--- /dev/null
+/*
+ * 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
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#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 show_fan(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 show_fan_alarm(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 get_pwm(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 set_pwm(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(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
+static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
+static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
+
+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");
Code Review / kvmfornfv.git / blobdiff