drivers/hwmon/g760a.c

   1 /*
   2  * g760a - Driver for the Global Mixed-mode Technology Inc. G760A
   3  *         fan speed PWM controller chip
   4  *
   5  * Copyright (C) 2007  Herbert Valerio Riedel <hvr@gnu.org>
   6  *
   7  * Complete datasheet is available at GMT's website:
   8  * http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/i2c.h>
  21 #include <linux/hwmon.h>
  22 #include <linux/hwmon-sysfs.h>
  23 #include <linux/err.h>
  24 #include <linux/mutex.h>
  25 #include <linux/sysfs.h>
  26
  27 enum g760a_regs {
  28         G760A_REG_SET_CNT = 0x00,
  29         G760A_REG_ACT_CNT = 0x01,
  30         G760A_REG_FAN_STA = 0x02
  31 };
  32
  33 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
  34 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
  35
  36 /* register data is read (and cached) at most once per second */
  37 #define G760A_UPDATE_INTERVAL (HZ)
  38
  39 struct g760a_data {
  40         struct i2c_client *client;
  41         struct mutex update_lock;
  42
  43         /* board specific parameters */
  44         u32 clk; /* default 32kHz */
  45         u16 fan_div; /* default P=2 */
  46
  47         /* g760a register cache */
  48         unsigned int valid:1;
  49         unsigned long last_updated; /* In jiffies */
  50
  51         u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
  52         u8 act_cnt; /*   formula: cnt = (CLK * 30)/(rpm * P) */
  53         u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
  54                      *   outside requested fan speed
  55                      * bit 1: set when fan speed below 1920 rpm
  56                      */
  57 };
  58
  59 #define G760A_DEFAULT_CLK 32768
  60 #define G760A_DEFAULT_FAN_DIV 2
  61
  62 #define PWM_FROM_CNT(cnt)       (0xff-(cnt))
  63 #define PWM_TO_CNT(pwm)         (0xff-(pwm))
  64
  65 static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
  66 {
  67         return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
  68 }
  69
  70 /* read/write wrappers */
  71 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  72 {
  73         return i2c_smbus_read_byte_data(client, reg);
  74 }
  75
  76 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
  77                              u16 value)
  78 {
  79         return i2c_smbus_write_byte_data(client, reg, value);
  80 }
  81
  82 /*
  83  * sysfs attributes
  84  */
  85
  86 static struct g760a_data *g760a_update_client(struct device *dev)
  87 {
  88         struct g760a_data *data = dev_get_drvdata(dev);
  89         struct i2c_client *client = data->client;
  90
  91         mutex_lock(&data->update_lock);
  92
  93         if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
  94             || !data->valid) {
  95                 dev_dbg(&client->dev, "Starting g760a update\n");
  96
  97                 data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
  98                 data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
  99                 data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
 100
 101                 data->last_updated = jiffies;
 102                 data->valid = 1;
 103         }
 104
 105         mutex_unlock(&data->update_lock);
 106
 107         return data;
 108 }
 109
 110 static ssize_t show_fan(struct device *dev, struct device_attribute *da,
 111                         char *buf)
 112 {
 113         struct g760a_data *data = g760a_update_client(dev);
 114         unsigned int rpm = 0;
 115
 116         mutex_lock(&data->update_lock);
 117         if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
 118                 rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
 119         mutex_unlock(&data->update_lock);
 120
 121         return sprintf(buf, "%d\n", rpm);
 122 }
 123
 124 static ssize_t show_fan_alarm(struct device *dev, struct device_attribute *da,
 125                               char *buf)
 126 {
 127         struct g760a_data *data = g760a_update_client(dev);
 128
 129         int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
 130
 131         return sprintf(buf, "%d\n", fan_alarm);
 132 }
 133
 134 static ssize_t get_pwm(struct device *dev, struct device_attribute *da,
 135                        char *buf)
 136 {
 137         struct g760a_data *data = g760a_update_client(dev);
 138
 139         return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
 140 }
 141
 142 static ssize_t set_pwm(struct device *dev, struct device_attribute *da,
 143                        const char *buf, size_t count)
 144 {
 145         struct g760a_data *data = g760a_update_client(dev);
 146         struct i2c_client *client = data->client;
 147         unsigned long val;
 148
 149         if (kstrtoul(buf, 10, &val))
 150                 return -EINVAL;
 151
 152         mutex_lock(&data->update_lock);
 153         data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255));
 154         g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
 155         mutex_unlock(&data->update_lock);
 156
 157         return count;
 158 }
 159
 160 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 161 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
 162 static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
 163
 164 static struct attribute *g760a_attrs[] = {
 165         &dev_attr_pwm1.attr,
 166         &dev_attr_fan1_input.attr,
 167         &dev_attr_fan1_alarm.attr,
 168         NULL
 169 };
 170
 171 ATTRIBUTE_GROUPS(g760a);
 172
 173 /*
 174  * new-style driver model code
 175  */
 176
 177 static int g760a_probe(struct i2c_client *client,
 178                         const struct i2c_device_id *id)
 179 {
 180         struct device *dev = &client->dev;
 181         struct g760a_data *data;
 182         struct device *hwmon_dev;
 183
 184         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 185                 return -EIO;
 186
 187         data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL);
 188         if (!data)
 189                 return -ENOMEM;
 190
 191         data->client = client;
 192         mutex_init(&data->update_lock);
 193
 194         /* setup default configuration for now */
 195         data->fan_div = G760A_DEFAULT_FAN_DIV;
 196         data->clk = G760A_DEFAULT_CLK;
 197
 198         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 199                                                            data,
 200                                                            g760a_groups);
 201         return PTR_ERR_OR_ZERO(hwmon_dev);
 202 }
 203
 204 static const struct i2c_device_id g760a_id[] = {
 205         { "g760a", 0 },
 206         { }
 207 };
 208 MODULE_DEVICE_TABLE(i2c, g760a_id);
 209
 210 static struct i2c_driver g760a_driver = {
 211         .driver = {
 212                 .name   = "g760a",
 213         },
 214         .probe    = g760a_probe,
 215         .id_table = g760a_id,
 216 };
 217
 218 module_i2c_driver(g760a_driver);
 219
 220 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 221 MODULE_DESCRIPTION("GMT G760A driver");
 222 MODULE_LICENSE("GPL");