drivers/hwmon/g760a.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * g760a - Driver for the Global Mixed-mode Technology Inc. G760A
0004  *     fan speed PWM controller chip
0005  *
0006  * Copyright (C) 2007  Herbert Valerio Riedel <hvr@gnu.org>
0007  *
0008  * Complete datasheet is available at GMT's website:
0009  * http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
0010  */
0011
0012 #include <linux/module.h>
0013 #include <linux/init.h>
0014 #include <linux/slab.h>
0015 #include <linux/jiffies.h>
0016 #include <linux/i2c.h>
0017 #include <linux/hwmon.h>
0018 #include <linux/hwmon-sysfs.h>
0019 #include <linux/err.h>
0020 #include <linux/mutex.h>
0021 #include <linux/sysfs.h>
0022
0023 enum g760a_regs {
0024     G760A_REG_SET_CNT = 0x00,
0025     G760A_REG_ACT_CNT = 0x01,
0026     G760A_REG_FAN_STA = 0x02
0027 };
0028
0029 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
0030 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
0031
0032 /* register data is read (and cached) at most once per second */
0033 #define G760A_UPDATE_INTERVAL (HZ)
0034
0035 struct g760a_data {
0036     struct i2c_client *client;
0037     struct mutex update_lock;
0038
0039     /* board specific parameters */
0040     u32 clk; /* default 32kHz */
0041     u16 fan_div; /* default P=2 */
0042
0043     /* g760a register cache */
0044     unsigned int valid:1;
0045     unsigned long last_updated; /* In jiffies */
0046
0047     u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
0048     u8 act_cnt; /*   formula: cnt = (CLK * 30)/(rpm * P) */
0049     u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
0050              *   outside requested fan speed
0051              * bit 1: set when fan speed below 1920 rpm
0052              */
0053 };
0054
0055 #define G760A_DEFAULT_CLK 32768
0056 #define G760A_DEFAULT_FAN_DIV 2
0057
0058 #define PWM_FROM_CNT(cnt)   (0xff-(cnt))
0059 #define PWM_TO_CNT(pwm)     (0xff-(pwm))
0060
0061 static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
0062 {
0063     return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
0064 }
0065
0066 /* read/write wrappers */
0067 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
0068 {
0069     return i2c_smbus_read_byte_data(client, reg);
0070 }
0071
0072 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
0073                  u16 value)
0074 {
0075     return i2c_smbus_write_byte_data(client, reg, value);
0076 }
0077
0078 /*
0079  * sysfs attributes
0080  */
0081
0082 static struct g760a_data *g760a_update_client(struct device *dev)
0083 {
0084     struct g760a_data *data = dev_get_drvdata(dev);
0085     struct i2c_client *client = data->client;
0086
0087     mutex_lock(&data->update_lock);
0088
0089     if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
0090         || !data->valid) {
0091         dev_dbg(&client->dev, "Starting g760a update\n");
0092
0093         data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
0094         data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
0095         data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
0096
0097         data->last_updated = jiffies;
0098         data->valid = true;
0099     }
0100
0101     mutex_unlock(&data->update_lock);
0102
0103     return data;
0104 }
0105
0106 static ssize_t fan1_input_show(struct device *dev,
0107                    struct device_attribute *da, char *buf)
0108 {
0109     struct g760a_data *data = g760a_update_client(dev);
0110     unsigned int rpm = 0;
0111
0112     mutex_lock(&data->update_lock);
0113     if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
0114         rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
0115     mutex_unlock(&data->update_lock);
0116
0117     return sprintf(buf, "%d\n", rpm);
0118 }
0119
0120 static ssize_t fan1_alarm_show(struct device *dev,
0121                    struct device_attribute *da, char *buf)
0122 {
0123     struct g760a_data *data = g760a_update_client(dev);
0124
0125     int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
0126
0127     return sprintf(buf, "%d\n", fan_alarm);
0128 }
0129
0130 static ssize_t pwm1_show(struct device *dev, struct device_attribute *da,
0131              char *buf)
0132 {
0133     struct g760a_data *data = g760a_update_client(dev);
0134
0135     return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
0136 }
0137
0138 static ssize_t pwm1_store(struct device *dev, struct device_attribute *da,
0139               const char *buf, size_t count)
0140 {
0141     struct g760a_data *data = g760a_update_client(dev);
0142     struct i2c_client *client = data->client;
0143     unsigned long val;
0144
0145     if (kstrtoul(buf, 10, &val))
0146         return -EINVAL;
0147
0148     mutex_lock(&data->update_lock);
0149     data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255));
0150     g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
0151     mutex_unlock(&data->update_lock);
0152
0153     return count;
0154 }
0155
0156 static DEVICE_ATTR_RW(pwm1);
0157 static DEVICE_ATTR_RO(fan1_input);
0158 static DEVICE_ATTR_RO(fan1_alarm);
0159
0160 static struct attribute *g760a_attrs[] = {
0161     &dev_attr_pwm1.attr,
0162     &dev_attr_fan1_input.attr,
0163     &dev_attr_fan1_alarm.attr,
0164     NULL
0165 };
0166
0167 ATTRIBUTE_GROUPS(g760a);
0168
0169 /*
0170  * new-style driver model code
0171  */
0172
0173 static int g760a_probe(struct i2c_client *client)
0174 {
0175     struct device *dev = &client->dev;
0176     struct g760a_data *data;
0177     struct device *hwmon_dev;
0178
0179     if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
0180         return -EIO;
0181
0182     data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL);
0183     if (!data)
0184         return -ENOMEM;
0185
0186     data->client = client;
0187     mutex_init(&data->update_lock);
0188
0189     /* setup default configuration for now */
0190     data->fan_div = G760A_DEFAULT_FAN_DIV;
0191     data->clk = G760A_DEFAULT_CLK;
0192
0193     hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
0194                                data,
0195                                g760a_groups);
0196     return PTR_ERR_OR_ZERO(hwmon_dev);
0197 }
0198
0199 static const struct i2c_device_id g760a_id[] = {
0200     { "g760a", 0 },
0201     { }
0202 };
0203 MODULE_DEVICE_TABLE(i2c, g760a_id);
0204
0205 static struct i2c_driver g760a_driver = {
0206     .driver = {
0207         .name   = "g760a",
0208     },
0209     .probe_new = g760a_probe,
0210     .id_table = g760a_id,
0211 };
0212
0213 module_i2c_driver(g760a_driver);
0214
0215 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
0216 MODULE_DESCRIPTION("GMT G760A driver");
0217 MODULE_LICENSE("GPL");