[PATCHv4,1/3] Add support for GMT G762/G763 PWM fan controller

Commit Message

Arnaud Ebalard June 4, 2013, 7:14 a.m. UTC

Signed-off-by: Arnaud Ebalard <[e-mail]>
---
 drivers/hwmon/Kconfig              |   10 +
 drivers/hwmon/Makefile             |    1 +
 drivers/hwmon/g762.c               | 1111 ++++++++++++++++++++++++++++++++++++
 include/linux/platform_data/g762.h |   47 ++
 4 files changed, 1169 insertions(+)
 create mode 100644 drivers/hwmon/g762.c
 create mode 100644 include/linux/platform_data/g762.h

Comments

Guenter Roeck June 11, 2013, 3:11 p.m. UTC | #1

On Tue, Jun 04, 2013 at 09:14:29AM +0200, Arnaud Ebalard wrote:
> 
> Signed-off-by: Arnaud Ebalard <[e-mail]>
> ---
>  drivers/hwmon/Kconfig              |   10 +
>  drivers/hwmon/Makefile             |    1 +
>  drivers/hwmon/g762.c               | 1111 ++++++++++++++++++++++++++++++++++++
>  include/linux/platform_data/g762.h |   47 ++
>  4 files changed, 1169 insertions(+)
>  create mode 100644 drivers/hwmon/g762.c
>  create mode 100644 include/linux/platform_data/g762.h
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 0428e8a..142bdf8 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -456,6 +456,16 @@ config SENSORS_G760A
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called g760a.
>  
> +config SENSORS_G762
> +	tristate "GMT G762 and G763"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for Global Mixed-mode
> +	  Technology Inc G762 and G763 fan speed PWM controller chips.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called g762.
> +
>  config SENSORS_GL518SM
>  	tristate "Genesys Logic GL518SM"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index d17d3e6..4f0fb52 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -60,6 +60,7 @@ obj-$(CONFIG_SENSORS_F75375S)	+= f75375s.o
>  obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o
>  obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o
>  obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
> +obj-$(CONFIG_SENSORS_G762)	+= g762.o
>  obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
>  obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
>  obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
> diff --git a/drivers/hwmon/g762.c b/drivers/hwmon/g762.c
> new file mode 100644
> index 0000000..194be43
> --- /dev/null
> +++ b/drivers/hwmon/g762.c
> @@ -0,0 +1,1111 @@
> +/*
> + * g762 - Driver for the Global Mixed-mode Technology Inc. fan speed
> + *        PWM controller chips from G762 family, i.e. G762 and G763
> + *
> + * Copyright (C) 2013, Arnaud EBALARD <[e-mail]>
> + *
> + * This work is based on a basic version for 2.6.31 kernel developed
> + * by Olivier Mouchet for LaCie. Updates and correction have been
> + * performed to run on recent kernels. Additional features, like the
> + * ability to configure various characteristics via .dts file, have
> + * been added. Detailed datasheet on which this development is based
> + * is available here:
> + *
> + *  http://natisbad.org/NAS/refs/GMT_EDS-762_763-080710-0.2.pdf
> + *
> + * Headers from previous developments have been kept below:
> + *
> + * Copyright (c) 2009 LaCie
> + *
> + * Author: Olivier Mouchet <[e-mail]>
> + *
> + * based on g760a code written by Herbert Valerio Riedel <[e-mail]>
> + * Copyright (C) 2007  Herbert Valerio Riedel <[e-mail]>
> + *
> + * g762: minimal datasheet available at:
> + *       http://www.gmt.com.tw/product/datasheet/EDS-762_3.pdf
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_data/g762.h>
> +
> +#define DRVNAME "g762"
> +
> +static const struct i2c_device_id g762_id[] = {
> +	{ "g762", 0 },
> +	{ "g763", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, g762_id);
> +
> +enum g762_regs {
> +	G762_REG_SET_CNT  = 0x00,
> +	G762_REG_ACT_CNT  = 0x01,
> +	G762_REG_FAN_STA  = 0x02,
> +	G762_REG_SET_OUT  = 0x03,
> +	G762_REG_FAN_CMD1 = 0x04,
> +	G762_REG_FAN_CMD2 = 0x05,
> +};
> +
> +/* Config register bits */
> +#define G762_REG_FAN_CMD1_DET_FAN_FAIL  0x80 /* enable fan_fail signal */
> +#define G762_REG_FAN_CMD1_DET_FAN_OOC   0x40 /* enable fan_out_of_control */
> +#define G762_REG_FAN_CMD1_OUT_MODE      0x20 /* out mode, PWM or DC */
> +#define G762_REG_FAN_CMD1_FAN_MODE      0x10 /* fan mode: closed/open loop */
> +#define G762_REG_FAN_CMD1_CLK_DIV_ID1   0x08 /* clock divisor value */
> +#define G762_REG_FAN_CMD1_CLK_DIV_ID0   0x04
> +#define G762_REG_FAN_CMD1_PWM_POLARITY  0x02 /* PWM polarity */
> +#define G762_REG_FAN_CMD1_PULSE_PER_REV 0x01 /* pulse per fan revolution */
> +
> +#define G762_REG_FAN_CMD2_GEAR_MODE_1   0x08 /* fan gear mode */
> +#define G762_REG_FAN_CMD2_GEAR_MODE_0   0x04
> +#define G762_REG_FAN_CMD2_FAN_STARTV_1  0x02 /* fan startup voltage */
> +#define G762_REG_FAN_CMD2_FAN_STARTV_0  0x01
> +
> +#define G762_REG_FAN_STA_FAIL           0x02 /* fan fail */
> +#define G762_REG_FAN_STA_OOC            0x01 /* fan out of control */
> +
> +/* config register values */
> +#define OUT_MODE_PWM            1
> +#define OUT_MODE_DC             0
> +
> +#define FAN_MODE_CLOSED_LOOP    2
> +#define FAN_MODE_OPEN_LOOP      1
> +
> +/* register data is read (and cached) at most once per second */
> +#define G762_UPDATE_INTERVAL    HZ
> +
> +/*
> + * extract pulse count per fan revolution value (2 or 4) from given
> + * FAN_CMD1 register value
> + */
> +#define PULSE_FROM_REG(reg) \
> +	((((reg) & G762_REG_FAN_CMD1_PULSE_PER_REV) + 1) << 1)
> +
> +/*
> + * extract fan clock divisor (1, 2, 4 or 8) from given FAN_CMD1
> + * register value
> + */
> +#define CLKDIV_FROM_REG(reg) \
> +	(1 << (((reg) & (G762_REG_FAN_CMD1_CLK_DIV_ID0 |	\
> +			 G762_REG_FAN_CMD1_CLK_DIV_ID1)) >> 2))
> +
> +/*
> + * extract fan gear mode multiplier value (0, 2 or 4) from given
> + * FAN_CMD2 register value
> + */
> +#define GEARMULT_FROM_REG(reg) \
> +	(1 << (((reg) & (G762_REG_FAN_CMD2_GEAR_MODE_0 |	\
> +			 G762_REG_FAN_CMD2_GEAR_MODE_1)) >> 2))
> +
> +struct g762_data {
> +	struct i2c_client *client;
> +	struct device *hwmon_dev;
> +
> +	/* update mutex */
> +	struct mutex update_lock;
> +
> +	/* board specific parameters. */
> +	u32 clk;
> +
> +	/* g762 register cache */
> +	bool valid;
> +	unsigned long last_updated; /* in jiffies */
> +
> +	u8 set_cnt;  /* controls fan rotation speed in closed-loop mode */
> +	u8 act_cnt;  /* provides access to current fan RPM value */
> +	u8 fan_sta;  /* bit 0: set when actual fan speed is more than
> +		      *        25% outside requested fan speed
> +		      * bit 1: set when no transition occurs on fan
> +		      *        pin for 0.7s
> +		      */
> +	u8 set_out;  /* controls fan rotation speed in open-loop mode */
> +	u8 fan_cmd1; /*   0: FG_PLS_ID0 FG pulses count per revolution
> +		      *      0: 2 counts per revolution
> +		      *      1: 4 counts per revolution
> +		      *   1: PWM_POLARITY 1: negative_duty
> +		      *                   0: positive_duty
> +		      * 2,3: [FG_CLOCK_ID0, FG_CLK_ID1]
> +		      *         00: Divide fan clock by 1
> +		      *         01: Divide fan clock by 2
> +		      *         10: Divide fan clock by 4
> +		      *         11: Divide fan clock by 8
> +		      *   4: FAN_MODE 1:closed-loop, 0:open-loop
> +		      *   5: OUT_MODE 1:PWM, 0:DC
> +		      *   6: DET_FAN_OOC enable "fan ooc" status
> +		      *   7: DET_FAN_FAIL enable "fan fail" status
> +		      */
> +	u8 fan_cmd2; /* 0,1: FAN_STARTV 0,1,2,3 -> 0,32,64,96 dac_code
> +		      * 2,3: FG_GEAR_MODE
> +		      *         00: multiplier = 1
> +		      *         01: multiplier = 2
> +		      *         10: multiplier = 4
> +		      *   4: Mask ALERT# (g763 only)
> +		      */
> +};
> +
> +/*
> + * sysfs PWM interface uses value from 0 to 255 when g762 FAN_SET_CNT register
> + * uses values from 255 (off) to 0 (full speed). Note that FAN_SET_OUT register
> + * uses values from 0 (off) to 255 (full speed), i.e. does not need translation.
> + */
> +#define PWM_FROM_CNT(cnt)       (0xff - (cnt))
> +#define PWM_TO_CNT(pwm)         (0xff - (pwm))
> +

Unused defines.

> +/*
> + * Convert count value from fan controller register (FAN_SET_CNT) into fan
> + * speed RPM value. Note that the datasheet documents a basic formula.
> + * Influence of additional parameters (fan clock divisor, fan gear mode)
> + * have been infered from examples in the datasheet and tests.
> + */
> +static inline unsigned int rpm_from_cnt(u8 cnt, u32 clk, u16 p,
> +					u8 clk_div, u8 gear_mult)
> +{
> +	if (cnt == 0xff)  /* cnt to 255 stops the fan */
> +		return 0;
> +
> +	return (clk * 30 * gear_mult) / ((cnt ? cnt : 1) * p * clk_div);
> +}
> +
> +/*
> + * Convert fan RPM value from sysfs into count value for fan controller
> + * register (FAN_SET_CNT).
> + */
> +static inline unsigned char cnt_from_rpm(u32 rpm, u32 clk, u16 p,
> +					 u8 clk_div, u8 gear_mult)
> +{
> +	if (!rpm)         /* to stop the fan, set cnt to 255 */
> +		return 0xff;
> +
> +	return clamp_val(((clk * 30 * gear_mult) / (rpm * p * clk_div)),
> +			 0, 255);
> +}
> +
> +/* helper to grab and cache data, at most one time per second */
> +static struct g762_data *g762_update_client(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = i2c_get_clientdata(client);
> +	int ret = 0;
> +
> +	mutex_lock(&data->update_lock);
> +	if (time_before(jiffies, data->last_updated + G762_UPDATE_INTERVAL) &&
> +	    likely(data->valid))
> +		goto out;
> +
> +	ret = i2c_smbus_read_byte_data(client, G762_REG_SET_CNT);
> +	if (ret < 0)
> +		goto out;
> +	data->set_cnt = ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, G762_REG_ACT_CNT);
> +	if (ret < 0)
> +		goto out;
> +	data->act_cnt = ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, G762_REG_FAN_STA);
> +	if (ret < 0)
> +		goto out;
> +	data->fan_sta = ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, G762_REG_SET_OUT);
> +	if (ret < 0)
> +		goto out;
> +	data->set_out = ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, G762_REG_FAN_CMD1);
> +	if (ret < 0)
> +		goto out;
> +	data->fan_cmd1 = ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, G762_REG_FAN_CMD2);
> +	if (ret < 0)
> +		goto out;
> +	data->fan_cmd2 = ret;
> +
> +	data->last_updated = jiffies;
> +	data->valid = true;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	if (ret < 0) /* upon error, encode it in return value */
> +		data = ERR_PTR(ret);
> +
> +	return data;
> +}
> +
> +/*
> + * helpers for passing hardware characteristics via DT. Some of those
> + * are also used by sysfs handlers (write functions) later in the file.
> + */

Not really true anymore for all functions. I don't mind the code, but you
might want to adjust the comment. "Helpers for writing hardware parameters" or
similar would be good enough.

> +
> +/* Set pwm mode. Accepts either 0 (PWM mode) or 1 (DC mode) */
> +static int do_set_pwm_mode(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case OUT_MODE_PWM:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_OUT_MODE;
> +		break;
> +	case OUT_MODE_DC:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_OUT_MODE;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * Set reference clock. Accepted values are between 0 and 0xffffff.
> + * Note that this is a characteristic of the system but an internal
> + * parameter, i.e. value is not passed to the device.
> + */

Looking into the data sheet, this is not the pwm frequency.
It is the input clock frequency on the CLK pin. pwm frequency
is always 25 kHz.

Please pick another name to avoid confusion. s/pwm_freq/clk_freq/g with
explanation what it is would be ok.

> +static int do_set_pwm_freq(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = i2c_get_clientdata(client);
> +
> +	if (val > 0xffffff)
> +		return -EINVAL;
> +
> +	data->clk = val;
> +
> +	return 0;
> +}
> +
> +/* Set fan clock divisor. Accepted values are 1, 2, 4 and 8. */
> +static int do_set_fan_div(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case 1:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID0;
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID1;
> +		break;
> +	case 2:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID0;
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID1;
> +		break;
> +	case 4:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID0;
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID1;
> +		break;
> +	case 8:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID0;
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID1;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Set fan gear mode. Accepted values are either 0, 1 or 2. */
> +static int do_set_fan_gear_mode(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case 0:
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_0;
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_1;
> +		break;
> +	case 1:
> +		data->fan_cmd2 |=  G762_REG_FAN_CMD2_GEAR_MODE_0;
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_1;
> +		break;
> +	case 2:
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_0;
> +		data->fan_cmd2 |=  G762_REG_FAN_CMD2_GEAR_MODE_1;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD2,
> +					data->fan_cmd2);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Set pulse per revolution value. Accepts either 2 or 4. */
> +static int do_set_fan_pulses(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case 2:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_PULSE_PER_REV;
> +		break;
> +	case 4:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_PULSE_PER_REV;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Set fan mode. Accepts either 1 (open-loop) or 2 (closed-loop). */
> +static int do_set_pwm_enable(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case FAN_MODE_OPEN_LOOP:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_FAN_MODE;
> +		break;
> +	case FAN_MODE_CLOSED_LOOP:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_FAN_MODE;
> +		break;
> +	default:
> +		goto out;
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Set PWM polarity (0 for negative duty, 1 for positive duty) */
> +static int do_set_pwm_polarity(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case 0: /* i.e. negative duty */
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_PWM_POLARITY;
> +		break;
> +	case 1: /* i.e. positive duty */
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_PWM_POLARITY;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * Set pwm value. Accepted values are between 0 (stops the fan) and
> + * 255 (full speed). This only makes sense in open-loop mode.
> + */
> +static int do_set_pwm(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	if (val > 255)
> +		return -EINVAL;
> +
> +	mutex_lock(&data->update_lock);
> +	data->set_out = val;
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_SET_OUT, val);
> +	data->valid = false;
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Set fan RPM value. This only makes sense in closed-loop mode. */
> +static int do_set_fan_target(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	data->set_cnt = cnt_from_rpm(val, data->clk,
> +				     PULSE_FROM_REG(data->fan_cmd1),
> +				     CLKDIV_FROM_REG(data->fan_cmd1),
> +				     GEARMULT_FROM_REG(data->fan_cmd2));
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_SET_CNT,
> +					data->set_cnt);
> +	data->valid = false;
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Enable/disable fan failure detection. Accepted values are 1 and 0. */
> +static int do_fan_failure_detection_toggle(struct device *dev,
> +					   unsigned long enable)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (enable) {
> +	case 0:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_DET_FAN_FAIL;
> +		break;
> +	case 1:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_DET_FAN_FAIL;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Enable/disable fan out of control detection. Accepted values are 1 and 0 */
> +static int do_fan_ooc_detection_toggle(struct device *dev, unsigned int enable)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (enable) {
> +	case 0:
> +		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_DET_FAN_OOC;
> +		break;
> +	case 1:
> +		data->fan_cmd1 |=  G762_REG_FAN_CMD1_DET_FAN_OOC;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
> +					data->fan_cmd1);
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/* Set fan startup voltage. Accepted values are either 0, 1, 2 or 3. */
> +static int do_set_fan_startv(struct device *dev, unsigned long val)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct g762_data *data = g762_update_client(dev);
> +	int ret = -EINVAL;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	switch (val) {
> +	case 0:
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_0;
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_1;
> +		data->valid = false;

Set multiple times, here and at end of switch statement. Once is enough.

> +		break;
> +	case 1:
> +		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_0;
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_1;
> +		data->valid = false;
> +		break;
> +	case 2:
> +		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_0;
> +		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_1;
> +		data->valid = false;
> +		break;
> +	case 3:
> +		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_0;
> +		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_1;
> +		data->valid = false;
> +		break;
> +	default:
> +		goto out;
> +	}
> +	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD2,
> +					data->fan_cmd2);
> +	data->valid = false;
> + out:
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * Configuration-related definitions
> + */
> +
> +/*
> + * Recover and set given property value from platform_data. In order to
> + * distinguish initialized values from uninitialized ones passed in a
> + * sparse structure using G762_ATTR_VAL(), MSB is checked.
> + */
> +static inline int g762_one_prop_commit(struct i2c_client *client,
> +				       u32 pval, const char *pname,
> +				       int (*psetter)(struct device *dev,
> +						      unsigned long val))
> +{
> +	int ret = 0;
> +
> +	if (pval & G762_VAL_TEST_BIT) {

G762_VAL_TEST_BIT is not really needed; see below. Please drop and rearrange
code to not require it.

> +		pval &= G762_VAL_TEST_MASK; /* recover val (clear test bit) */
> +		if ((*psetter)(&client->dev, pval)) {
> +			dev_err(&client->dev, "unable to set %s (%d)\n",
> +				pname, pval);
> +			ret = -EINVAL;

Please don't hide the original error code.

> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static int g762_platform_data_commit(struct i2c_client *client,
> +				     struct g762_platform_data *pdata)
> +{
> +	int ret;
> +
> +	ret = g762_one_prop_commit(client, pdata->fan_startv,
> +				   "fan_startv", do_set_fan_startv);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = g762_one_prop_commit(client, pdata->fan_pulses,
> +				   "fan_pulses", do_set_fan_pulses);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = g762_one_prop_commit(client, pdata->pwm_freq,
> +				   "pwm_freq", do_set_pwm_freq);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = g762_one_prop_commit(client, pdata->fan_gear_mode,
> +				   "fan_gear_mode", do_set_fan_gear_mode);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = g762_one_prop_commit(client, pdata->pwm_polarity,
> +				   "pwm_polarity", do_set_pwm_polarity);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +/*
> + * Helpers to import hardware characteristics from .dts file and overload
> + * default platform data values.
> + */
> +
> +#ifdef CONFIG_OF
> +static struct of_device_id g762_dt_match[] = {
> +	{ .compatible = "gmt,g762" },
> +	{ .compatible = "gmt,g763" },
> +	{ },
> +};
> +
> +static inline void g762_of_import_one_prop(struct i2c_client *client,
> +					   u32 *dest, const char *pname)
> +{
> +	const __be32 *prop;
> +	int len;
> +
> +	prop = of_get_property(client->dev.of_node, pname, &len);
> +	if (prop && len == sizeof(u32)) {
> +		*dest = G762_ATTR_VAL(be32_to_cpu(prop[0]));
> +		dev_dbg(&client->dev, "found %s (%d)\n", pname, *dest);
> +	}
> +}
> +
> +static void g762_platform_data_of_overload(struct i2c_client *client,
> +					   struct g762_platform_data *pdata)
> +{
> +	if (!client->dev.of_node)
> +		return;
> +
> +	g762_of_import_one_prop(client, &pdata->fan_startv, "fan_startv");
> +	g762_of_import_one_prop(client, &pdata->fan_gear_mode, "fan_gear_mode");
> +	g762_of_import_one_prop(client, &pdata->fan_pulses, "fan_pulses");

fanX_pulses is a standard sysfs attribute. Please use it.

> +	g762_of_import_one_prop(client, &pdata->pwm_polarity, "pwm_polarity");
> +	g762_of_import_one_prop(client, &pdata->pwm_freq, "pwm_freq");

misleading naming. See above. Should be clk_freq or similar, with a default
of 32768 if not set.

Actually, since it is a clock, you should look into clock properties and use
one instead, ie define a static clock via devicetree and use it.

> +}
> +#else
> +static void g762_platform_data_of_overload(struct i2c_client *client,
> +				    struct g762_platform_data *pdata) { }
> +#endif
> +
> +/*
> + * helper to overload driver parameters from board init file for those
> + * not already converted to device tree
> + */
> +static void g762_platform_data_overload(struct i2c_client *client,
> +					struct g762_platform_data *pdata)
> +{
> +	struct g762_platform_data *opdata = client->dev.platform_data;
> +
> +	if (!opdata)
> +		return;
> +
> +	if (opdata->fan_startv & G762_VAL_TEST_BIT)
> +		pdata->fan_startv = opdata->fan_startv;
> +	if (opdata->fan_gear_mode & G762_VAL_TEST_BIT)
> +		pdata->fan_gear_mode = opdata->fan_gear_mode;
> +	if (opdata->fan_pulses & G762_VAL_TEST_BIT)
> +		pdata->fan_pulses = opdata->fan_pulses;
> +	if (opdata->pwm_polarity & G762_VAL_TEST_BIT)
> +		pdata->pwm_polarity = opdata->pwm_polarity;
> +	if (opdata->pwm_freq & G762_VAL_TEST_BIT)
> +		pdata->pwm_freq = opdata->pwm_freq;
> +}

AFAICS you can use defaults for all attributes if the value is 0.

startv: 0 is good enough as default
gear_mode: 0 is good enough as default
pulses: should be sysfs attribute.
polarity: 0 = positive duty, good enough
pwm_freq (or, rather, clk_freq): default is 32,768 Hz

So all that complexity with G762_VAL_TEST_BIT is not really needed. Please drop.

Sure, that means all-or-nothing for configuration with platform data,
but I don't see a problem with that. It is pretty much common for other
drivers as well. An alternative would be to use well defined values > 0
for explicit (non-default) values; configuration values don't have to reflect
register values.

> +
> +/*
> + * sysfs attributes
> + */
> +
> +/*
> + * Read function for fan1_input sysfs file. Return current fan RPM value, or
> + * 0 if fan is out of control.
> + */
> +static ssize_t get_fan_rpm(struct device *dev, struct device_attribute *da,
> +			   char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +	unsigned int rpm = 0;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	/* reverse logic: fan out of control reporting is enabled low */
> +	if (data->fan_sta & G762_REG_FAN_STA_OOC) {
> +		rpm = rpm_from_cnt(data->act_cnt, data->clk,
> +				   PULSE_FROM_REG(data->fan_cmd1),
> +				   CLKDIV_FROM_REG(data->fan_cmd1),
> +				   GEARMULT_FROM_REG(data->fan_cmd2));
> +	}
> +	mutex_unlock(&data->update_lock);
> +
> +	return sprintf(buf, "%u\n", rpm);
> +}
> +
> +/*
> + * Read and write functions for pwm1_mode sysfs file. Get and set fan speed
> + * control mode i.e. PWM (1) or DC (0).
> + */
> +static ssize_t get_pwm_mode(struct device *dev, struct device_attribute *da,
> +			    char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	return sprintf(buf, "%d\n",
> +		       !!(data->fan_cmd1 & G762_REG_FAN_CMD1_OUT_MODE));
> +}
> +
> +static ssize_t set_pwm_mode(struct device *dev, struct device_attribute *da,
> +			    const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int ret;
> +
> +	if (kstrtoul(buf, 10, &val))
> +		return -EINVAL;
> +
> +	ret = do_set_pwm_mode(dev, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +/*
> + * Read and write functions for fan1_div sysfs file. Get and set fan
> + * controller prescaler value
> + */
> +static ssize_t get_fan_div(struct device *dev,
> +			   struct device_attribute *da, char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	return sprintf(buf, "%d\n", CLKDIV_FROM_REG(data->fan_cmd1));
> +}
> +
> +static ssize_t set_fan_div(struct device *dev,
> +			   struct device_attribute *da,
> +			   const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int ret;
> +
> +	if (kstrtoul(buf, 10, &val))
> +		return -EINVAL;
> +
> +	ret = do_set_fan_div(dev, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +/*
> + * Read and write functions for pwm1_enable. Get and set the fan speed control
> + * mode (i.e. closed or open-loop).
> + *
> + * Following documentation about hwmon's sysfs interface, a pwm1_enable node
> + * should accept followings:
> + *
> + *  0 : no fan speed control (i.e. fan at full speed)
> + *  1 : manual fan speed control enabled (use pwm[1-*]) (open-loop)
> + *  2+: automatic fan speed control enabled (use fan[1-*]_target) (closed-loop)
> + *
> + * but we do not accept 0 as "no-control" mode is not supported by g762,
> + * -EINVAL is returned in this case.

You could set the fan to open loop and full speed for a value of 0.
It is not really true that the chip would not support that.
This has nothing to do with the chip, but it is your choice
to not support it. Please either fix the comment or your code.

> + */
> +static ssize_t get_pwm_enable(struct device *dev,
> +			      struct device_attribute *da, char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	return sprintf(buf, "%d\n",
> +		       (!!(data->fan_cmd1 & G762_REG_FAN_CMD1_FAN_MODE)) + 1);
> +}
> +
> +static ssize_t set_pwm_enable(struct device *dev,
> +			      struct device_attribute *da,
> +			      const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int ret;
> +
> +	if (kstrtoul(buf, 10, &val))
> +		return -EINVAL;
> +
> +	ret = do_set_pwm_enable(dev, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +/*
> + * Read and write functions for pwm1 sysfs file. Get and set the fan speed
> + * in both open-loop mode. Speed is given as a value between 0 and 255:
> + * 0 stops the fan and 255 makes it run at full speed.

"in both" is no longer accurate. It also doesn't set the fan speed but the pwm
value which affects the fan speed.

> + */
> +static ssize_t get_pwm(struct device *dev, struct device_attribute *da,
> +		       char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	return sprintf(buf, "%d\n", data->set_out);
> +}
> +
> +static ssize_t set_pwm(struct device *dev, struct device_attribute *da,
> +		       const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int ret;
> +
> +	if (kstrtoul(buf, 10, &val))
> +		return -EINVAL;
> +
> +	ret = do_set_pwm(dev, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +/*
> + * Read and write function for fan1_target sysfs file. Get/set the fan speed in
> + * closed-loop mode. Speed is given as a RPM value; then the chip will regulate
> + * the fan speed using pulses from fan tachometer.
> + *
> + * Refer to rpm_from_cnt() implementation above to get info about count number
> + * calculation.
> + *
> + * Also note that due to rounding errors it is possible that you don't read
> + * back exactly the value you have set.
> + */
> +static ssize_t get_fan_target(struct device *dev, struct device_attribute *da,
> +			      char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +	ssize_t ret = -EINVAL;

Unnecessary initialization.

> +	unsigned int rpm;
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	mutex_lock(&data->update_lock);
> +	rpm = rpm_from_cnt(data->set_cnt, data->clk,
> +			   PULSE_FROM_REG(data->fan_cmd1),
> +			   CLKDIV_FROM_REG(data->fan_cmd1),
> +			   GEARMULT_FROM_REG(data->fan_cmd2));
> +	ret = sprintf(buf, "%u\n", rpm);
> +	mutex_unlock(&data->update_lock);
> +
> +	return ret;
> +}
> +
> +static ssize_t set_fan_target(struct device *dev, struct device_attribute *da,
> +			      const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int ret;
> +
> +	if (kstrtoul(buf, 10, &val))
> +		return -EINVAL;
> +
> +	ret = do_set_fan_target(dev, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +/* read function for fan1_fault sysfs file. */
> +static ssize_t get_fan_failure(struct device *dev, struct device_attribute *da,
> +			       char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	return sprintf(buf, "%u\n", !!(data->fan_sta & G762_REG_FAN_STA_FAIL));
> +}
> +
> +/*
> + * read function for fan1_alarm sysfs file. Note that OOC condition is
> + * enabled low
> + */
> +static ssize_t get_fan_ooc(struct device *dev, struct device_attribute *da,
> +			   char *buf)
> +{
> +	struct g762_data *data = g762_update_client(dev);
> +
> +	if (IS_ERR(data))
> +		return PTR_ERR(data);
> +
> +	return sprintf(buf, "%u\n", !(data->fan_sta & G762_REG_FAN_STA_OOC));
> +}
> +
> +static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
> +static DEVICE_ATTR(pwm1_mode, S_IWUSR | S_IRUGO, get_pwm_mode, set_pwm_mode);
> +static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO,
> +		   get_pwm_enable, set_pwm_enable);
> +static DEVICE_ATTR(fan1_input, S_IRUGO, get_fan_rpm, NULL);
> +static DEVICE_ATTR(fan1_alarm, S_IRUGO, get_fan_ooc, NULL);
> +static DEVICE_ATTR(fan1_fault, S_IRUGO, get_fan_failure, NULL);
> +static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO,
> +		   get_fan_target, set_fan_target);
> +static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_fan_div, set_fan_div);
> +
> +/* Driver data */
> +static struct attribute *g762_attributes[] = {
> +	&dev_attr_fan1_input.attr,
> +	&dev_attr_fan1_alarm.attr,
> +	&dev_attr_fan1_fault.attr,
> +	&dev_attr_fan1_target.attr,
> +	&dev_attr_fan1_div.attr,
> +	&dev_attr_pwm1.attr,
> +	&dev_attr_pwm1_mode.attr,
> +	&dev_attr_pwm1_enable.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group g762_group = {
> +	.attrs = g762_attributes,
> +};
> +
> +static int g762_probe(struct i2c_client *client, const struct i2c_device_id *id)
> +{
> +	struct g762_platform_data pdata = { .pwm_freq = G762_ATTR_VAL(32768) };
> +	struct g762_data *data;
> +	int err;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -ENODEV;
> +
> +	data = devm_kzalloc(&client->dev, sizeof(struct g762_data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, data);
> +
> +	data->client = client;
> +	mutex_init(&data->update_lock);
> +
> +	/* Enable fan protection and fan fail detection by default */
> +	do_fan_ooc_detection_toggle(&client->dev, 1);
> +	do_fan_failure_detection_toggle(&client->dev, 1);
> +
> +	/*
> +	 * Set default configuration values before passing the structure
> +	 * first to overload routine used by boards non converted to DT and
> +	 * then to OF helper (to overload them using those provided by .dts
> +	 * file, if any). Final result is then commited.
> +	 */
> +	g762_platform_data_overload(client, &pdata);
> +	g762_platform_data_of_overload(client, &pdata);
> +	err = g762_platform_data_commit(client, &pdata);
> +	if (err)
> +		return err;
> +
> +	/* Register sysfs hooks */
> +	err = sysfs_create_group(&client->dev.kobj, &g762_group);
> +	if (err)
> +		return err;
> +
> +	data->hwmon_dev = (struct device *)hwmon_device_register(&client->dev);

Unnecessary typecast.

> +	if (IS_ERR(data->hwmon_dev)) {
> +		err = PTR_ERR(data->hwmon_dev);
> +		goto err_out;
> +	}
> +
> +	return 0;
> +
> + err_out:
> +	sysfs_remove_group(&client->dev.kobj, &g762_group);
> +	return err;
> +}
> +
> +static int g762_remove(struct i2c_client *client)
> +{
> +	struct g762_data *data = i2c_get_clientdata(client);
> +
> +	hwmon_device_unregister(data->hwmon_dev);
> +	sysfs_remove_group(&client->dev.kobj, &g762_group);
> +
> +	return 0;
> +}
> +
> +static struct i2c_driver g762_driver = {
> +	.driver = {
> +		.name = DRVNAME,
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(g762_dt_match),
> +	},
> +	.probe	  = g762_probe,
> +	.remove	  = g762_remove,
> +	.id_table = g762_id,
> +};
> +
> +module_i2c_driver(g762_driver);
> +
> +MODULE_AUTHOR("Arnaud EBALARD <[e-mail]>");
> +MODULE_DESCRIPTION("GMT G762/G763 driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/platform_data/g762.h b/include/linux/platform_data/g762.h
> new file mode 100644
> index 0000000..cfaf2f3
> --- /dev/null
> +++ b/include/linux/platform_data/g762.h
> @@ -0,0 +1,47 @@
> +/*
> + * Platform data structure for g762 fan controller driver
> + *
> + * Copyright (C) 2013, Arnaud EBALARD <[e-mail]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +#ifndef __LINUX_PLATFORM_DATA_G762_H__
> +#define __LINUX_PLATFORM_DATA_G762_H__
> +
> +/*
> + * Following structure can be used to set g762 driver platform specific data
> + * during board init. Attributes must *always* be set using G762_ATTR_VAL()
> + * macro defined below, i.e. it is not possible to pass a value directly.
> + * Defining a sparse structure is possible. For instance, if one only needs
> + * to set pwm_freq to 8192 and fan_pulses to 2, the following can be done:
> + *
> + * static struct g762_platform_data pdata = { .pwm_freq = G762_ATTR_VAL(8192),
> + *                                            .fan_pulses = G762_ATTR_VAL(2), };
> + *
> + */
> +
> +#define G762_VAL_TEST_BIT  (1 << 31)
> +#define G762_VAL_TEST_MASK (~G762_VAL_TEST_BIT)
> +#define G762_ATTR_VAL(val) ((val) | G762_VAL_TEST_BIT)
> +
> +struct g762_platform_data {
> +	u32 fan_startv;
> +	u32 fan_gear_mode;
> +	u32 fan_pulses;
> +	u32 pwm_polarity;
> +	u32 pwm_freq;
> +};
> +
> +#endif /* __LINUX_PLATFORM_DATA_G762_H__ */
> -- 
> 1.7.10.4
> 
>

Patch

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 0428e8a..142bdf8 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -456,6 +456,16 @@  config SENSORS_G760A
 	  This driver can also be built as a module.  If so, the module
 	  will be called g760a.
 
+config SENSORS_G762
+	tristate "GMT G762 and G763"
+	depends on I2C
+	help
+	  If you say yes here you get support for Global Mixed-mode
+	  Technology Inc G762 and G763 fan speed PWM controller chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called g762.
+
 config SENSORS_GL518SM
 	tristate "Genesys Logic GL518SM"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index d17d3e6..4f0fb52 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -60,6 +60,7 @@  obj-$(CONFIG_SENSORS_F75375S)	+= f75375s.o
 obj-$(CONFIG_SENSORS_FAM15H_POWER) += fam15h_power.o
 obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o
 obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
+obj-$(CONFIG_SENSORS_G762)	+= g762.o
 obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
diff --git a/drivers/hwmon/g762.c b/drivers/hwmon/g762.c
new file mode 100644
index 0000000..194be43
--- /dev/null
+++ b/drivers/hwmon/g762.c
@@ -0,0 +1,1111 @@ 
+/*
+ * g762 - Driver for the Global Mixed-mode Technology Inc. fan speed
+ *        PWM controller chips from G762 family, i.e. G762 and G763
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <[e-mail]>
+ *
+ * This work is based on a basic version for 2.6.31 kernel developed
+ * by Olivier Mouchet for LaCie. Updates and correction have been
+ * performed to run on recent kernels. Additional features, like the
+ * ability to configure various characteristics via .dts file, have
+ * been added. Detailed datasheet on which this development is based
+ * is available here:
+ *
+ *  http://natisbad.org/NAS/refs/GMT_EDS-762_763-080710-0.2.pdf
+ *
+ * Headers from previous developments have been kept below:
+ *
+ * Copyright (c) 2009 LaCie
+ *
+ * Author: Olivier Mouchet <[e-mail]>
+ *
+ * based on g760a code written by Herbert Valerio Riedel <[e-mail]>
+ * Copyright (C) 2007  Herbert Valerio Riedel <[e-mail]>
+ *
+ * g762: minimal datasheet available at:
+ *       http://www.gmt.com.tw/product/datasheet/EDS-762_3.pdf
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_data/g762.h>
+
+#define DRVNAME "g762"
+
+static const struct i2c_device_id g762_id[] = {
+	{ "g762", 0 },
+	{ "g763", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, g762_id);
+
+enum g762_regs {
+	G762_REG_SET_CNT  = 0x00,
+	G762_REG_ACT_CNT  = 0x01,
+	G762_REG_FAN_STA  = 0x02,
+	G762_REG_SET_OUT  = 0x03,
+	G762_REG_FAN_CMD1 = 0x04,
+	G762_REG_FAN_CMD2 = 0x05,
+};
+
+/* Config register bits */
+#define G762_REG_FAN_CMD1_DET_FAN_FAIL  0x80 /* enable fan_fail signal */
+#define G762_REG_FAN_CMD1_DET_FAN_OOC   0x40 /* enable fan_out_of_control */
+#define G762_REG_FAN_CMD1_OUT_MODE      0x20 /* out mode, PWM or DC */
+#define G762_REG_FAN_CMD1_FAN_MODE      0x10 /* fan mode: closed/open loop */
+#define G762_REG_FAN_CMD1_CLK_DIV_ID1   0x08 /* clock divisor value */
+#define G762_REG_FAN_CMD1_CLK_DIV_ID0   0x04
+#define G762_REG_FAN_CMD1_PWM_POLARITY  0x02 /* PWM polarity */
+#define G762_REG_FAN_CMD1_PULSE_PER_REV 0x01 /* pulse per fan revolution */
+
+#define G762_REG_FAN_CMD2_GEAR_MODE_1   0x08 /* fan gear mode */
+#define G762_REG_FAN_CMD2_GEAR_MODE_0   0x04
+#define G762_REG_FAN_CMD2_FAN_STARTV_1  0x02 /* fan startup voltage */
+#define G762_REG_FAN_CMD2_FAN_STARTV_0  0x01
+
+#define G762_REG_FAN_STA_FAIL           0x02 /* fan fail */
+#define G762_REG_FAN_STA_OOC            0x01 /* fan out of control */
+
+/* config register values */
+#define OUT_MODE_PWM            1
+#define OUT_MODE_DC             0
+
+#define FAN_MODE_CLOSED_LOOP    2
+#define FAN_MODE_OPEN_LOOP      1
+
+/* register data is read (and cached) at most once per second */
+#define G762_UPDATE_INTERVAL    HZ
+
+/*
+ * extract pulse count per fan revolution value (2 or 4) from given
+ * FAN_CMD1 register value
+ */
+#define PULSE_FROM_REG(reg) \
+	((((reg) & G762_REG_FAN_CMD1_PULSE_PER_REV) + 1) << 1)
+
+/*
+ * extract fan clock divisor (1, 2, 4 or 8) from given FAN_CMD1
+ * register value
+ */
+#define CLKDIV_FROM_REG(reg) \
+	(1 << (((reg) & (G762_REG_FAN_CMD1_CLK_DIV_ID0 |	\
+			 G762_REG_FAN_CMD1_CLK_DIV_ID1)) >> 2))
+
+/*
+ * extract fan gear mode multiplier value (0, 2 or 4) from given
+ * FAN_CMD2 register value
+ */
+#define GEARMULT_FROM_REG(reg) \
+	(1 << (((reg) & (G762_REG_FAN_CMD2_GEAR_MODE_0 |	\
+			 G762_REG_FAN_CMD2_GEAR_MODE_1)) >> 2))
+
+struct g762_data {
+	struct i2c_client *client;
+	struct device *hwmon_dev;
+
+	/* update mutex */
+	struct mutex update_lock;
+
+	/* board specific parameters. */
+	u32 clk;
+
+	/* g762 register cache */
+	bool valid;
+	unsigned long last_updated; /* in jiffies */
+
+	u8 set_cnt;  /* controls fan rotation speed in closed-loop mode */
+	u8 act_cnt;  /* provides access to current fan RPM value */
+	u8 fan_sta;  /* bit 0: set when actual fan speed is more than
+		      *        25% outside requested fan speed
+		      * bit 1: set when no transition occurs on fan
+		      *        pin for 0.7s
+		      */
+	u8 set_out;  /* controls fan rotation speed in open-loop mode */
+	u8 fan_cmd1; /*   0: FG_PLS_ID0 FG pulses count per revolution
+		      *      0: 2 counts per revolution
+		      *      1: 4 counts per revolution
+		      *   1: PWM_POLARITY 1: negative_duty
+		      *                   0: positive_duty
+		      * 2,3: [FG_CLOCK_ID0, FG_CLK_ID1]
+		      *         00: Divide fan clock by 1
+		      *         01: Divide fan clock by 2
+		      *         10: Divide fan clock by 4
+		      *         11: Divide fan clock by 8
+		      *   4: FAN_MODE 1:closed-loop, 0:open-loop
+		      *   5: OUT_MODE 1:PWM, 0:DC
+		      *   6: DET_FAN_OOC enable "fan ooc" status
+		      *   7: DET_FAN_FAIL enable "fan fail" status
+		      */
+	u8 fan_cmd2; /* 0,1: FAN_STARTV 0,1,2,3 -> 0,32,64,96 dac_code
+		      * 2,3: FG_GEAR_MODE
+		      *         00: multiplier = 1
+		      *         01: multiplier = 2
+		      *         10: multiplier = 4
+		      *   4: Mask ALERT# (g763 only)
+		      */
+};
+
+/*
+ * sysfs PWM interface uses value from 0 to 255 when g762 FAN_SET_CNT register
+ * uses values from 255 (off) to 0 (full speed). Note that FAN_SET_OUT register
+ * uses values from 0 (off) to 255 (full speed), i.e. does not need translation.
+ */
+#define PWM_FROM_CNT(cnt)       (0xff - (cnt))
+#define PWM_TO_CNT(pwm)         (0xff - (pwm))
+
+/*
+ * Convert count value from fan controller register (FAN_SET_CNT) into fan
+ * speed RPM value. Note that the datasheet documents a basic formula.
+ * Influence of additional parameters (fan clock divisor, fan gear mode)
+ * have been infered from examples in the datasheet and tests.
+ */
+static inline unsigned int rpm_from_cnt(u8 cnt, u32 clk, u16 p,
+					u8 clk_div, u8 gear_mult)
+{
+	if (cnt == 0xff)  /* cnt to 255 stops the fan */
+		return 0;
+
+	return (clk * 30 * gear_mult) / ((cnt ? cnt : 1) * p * clk_div);
+}
+
+/*
+ * Convert fan RPM value from sysfs into count value for fan controller
+ * register (FAN_SET_CNT).
+ */
+static inline unsigned char cnt_from_rpm(u32 rpm, u32 clk, u16 p,
+					 u8 clk_div, u8 gear_mult)
+{
+	if (!rpm)         /* to stop the fan, set cnt to 255 */
+		return 0xff;
+
+	return clamp_val(((clk * 30 * gear_mult) / (rpm * p * clk_div)),
+			 0, 255);
+}
+
+/* helper to grab and cache data, at most one time per second */
+static struct g762_data *g762_update_client(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = i2c_get_clientdata(client);
+	int ret = 0;
+
+	mutex_lock(&data->update_lock);
+	if (time_before(jiffies, data->last_updated + G762_UPDATE_INTERVAL) &&
+	    likely(data->valid))
+		goto out;
+
+	ret = i2c_smbus_read_byte_data(client, G762_REG_SET_CNT);
+	if (ret < 0)
+		goto out;
+	data->set_cnt = ret;
+
+	ret = i2c_smbus_read_byte_data(client, G762_REG_ACT_CNT);
+	if (ret < 0)
+		goto out;
+	data->act_cnt = ret;
+
+	ret = i2c_smbus_read_byte_data(client, G762_REG_FAN_STA);
+	if (ret < 0)
+		goto out;
+	data->fan_sta = ret;
+
+	ret = i2c_smbus_read_byte_data(client, G762_REG_SET_OUT);
+	if (ret < 0)
+		goto out;
+	data->set_out = ret;
+
+	ret = i2c_smbus_read_byte_data(client, G762_REG_FAN_CMD1);
+	if (ret < 0)
+		goto out;
+	data->fan_cmd1 = ret;
+
+	ret = i2c_smbus_read_byte_data(client, G762_REG_FAN_CMD2);
+	if (ret < 0)
+		goto out;
+	data->fan_cmd2 = ret;
+
+	data->last_updated = jiffies;
+	data->valid = true;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	if (ret < 0) /* upon error, encode it in return value */
+		data = ERR_PTR(ret);
+
+	return data;
+}
+
+/*
+ * helpers for passing hardware characteristics via DT. Some of those
+ * are also used by sysfs handlers (write functions) later in the file.
+ */
+
+/* Set pwm mode. Accepts either 0 (PWM mode) or 1 (DC mode) */
+static int do_set_pwm_mode(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case OUT_MODE_PWM:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_OUT_MODE;
+		break;
+	case OUT_MODE_DC:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_OUT_MODE;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/*
+ * Set reference clock. Accepted values are between 0 and 0xffffff.
+ * Note that this is a characteristic of the system but an internal
+ * parameter, i.e. value is not passed to the device.
+ */
+static int do_set_pwm_freq(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = i2c_get_clientdata(client);
+
+	if (val > 0xffffff)
+		return -EINVAL;
+
+	data->clk = val;
+
+	return 0;
+}
+
+/* Set fan clock divisor. Accepted values are 1, 2, 4 and 8. */
+static int do_set_fan_div(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case 1:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID0;
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID1;
+		break;
+	case 2:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID0;
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID1;
+		break;
+	case 4:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_CLK_DIV_ID0;
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID1;
+		break;
+	case 8:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID0;
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_CLK_DIV_ID1;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Set fan gear mode. Accepted values are either 0, 1 or 2. */
+static int do_set_fan_gear_mode(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case 0:
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_0;
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_1;
+		break;
+	case 1:
+		data->fan_cmd2 |=  G762_REG_FAN_CMD2_GEAR_MODE_0;
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_1;
+		break;
+	case 2:
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_GEAR_MODE_0;
+		data->fan_cmd2 |=  G762_REG_FAN_CMD2_GEAR_MODE_1;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD2,
+					data->fan_cmd2);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Set pulse per revolution value. Accepts either 2 or 4. */
+static int do_set_fan_pulses(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case 2:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_PULSE_PER_REV;
+		break;
+	case 4:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_PULSE_PER_REV;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Set fan mode. Accepts either 1 (open-loop) or 2 (closed-loop). */
+static int do_set_pwm_enable(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case FAN_MODE_OPEN_LOOP:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_FAN_MODE;
+		break;
+	case FAN_MODE_CLOSED_LOOP:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_FAN_MODE;
+		break;
+	default:
+		goto out;
+	}
+
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Set PWM polarity (0 for negative duty, 1 for positive duty) */
+static int do_set_pwm_polarity(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case 0: /* i.e. negative duty */
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_PWM_POLARITY;
+		break;
+	case 1: /* i.e. positive duty */
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_PWM_POLARITY;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/*
+ * Set pwm value. Accepted values are between 0 (stops the fan) and
+ * 255 (full speed). This only makes sense in open-loop mode.
+ */
+static int do_set_pwm(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	if (val > 255)
+		return -EINVAL;
+
+	mutex_lock(&data->update_lock);
+	data->set_out = val;
+	ret = i2c_smbus_write_byte_data(client, G762_REG_SET_OUT, val);
+	data->valid = false;
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Set fan RPM value. This only makes sense in closed-loop mode. */
+static int do_set_fan_target(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	data->set_cnt = cnt_from_rpm(val, data->clk,
+				     PULSE_FROM_REG(data->fan_cmd1),
+				     CLKDIV_FROM_REG(data->fan_cmd1),
+				     GEARMULT_FROM_REG(data->fan_cmd2));
+	ret = i2c_smbus_write_byte_data(client, G762_REG_SET_CNT,
+					data->set_cnt);
+	data->valid = false;
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Enable/disable fan failure detection. Accepted values are 1 and 0. */
+static int do_fan_failure_detection_toggle(struct device *dev,
+					   unsigned long enable)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (enable) {
+	case 0:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_DET_FAN_FAIL;
+		break;
+	case 1:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_DET_FAN_FAIL;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Enable/disable fan out of control detection. Accepted values are 1 and 0 */
+static int do_fan_ooc_detection_toggle(struct device *dev, unsigned int enable)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (enable) {
+	case 0:
+		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_DET_FAN_OOC;
+		break;
+	case 1:
+		data->fan_cmd1 |=  G762_REG_FAN_CMD1_DET_FAN_OOC;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
+					data->fan_cmd1);
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/* Set fan startup voltage. Accepted values are either 0, 1, 2 or 3. */
+static int do_set_fan_startv(struct device *dev, unsigned long val)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct g762_data *data = g762_update_client(dev);
+	int ret = -EINVAL;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	switch (val) {
+	case 0:
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_0;
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_1;
+		data->valid = false;
+		break;
+	case 1:
+		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_0;
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_1;
+		data->valid = false;
+		break;
+	case 2:
+		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_0;
+		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_1;
+		data->valid = false;
+		break;
+	case 3:
+		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_0;
+		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_1;
+		data->valid = false;
+		break;
+	default:
+		goto out;
+	}
+	ret = i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD2,
+					data->fan_cmd2);
+	data->valid = false;
+ out:
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+/*
+ * Configuration-related definitions
+ */
+
+/*
+ * Recover and set given property value from platform_data. In order to
+ * distinguish initialized values from uninitialized ones passed in a
+ * sparse structure using G762_ATTR_VAL(), MSB is checked.
+ */
+static inline int g762_one_prop_commit(struct i2c_client *client,
+				       u32 pval, const char *pname,
+				       int (*psetter)(struct device *dev,
+						      unsigned long val))
+{
+	int ret = 0;
+
+	if (pval & G762_VAL_TEST_BIT) {
+		pval &= G762_VAL_TEST_MASK; /* recover val (clear test bit) */
+		if ((*psetter)(&client->dev, pval)) {
+			dev_err(&client->dev, "unable to set %s (%d)\n",
+				pname, pval);
+			ret = -EINVAL;
+		}
+	}
+
+	return ret;
+}
+
+static int g762_platform_data_commit(struct i2c_client *client,
+				     struct g762_platform_data *pdata)
+{
+	int ret;
+
+	ret = g762_one_prop_commit(client, pdata->fan_startv,
+				   "fan_startv", do_set_fan_startv);
+	if (ret < 0)
+		return ret;
+
+	ret = g762_one_prop_commit(client, pdata->fan_pulses,
+				   "fan_pulses", do_set_fan_pulses);
+	if (ret < 0)
+		return ret;
+
+	ret = g762_one_prop_commit(client, pdata->pwm_freq,
+				   "pwm_freq", do_set_pwm_freq);
+	if (ret < 0)
+		return ret;
+
+	ret = g762_one_prop_commit(client, pdata->fan_gear_mode,
+				   "fan_gear_mode", do_set_fan_gear_mode);
+	if (ret < 0)
+		return ret;
+
+	ret = g762_one_prop_commit(client, pdata->pwm_polarity,
+				   "pwm_polarity", do_set_pwm_polarity);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+/*
+ * Helpers to import hardware characteristics from .dts file and overload
+ * default platform data values.
+ */
+
+#ifdef CONFIG_OF
+static struct of_device_id g762_dt_match[] = {
+	{ .compatible = "gmt,g762" },
+	{ .compatible = "gmt,g763" },
+	{ },
+};
+
+static inline void g762_of_import_one_prop(struct i2c_client *client,
+					   u32 *dest, const char *pname)
+{
+	const __be32 *prop;
+	int len;
+
+	prop = of_get_property(client->dev.of_node, pname, &len);
+	if (prop && len == sizeof(u32)) {
+		*dest = G762_ATTR_VAL(be32_to_cpu(prop[0]));
+		dev_dbg(&client->dev, "found %s (%d)\n", pname, *dest);
+	}
+}
+
+static void g762_platform_data_of_overload(struct i2c_client *client,
+					   struct g762_platform_data *pdata)
+{
+	if (!client->dev.of_node)
+		return;
+
+	g762_of_import_one_prop(client, &pdata->fan_startv, "fan_startv");
+	g762_of_import_one_prop(client, &pdata->fan_gear_mode, "fan_gear_mode");
+	g762_of_import_one_prop(client, &pdata->fan_pulses, "fan_pulses");
+	g762_of_import_one_prop(client, &pdata->pwm_polarity, "pwm_polarity");
+	g762_of_import_one_prop(client, &pdata->pwm_freq, "pwm_freq");
+}
+#else
+static void g762_platform_data_of_overload(struct i2c_client *client,
+				    struct g762_platform_data *pdata) { }
+#endif
+
+/*
+ * helper to overload driver parameters from board init file for those
+ * not already converted to device tree
+ */
+static void g762_platform_data_overload(struct i2c_client *client,
+					struct g762_platform_data *pdata)
+{
+	struct g762_platform_data *opdata = client->dev.platform_data;
+
+	if (!opdata)
+		return;
+
+	if (opdata->fan_startv & G762_VAL_TEST_BIT)
+		pdata->fan_startv = opdata->fan_startv;
+	if (opdata->fan_gear_mode & G762_VAL_TEST_BIT)
+		pdata->fan_gear_mode = opdata->fan_gear_mode;
+	if (opdata->fan_pulses & G762_VAL_TEST_BIT)
+		pdata->fan_pulses = opdata->fan_pulses;
+	if (opdata->pwm_polarity & G762_VAL_TEST_BIT)
+		pdata->pwm_polarity = opdata->pwm_polarity;
+	if (opdata->pwm_freq & G762_VAL_TEST_BIT)
+		pdata->pwm_freq = opdata->pwm_freq;
+}
+
+/*
+ * sysfs attributes
+ */
+
+/*
+ * Read function for fan1_input sysfs file. Return current fan RPM value, or
+ * 0 if fan is out of control.
+ */
+static ssize_t get_fan_rpm(struct device *dev, struct device_attribute *da,
+			   char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+	unsigned int rpm = 0;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	/* reverse logic: fan out of control reporting is enabled low */
+	if (data->fan_sta & G762_REG_FAN_STA_OOC) {
+		rpm = rpm_from_cnt(data->act_cnt, data->clk,
+				   PULSE_FROM_REG(data->fan_cmd1),
+				   CLKDIV_FROM_REG(data->fan_cmd1),
+				   GEARMULT_FROM_REG(data->fan_cmd2));
+	}
+	mutex_unlock(&data->update_lock);
+
+	return sprintf(buf, "%u\n", rpm);
+}
+
+/*
+ * Read and write functions for pwm1_mode sysfs file. Get and set fan speed
+ * control mode i.e. PWM (1) or DC (0).
+ */
+static ssize_t get_pwm_mode(struct device *dev, struct device_attribute *da,
+			    char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n",
+		       !!(data->fan_cmd1 & G762_REG_FAN_CMD1_OUT_MODE));
+}
+
+static ssize_t set_pwm_mode(struct device *dev, struct device_attribute *da,
+			    const char *buf, size_t count)
+{
+	unsigned long val;
+	int ret;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	ret = do_set_pwm_mode(dev, val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+/*
+ * Read and write functions for fan1_div sysfs file. Get and set fan
+ * controller prescaler value
+ */
+static ssize_t get_fan_div(struct device *dev,
+			   struct device_attribute *da, char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n", CLKDIV_FROM_REG(data->fan_cmd1));
+}
+
+static ssize_t set_fan_div(struct device *dev,
+			   struct device_attribute *da,
+			   const char *buf, size_t count)
+{
+	unsigned long val;
+	int ret;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	ret = do_set_fan_div(dev, val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+/*
+ * Read and write functions for pwm1_enable. Get and set the fan speed control
+ * mode (i.e. closed or open-loop).
+ *
+ * Following documentation about hwmon's sysfs interface, a pwm1_enable node
+ * should accept followings:
+ *
+ *  0 : no fan speed control (i.e. fan at full speed)
+ *  1 : manual fan speed control enabled (use pwm[1-*]) (open-loop)
+ *  2+: automatic fan speed control enabled (use fan[1-*]_target) (closed-loop)
+ *
+ * but we do not accept 0 as "no-control" mode is not supported by g762,
+ * -EINVAL is returned in this case.
+ */
+static ssize_t get_pwm_enable(struct device *dev,
+			      struct device_attribute *da, char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n",
+		       (!!(data->fan_cmd1 & G762_REG_FAN_CMD1_FAN_MODE)) + 1);
+}
+
+static ssize_t set_pwm_enable(struct device *dev,
+			      struct device_attribute *da,
+			      const char *buf, size_t count)
+{
+	unsigned long val;
+	int ret;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	ret = do_set_pwm_enable(dev, val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+/*
+ * Read and write functions for pwm1 sysfs file. Get and set the fan speed
+ * in both open-loop mode. Speed is given as a value between 0 and 255:
+ * 0 stops the fan and 255 makes it run at full speed.
+ */
+static ssize_t get_pwm(struct device *dev, struct device_attribute *da,
+		       char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%d\n", data->set_out);
+}
+
+static ssize_t set_pwm(struct device *dev, struct device_attribute *da,
+		       const char *buf, size_t count)
+{
+	unsigned long val;
+	int ret;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	ret = do_set_pwm(dev, val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+/*
+ * Read and write function for fan1_target sysfs file. Get/set the fan speed in
+ * closed-loop mode. Speed is given as a RPM value; then the chip will regulate
+ * the fan speed using pulses from fan tachometer.
+ *
+ * Refer to rpm_from_cnt() implementation above to get info about count number
+ * calculation.
+ *
+ * Also note that due to rounding errors it is possible that you don't read
+ * back exactly the value you have set.
+ */
+static ssize_t get_fan_target(struct device *dev, struct device_attribute *da,
+			      char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+	ssize_t ret = -EINVAL;
+	unsigned int rpm;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	mutex_lock(&data->update_lock);
+	rpm = rpm_from_cnt(data->set_cnt, data->clk,
+			   PULSE_FROM_REG(data->fan_cmd1),
+			   CLKDIV_FROM_REG(data->fan_cmd1),
+			   GEARMULT_FROM_REG(data->fan_cmd2));
+	ret = sprintf(buf, "%u\n", rpm);
+	mutex_unlock(&data->update_lock);
+
+	return ret;
+}
+
+static ssize_t set_fan_target(struct device *dev, struct device_attribute *da,
+			      const char *buf, size_t count)
+{
+	unsigned long val;
+	int ret;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	ret = do_set_fan_target(dev, val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+/* read function for fan1_fault sysfs file. */
+static ssize_t get_fan_failure(struct device *dev, struct device_attribute *da,
+			       char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%u\n", !!(data->fan_sta & G762_REG_FAN_STA_FAIL));
+}
+
+/*
+ * read function for fan1_alarm sysfs file. Note that OOC condition is
+ * enabled low
+ */
+static ssize_t get_fan_ooc(struct device *dev, struct device_attribute *da,
+			   char *buf)
+{
+	struct g762_data *data = g762_update_client(dev);
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	return sprintf(buf, "%u\n", !(data->fan_sta & G762_REG_FAN_STA_OOC));
+}
+
+static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
+static DEVICE_ATTR(pwm1_mode, S_IWUSR | S_IRUGO, get_pwm_mode, set_pwm_mode);
+static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO,
+		   get_pwm_enable, set_pwm_enable);
+static DEVICE_ATTR(fan1_input, S_IRUGO, get_fan_rpm, NULL);
+static DEVICE_ATTR(fan1_alarm, S_IRUGO, get_fan_ooc, NULL);
+static DEVICE_ATTR(fan1_fault, S_IRUGO, get_fan_failure, NULL);
+static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO,
+		   get_fan_target, set_fan_target);
+static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_fan_div, set_fan_div);
+
+/* Driver data */
+static struct attribute *g762_attributes[] = {
+	&dev_attr_fan1_input.attr,
+	&dev_attr_fan1_alarm.attr,
+	&dev_attr_fan1_fault.attr,
+	&dev_attr_fan1_target.attr,
+	&dev_attr_fan1_div.attr,
+	&dev_attr_pwm1.attr,
+	&dev_attr_pwm1_mode.attr,
+	&dev_attr_pwm1_enable.attr,
+	NULL
+};
+
+static const struct attribute_group g762_group = {
+	.attrs = g762_attributes,
+};
+
+static int g762_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	struct g762_platform_data pdata = { .pwm_freq = G762_ATTR_VAL(32768) };
+	struct g762_data *data;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct g762_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, data);
+
+	data->client = client;
+	mutex_init(&data->update_lock);
+
+	/* Enable fan protection and fan fail detection by default */
+	do_fan_ooc_detection_toggle(&client->dev, 1);
+	do_fan_failure_detection_toggle(&client->dev, 1);
+
+	/*
+	 * Set default configuration values before passing the structure
+	 * first to overload routine used by boards non converted to DT and
+	 * then to OF helper (to overload them using those provided by .dts
+	 * file, if any). Final result is then commited.
+	 */
+	g762_platform_data_overload(client, &pdata);
+	g762_platform_data_of_overload(client, &pdata);
+	err = g762_platform_data_commit(client, &pdata);
+	if (err)
+		return err;
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&client->dev.kobj, &g762_group);
+	if (err)
+		return err;
+
+	data->hwmon_dev = (struct device *)hwmon_device_register(&client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		err = PTR_ERR(data->hwmon_dev);
+		goto err_out;
+	}
+
+	return 0;
+
+ err_out:
+	sysfs_remove_group(&client->dev.kobj, &g762_group);
+	return err;
+}
+
+static int g762_remove(struct i2c_client *client)
+{
+	struct g762_data *data = i2c_get_clientdata(client);
+
+	hwmon_device_unregister(data->hwmon_dev);
+	sysfs_remove_group(&client->dev.kobj, &g762_group);
+
+	return 0;
+}
+
+static struct i2c_driver g762_driver = {
+	.driver = {
+		.name = DRVNAME,
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(g762_dt_match),
+	},
+	.probe	  = g762_probe,
+	.remove	  = g762_remove,
+	.id_table = g762_id,
+};
+
+module_i2c_driver(g762_driver);
+
+MODULE_AUTHOR("Arnaud EBALARD <[e-mail]>");
+MODULE_DESCRIPTION("GMT G762/G763 driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/platform_data/g762.h b/include/linux/platform_data/g762.h
new file mode 100644
index 0000000..cfaf2f3
--- /dev/null
+++ b/include/linux/platform_data/g762.h
@@ -0,0 +1,47 @@ 
+/*
+ * Platform data structure for g762 fan controller driver
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#ifndef __LINUX_PLATFORM_DATA_G762_H__
+#define __LINUX_PLATFORM_DATA_G762_H__
+
+/*
+ * Following structure can be used to set g762 driver platform specific data
+ * during board init. Attributes must *always* be set using G762_ATTR_VAL()
+ * macro defined below, i.e. it is not possible to pass a value directly.
+ * Defining a sparse structure is possible. For instance, if one only needs
+ * to set pwm_freq to 8192 and fan_pulses to 2, the following can be done:
+ *
+ * static struct g762_platform_data pdata = { .pwm_freq = G762_ATTR_VAL(8192),
+ *                                            .fan_pulses = G762_ATTR_VAL(2), };
+ *
+ */
+
+#define G762_VAL_TEST_BIT  (1 << 31)
+#define G762_VAL_TEST_MASK (~G762_VAL_TEST_BIT)
+#define G762_ATTR_VAL(val) ((val) | G762_VAL_TEST_BIT)
+
+struct g762_platform_data {
+	u32 fan_startv;
+	u32 fan_gear_mode;
+	u32 fan_pulses;
+	u32 pwm_polarity;
+	u32 pwm_freq;
+};
+
+#endif /* __LINUX_PLATFORM_DATA_G762_H__ */