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/datasheet/g760a.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 #define G760A_DEFAULT_CLK 32768
  66 #define G760A_DEFAULT_FAN_DIV 2
  67
  68 #define PWM_FROM_CNT(cnt)       (0xff-(cnt))
  69 #define PWM_TO_CNT(pwm)         (0xff-(pwm))
  70
  71 unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
  72 {
  73         return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
  74 }
  75
  76 /* new-style driver model */
  77 static int g760a_probe(struct i2c_client *client,
  78                         const struct i2c_device_id *id);
  79 static int g760a_remove(struct i2c_client *client);
  80
  81 static struct i2c_driver g760a_driver = {
  82         .driver = {
  83                 .name   = "g760a",
  84         },
  85         .probe    = g760a_probe,
  86         .remove   = g760a_remove,
  87         .id_table = g760a_id,
  88 };
  89
  90 /* read/write wrappers */
  91 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  92 {
  93         return i2c_smbus_read_byte_data(client, reg);
  94 }
  95
  96 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
  97                              u16 value)
  98 {
  99         return i2c_smbus_write_byte_data(client, reg, value);
 100 }
 101
 102 /****************************************************************************
 103  * sysfs attributes
 104  */
 105
 106 static struct g760a_data *g760a_update_client(struct device *dev)
 107 {
 108         struct i2c_client *client = to_i2c_client(dev);
 109         struct g760a_data *data = i2c_get_clientdata(client);
 110
 111         mutex_lock(&data->update_lock);
 112
 113         if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
 114             || !data->valid) {
 115                 dev_dbg(&client->dev, "Starting g760a update\n");
 116
 117                 data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
 118                 data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
 119                 data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
 120
 121                 data->last_updated = jiffies;
 122                 data->valid = 1;
 123         }
 124
 125         mutex_unlock(&data->update_lock);
 126
 127         return data;
 128 }
 129
 130 static ssize_t show_fan(struct device *dev, struct device_attribute *da,
 131                         char *buf)
 132 {
 133         struct g760a_data *data = g760a_update_client(dev);
 134         unsigned int rpm = 0;
 135
 136         mutex_lock(&data->update_lock);
 137         if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
 138                 rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
 139         mutex_unlock(&data->update_lock);
 140
 141         return sprintf(buf, "%d\n", rpm);
 142 }
 143
 144 static ssize_t show_fan_alarm(struct device *dev, struct device_attribute *da,
 145                               char *buf)
 146 {
 147         struct g760a_data *data = g760a_update_client(dev);
 148
 149         int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
 150
 151         return sprintf(buf, "%d\n", fan_alarm);
 152 }
 153
 154 static ssize_t get_pwm(struct device *dev, struct device_attribute *da,
 155                        char *buf)
 156 {
 157         struct g760a_data *data = g760a_update_client(dev);
 158
 159         return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
 160 }
 161
 162 static ssize_t set_pwm(struct device *dev, struct device_attribute *da,
 163                        const char *buf, size_t count)
 164 {
 165         struct i2c_client *client = to_i2c_client(dev);
 166         struct g760a_data *data = g760a_update_client(dev);
 167         unsigned long val;
 168
 169         if (strict_strtoul(buf, 10, &val))
 170                 return -EINVAL;
 171
 172         mutex_lock(&data->update_lock);
 173         data->set_cnt = PWM_TO_CNT(SENSORS_LIMIT(val, 0, 255));
 174         g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
 175         mutex_unlock(&data->update_lock);
 176
 177         return count;
 178 }
 179
 180 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 181 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
 182 static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
 183
 184 static struct attribute *g760a_attributes[] = {
 185         &dev_attr_pwm1.attr,
 186         &dev_attr_fan1_input.attr,
 187         &dev_attr_fan1_alarm.attr,
 188         NULL
 189 };
 190
 191 static const struct attribute_group g760a_group = {
 192         .attrs = g760a_attributes,
 193 };
 194
 195 /****************************************************************************
 196  * new-style driver model code
 197  */
 198
 199 static int g760a_probe(struct i2c_client *client,
 200                         const struct i2c_device_id *id)
 201 {
 202         struct g760a_data *data;
 203         int err;
 204
 205         if (!i2c_check_functionality(client->adapter,
 206                                      I2C_FUNC_SMBUS_BYTE_DATA))
 207                 return -EIO;
 208
 209         data = kzalloc(sizeof(struct g760a_data), GFP_KERNEL);
 210         if (!data)
 211                 return -ENOMEM;
 212
 213         i2c_set_clientdata(client, data);
 214
 215         data->client = client;
 216         mutex_init(&data->update_lock);
 217
 218         /* setup default configuration for now */
 219         data->fan_div = G760A_DEFAULT_FAN_DIV;
 220         data->clk = G760A_DEFAULT_CLK;
 221
 222         /* Register sysfs hooks */
 223         err = sysfs_create_group(&client->dev.kobj, &g760a_group);
 224         if (err)
 225                 goto error_sysfs_create_group;
 226
 227         data->hwmon_dev = hwmon_device_register(&client->dev);
 228         if (IS_ERR(data->hwmon_dev)) {
 229                 err = PTR_ERR(data->hwmon_dev);
 230                 goto error_hwmon_device_register;
 231         }
 232
 233         return 0;
 234
 235 error_hwmon_device_register:
 236         sysfs_remove_group(&client->dev.kobj, &g760a_group);
 237 error_sysfs_create_group:
 238         kfree(data);
 239         i2c_set_clientdata(client, NULL);
 240
 241         return err;
 242 }
 243
 244 static int g760a_remove(struct i2c_client *client)
 245 {
 246         struct g760a_data *data = i2c_get_clientdata(client);
 247         hwmon_device_unregister(data->hwmon_dev);
 248         sysfs_remove_group(&client->dev.kobj, &g760a_group);
 249         kfree(data);
 250         i2c_set_clientdata(client, NULL);
 251
 252         return 0;
 253 }
 254
 255 /* module management */
 256
 257 static int __init g760a_init(void)
 258 {
 259         return i2c_add_driver(&g760a_driver);
 260 }
 261
 262 static void __exit g760a_exit(void)
 263 {
 264         i2c_del_driver(&g760a_driver);
 265 }
 266
 267 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 268 MODULE_DESCRIPTION("GMT G760A driver");
 269 MODULE_LICENSE("GPL");
 270
 271 module_init(g760a_init);
 272 module_exit(g760a_exit);