1 /*
2 g760a - Driver for the Global Mixed-mode Technology Inc. G760A
3 fan speed PWM controller chip
4
5 Copyright (C) 2007 Herbert Valerio Riedel <hvr@gnu.org>
6
7 Complete datasheet is available at GMT's website:
8 http://www.gmt.com.tw/datasheet/g760a.pdf
9
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2 of the License, or
13 (at your option) any later version.
14 */
15
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/slab.h>
19 #include <linux/jiffies.h>
20 #include <linux/i2c.h>
21 #include <linux/hwmon.h>
22 #include <linux/hwmon-sysfs.h>
23 #include <linux/err.h>
24 #include <linux/mutex.h>
25 #include <linux/sysfs.h>
26
27 static const struct i2c_device_id g760a_id[] = {
28 { "g760a", 0 },
29 { }
30 };
31 MODULE_DEVICE_TABLE(i2c, g760a_id);
32
33 enum g760a_regs {
34 G760A_REG_SET_CNT = 0x00,
35 G760A_REG_ACT_CNT = 0x01,
36 G760A_REG_FAN_STA = 0x02
37 };
38
39 #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
40 #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
41
42 /* register data is read (and cached) at most once per second */
43 #define G760A_UPDATE_INTERVAL (HZ)
44
45 struct g760a_data {
46 struct i2c_client *client;
47 struct device *hwmon_dev;
48 struct mutex update_lock;
49
50 /* board specific parameters */
51 u32 clk; /* default 32kHz */
52 u16 fan_div; /* default P=2 */
53
54 /* g760a register cache */
55 unsigned int valid:1;
56 unsigned long last_updated; /* In jiffies */
57
58 u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
59 u8 act_cnt; /* formula: cnt = (CLK * 30)/(rpm * P) */
60 u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
61 * outside requested fan speed
62 * bit 1: set when fan speed below 1920 rpm */
63 };
64
65 #define G760A_DEFAULT_CLK 32768
66 #define G760A_DEFAULT_FAN_DIV 2
67
68 #define PWM_FROM_CNT(cnt) (0xff-(cnt))
69 #define PWM_TO_CNT(pwm) (0xff-(pwm))
70
71 unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
72 {
73 return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
74 }
75
76 /* new-style driver model */
77 static int g760a_probe(struct i2c_client *client,
78 const struct i2c_device_id *id);
79 static int g760a_remove(struct i2c_client *client);
80
81 static struct i2c_driver g760a_driver = {
82 .driver = {
83 .name = "g760a",
84 },
85 .probe = g760a_probe,
86 .remove = g760a_remove,
87 .id_table = g760a_id,
88 };
89
90 /* read/write wrappers */
91 static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
92 {
93 return i2c_smbus_read_byte_data(client, reg);
94 }
95
96 static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
97 u16 value)
98 {
99 return i2c_smbus_write_byte_data(client, reg, value);
100 }
101
102 /****************************************************************************
103 * sysfs attributes
104 */
105
106 static struct g760a_data *g760a_update_client(struct device *dev)
107 {
108 struct i2c_client *client = to_i2c_client(dev);
109 struct g760a_data *data = i2c_get_clientdata(client);
110
111 mutex_lock(&data->update_lock);
112
113 if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
114 || !data->valid) {
115 dev_dbg(&client->dev, "Starting g760a update\n");
116
117 data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
118 data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
119 data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
120
121 data->last_updated = jiffies;
122 data->valid = 1;
123 }
124
125 mutex_unlock(&data->update_lock);
126
127 return data;
128 }
129
130 static ssize_t show_fan(struct device *dev, struct device_attribute *da,
131 char *buf)
132 {
133 struct g760a_data *data = g760a_update_client(dev);
134 unsigned int rpm = 0;
135
136 mutex_lock(&data->update_lock);
137 if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
138 rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
139 mutex_unlock(&data->update_lock);
140
141 return sprintf(buf, "%d\n", rpm);
142 }
143
144 static ssize_t show_fan_alarm(struct device *dev, struct device_attribute *da,
145 char *buf)
146 {
147 struct g760a_data *data = g760a_update_client(dev);
148
149 int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
150
151 return sprintf(buf, "%d\n", fan_alarm);
152 }
153
154 static ssize_t get_pwm(struct device *dev, struct device_attribute *da,
155 char *buf)
156 {
157 struct g760a_data *data = g760a_update_client(dev);
158
159 return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
160 }
161
162 static ssize_t set_pwm(struct device *dev, struct device_attribute *da,
163 const char *buf, size_t count)
164 {
165 struct i2c_client *client = to_i2c_client(dev);
166 struct g760a_data *data = g760a_update_client(dev);
167 unsigned long val;
168
169 if (strict_strtoul(buf, 10, &val))
170 return -EINVAL;
171
172 mutex_lock(&data->update_lock);
173 data->set_cnt = PWM_TO_CNT(SENSORS_LIMIT(val, 0, 255));
174 g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
175 mutex_unlock(&data->update_lock);
176
177 return count;
178 }
179
180 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
181 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
182 static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
183
184 static struct attribute *g760a_attributes[] = {
185 &dev_attr_pwm1.attr,
186 &dev_attr_fan1_input.attr,
187 &dev_attr_fan1_alarm.attr,
188 NULL
189 };
190
191 static const struct attribute_group g760a_group = {
192 .attrs = g760a_attributes,
193 };
194
195 /****************************************************************************
196 * new-style driver model code
197 */
198
199 static int g760a_probe(struct i2c_client *client,
200 const struct i2c_device_id *id)
201 {
202 struct g760a_data *data;
203 int err;
204
205 if (!i2c_check_functionality(client->adapter,
206 I2C_FUNC_SMBUS_BYTE_DATA))
207 return -EIO;
208
209 data = kzalloc(sizeof(struct g760a_data), GFP_KERNEL);
210 if (!data)
211 return -ENOMEM;
212
213 i2c_set_clientdata(client, data);
214
215 data->client = client;
216 mutex_init(&data->update_lock);
217
218 /* setup default configuration for now */
219 data->fan_div = G760A_DEFAULT_FAN_DIV;
220 data->clk = G760A_DEFAULT_CLK;
221
222 /* Register sysfs hooks */
223 err = sysfs_create_group(&client->dev.kobj, &g760a_group);
224 if (err)
225 goto error_sysfs_create_group;
226
227 data->hwmon_dev = hwmon_device_register(&client->dev);
228 if (IS_ERR(data->hwmon_dev)) {
229 err = PTR_ERR(data->hwmon_dev);
230 goto error_hwmon_device_register;
231 }
232
233 return 0;
234
235 error_hwmon_device_register:
236 sysfs_remove_group(&client->dev.kobj, &g760a_group);
237 error_sysfs_create_group:
238 kfree(data);
239 i2c_set_clientdata(client, NULL);
240
241 return err;
242 }
243
244 static int g760a_remove(struct i2c_client *client)
245 {
246 struct g760a_data *data = i2c_get_clientdata(client);
247 hwmon_device_unregister(data->hwmon_dev);
248 sysfs_remove_group(&client->dev.kobj, &g760a_group);
249 kfree(data);
250 i2c_set_clientdata(client, NULL);
251
252 return 0;
253 }
254
255 /* module management */
256
257 static int __init g760a_init(void)
258 {
259 return i2c_add_driver(&g760a_driver);
260 }
261
262 static void __exit g760a_exit(void)
263 {
264 i2c_del_driver(&g760a_driver);
265 }
266
267 MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
268 MODULE_DESCRIPTION("GMT G760A driver");
269 MODULE_LICENSE("GPL");
270
271 module_init(g760a_init);
272 module_exit(g760a_exit);
273
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