diff options
Diffstat (limited to 'drivers/hwmon/g760a.c')
| -rw-r--r-- | drivers/hwmon/g760a.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/hwmon/g760a.c b/drivers/hwmon/g760a.c new file mode 100644 index 000000000..36717b524 --- /dev/null +++ b/drivers/hwmon/g760a.c @@ -0,0 +1,217 @@ +// 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 = true; + } + + 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) +{ + 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_new = 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"); |