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 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 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 72 static 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 */ 78 static int g760a_probe(struct i2c_client *client, 79 const struct i2c_device_id *id); 80 static int g760a_remove(struct i2c_client *client); 81 82 static 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 */ 92 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg) 93 { 94 return i2c_smbus_read_byte_data(client, reg); 95 } 96 97 static 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 */ 106 107 static 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 } 130 131 static 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 } 144 145 static 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 } 154 155 static 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 } 162 163 static 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(clamp_val(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 } 180 181 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm); 182 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL); 183 static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL); 184 185 static struct attribute *g760a_attributes[] = { 186 &dev_attr_pwm1.attr, 187 &dev_attr_fan1_input.attr, 188 &dev_attr_fan1_alarm.attr, 189 NULL 190 }; 191 192 static const struct attribute_group g760a_group = { 193 .attrs = g760a_attributes, 194 }; 195 196 /* 197 * new-style driver model code 198 */ 199 200 static 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 = devm_kzalloc(&client->dev, sizeof(struct g760a_data), 211 GFP_KERNEL); 212 if (!data) 213 return -ENOMEM; 214 215 i2c_set_clientdata(client, data); 216 217 data->client = client; 218 mutex_init(&data->update_lock); 219 220 /* setup default configuration for now */ 221 data->fan_div = G760A_DEFAULT_FAN_DIV; 222 data->clk = G760A_DEFAULT_CLK; 223 224 /* Register sysfs hooks */ 225 err = sysfs_create_group(&client->dev.kobj, &g760a_group); 226 if (err) 227 return err; 228 229 data->hwmon_dev = hwmon_device_register(&client->dev); 230 if (IS_ERR(data->hwmon_dev)) { 231 err = PTR_ERR(data->hwmon_dev); 232 goto error_hwmon_device_register; 233 } 234 235 return 0; 236 237 error_hwmon_device_register: 238 sysfs_remove_group(&client->dev.kobj, &g760a_group); 239 return err; 240 } 241 242 static int g760a_remove(struct i2c_client *client) 243 { 244 struct g760a_data *data = i2c_get_clientdata(client); 245 hwmon_device_unregister(data->hwmon_dev); 246 sysfs_remove_group(&client->dev.kobj, &g760a_group); 247 return 0; 248 } 249 250 module_i2c_driver(g760a_driver); 251 252 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>"); 253 MODULE_DESCRIPTION("GMT G760A driver"); 254 MODULE_LICENSE("GPL"); 255