ch) (((ch) & 7) << MAX127_CTRL_SEL_SHIFT) > > + > > +/* > > + * MAX127 channel input ranges. Refer to MAX127 datasheet, Table 3 "Range > > + * and Polarity Selection" for details. > > + */ > > +#define MAX127_FULL_RANGE 10000 /* 10V */ > > +#define MAX127_HALF_RANGE 5000 /* 5V */ > > + > > +/* > > + * MAX127 returns 2 bytes at read: > > + * - the first byte contains data[11:4]. > > + * - the second byte contains data[3:0] (MSB) and 4 dummy 0s (LSB). > > + * Refer to MAX127 datasheet, "Read a Conversion (Read Cycle)" section > > + * for details. > > + */ > > +#define MAX127_DATA_LEN 2 > > +#define MAX127_DATA_SHIFT 4 > > + > > +#define MAX127_SIGN_BIT BIT(11) > > + > > +struct max127_data { > > + struct mutex lock; > > + struct i2c_client *client; > > + u8 ctrl_byte[MAX127_NUM_CHANNELS]; > > +}; > > + > > +static int max127_select_channel(struct i2c_client *client, u8 ctrl_byte) > > +{ > > + int status; > > + struct i2c_msg msg = { > > + .addr = client->addr, > > + .flags = 0, > > + .len = sizeof(ctrl_byte), > > + .buf = &ctrl_byte, > > + }; > > + > > + status = i2c_transfer(client->adapter, &msg, 1); > > + > > + return (status == 1) ? 0 : -EIO; > > This isn't what I said and asked for. It drops the unnecessary else, > but now it overwrites an error value. > > Guenter > > > +} > > + > > +static int max127_read_channel(struct i2c_client *client, long *val) > > +{ > > + int status; > > + u8 i2c_data[MAX127_DATA_LEN]; > > + struct i2c_msg msg = { > > + .addr = client->addr, > > + .flags = I2C_M_RD, > > + .len = sizeof(i2c_data), > > + .buf = i2c_data, > > + }; > > + > > + status = i2c_transfer(client->adapter, &msg, 1); > > + if (status != 1) > > + return -EIO; > > This isn't what I asked for. > > Guenter Both places are fixed in v5. Thanks for the clarify, Guenter. Cheers, Tao
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index 9d600e0c5584..716df51edc87 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -950,6 +950,15 @@ config SENSORS_MAX1111 This driver can also be built as a module. If so, the module will be called max1111. +config SENSORS_MAX127 + tristate "Maxim MAX127 12-bit 8-channel Data Acquisition System" + depends on I2C + help + Say y here to support Maxim's MAX127 DAS chips. + + This driver can also be built as a module. If so, the module + will be called max127. + config SENSORS_MAX16065 tristate "Maxim MAX16065 System Manager and compatibles" depends on I2C diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 1083bbfac779..01ca5d3fbad4 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -127,6 +127,7 @@ obj-$(CONFIG_SENSORS_LTC4260) += ltc4260.o obj-$(CONFIG_SENSORS_LTC4261) += ltc4261.o obj-$(CONFIG_SENSORS_LTQ_CPUTEMP) += ltq-cputemp.o obj-$(CONFIG_SENSORS_MAX1111) += max1111.o +obj-$(CONFIG_SENSORS_MAX127) += max127.o obj-$(CONFIG_SENSORS_MAX16065) += max16065.o obj-$(CONFIG_SENSORS_MAX1619) += max1619.o obj-$(CONFIG_SENSORS_MAX1668) += max1668.o diff --git a/drivers/hwmon/max127.c b/drivers/hwmon/max127.c new file mode 100644 index 000000000000..1c54146b6086 --- /dev/null +++ b/drivers/hwmon/max127.c @@ -0,0 +1,346 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Hardware monitoring driver for MAX127. + * + * Copyright (c) 2020 Facebook Inc. + */ + +#include <linux/err.h> +#include <linux/hwmon.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/module.h> + +/* + * MAX127 Control Byte. Refer to MAX127 datasheet, Table 1 "Control-Byte + * Format" for details. + */ +#define MAX127_CTRL_START BIT(7) +#define MAX127_CTRL_SEL_SHIFT 4 +#define MAX127_CTRL_RNG BIT(3) +#define MAX127_CTRL_BIP BIT(2) +#define MAX127_CTRL_PD1 BIT(1) +#define MAX127_CTRL_PD0 BIT(0) + +#define MAX127_NUM_CHANNELS 8 +#define MAX127_SET_CHANNEL(ch) (((ch) & 7) << MAX127_CTRL_SEL_SHIFT) + +/* + * MAX127 channel input ranges. Refer to MAX127 datasheet, Table 3 "Range + * and Polarity Selection" for details. + */ +#define MAX127_FULL_RANGE 10000 /* 10V */ +#define MAX127_HALF_RANGE 5000 /* 5V */ + +/* + * MAX127 returns 2 bytes at read: + * - the first byte contains data[11:4]. + * - the second byte contains data[3:0] (MSB) and 4 dummy 0s (LSB). + * Refer to MAX127 datasheet, "Read a Conversion (Read Cycle)" section + * for details. + */ +#define MAX127_DATA_LEN 2 +#define MAX127_DATA_SHIFT 4 + +#define MAX127_SIGN_BIT BIT(11) + +struct max127_data { + struct mutex lock; + struct i2c_client *client; + u8 ctrl_byte[MAX127_NUM_CHANNELS]; +}; + +static int max127_select_channel(struct i2c_client *client, u8 ctrl_byte) +{ + int status; + struct i2c_msg msg = { + .addr = client->addr, + .flags = 0, + .len = sizeof(ctrl_byte), + .buf = &ctrl_byte, + }; + + status = i2c_transfer(client->adapter, &msg, 1); + + return (status == 1) ? 0 : -EIO; +} + +static int max127_read_channel(struct i2c_client *client, long *val) +{ + int status; + u8 i2c_data[MAX127_DATA_LEN]; + struct i2c_msg msg = { + .addr = client->addr, + .flags = I2C_M_RD, + .len = sizeof(i2c_data), + .buf = i2c_data, + }; + + status = i2c_transfer(client->adapter, &msg, 1); + if (status != 1) + return -EIO; + + *val = (i2c_data[1] >> MAX127_DATA_SHIFT) | + ((u16)i2c_data[0] << MAX127_DATA_SHIFT); + return 0; +} + +static long max127_process_raw(u8 ctrl_byte, long raw) +{ + long scale, weight; + + /* + * MAX127's data coding is binary in unipolar mode with 1 LSB = + * (Full-Scale/4096) and two’s complement binary in bipolar mode + * with 1 LSB = [(2 x |FS|)/4096]. + * Refer to MAX127 datasheet, "Transfer Function" section for + * details. + */ + scale = (ctrl_byte & MAX127_CTRL_RNG) ? MAX127_FULL_RANGE : + MAX127_HALF_RANGE; + if (ctrl_byte & MAX127_CTRL_BIP) { + weight = (raw & MAX127_SIGN_BIT); + raw &= ~MAX127_SIGN_BIT; + raw -= weight; + raw *= 2; + } + + return raw * scale / 4096; +} + +static int max127_read_input(struct max127_data *data, int channel, long *val) +{ + long raw; + int status; + struct i2c_client *client = data->client; + u8 ctrl_byte = data->ctrl_byte[channel]; + + mutex_lock(&data->lock); + + status = max127_select_channel(client, ctrl_byte); + if (status) + goto exit; + + status = max127_read_channel(client, &raw); + if (status) + goto exit; + + *val = max127_process_raw(ctrl_byte, raw); + +exit: + mutex_unlock(&data->lock); + return status; +} + +static int max127_read_min(struct max127_data *data, int channel, long *val) +{ + u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3; + static const int min_input_map[4] = { + 0, /* RNG=0, BIP=0 */ + -MAX127_HALF_RANGE, /* RNG=0, BIP=1 */ + 0, /* RNG=1, BIP=0 */ + -MAX127_FULL_RANGE, /* RNG=1, BIP=1 */ + }; + + *val = min_input_map[rng_bip]; + return 0; +} + +static int max127_read_max(struct max127_data *data, int channel, long *val) +{ + u8 rng_bip = (data->ctrl_byte[channel] >> 2) & 3; + static const int max_input_map[4] = { + MAX127_HALF_RANGE, /* RNG=0, BIP=0 */ + MAX127_HALF_RANGE, /* RNG=0, BIP=1 */ + MAX127_FULL_RANGE, /* RNG=1, BIP=0 */ + MAX127_FULL_RANGE, /* RNG=1, BIP=1 */ + }; + + *val = max_input_map[rng_bip]; + return 0; +} + +static int max127_write_min(struct max127_data *data, int channel, long val) +{ + u8 ctrl; + + mutex_lock(&data->lock); + + ctrl = data->ctrl_byte[channel]; + if (val <= -MAX127_FULL_RANGE) { + ctrl |= (MAX127_CTRL_RNG | MAX127_CTRL_BIP); + } else if (val < 0) { + ctrl |= MAX127_CTRL_BIP; + ctrl &= ~MAX127_CTRL_RNG; + } else { + ctrl &= ~MAX127_CTRL_BIP; + } + data->ctrl_byte[channel] = ctrl; + + mutex_unlock(&data->lock); + + return 0; +} + +static int max127_write_max(struct max127_data *data, int channel, long val) +{ + mutex_lock(&data->lock); + + if (val >= MAX127_FULL_RANGE) + data->ctrl_byte[channel] |= MAX127_CTRL_RNG; + else + data->ctrl_byte[channel] &= ~MAX127_CTRL_RNG; + + mutex_unlock(&data->lock); + + return 0; +} + +static umode_t max127_is_visible(const void *_data, + enum hwmon_sensor_types type, + u32 attr, int channel) +{ + if (type == hwmon_in) { + switch (attr) { + case hwmon_in_input: + return 0444; + + case hwmon_in_min: + case hwmon_in_max: + return 0644; + + default: + break; + } + } + + return 0; +} + +static int max127_read(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long *val) +{ + int status; + struct max127_data *data = dev_get_drvdata(dev); + + if (type != hwmon_in) + return -EOPNOTSUPP; + + switch (attr) { + case hwmon_in_input: + status = max127_read_input(data, channel, val); + break; + + case hwmon_in_min: + status = max127_read_min(data, channel, val); + break; + + case hwmon_in_max: + status = max127_read_max(data, channel, val); + break; + + default: + status = -EOPNOTSUPP; + break; + } + + return status; +} + +static int max127_write(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long val) +{ + int status; + struct max127_data *data = dev_get_drvdata(dev); + + if (type != hwmon_in) + return -EOPNOTSUPP; + + switch (attr) { + case hwmon_in_min: + status = max127_write_min(data, channel, val); + break; + + case hwmon_in_max: + status = max127_write_max(data, channel, val); + break; + + default: + status = -EOPNOTSUPP; + break; + } + + return status; +} + +static const struct hwmon_ops max127_hwmon_ops = { + .is_visible = max127_is_visible, + .read = max127_read, + .write = max127_write, +}; + +static const struct hwmon_channel_info *max127_info[] = { + HWMON_CHANNEL_INFO(in, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX, + HWMON_I_INPUT | HWMON_I_MIN | HWMON_I_MAX), + NULL, +}; + +static const struct hwmon_chip_info max127_chip_info = { + .ops = &max127_hwmon_ops, + .info = max127_info, +}; + +static int max127_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + int i; + struct device *hwmon_dev; + struct max127_data *data; + struct device *dev = &client->dev; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->client = client; + mutex_init(&data->lock); + for (i = 0; i < ARRAY_SIZE(data->ctrl_byte); i++) + data->ctrl_byte[i] = (MAX127_CTRL_START | + MAX127_SET_CHANNEL(i)); + + hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, + data, + &max127_chip_info, + NULL); + + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct i2c_device_id max127_id[] = { + { "max127", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max127_id); + +static struct i2c_driver max127_driver = { + .class = I2C_CLASS_HWMON, + .driver = { + .name = "max127", + }, + .probe = max127_probe, + .id_table = max127_id, +}; + +module_i2c_driver(max127_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Mike Choi <mikechoi@fb.com>"); +MODULE_AUTHOR("Tao Ren <rentao.bupt@gmail.com>"); +MODULE_DESCRIPTION("MAX127 Hardware Monitoring driver");