218 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * g760a - Driver for the Global Mixed-mode Technology Inc. G760A4 * fan speed PWM controller chip5 *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.pdf10 */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 23enum g760a_regs {24 G760A_REG_SET_CNT = 0x00,25 G760A_REG_ACT_CNT = 0x01,26 G760A_REG_FAN_STA = 0x0227};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 35struct 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 speed51 * bit 1: set when fan speed below 1920 rpm52 */53};54 55#define G760A_DEFAULT_CLK 3276856#define G760A_DEFAULT_FAN_DIV 257 58#define PWM_FROM_CNT(cnt) (0xff-(cnt))59#define PWM_TO_CNT(pwm) (0xff-(pwm))60 61static 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 */67static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)68{69 return i2c_smbus_read_byte_data(client, reg);70}71 72static 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 attributes80 */81 82static 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 = true;99 }100 101 mutex_unlock(&data->update_lock);102 103 return data;104}105 106static 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 120static 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 130static 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 138static 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 156static DEVICE_ATTR_RW(pwm1);157static DEVICE_ATTR_RO(fan1_input);158static DEVICE_ATTR_RO(fan1_alarm);159 160static struct attribute *g760a_attrs[] = {161 &dev_attr_pwm1.attr,162 &dev_attr_fan1_input.attr,163 &dev_attr_fan1_alarm.attr,164 NULL165};166 167ATTRIBUTE_GROUPS(g760a);168 169/*170 * new-style driver model code171 */172 173static 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 199static const struct i2c_device_id g760a_id[] = {200 { "g760a" },201 { }202};203MODULE_DEVICE_TABLE(i2c, g760a_id);204 205static struct i2c_driver g760a_driver = {206 .driver = {207 .name = "g760a",208 },209 .probe = g760a_probe,210 .id_table = g760a_id,211};212 213module_i2c_driver(g760a_driver);214 215MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");216MODULE_DESCRIPTION("GMT G760A driver");217MODULE_LICENSE("GPL");218