linux/drivers/hwmon/g760a.c
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   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
  27static const struct i2c_device_id g760a_id[] = {
  28        { "g760a", 0 },
  29        { }
  30};
  31MODULE_DEVICE_TABLE(i2c, g760a_id);
  32
  33enum 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
  45struct 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
  71static inline 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 */
  77static int g760a_probe(struct i2c_client *client,
  78                        const struct i2c_device_id *id);
  79static int g760a_remove(struct i2c_client *client);
  80
  81static 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 */
  91static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  92{
  93        return i2c_smbus_read_byte_data(client, reg);
  94}
  95
  96static 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
 106static 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
 130static 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
 144static 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
 154static 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
 162static 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
 180static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 181static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
 182static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
 183
 184static 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
 191static const struct attribute_group g760a_group = {
 192        .attrs = g760a_attributes,
 193};
 194
 195/****************************************************************************
 196 * new-style driver model code
 197 */
 198
 199static 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
 235error_hwmon_device_register:
 236        sysfs_remove_group(&client->dev.kobj, &g760a_group);
 237error_sysfs_create_group:
 238        kfree(data);
 239
 240        return err;
 241}
 242
 243static int g760a_remove(struct i2c_client *client)
 244{
 245        struct g760a_data *data = i2c_get_clientdata(client);
 246        hwmon_device_unregister(data->hwmon_dev);
 247        sysfs_remove_group(&client->dev.kobj, &g760a_group);
 248        kfree(data);
 249
 250        return 0;
 251}
 252
 253/* module management */
 254
 255static int __init g760a_init(void)
 256{
 257        return i2c_add_driver(&g760a_driver);
 258}
 259
 260static void __exit g760a_exit(void)
 261{
 262        i2c_del_driver(&g760a_driver);
 263}
 264
 265MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 266MODULE_DESCRIPTION("GMT G760A driver");
 267MODULE_LICENSE("GPL");
 268
 269module_init(g760a_init);
 270module_exit(g760a_exit);
 271