/*
   * 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 <arno@natisbad.org>
   *
   * 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 or
   * board init 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 <olivier.mouchet@gmail.com>
   *
   * based on g760a code written by Herbert Valerio Riedel <hvr@gnu.org>
   * Copyright (C) 2007  Herbert Valerio Riedel <hvr@gnu.org>
   *
   * 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/clk.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 G762_OUT_MODE_PWM            1
  #define G762_OUT_MODE_DC             0
  
  #define G762_FAN_MODE_CLOSED_LOOP    2
  #define G762_FAN_MODE_OPEN_LOOP      1
  
  #define G762_PWM_POLARITY_NEGATIVE   1
  #define G762_PWM_POLARITY_POSITIVE   0
  
  /* 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 G762_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 G762_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 G762_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;
  	struct clk *clk;
  
  	/* update mutex */
  	struct mutex update_lock;
  
  	/* board specific parameters. */
  	u32 clk_freq;
  
  	/* 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)
  		      */
  };
  
  /*
   * 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_freq, u16 p,
  					u8 clk_div, u8 gear_mult)
  {
  	if (cnt == 0xff)  /* setting cnt to 255 stops the fan */
  		return 0;
  
  	return (clk_freq * 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_freq, u16 p,
  					 u8 clk_div, u8 gear_mult)
  {
  	if (!rpm)         /* to stop the fan, set cnt to 255 */
  		return 0xff;
  
  	return clamp_val(((clk_freq * 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 writing hardware parameters */
  
  /*
   * Set input clock frequency received on CLK pin of the chip. Accepted values
   * are between 0 and 0xffffff. If zero is given, then default frequency
   * (32,768Hz) is used. Note that clock frequency is a characteristic of the
   * system but an internal parameter, i.e. value is not passed to the device.
   */
  static int do_set_clk_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;
  	if (!val)
  		val = 32768;
  
  	data->clk_freq = val;
  
  	return 0;
  }
  
  /* 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;
  
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	mutex_lock(&data->update_lock);
  	switch (val) {
  	case G762_OUT_MODE_PWM:
  		data->fan_cmd1 |=  G762_REG_FAN_CMD1_OUT_MODE;
  		break;
  	case G762_OUT_MODE_DC:
  		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_OUT_MODE;
  		break;
  	default:
  		ret = -EINVAL;
  		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 clock divisor. Accepts either 1, 2, 4 or 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;
  
  	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:
  		ret = -EINVAL;
  		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. Accepts 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;
  
  	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:
  		ret = -EINVAL;
  		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 number of fan pulses per revolution. 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;
  
  	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:
  		ret = -EINVAL;
  		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;
  
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	mutex_lock(&data->update_lock);
  	switch (val) {
  	case G762_FAN_MODE_CLOSED_LOOP:
  		data->fan_cmd1 |=  G762_REG_FAN_CMD1_FAN_MODE;
  		break;
  	case G762_FAN_MODE_OPEN_LOOP:
  		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_FAN_MODE;
  		/*
  		 * BUG FIX: if SET_CNT register value is 255 then, for some
  		 * unknown reason, fan will not rotate as expected, no matter
  		 * the value of SET_OUT (to be specific, this seems to happen
  		 * only in PWM mode). To workaround this bug, we give SET_CNT
  		 * value of 254 if it is 255 when switching to open-loop.
  		 */
  		if (data->set_cnt == 0xff)
  			i2c_smbus_write_byte_data(client, G762_REG_SET_CNT,
  						  254);
  		break;
  	default:
  		ret = -EINVAL;
  		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. Accepts either 0 (positive duty) or 1 (negative 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;
  
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	mutex_lock(&data->update_lock);
  	switch (val) {
  	case G762_PWM_POLARITY_POSITIVE:
  		data->fan_cmd1 &= ~G762_REG_FAN_CMD1_PWM_POLARITY;
  		break;
  	case G762_PWM_POLARITY_NEGATIVE:
  		data->fan_cmd1 |=  G762_REG_FAN_CMD1_PWM_POLARITY;
  		break;
  	default:
  		ret = -EINVAL;
  		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. Accepts values 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 = i2c_get_clientdata(client);
  	int ret;
  
  	if (val > 255)
  		return -EINVAL;
  
  	mutex_lock(&data->update_lock);
  	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. Can be called both in closed and open-loop mode
   * but effect will only be seen after closed-loop mode is configured.
   */
  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_freq,
  				     G762_PULSE_FROM_REG(data->fan_cmd1),
  				     G762_CLKDIV_FROM_REG(data->fan_cmd1),
  				     G762_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;
  }
  
  /* 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;
  
  	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;
  		break;
  	case 1:
  		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_0;
  		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_1;
  		break;
  	case 2:
  		data->fan_cmd2 &= ~G762_REG_FAN_CMD2_FAN_STARTV_0;
  		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_1;
  		break;
  	case 3:
  		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_0;
  		data->fan_cmd2 |=  G762_REG_FAN_CMD2_FAN_STARTV_1;
  		break;
  	default:
  		ret = -EINVAL;
  		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;
  }
  
  /*
   * Helper to import hardware characteristics from .dts file and push
   * those to the chip.
   */
  
  #ifdef CONFIG_OF
  static struct of_device_id g762_dt_match[] = {
  	{ .compatible = "gmt,g762" },
  	{ .compatible = "gmt,g763" },
  	{ },
  };
  
  /*
   * Grab clock (a required property), enable it, get (fixed) clock frequency
   * and store it. Note: upon success, clock has been prepared and enabled; it
   * must later be unprepared and disabled (e.g. during module unloading) by a
   * call to g762_of_clock_disable(). Note that a reference to clock is kept
   * in our private data structure to be used in this function.
   */
  static int g762_of_clock_enable(struct i2c_client *client)
  {
  	struct g762_data *data;
  	unsigned long clk_freq;
  	struct clk *clk;
  	int ret;
  
  	if (!client->dev.of_node)
  		return 0;
  
  	clk = of_clk_get(client->dev.of_node, 0);
  	if (IS_ERR(clk)) {
  		dev_err(&client->dev, "failed to get clock
  ");
  		return PTR_ERR(clk);
  	}
  
  	ret = clk_prepare_enable(clk);
  	if (ret) {
  		dev_err(&client->dev, "failed to enable clock
  ");
  		goto clk_put;
  	}
  
  	clk_freq = clk_get_rate(clk);
  	ret = do_set_clk_freq(&client->dev, clk_freq);
  	if (ret) {
  		dev_err(&client->dev, "invalid clock freq %lu
  ", clk_freq);
  		goto clk_unprep;
  	}
  
  	data = i2c_get_clientdata(client);
  	data->clk = clk;
  
  	return 0;
  
   clk_unprep:
  	clk_disable_unprepare(clk);
  
   clk_put:
  	clk_put(clk);
  
  	return ret;
  }
  
  static void g762_of_clock_disable(struct i2c_client *client)
  {
  	struct g762_data *data = i2c_get_clientdata(client);
  
  	if (!data->clk)
  		return;
  
  	clk_disable_unprepare(data->clk);
  	clk_put(data->clk);
  }
  
  static int g762_of_prop_import_one(struct i2c_client *client,
  				   const char *pname,
  				   int (*psetter)(struct device *dev,
  						  unsigned long val))
  {
  	const __be32 *prop;
  	int len, ret;
  	u32 pval;
  
  	prop = of_get_property(client->dev.of_node, pname, &len);
  	if (!prop || len != sizeof(u32))
  		return 0;
  
  	pval = be32_to_cpu(prop[0]);
  	dev_dbg(&client->dev, "found %s (%d)
  ", pname, pval);
  	ret = (*psetter)(&client->dev, pval);
  	if (ret)
  		dev_err(&client->dev, "unable to set %s (%d)
  ", pname, pval);
  
  	return ret;
  }
  
  static int g762_of_prop_import(struct i2c_client *client)
  {
  	int ret;
  
  	if (!client->dev.of_node)
  		return 0;
  
  	ret = g762_of_prop_import_one(client, "fan_gear_mode",
  				      do_set_fan_gear_mode);
  	if (ret)
  		return ret;
  
  	ret = g762_of_prop_import_one(client, "pwm_polarity",
  				      do_set_pwm_polarity);
  	if (ret)
  		return ret;
  
  	return g762_of_prop_import_one(client, "fan_startv",
  				       do_set_fan_startv);
  }
  
  #else
  static int g762_of_prop_import(struct i2c_client *client)
  {
  	return 0;
  }
  
  static int g762_of_clock_enable(struct i2c_client *client)
  {
  	return 0;
  }
  
  static void g762_of_clock_disable(struct i2c_client *client) { }
  #endif
  
  /*
   * Helper to import hardware characteristics from .dts file and push
   * those to the chip.
   */
  
  static int g762_pdata_prop_import(struct i2c_client *client)
  {
  	struct g762_platform_data *pdata = dev_get_platdata(&client->dev);
  	int ret;
  
  	if (!pdata)
  		return 0;
  
  	ret = do_set_fan_gear_mode(&client->dev, pdata->fan_gear_mode);
  	if (ret)
  		return ret;
  
  	ret = do_set_pwm_polarity(&client->dev, pdata->pwm_polarity);
  	if (ret)
  		return ret;
  
  	ret = do_set_fan_startv(&client->dev, pdata->fan_startv);
  	if (ret)
  		return ret;
  
  	return do_set_clk_freq(&client->dev, pdata->clk_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_freq,
  				   G762_PULSE_FROM_REG(data->fan_cmd1),
  				   G762_CLKDIV_FROM_REG(data->fan_cmd1),
  				   G762_GEARMULT_FROM_REG(data->fan_cmd2));
  	}
  	mutex_unlock(&data->update_lock);
  
  	return sprintf(buf, "%u
  ", 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
  ",
  		       !!(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
  ", G762_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 fan1_pulses sysfs file. Get and set number
   * of tachometer pulses per fan revolution.
   */
  static ssize_t get_fan_pulses(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
  ", G762_PULSE_FROM_REG(data->fan_cmd1));
  }
  
  static ssize_t set_fan_pulses(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_pulses(dev, val);
  	if (ret < 0)
  		return ret;
  
  	return count;
  }
  
  /*
   * Read and write functions for pwm1_enable. Get and set 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 this mode is not natively supported by the chip
   * and it is not emulated by g762 driver. -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
  ",
  		       (!!(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 pwm value
   * (which affects fan speed) in open-loop mode. 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
  ", 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);
  	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_freq,
  			   G762_PULSE_FROM_REG(data->fan_cmd1),
  			   G762_CLKDIV_FROM_REG(data->fan_cmd1),
  			   G762_GEARMULT_FROM_REG(data->fan_cmd2));
  	mutex_unlock(&data->update_lock);
  
  	return sprintf(buf, "%u
  ", rpm);
  }
  
  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
  ", !!(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
  ", !(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);
  static DEVICE_ATTR(fan1_pulses, S_IWUSR | S_IRUGO,
  		   get_fan_pulses, set_fan_pulses);
  
  /* 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_fan1_pulses.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,
  };
  
  /*
   * Enable both fan failure detection and fan out of control protection. The
   * function does not protect change/access to data structure; it must thus
   * only be called during initialization.
   */
  static inline int g762_fan_init(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct g762_data *data = g762_update_client(dev);
  
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	data->fan_cmd1 |= G762_REG_FAN_CMD1_DET_FAN_FAIL;
  	data->fan_cmd1 |= G762_REG_FAN_CMD1_DET_FAN_OOC;
  	data->valid = false;
  
  	return i2c_smbus_write_byte_data(client, G762_REG_FAN_CMD1,
  					 data->fan_cmd1);
  }
  
  static int g762_probe(struct i2c_client *client, const struct i2c_device_id *id)
  {
  	struct g762_data *data;
  	int ret;
  
  	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 failure detection and fan out of control protection */
  	ret = g762_fan_init(&client->dev);
  	if (ret)
  		return ret;
  
  	/* Get configuration via DT ... */
  	ret = g762_of_clock_enable(client);
  	if (ret)
  		return ret;
  	ret = g762_of_prop_import(client);
  	if (ret)
  		goto clock_dis;
  	/* ... or platform_data */
  	ret = g762_pdata_prop_import(client);
  	if (ret)
  		goto clock_dis;
  
  	/* Register sysfs hooks */
  	ret = sysfs_create_group(&client->dev.kobj, &g762_group);
  	if (ret)
  		goto clock_dis;
  
  	data->hwmon_dev = hwmon_device_register(&client->dev);
  	if (IS_ERR(data->hwmon_dev)) {
  		ret = PTR_ERR(data->hwmon_dev);
  		goto sysfs_rem;
  	}
  
  	return 0;
  
   sysfs_rem:
  	sysfs_remove_group(&client->dev.kobj, &g762_group);
  
   clock_dis:
  	g762_of_clock_disable(client);
  
  	return ret;
  }
  
  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);
  	g762_of_clock_disable(client);
  
  	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 <arno@natisbad.org>");
  MODULE_DESCRIPTION("GMT G762/G763 driver");
  MODULE_LICENSE("GPL");