// SPDX-License-Identifier: GPL-2.0-or-later /* * g760a - Driver for the Global Mixed-mode Technology Inc. G760A * fan speed PWM controller chip * * Copyright (C) 2007 Herbert Valerio Riedel <hvr@gnu.org> * * Complete datasheet is available at GMT's website: * http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf */ #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/jiffies.h> #include <linux/i2c.h> #include <linux/hwmon.h> #include <linux/hwmon-sysfs.h> #include <linux/err.h> #include <linux/mutex.h> #include <linux/sysfs.h> enum g760a_regs { G760A_REG_SET_CNT = 0x00, G760A_REG_ACT_CNT = 0x01, G760A_REG_FAN_STA = 0x02 }; #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */ #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */ /* register data is read (and cached) at most once per second */ #define G760A_UPDATE_INTERVAL (HZ) struct g760a_data { struct i2c_client *client; struct mutex update_lock; /* board specific parameters */ u32 clk; /* default 32kHz */ u16 fan_div; /* default P=2 */ /* g760a register cache */ unsigned int valid:1; unsigned long last_updated; /* In jiffies */ u8 set_cnt; /* PWM (period) count number; 0xff stops fan */ u8 act_cnt; /* formula: cnt = (CLK * 30)/(rpm * P) */ u8 fan_sta; /* bit 0: set when actual fan speed more than 20% * outside requested fan speed * bit 1: set when fan speed below 1920 rpm */ }; #define G760A_DEFAULT_CLK 32768 #define G760A_DEFAULT_FAN_DIV 2 #define PWM_FROM_CNT(cnt) (0xff-(cnt)) #define PWM_TO_CNT(pwm) (0xff-(pwm)) static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div) { return ((val == 0x00) ? 0 : ((clk*30)/(val*div))); } /* read/write wrappers */ static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg) { return i2c_smbus_read_byte_data(client, reg); } static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg, u16 value) { return i2c_smbus_write_byte_data(client, reg, value); } /* * sysfs attributes */ static struct g760a_data *g760a_update_client(struct device *dev) { struct g760a_data *data = dev_get_drvdata(dev); struct i2c_client *client = data->client; mutex_lock(&data->update_lock); if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL) || !data->valid) { dev_dbg(&client->dev, "Starting g760a update\n"); data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT); data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT); data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA); data->last_updated = jiffies; data->valid = 1; } mutex_unlock(&data->update_lock); return data; } static ssize_t fan1_input_show(struct device *dev, struct device_attribute *da, char *buf) { struct g760a_data *data = g760a_update_client(dev); unsigned int rpm = 0; mutex_lock(&data->update_lock); if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW)) rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div); mutex_unlock(&data->update_lock); return sprintf(buf, "%d\n", rpm); } static ssize_t fan1_alarm_show(struct device *dev, struct device_attribute *da, char *buf) { struct g760a_data *data = g760a_update_client(dev); int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0; return sprintf(buf, "%d\n", fan_alarm); } static ssize_t pwm1_show(struct device *dev, struct device_attribute *da, char *buf) { struct g760a_data *data = g760a_update_client(dev); return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt)); } static ssize_t pwm1_store(struct device *dev, struct device_attribute *da, const char *buf, size_t count) { struct g760a_data *data = g760a_update_client(dev); struct i2c_client *client = data->client; unsigned long val; if (kstrtoul(buf, 10, &val)) return -EINVAL; mutex_lock(&data->update_lock); data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255)); g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt); mutex_unlock(&data->update_lock); return count; } static DEVICE_ATTR_RW(pwm1); static DEVICE_ATTR_RO(fan1_input); static DEVICE_ATTR_RO(fan1_alarm); static struct attribute *g760a_attrs[] = { &dev_attr_pwm1.attr, &dev_attr_fan1_input.attr, &dev_attr_fan1_alarm.attr, NULL }; ATTRIBUTE_GROUPS(g760a); /* * new-style driver model code */ static int g760a_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct device *dev = &client->dev; struct g760a_data *data; struct device *hwmon_dev; if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)) return -EIO; data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL); if (!data) return -ENOMEM; data->client = client; mutex_init(&data->update_lock); /* setup default configuration for now */ data->fan_div = G760A_DEFAULT_FAN_DIV; data->clk = G760A_DEFAULT_CLK; hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, data, g760a_groups); return PTR_ERR_OR_ZERO(hwmon_dev); } static const struct i2c_device_id g760a_id[] = { { "g760a", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, g760a_id); static struct i2c_driver g760a_driver = { .driver = { .name = "g760a", }, .probe = g760a_probe, .id_table = g760a_id, }; module_i2c_driver(g760a_driver); MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>"); MODULE_DESCRIPTION("GMT G760A driver"); MODULE_LICENSE("GPL");