PageRenderTime 31ms CodeModel.GetById 18ms app.highlight 11ms RepoModel.GetById 0ms app.codeStats 0ms

/drivers/hwmon/g760a.c

https://bitbucket.org/ndreys/linux-sunxi
C | 270 lines | 182 code | 58 blank | 30 comment | 9 complexity | ed6044e0931b98179ad997b18baf05de MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  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/product/datasheet/EDS-760A.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
 27static const struct i2c_device_id g760a_id[] = {
 28	{ "g760a", 0 },
 29	{ }
 30};
 31MODULE_DEVICE_TABLE(i2c, g760a_id);
 32
 33enum 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
 45struct 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
 71static inline 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 */
 77static int g760a_probe(struct i2c_client *client,
 78			const struct i2c_device_id *id);
 79static int g760a_remove(struct i2c_client *client);
 80
 81static 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 */
 91static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
 92{
 93	return i2c_smbus_read_byte_data(client, reg);
 94}
 95
 96static 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
106static 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
130static 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
144static 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
154static 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
162static 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
180static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
181static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
182static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
183
184static 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
191static const struct attribute_group g760a_group = {
192	.attrs = g760a_attributes,
193};
194
195/****************************************************************************
196 * new-style driver model code
197 */
198
199static 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
235error_hwmon_device_register:
236	sysfs_remove_group(&client->dev.kobj, &g760a_group);
237error_sysfs_create_group:
238	kfree(data);
239
240	return err;
241}
242
243static int g760a_remove(struct i2c_client *client)
244{
245	struct g760a_data *data = i2c_get_clientdata(client);
246	hwmon_device_unregister(data->hwmon_dev);
247	sysfs_remove_group(&client->dev.kobj, &g760a_group);
248	kfree(data);
249
250	return 0;
251}
252
253/* module management */
254
255static int __init g760a_init(void)
256{
257	return i2c_add_driver(&g760a_driver);
258}
259
260static void __exit g760a_exit(void)
261{
262	i2c_del_driver(&g760a_driver);
263}
264
265MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
266MODULE_DESCRIPTION("GMT G760A driver");
267MODULE_LICENSE("GPL");
268
269module_init(g760a_init);
270module_exit(g760a_exit);