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 enum g760a_regs { 28 G760A_REG_SET_CNT = 0x00, 29 G760A_REG_ACT_CNT = 0x01, 30 G760A_REG_FAN_STA = 0x02 31 }; 32 33 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */ 34 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */ 35 36 /* register data is read (and cached) at most once per second */ 37 #define G760A_UPDATE_INTERVAL (HZ) 38 39 struct g760a_data { 40 struct i2c_client *client; 41 struct mutex update_lock; 42 43 /* board specific parameters */ 44 u32 clk; /* default 32kHz */ 45 u16 fan_div; /* default P=2 */ 46 47 /* g760a register cache */ 48 unsigned int valid:1; 49 unsigned long last_updated; /* In jiffies */ 50 51 u8 set_cnt; /* PWM (period) count number; 0xff stops fan */ 52 u8 act_cnt; /* formula: cnt = (CLK * 30)/(rpm * P) */ 53 u8 fan_sta; /* bit 0: set when actual fan speed more than 20% 54 * outside requested fan speed 55 * bit 1: set when fan speed below 1920 rpm 56 */ 57 }; 58 59 #define G760A_DEFAULT_CLK 32768 60 #define G760A_DEFAULT_FAN_DIV 2 61 62 #define PWM_FROM_CNT(cnt) (0xff-(cnt)) 63 #define PWM_TO_CNT(pwm) (0xff-(pwm)) 64 65 static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div) 66 { 67 return ((val == 0x00) ? 0 : ((clk*30)/(val*div))); 68 } 69 70 /* read/write wrappers */ 71 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg) 72 { 73 return i2c_smbus_read_byte_data(client, reg); 74 } 75 76 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg, 77 u16 value) 78 { 79 return i2c_smbus_write_byte_data(client, reg, value); 80 } 81 82 /* 83 * sysfs attributes 84 */ 85 86 static struct g760a_data *g760a_update_client(struct device *dev) 87 { 88 struct g760a_data *data = dev_get_drvdata(dev); 89 struct i2c_client *client = data->client; 90 91 mutex_lock(&data->update_lock); 92 93 if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL) 94 || !data->valid) { 95 dev_dbg(&client->dev, "Starting g760a update\n"); 96 97 data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT); 98 data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT); 99 data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA); 100 101 data->last_updated = jiffies; 102 data->valid = 1; 103 } 104 105 mutex_unlock(&data->update_lock); 106 107 return data; 108 } 109 110 static ssize_t show_fan(struct device *dev, struct device_attribute *da, 111 char *buf) 112 { 113 struct g760a_data *data = g760a_update_client(dev); 114 unsigned int rpm = 0; 115 116 mutex_lock(&data->update_lock); 117 if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW)) 118 rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div); 119 mutex_unlock(&data->update_lock); 120 121 return sprintf(buf, "%d\n", rpm); 122 } 123 124 static ssize_t show_fan_alarm(struct device *dev, struct device_attribute *da, 125 char *buf) 126 { 127 struct g760a_data *data = g760a_update_client(dev); 128 129 int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0; 130 131 return sprintf(buf, "%d\n", fan_alarm); 132 } 133 134 static ssize_t get_pwm(struct device *dev, struct device_attribute *da, 135 char *buf) 136 { 137 struct g760a_data *data = g760a_update_client(dev); 138 139 return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt)); 140 } 141 142 static ssize_t set_pwm(struct device *dev, struct device_attribute *da, 143 const char *buf, size_t count) 144 { 145 struct g760a_data *data = g760a_update_client(dev); 146 struct i2c_client *client = data->client; 147 unsigned long val; 148 149 if (kstrtoul(buf, 10, &val)) 150 return -EINVAL; 151 152 mutex_lock(&data->update_lock); 153 data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255)); 154 g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt); 155 mutex_unlock(&data->update_lock); 156 157 return count; 158 } 159 160 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm); 161 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL); 162 static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL); 163 164 static struct attribute *g760a_attrs[] = { 165 &dev_attr_pwm1.attr, 166 &dev_attr_fan1_input.attr, 167 &dev_attr_fan1_alarm.attr, 168 NULL 169 }; 170 171 ATTRIBUTE_GROUPS(g760a); 172 173 /* 174 * new-style driver model code 175 */ 176 177 static int g760a_probe(struct i2c_client *client, 178 const struct i2c_device_id *id) 179 { 180 struct device *dev = &client->dev; 181 struct g760a_data *data; 182 struct device *hwmon_dev; 183 184 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 185 return -EIO; 186 187 data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL); 188 if (!data) 189 return -ENOMEM; 190 191 data->client = client; 192 mutex_init(&data->update_lock); 193 194 /* setup default configuration for now */ 195 data->fan_div = G760A_DEFAULT_FAN_DIV; 196 data->clk = G760A_DEFAULT_CLK; 197 198 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 199 data, 200 g760a_groups); 201 return PTR_ERR_OR_ZERO(hwmon_dev); 202 } 203 204 static const struct i2c_device_id g760a_id[] = { 205 { "g760a", 0 }, 206 { } 207 }; 208 MODULE_DEVICE_TABLE(i2c, g760a_id); 209 210 static struct i2c_driver g760a_driver = { 211 .driver = { 212 .name = "g760a", 213 }, 214 .probe = g760a_probe, 215 .id_table = g760a_id, 216 }; 217 218 module_i2c_driver(g760a_driver); 219 220 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>"); 221 MODULE_DESCRIPTION("GMT G760A driver"); 222 MODULE_LICENSE("GPL"); 223