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_device.h> 17 #include <linux/of.h> 18 19 /* 20 * SB-TSI registers only support SMBus byte data access. "_INT" registers are 21 * the integer part of a temperature value or limit, and "_DEC" registers are 22 * corresponding decimal parts. 23 */ 24 #define SBTSI_REG_TEMP_INT 0x01 /* RO */ 25 #define SBTSI_REG_STATUS 0x02 /* RO */ 26 #define SBTSI_REG_CONFIG 0x03 /* RO */ 27 #define SBTSI_REG_TEMP_HIGH_INT 0x07 /* RW */ 28 #define SBTSI_REG_TEMP_LOW_INT 0x08 /* RW */ 29 #define SBTSI_REG_TEMP_DEC 0x10 /* RW */ 30 #define SBTSI_REG_TEMP_HIGH_DEC 0x13 /* RW */ 31 #define SBTSI_REG_TEMP_LOW_DEC 0x14 /* RW */ 32 33 #define SBTSI_CONFIG_READ_ORDER_SHIFT 5 34 35 #define SBTSI_TEMP_MIN 0 36 #define SBTSI_TEMP_MAX 255875 37 38 /* Each client has this additional data */ 39 struct sbtsi_data { 40 struct i2c_client *client; 41 struct mutex lock; 42 }; 43 44 /* 45 * From SB-TSI spec: CPU temperature readings and limit registers encode the 46 * temperature in increments of 0.125 from 0 to 255.875. The "high byte" 47 * register encodes the base-2 of the integer portion, and the upper 3 bits of 48 * the "low byte" encode in base-2 the decimal portion. 49 * 50 * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius 51 * 52 * Therefore temperature in millidegree Celsius = 53 * (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125 54 */ 55 static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal) 56 { 57 return ((integer << 3) + (decimal >> 5)) * 125; 58 } 59 60 /* 61 * Inversely, given temperature in millidegree Celsius 62 * INT = (TEMP / 125) / 8 63 * DEC = ((TEMP / 125) % 8) * 32 64 * Caller have to make sure temp doesn't exceed 255875, the max valid value. 65 */ 66 static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal) 67 { 68 temp /= 125; 69 *integer = temp >> 3; 70 *decimal = (temp & 0x7) << 5; 71 } 72 73 static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type, 74 u32 attr, int channel, long *val) 75 { 76 struct sbtsi_data *data = dev_get_drvdata(dev); 77 s32 temp_int, temp_dec; 78 int err; 79 80 switch (attr) { 81 case hwmon_temp_input: 82 /* 83 * ReadOrder bit specifies the reading order of integer and 84 * decimal part of CPU temp for atomic reads. If bit == 0, 85 * reading integer part triggers latching of the decimal part, 86 * so integer part should be read first. If bit == 1, read 87 * order should be reversed. 88 */ 89 err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG); 90 if (err < 0) 91 return err; 92 93 mutex_lock(&data->lock); 94 if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) { 95 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC); 96 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT); 97 } else { 98 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT); 99 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC); 100 } 101 mutex_unlock(&data->lock); 102 break; 103 case hwmon_temp_max: 104 mutex_lock(&data->lock); 105 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_INT); 106 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_DEC); 107 mutex_unlock(&data->lock); 108 break; 109 case hwmon_temp_min: 110 mutex_lock(&data->lock); 111 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_INT); 112 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_DEC); 113 mutex_unlock(&data->lock); 114 break; 115 default: 116 return -EINVAL; 117 } 118 119 120 if (temp_int < 0) 121 return temp_int; 122 if (temp_dec < 0) 123 return temp_dec; 124 125 *val = sbtsi_reg_to_mc(temp_int, temp_dec); 126 127 return 0; 128 } 129 130 static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type, 131 u32 attr, int channel, long val) 132 { 133 struct sbtsi_data *data = dev_get_drvdata(dev); 134 int reg_int, reg_dec, err; 135 u8 temp_int, temp_dec; 136 137 switch (attr) { 138 case hwmon_temp_max: 139 reg_int = SBTSI_REG_TEMP_HIGH_INT; 140 reg_dec = SBTSI_REG_TEMP_HIGH_DEC; 141 break; 142 case hwmon_temp_min: 143 reg_int = SBTSI_REG_TEMP_LOW_INT; 144 reg_dec = SBTSI_REG_TEMP_LOW_DEC; 145 break; 146 default: 147 return -EINVAL; 148 } 149 150 val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX); 151 sbtsi_mc_to_reg(val, &temp_int, &temp_dec); 152 153 mutex_lock(&data->lock); 154 err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int); 155 if (err) 156 goto exit; 157 158 err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec); 159 exit: 160 mutex_unlock(&data->lock); 161 return err; 162 } 163 164 static umode_t sbtsi_is_visible(const void *data, 165 enum hwmon_sensor_types type, 166 u32 attr, int channel) 167 { 168 switch (type) { 169 case hwmon_temp: 170 switch (attr) { 171 case hwmon_temp_input: 172 return 0444; 173 case hwmon_temp_min: 174 return 0644; 175 case hwmon_temp_max: 176 return 0644; 177 } 178 break; 179 default: 180 break; 181 } 182 return 0; 183 } 184 185 static const struct hwmon_channel_info *sbtsi_info[] = { 186 HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ), 187 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX), 188 NULL 189 }; 190 191 static const struct hwmon_ops sbtsi_hwmon_ops = { 192 .is_visible = sbtsi_is_visible, 193 .read = sbtsi_read, 194 .write = sbtsi_write, 195 }; 196 197 static const struct hwmon_chip_info sbtsi_chip_info = { 198 .ops = &sbtsi_hwmon_ops, 199 .info = sbtsi_info, 200 }; 201 202 static int sbtsi_probe(struct i2c_client *client) 203 { 204 struct device *dev = &client->dev; 205 struct device *hwmon_dev; 206 struct sbtsi_data *data; 207 208 data = devm_kzalloc(dev, sizeof(struct sbtsi_data), GFP_KERNEL); 209 if (!data) 210 return -ENOMEM; 211 212 data->client = client; 213 mutex_init(&data->lock); 214 215 hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data, &sbtsi_chip_info, 216 NULL); 217 218 return PTR_ERR_OR_ZERO(hwmon_dev); 219 } 220 221 static const struct i2c_device_id sbtsi_id[] = { 222 {"sbtsi", 0}, 223 {} 224 }; 225 MODULE_DEVICE_TABLE(i2c, sbtsi_id); 226 227 static const struct of_device_id __maybe_unused sbtsi_of_match[] = { 228 { 229 .compatible = "amd,sbtsi", 230 }, 231 { }, 232 }; 233 MODULE_DEVICE_TABLE(of, sbtsi_of_match); 234 235 static struct i2c_driver sbtsi_driver = { 236 .class = I2C_CLASS_HWMON, 237 .driver = { 238 .name = "sbtsi", 239 .of_match_table = of_match_ptr(sbtsi_of_match), 240 }, 241 .probe_new = sbtsi_probe, 242 .id_table = sbtsi_id, 243 }; 244 245 module_i2c_driver(sbtsi_driver); 246 247 MODULE_AUTHOR("Kun Yi <kunyi@google.com>"); 248 MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor"); 249 MODULE_LICENSE("GPL"); 250