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 | |
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 */ |
67 | static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg) |
68 | { |
69 | return i2c_smbus_read_byte_data(client, command: reg); |
70 | } |
71 | |
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, command: reg, value); |
76 | } |
77 | |
78 | /* |
79 | * sysfs attributes |
80 | */ |
81 | |
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, reg: G760A_REG_SET_CNT); |
94 | data->act_cnt = g760a_read_value(client, reg: G760A_REG_ACT_CNT); |
95 | data->fan_sta = g760a_read_value(client, reg: G760A_REG_FAN_STA); |
96 | |
97 | data->last_updated = jiffies; |
98 | data->valid = true; |
99 | } |
100 | |
101 | mutex_unlock(lock: &data->update_lock); |
102 | |
103 | return data; |
104 | } |
105 | |
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(val: data->act_cnt, clk: data->clk, div: data->fan_div); |
115 | mutex_unlock(lock: &data->update_lock); |
116 | |
117 | return sprintf(buf, fmt: "%d\n" , rpm); |
118 | } |
119 | |
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, fmt: "%d\n" , fan_alarm); |
128 | } |
129 | |
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, fmt: "%d\n" , PWM_FROM_CNT(data->set_cnt)); |
136 | } |
137 | |
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(s: buf, base: 10, res: &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, reg: G760A_REG_SET_CNT, value: data->set_cnt); |
151 | mutex_unlock(lock: &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 | |
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(adap: client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)) |
180 | return -EIO; |
181 | |
182 | data = devm_kzalloc(dev, size: 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, name: client->name, |
194 | drvdata: data, |
195 | groups: g760a_groups); |
196 | return PTR_ERR_OR_ZERO(ptr: 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 | |