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 static const struct i2c_device_id g760a_id[] = {
  28         { "g760a", 0 },
  29         { }
  30 };
  31 MODULE_DEVICE_TABLE(i2c, g760a_id);
  32
  33 enum g760a_regs {
  34         G760A_REG_SET_CNT = 0x00,
  35         G760A_REG_ACT_CNT = 0x01,
  36         G760A_REG_FAN_STA = 0x02
  37 };
  38
  39 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
  40 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
  41
  42 /* register data is read (and cached) at most once per second */
  43 #define G760A_UPDATE_INTERVAL (HZ)
  44
  45 struct g760a_data {
  46         struct i2c_client *client;
  47         struct device *hwmon_dev;
  48         struct mutex update_lock;
  49
  50         /* board specific parameters */
  51         u32 clk; /* default 32kHz */
  52         u16 fan_div; /* default P=2 */
  53
  54         /* g760a register cache */
  55         unsigned int valid:1;
  56         unsigned long last_updated; /* In jiffies */
  57
  58         u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
  59         u8 act_cnt; /*   formula: cnt = (CLK * 30)/(rpm * P) */
  60         u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
  61                      *   outside requested fan speed
  62                      * bit 1: set when fan speed below 1920 rpm
  63                      */
  64 };
  65
  66 #define G760A_DEFAULT_CLK 32768
  67 #define G760A_DEFAULT_FAN_DIV 2
  68
  69 #define PWM_FROM_CNT(cnt)       (0xff-(cnt))
  70 #define PWM_TO_CNT(pwm)         (0xff-(pwm))
  71
  72 static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
  73 {
  74         return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
  75 }
  76
  77 /* new-style driver model */
  78 static int g760a_probe(struct i2c_client *client,
  79                         const struct i2c_device_id *id);
  80 static int g760a_remove(struct i2c_client *client);
  81
  82 static struct i2c_driver g760a_driver = {
  83         .driver = {
  84                 .name   = "g760a",
  85         },
  86         .probe    = g760a_probe,
  87         .remove   = g760a_remove,
  88         .id_table = g760a_id,
  89 };
  90
  91 /* read/write wrappers */
  92 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  93 {
  94         return i2c_smbus_read_byte_data(client, reg);
  95 }
  96
  97 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
  98                              u16 value)
  99 {
 100         return i2c_smbus_write_byte_data(client, reg, value);
 101 }
 102
 103 /*
 104  * sysfs attributes
 105  */
 106
 107 static struct g760a_data *g760a_update_client(struct device *dev)
 108 {
 109         struct i2c_client *client = to_i2c_client(dev);
 110         struct g760a_data *data = i2c_get_clientdata(client);
 111
 112         mutex_lock(&data->update_lock);
 113
 114         if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
 115             || !data->valid) {
 116                 dev_dbg(&client->dev, "Starting g760a update\n");
 117
 118                 data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
 119                 data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
 120                 data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
 121
 122                 data->last_updated = jiffies;
 123                 data->valid = 1;
 124         }
 125
 126         mutex_unlock(&data->update_lock);
 127
 128         return data;
 129 }
 130
 131 static ssize_t show_fan(struct device *dev, struct device_attribute *da,
 132                         char *buf)
 133 {
 134         struct g760a_data *data = g760a_update_client(dev);
 135         unsigned int rpm = 0;
 136
 137         mutex_lock(&data->update_lock);
 138         if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
 139                 rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
 140         mutex_unlock(&data->update_lock);
 141
 142         return sprintf(buf, "%d\n", rpm);
 143 }
 144
 145 static ssize_t show_fan_alarm(struct device *dev, struct device_attribute *da,
 146                               char *buf)
 147 {
 148         struct g760a_data *data = g760a_update_client(dev);
 149
 150         int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
 151
 152         return sprintf(buf, "%d\n", fan_alarm);
 153 }
 154
 155 static ssize_t get_pwm(struct device *dev, struct device_attribute *da,
 156                        char *buf)
 157 {
 158         struct g760a_data *data = g760a_update_client(dev);
 159
 160         return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
 161 }
 162
 163 static ssize_t set_pwm(struct device *dev, struct device_attribute *da,
 164                        const char *buf, size_t count)
 165 {
 166         struct i2c_client *client = to_i2c_client(dev);
 167         struct g760a_data *data = g760a_update_client(dev);
 168         unsigned long val;
 169
 170         if (kstrtoul(buf, 10, &val))
 171                 return -EINVAL;
 172
 173         mutex_lock(&data->update_lock);
 174         data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255));
 175         g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
 176         mutex_unlock(&data->update_lock);
 177
 178         return count;
 179 }
 180
 181 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 182 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
 183 static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
 184
 185 static struct attribute *g760a_attributes[] = {
 186         &dev_attr_pwm1.attr,
 187         &dev_attr_fan1_input.attr,
 188         &dev_attr_fan1_alarm.attr,
 189         NULL
 190 };
 191
 192 static const struct attribute_group g760a_group = {
 193         .attrs = g760a_attributes,
 194 };
 195
 196 /*
 197  * new-style driver model code
 198  */
 199
 200 static int g760a_probe(struct i2c_client *client,
 201                         const struct i2c_device_id *id)
 202 {
 203         struct g760a_data *data;
 204         int err;
 205
 206         if (!i2c_check_functionality(client->adapter,
 207                                      I2C_FUNC_SMBUS_BYTE_DATA))
 208                 return -EIO;
 209
 210         data = devm_kzalloc(&client->dev, sizeof(struct g760a_data),
 211                             GFP_KERNEL);
 212         if (!data)
 213                 return -ENOMEM;
 214
 215         i2c_set_clientdata(client, data);
 216
 217         data->client = client;
 218         mutex_init(&data->update_lock);
 219
 220         /* setup default configuration for now */
 221         data->fan_div = G760A_DEFAULT_FAN_DIV;
 222         data->clk = G760A_DEFAULT_CLK;
 223
 224         /* Register sysfs hooks */
 225         err = sysfs_create_group(&client->dev.kobj, &g760a_group);
 226         if (err)
 227                 return err;
 228
 229         data->hwmon_dev = hwmon_device_register(&client->dev);
 230         if (IS_ERR(data->hwmon_dev)) {
 231                 err = PTR_ERR(data->hwmon_dev);
 232                 goto error_hwmon_device_register;
 233         }
 234
 235         return 0;
 236
 237 error_hwmon_device_register:
 238         sysfs_remove_group(&client->dev.kobj, &g760a_group);
 239         return err;
 240 }
 241
 242 static int g760a_remove(struct i2c_client *client)
 243 {
 244         struct g760a_data *data = i2c_get_clientdata(client);
 245         hwmon_device_unregister(data->hwmon_dev);
 246         sysfs_remove_group(&client->dev.kobj, &g760a_group);
 247         return 0;
 248 }
 249
 250 module_i2c_driver(g760a_driver);
 251
 252 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 253 MODULE_DESCRIPTION("GMT G760A driver");
 254 MODULE_LICENSE("GPL");