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
  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
  72static 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 */
  78static int g760a_probe(struct i2c_client *client,
  79                        const struct i2c_device_id *id);
  80static int g760a_remove(struct i2c_client *client);
  81
  82static 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 */
  92static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  93{
  94        return i2c_smbus_read_byte_data(client, reg);
  95}
  96
  97static 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
 107static 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
 131static 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
 145static 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
 155static 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
 163static 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(SENSORS_LIMIT(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
 181static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
 182static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
 183static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
 184
 185static 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
 192static const struct attribute_group g760a_group = {
 193        .attrs = g760a_attributes,
 194};
 195
 196/*
 197 * new-style driver model code
 198 */
 199
 200static 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 = kzalloc(sizeof(struct g760a_data), GFP_KERNEL);
 211        if (!data)
 212                return -ENOMEM;
 213
 214        i2c_set_clientdata(client, data);
 215
 216        data->client = client;
 217        mutex_init(&data->update_lock);
 218
 219        /* setup default configuration for now */
 220        data->fan_div = G760A_DEFAULT_FAN_DIV;
 221        data->clk = G760A_DEFAULT_CLK;
 222
 223        /* Register sysfs hooks */
 224        err = sysfs_create_group(&client->dev.kobj, &g760a_group);
 225        if (err)
 226                goto error_sysfs_create_group;
 227
 228        data->hwmon_dev = hwmon_device_register(&client->dev);
 229        if (IS_ERR(data->hwmon_dev)) {
 230                err = PTR_ERR(data->hwmon_dev);
 231                goto error_hwmon_device_register;
 232        }
 233
 234        return 0;
 235
 236error_hwmon_device_register:
 237        sysfs_remove_group(&client->dev.kobj, &g760a_group);
 238error_sysfs_create_group:
 239        kfree(data);
 240
 241        return err;
 242}
 243
 244static 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
 251        return 0;
 252}
 253
 254module_i2c_driver(g760a_driver);
 255
 256MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 257MODULE_DESCRIPTION("GMT G760A driver");
 258MODULE_LICENSE("GPL");
 259
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