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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 | |
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 | |
66 | #define G760A_DEFAULT_CLK 32768 |
67 | #define G760A_DEFAULT_FAN_DIV 2 |
68 | |
69 | #define PWM_FROM_CNT(cnt) (0xff-(cnt)) |
70 | #define PWM_TO_CNT(pwm) (0xff-(pwm)) |
71 | |
72 | static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div) |
73 | { |
74 | return ((val == 0x00) ? 0 : ((clk*30)/(val*div))); |
75 | } |
76 | |
77 | /* new-style driver model */ |
78 | static int g760a_probe(struct i2c_client *client, |
79 | const struct i2c_device_id *id); |
80 | static int g760a_remove(struct i2c_client *client); |
81 | |
82 | static struct i2c_driver g760a_driver = { |
83 | .driver = { |
84 | .name = "g760a", |
85 | }, |
86 | .probe = g760a_probe, |
87 | .remove = g760a_remove, |
88 | .id_table = g760a_id, |
89 | }; |
90 | |
91 | /* read/write wrappers */ |
92 | static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg) |
93 | { |
94 | return i2c_smbus_read_byte_data(client, reg); |
95 | } |
96 | |
97 | static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg, |
98 | u16 value) |
99 | { |
100 | return i2c_smbus_write_byte_data(client, reg, value); |
101 | } |
102 | |
103 | /* |
104 | * sysfs attributes |
105 | */ |
106 | |
107 | static struct g760a_data *g760a_update_client(struct device *dev) |
108 | { |
109 | struct i2c_client *client = to_i2c_client(dev); |
110 | struct g760a_data *data = i2c_get_clientdata(client); |
111 | |
112 | mutex_lock(&data->update_lock); |
113 | |
114 | if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL) |
115 | || !data->valid) { |
116 | dev_dbg(&client->dev, "Starting g760a update\n"); |
117 | |
118 | data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT); |
119 | data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT); |
120 | data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA); |
121 | |
122 | data->last_updated = jiffies; |
123 | data->valid = 1; |
124 | } |
125 | |
126 | mutex_unlock(&data->update_lock); |
127 | |
128 | return data; |
129 | } |
130 | |
131 | static ssize_t show_fan(struct device *dev, struct device_attribute *da, |
132 | char *buf) |
133 | { |
134 | struct g760a_data *data = g760a_update_client(dev); |
135 | unsigned int rpm = 0; |
136 | |
137 | mutex_lock(&data->update_lock); |
138 | if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW)) |
139 | rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div); |
140 | mutex_unlock(&data->update_lock); |
141 | |
142 | return sprintf(buf, "%d\n", rpm); |
143 | } |
144 | |
145 | static ssize_t show_fan_alarm(struct device *dev, struct device_attribute *da, |
146 | char *buf) |
147 | { |
148 | struct g760a_data *data = g760a_update_client(dev); |
149 | |
150 | int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0; |
151 | |
152 | return sprintf(buf, "%d\n", fan_alarm); |
153 | } |
154 | |
155 | static ssize_t get_pwm(struct device *dev, struct device_attribute *da, |
156 | char *buf) |
157 | { |
158 | struct g760a_data *data = g760a_update_client(dev); |
159 | |
160 | return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt)); |
161 | } |
162 | |
163 | static ssize_t set_pwm(struct device *dev, struct device_attribute *da, |
164 | const char *buf, size_t count) |
165 | { |
166 | struct i2c_client *client = to_i2c_client(dev); |
167 | struct g760a_data *data = g760a_update_client(dev); |
168 | unsigned long val; |
169 | |
170 | if (kstrtoul(buf, 10, &val)) |
171 | return -EINVAL; |
172 | |
173 | mutex_lock(&data->update_lock); |
174 | data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255)); |
175 | g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt); |
176 | mutex_unlock(&data->update_lock); |
177 | |
178 | return count; |
179 | } |
180 | |
181 | static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm); |
182 | static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL); |
183 | static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL); |
184 | |
185 | static struct attribute *g760a_attributes[] = { |
186 | &dev_attr_pwm1.attr, |
187 | &dev_attr_fan1_input.attr, |
188 | &dev_attr_fan1_alarm.attr, |
189 | NULL |
190 | }; |
191 | |
192 | static const struct attribute_group g760a_group = { |
193 | .attrs = g760a_attributes, |
194 | }; |
195 | |
196 | /* |
197 | * new-style driver model code |
198 | */ |
199 | |
200 | static int g760a_probe(struct i2c_client *client, |
201 | const struct i2c_device_id *id) |
202 | { |
203 | struct g760a_data *data; |
204 | int err; |
205 | |
206 | if (!i2c_check_functionality(client->adapter, |
207 | I2C_FUNC_SMBUS_BYTE_DATA)) |
208 | return -EIO; |
209 | |
210 | data = devm_kzalloc(&client->dev, sizeof(struct g760a_data), |
211 | GFP_KERNEL); |
212 | if (!data) |
213 | return -ENOMEM; |
214 | |
215 | i2c_set_clientdata(client, data); |
216 | |
217 | data->client = client; |
218 | mutex_init(&data->update_lock); |
219 | |
220 | /* setup default configuration for now */ |
221 | data->fan_div = G760A_DEFAULT_FAN_DIV; |
222 | data->clk = G760A_DEFAULT_CLK; |
223 | |
224 | /* Register sysfs hooks */ |
225 | err = sysfs_create_group(&client->dev.kobj, &g760a_group); |
226 | if (err) |
227 | return err; |
228 | |
229 | data->hwmon_dev = hwmon_device_register(&client->dev); |
230 | if (IS_ERR(data->hwmon_dev)) { |
231 | err = PTR_ERR(data->hwmon_dev); |
232 | goto error_hwmon_device_register; |
233 | } |
234 | |
235 | return 0; |
236 | |
237 | error_hwmon_device_register: |
238 | sysfs_remove_group(&client->dev.kobj, &g760a_group); |
239 | return err; |
240 | } |
241 | |
242 | static int g760a_remove(struct i2c_client *client) |
243 | { |
244 | struct g760a_data *data = i2c_get_clientdata(client); |
245 | hwmon_device_unregister(data->hwmon_dev); |
246 | sysfs_remove_group(&client->dev.kobj, &g760a_group); |
247 | return 0; |
248 | } |
249 | |
250 | module_i2c_driver(g760a_driver); |
251 | |
252 | MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>"); |
253 | MODULE_DESCRIPTION("GMT G760A driver"); |
254 | MODULE_LICENSE("GPL"); |
255 |
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