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// 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)
{
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");
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