1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * sbtsi_temp.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI) |
4 | * compliant AMD SoC temperature device. |
5 | * |
6 | * Copyright (c) 2020, Google Inc. |
7 | * Copyright (c) 2020, Kun Yi <kunyi@google.com> |
8 | */ |
9 | |
10 | #include <linux/err.h> |
11 | #include <linux/i2c.h> |
12 | #include <linux/init.h> |
13 | #include <linux/hwmon.h> |
14 | #include <linux/module.h> |
15 | #include <linux/mutex.h> |
16 | #include <linux/of.h> |
17 | |
18 | /* |
19 | * SB-TSI registers only support SMBus byte data access. "_INT" registers are |
20 | * the integer part of a temperature value or limit, and "_DEC" registers are |
21 | * corresponding decimal parts. |
22 | */ |
23 | #define SBTSI_REG_TEMP_INT 0x01 /* RO */ |
24 | #define SBTSI_REG_STATUS 0x02 /* RO */ |
25 | #define SBTSI_REG_CONFIG 0x03 /* RO */ |
26 | #define SBTSI_REG_TEMP_HIGH_INT 0x07 /* RW */ |
27 | #define SBTSI_REG_TEMP_LOW_INT 0x08 /* RW */ |
28 | #define SBTSI_REG_TEMP_DEC 0x10 /* RW */ |
29 | #define SBTSI_REG_TEMP_HIGH_DEC 0x13 /* RW */ |
30 | #define SBTSI_REG_TEMP_LOW_DEC 0x14 /* RW */ |
31 | |
32 | #define SBTSI_CONFIG_READ_ORDER_SHIFT 5 |
33 | |
34 | #define SBTSI_TEMP_MIN 0 |
35 | #define SBTSI_TEMP_MAX 255875 |
36 | |
37 | /* Each client has this additional data */ |
38 | struct sbtsi_data { |
39 | struct i2c_client *client; |
40 | struct mutex lock; |
41 | }; |
42 | |
43 | /* |
44 | * From SB-TSI spec: CPU temperature readings and limit registers encode the |
45 | * temperature in increments of 0.125 from 0 to 255.875. The "high byte" |
46 | * register encodes the base-2 of the integer portion, and the upper 3 bits of |
47 | * the "low byte" encode in base-2 the decimal portion. |
48 | * |
49 | * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius |
50 | * |
51 | * Therefore temperature in millidegree Celsius = |
52 | * (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125 |
53 | */ |
54 | static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal) |
55 | { |
56 | return ((integer << 3) + (decimal >> 5)) * 125; |
57 | } |
58 | |
59 | /* |
60 | * Inversely, given temperature in millidegree Celsius |
61 | * INT = (TEMP / 125) / 8 |
62 | * DEC = ((TEMP / 125) % 8) * 32 |
63 | * Caller have to make sure temp doesn't exceed 255875, the max valid value. |
64 | */ |
65 | static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal) |
66 | { |
67 | temp /= 125; |
68 | *integer = temp >> 3; |
69 | *decimal = (temp & 0x7) << 5; |
70 | } |
71 | |
72 | static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type, |
73 | u32 attr, int channel, long *val) |
74 | { |
75 | struct sbtsi_data *data = dev_get_drvdata(dev); |
76 | s32 temp_int, temp_dec; |
77 | int err; |
78 | |
79 | switch (attr) { |
80 | case hwmon_temp_input: |
81 | /* |
82 | * ReadOrder bit specifies the reading order of integer and |
83 | * decimal part of CPU temp for atomic reads. If bit == 0, |
84 | * reading integer part triggers latching of the decimal part, |
85 | * so integer part should be read first. If bit == 1, read |
86 | * order should be reversed. |
87 | */ |
88 | err = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_CONFIG); |
89 | if (err < 0) |
90 | return err; |
91 | |
92 | mutex_lock(&data->lock); |
93 | if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) { |
94 | temp_dec = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_DEC); |
95 | temp_int = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_INT); |
96 | } else { |
97 | temp_int = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_INT); |
98 | temp_dec = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_DEC); |
99 | } |
100 | mutex_unlock(lock: &data->lock); |
101 | break; |
102 | case hwmon_temp_max: |
103 | mutex_lock(&data->lock); |
104 | temp_int = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_HIGH_INT); |
105 | temp_dec = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_HIGH_DEC); |
106 | mutex_unlock(lock: &data->lock); |
107 | break; |
108 | case hwmon_temp_min: |
109 | mutex_lock(&data->lock); |
110 | temp_int = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_LOW_INT); |
111 | temp_dec = i2c_smbus_read_byte_data(client: data->client, SBTSI_REG_TEMP_LOW_DEC); |
112 | mutex_unlock(lock: &data->lock); |
113 | break; |
114 | default: |
115 | return -EINVAL; |
116 | } |
117 | |
118 | |
119 | if (temp_int < 0) |
120 | return temp_int; |
121 | if (temp_dec < 0) |
122 | return temp_dec; |
123 | |
124 | *val = sbtsi_reg_to_mc(integer: temp_int, decimal: temp_dec); |
125 | |
126 | return 0; |
127 | } |
128 | |
129 | static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type, |
130 | u32 attr, int channel, long val) |
131 | { |
132 | struct sbtsi_data *data = dev_get_drvdata(dev); |
133 | int reg_int, reg_dec, err; |
134 | u8 temp_int, temp_dec; |
135 | |
136 | switch (attr) { |
137 | case hwmon_temp_max: |
138 | reg_int = SBTSI_REG_TEMP_HIGH_INT; |
139 | reg_dec = SBTSI_REG_TEMP_HIGH_DEC; |
140 | break; |
141 | case hwmon_temp_min: |
142 | reg_int = SBTSI_REG_TEMP_LOW_INT; |
143 | reg_dec = SBTSI_REG_TEMP_LOW_DEC; |
144 | break; |
145 | default: |
146 | return -EINVAL; |
147 | } |
148 | |
149 | val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX); |
150 | sbtsi_mc_to_reg(temp: val, integer: &temp_int, decimal: &temp_dec); |
151 | |
152 | mutex_lock(&data->lock); |
153 | err = i2c_smbus_write_byte_data(client: data->client, command: reg_int, value: temp_int); |
154 | if (err) |
155 | goto exit; |
156 | |
157 | err = i2c_smbus_write_byte_data(client: data->client, command: reg_dec, value: temp_dec); |
158 | exit: |
159 | mutex_unlock(lock: &data->lock); |
160 | return err; |
161 | } |
162 | |
163 | static umode_t sbtsi_is_visible(const void *data, |
164 | enum hwmon_sensor_types type, |
165 | u32 attr, int channel) |
166 | { |
167 | switch (type) { |
168 | case hwmon_temp: |
169 | switch (attr) { |
170 | case hwmon_temp_input: |
171 | return 0444; |
172 | case hwmon_temp_min: |
173 | return 0644; |
174 | case hwmon_temp_max: |
175 | return 0644; |
176 | } |
177 | break; |
178 | default: |
179 | break; |
180 | } |
181 | return 0; |
182 | } |
183 | |
184 | static const struct hwmon_channel_info * const sbtsi_info[] = { |
185 | HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ), |
186 | HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX), |
187 | NULL |
188 | }; |
189 | |
190 | static const struct hwmon_ops sbtsi_hwmon_ops = { |
191 | .is_visible = sbtsi_is_visible, |
192 | .read = sbtsi_read, |
193 | .write = sbtsi_write, |
194 | }; |
195 | |
196 | static const struct hwmon_chip_info sbtsi_chip_info = { |
197 | .ops = &sbtsi_hwmon_ops, |
198 | .info = sbtsi_info, |
199 | }; |
200 | |
201 | static int sbtsi_probe(struct i2c_client *client) |
202 | { |
203 | struct device *dev = &client->dev; |
204 | struct device *hwmon_dev; |
205 | struct sbtsi_data *data; |
206 | |
207 | data = devm_kzalloc(dev, size: sizeof(struct sbtsi_data), GFP_KERNEL); |
208 | if (!data) |
209 | return -ENOMEM; |
210 | |
211 | data->client = client; |
212 | mutex_init(&data->lock); |
213 | |
214 | hwmon_dev = devm_hwmon_device_register_with_info(dev, name: client->name, drvdata: data, info: &sbtsi_chip_info, |
215 | NULL); |
216 | |
217 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
218 | } |
219 | |
220 | static const struct i2c_device_id sbtsi_id[] = { |
221 | {"sbtsi" , 0}, |
222 | {} |
223 | }; |
224 | MODULE_DEVICE_TABLE(i2c, sbtsi_id); |
225 | |
226 | static const struct of_device_id __maybe_unused sbtsi_of_match[] = { |
227 | { |
228 | .compatible = "amd,sbtsi" , |
229 | }, |
230 | { }, |
231 | }; |
232 | MODULE_DEVICE_TABLE(of, sbtsi_of_match); |
233 | |
234 | static struct i2c_driver sbtsi_driver = { |
235 | .driver = { |
236 | .name = "sbtsi" , |
237 | .of_match_table = of_match_ptr(sbtsi_of_match), |
238 | }, |
239 | .probe = sbtsi_probe, |
240 | .id_table = sbtsi_id, |
241 | }; |
242 | |
243 | module_i2c_driver(sbtsi_driver); |
244 | |
245 | MODULE_AUTHOR("Kun Yi <kunyi@google.com>" ); |
246 | MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor" ); |
247 | MODULE_LICENSE("GPL" ); |
248 | |