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 static 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 */ 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); 239 240 return err; 241 } 242 243 static 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 */ 254 255 static int __init g760a_init(void) 256 { 257 return i2c_add_driver(&g760a_driver); 258 } 259 260 static void __exit g760a_exit(void) 261 { 262 i2c_del_driver(&g760a_driver); 263 } 264 265 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>"); 266 MODULE_DESCRIPTION("GMT G760A driver"); 267 MODULE_LICENSE("GPL"); 268 269 module_init(g760a_init); 270 module_exit(g760a_exit); 271