xref: /openbmc/linux/drivers/hwmon/g760a.c (revision 1975d167)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * g760a - Driver for the Global Mixed-mode Technology Inc. G760A
4  *	   fan speed PWM controller chip
5  *
6  * Copyright (C) 2007  Herbert Valerio Riedel <hvr@gnu.org>
7  *
8  * Complete datasheet is available at GMT's website:
9  * http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
10  */
11 
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/slab.h>
15 #include <linux/jiffies.h>
16 #include <linux/i2c.h>
17 #include <linux/hwmon.h>
18 #include <linux/hwmon-sysfs.h>
19 #include <linux/err.h>
20 #include <linux/mutex.h>
21 #include <linux/sysfs.h>
22 
23 enum g760a_regs {
24 	G760A_REG_SET_CNT = 0x00,
25 	G760A_REG_ACT_CNT = 0x01,
26 	G760A_REG_FAN_STA = 0x02
27 };
28 
29 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
30 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
31 
32 /* register data is read (and cached) at most once per second */
33 #define G760A_UPDATE_INTERVAL (HZ)
34 
35 struct g760a_data {
36 	struct i2c_client *client;
37 	struct mutex update_lock;
38 
39 	/* board specific parameters */
40 	u32 clk; /* default 32kHz */
41 	u16 fan_div; /* default P=2 */
42 
43 	/* g760a register cache */
44 	unsigned int valid:1;
45 	unsigned long last_updated; /* In jiffies */
46 
47 	u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
48 	u8 act_cnt; /*   formula: cnt = (CLK * 30)/(rpm * P) */
49 	u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
50 		     *   outside requested fan speed
51 		     * bit 1: set when fan speed below 1920 rpm
52 		     */
53 };
54 
55 #define G760A_DEFAULT_CLK 32768
56 #define G760A_DEFAULT_FAN_DIV 2
57 
58 #define PWM_FROM_CNT(cnt)	(0xff-(cnt))
59 #define PWM_TO_CNT(pwm)		(0xff-(pwm))
60 
rpm_from_cnt(u8 val,u32 clk,u16 div)61 static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
62 {
63 	return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
64 }
65 
66 /* read/write wrappers */
g760a_read_value(struct i2c_client * client,enum g760a_regs reg)67 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
68 {
69 	return i2c_smbus_read_byte_data(client, reg);
70 }
71 
g760a_write_value(struct i2c_client * client,enum g760a_regs reg,u16 value)72 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
73 			     u16 value)
74 {
75 	return i2c_smbus_write_byte_data(client, reg, value);
76 }
77 
78 /*
79  * sysfs attributes
80  */
81 
g760a_update_client(struct device * dev)82 static struct g760a_data *g760a_update_client(struct device *dev)
83 {
84 	struct g760a_data *data = dev_get_drvdata(dev);
85 	struct i2c_client *client = data->client;
86 
87 	mutex_lock(&data->update_lock);
88 
89 	if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
90 	    || !data->valid) {
91 		dev_dbg(&client->dev, "Starting g760a update\n");
92 
93 		data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
94 		data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
95 		data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
96 
97 		data->last_updated = jiffies;
98 		data->valid = true;
99 	}
100 
101 	mutex_unlock(&data->update_lock);
102 
103 	return data;
104 }
105 
fan1_input_show(struct device * dev,struct device_attribute * da,char * buf)106 static ssize_t fan1_input_show(struct device *dev,
107 			       struct device_attribute *da, char *buf)
108 {
109 	struct g760a_data *data = g760a_update_client(dev);
110 	unsigned int rpm = 0;
111 
112 	mutex_lock(&data->update_lock);
113 	if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
114 		rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
115 	mutex_unlock(&data->update_lock);
116 
117 	return sprintf(buf, "%d\n", rpm);
118 }
119 
fan1_alarm_show(struct device * dev,struct device_attribute * da,char * buf)120 static ssize_t fan1_alarm_show(struct device *dev,
121 			       struct device_attribute *da, char *buf)
122 {
123 	struct g760a_data *data = g760a_update_client(dev);
124 
125 	int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
126 
127 	return sprintf(buf, "%d\n", fan_alarm);
128 }
129 
pwm1_show(struct device * dev,struct device_attribute * da,char * buf)130 static ssize_t pwm1_show(struct device *dev, struct device_attribute *da,
131 			 char *buf)
132 {
133 	struct g760a_data *data = g760a_update_client(dev);
134 
135 	return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
136 }
137 
pwm1_store(struct device * dev,struct device_attribute * da,const char * buf,size_t count)138 static ssize_t pwm1_store(struct device *dev, struct device_attribute *da,
139 			  const char *buf, size_t count)
140 {
141 	struct g760a_data *data = g760a_update_client(dev);
142 	struct i2c_client *client = data->client;
143 	unsigned long val;
144 
145 	if (kstrtoul(buf, 10, &val))
146 		return -EINVAL;
147 
148 	mutex_lock(&data->update_lock);
149 	data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255));
150 	g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
151 	mutex_unlock(&data->update_lock);
152 
153 	return count;
154 }
155 
156 static DEVICE_ATTR_RW(pwm1);
157 static DEVICE_ATTR_RO(fan1_input);
158 static DEVICE_ATTR_RO(fan1_alarm);
159 
160 static struct attribute *g760a_attrs[] = {
161 	&dev_attr_pwm1.attr,
162 	&dev_attr_fan1_input.attr,
163 	&dev_attr_fan1_alarm.attr,
164 	NULL
165 };
166 
167 ATTRIBUTE_GROUPS(g760a);
168 
169 /*
170  * new-style driver model code
171  */
172 
g760a_probe(struct i2c_client * client)173 static int g760a_probe(struct i2c_client *client)
174 {
175 	struct device *dev = &client->dev;
176 	struct g760a_data *data;
177 	struct device *hwmon_dev;
178 
179 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
180 		return -EIO;
181 
182 	data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL);
183 	if (!data)
184 		return -ENOMEM;
185 
186 	data->client = client;
187 	mutex_init(&data->update_lock);
188 
189 	/* setup default configuration for now */
190 	data->fan_div = G760A_DEFAULT_FAN_DIV;
191 	data->clk = G760A_DEFAULT_CLK;
192 
193 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
194 							   data,
195 							   g760a_groups);
196 	return PTR_ERR_OR_ZERO(hwmon_dev);
197 }
198 
199 static const struct i2c_device_id g760a_id[] = {
200 	{ "g760a", 0 },
201 	{ }
202 };
203 MODULE_DEVICE_TABLE(i2c, g760a_id);
204 
205 static struct i2c_driver g760a_driver = {
206 	.driver = {
207 		.name	= "g760a",
208 	},
209 	.probe = g760a_probe,
210 	.id_table = g760a_id,
211 };
212 
213 module_i2c_driver(g760a_driver);
214 
215 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
216 MODULE_DESCRIPTION("GMT G760A driver");
217 MODULE_LICENSE("GPL");
218