drivers/hwmon/g760a.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * g760a - Driver for the Global Mixed-mode Technology Inc. G760A
   4  *         fan speed PWM controller chip
   5  *
   6  * Copyright (C) 2007  Herbert Valerio Riedel <hvr@gnu.org>
   7  *
   8  * Complete datasheet is available at GMT's website:
   9  * http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/i2c.h>
  17 #include <linux/hwmon.h>
  18 #include <linux/hwmon-sysfs.h>
  19 #include <linux/err.h>
  20 #include <linux/mutex.h>
  21 #include <linux/sysfs.h>
  22
  23 enum g760a_regs {
  24         G760A_REG_SET_CNT = 0x00,
  25         G760A_REG_ACT_CNT = 0x01,
  26         G760A_REG_FAN_STA = 0x02
  27 };
  28
  29 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
  30 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
  31
  32 /* register data is read (and cached) at most once per second */
  33 #define G760A_UPDATE_INTERVAL (HZ)
  34
  35 struct g760a_data {
  36         struct i2c_client *client;
  37         struct mutex update_lock;
  38
  39         /* board specific parameters */
  40         u32 clk; /* default 32kHz */
  41         u16 fan_div; /* default P=2 */
  42
  43         /* g760a register cache */
  44         unsigned int valid:1;
  45         unsigned long last_updated; /* In jiffies */
  46
  47         u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
  48         u8 act_cnt; /*   formula: cnt = (CLK * 30)/(rpm * P) */
  49         u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
  50                      *   outside requested fan speed
  51                      * bit 1: set when fan speed below 1920 rpm
  52                      */
  53 };
  54
  55 #define G760A_DEFAULT_CLK 32768
  56 #define G760A_DEFAULT_FAN_DIV 2
  57
  58 #define PWM_FROM_CNT(cnt)       (0xff-(cnt))
  59 #define PWM_TO_CNT(pwm)         (0xff-(pwm))
  60
  61 static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
  62 {
  63         return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
  64 }
  65
  66 /* read/write wrappers */
  67 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  68 {
  69         return i2c_smbus_read_byte_data(client, reg);
  70 }
  71
  72 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
  73                              u16 value)
  74 {
  75         return i2c_smbus_write_byte_data(client, reg, value);
  76 }
  77
  78 /*
  79  * sysfs attributes
  80  */
  81
  82 static struct g760a_data *g760a_update_client(struct device *dev)
  83 {
  84         struct g760a_data *data = dev_get_drvdata(dev);
  85         struct i2c_client *client = data->client;
  86
  87         mutex_lock(&data->update_lock);
  88
  89         if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
  90             || !data->valid) {
  91                 dev_dbg(&client->dev, "Starting g760a update\n");
  92
  93                 data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
  94                 data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
  95                 data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
  96
  97                 data->last_updated = jiffies;
  98                 data->valid = 1;
  99         }
 100
 101         mutex_unlock(&data->update_lock);
 102
 103         return data;
 104 }
 105
 106 static ssize_t fan1_input_show(struct device *dev,
 107                                struct device_attribute *da, char *buf)
 108 {
 109         struct g760a_data *data = g760a_update_client(dev);
 110         unsigned int rpm = 0;
 111
 112         mutex_lock(&data->update_lock);
 113         if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
 114                 rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
 115         mutex_unlock(&data->update_lock);
 116
 117         return sprintf(buf, "%d\n", rpm);
 118 }
 119
 120 static ssize_t fan1_alarm_show(struct device *dev,
 121                                struct device_attribute *da, char *buf)
 122 {
 123         struct g760a_data *data = g760a_update_client(dev);
 124
 125         int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
 126
 127         return sprintf(buf, "%d\n", fan_alarm);
 128 }
 129
 130 static ssize_t pwm1_show(struct device *dev, struct device_attribute *da,
 131                          char *buf)
 132 {
 133         struct g760a_data *data = g760a_update_client(dev);
 134
 135         return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
 136 }
 137
 138 static ssize_t pwm1_store(struct device *dev, struct device_attribute *da,
 139                           const char *buf, size_t count)
 140 {
 141         struct g760a_data *data = g760a_update_client(dev);
 142         struct i2c_client *client = data->client;
 143         unsigned long val;
 144
 145         if (kstrtoul(buf, 10, &val))
 146                 return -EINVAL;
 147
 148         mutex_lock(&data->update_lock);
 149         data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255));
 150         g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
 151         mutex_unlock(&data->update_lock);
 152
 153         return count;
 154 }
 155
 156 static DEVICE_ATTR_RW(pwm1);
 157 static DEVICE_ATTR_RO(fan1_input);
 158 static DEVICE_ATTR_RO(fan1_alarm);
 159
 160 static struct attribute *g760a_attrs[] = {
 161         &dev_attr_pwm1.attr,
 162         &dev_attr_fan1_input.attr,
 163         &dev_attr_fan1_alarm.attr,
 164         NULL
 165 };
 166
 167 ATTRIBUTE_GROUPS(g760a);
 168
 169 /*
 170  * new-style driver model code
 171  */
 172
 173 static int g760a_probe(struct i2c_client *client)
 174 {
 175         struct device *dev = &client->dev;
 176         struct g760a_data *data;
 177         struct device *hwmon_dev;
 178
 179         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 180                 return -EIO;
 181
 182         data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL);
 183         if (!data)
 184                 return -ENOMEM;
 185
 186         data->client = client;
 187         mutex_init(&data->update_lock);
 188
 189         /* setup default configuration for now */
 190         data->fan_div = G760A_DEFAULT_FAN_DIV;
 191         data->clk = G760A_DEFAULT_CLK;
 192
 193         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 194                                                            data,
 195                                                            g760a_groups);
 196         return PTR_ERR_OR_ZERO(hwmon_dev);
 197 }
 198
 199 static const struct i2c_device_id g760a_id[] = {
 200         { "g760a", 0 },
 201         { }
 202 };
 203 MODULE_DEVICE_TABLE(i2c, g760a_id);
 204
 205 static struct i2c_driver g760a_driver = {
 206         .driver = {
 207                 .name   = "g760a",
 208         },
 209         .probe_new = g760a_probe,
 210         .id_table = g760a_id,
 211 };
 212
 213 module_i2c_driver(g760a_driver);
 214
 215 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
 216 MODULE_DESCRIPTION("GMT G760A driver");
 217 MODULE_LICENSE("GPL");