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/auxiliary_bus.h> 11 #include <linux/err.h> 12 #include <linux/hwmon.h> 13 #include <linux/init.h> 14 #include <linux/module.h> 15 #include <linux/misc/tsi.h> 16 17 /* 18 * SB-TSI registers only support SMBus byte data access. "_INT" registers are 19 * the integer part of a temperature value or limit, and "_DEC" registers are 20 * corresponding decimal parts. 21 */ 22 #define SBTSI_REG_TEMP_INT 0x01 /* RO */ 23 #define SBTSI_REG_STATUS 0x02 /* RO */ 24 #define SBTSI_REG_TEMP_HIGH_INT 0x07 /* RW */ 25 #define SBTSI_REG_TEMP_LOW_INT 0x08 /* RW */ 26 #define SBTSI_REG_TEMP_DEC 0x10 /* RW */ 27 #define SBTSI_REG_TEMP_HIGH_DEC 0x13 /* RW */ 28 #define SBTSI_REG_TEMP_LOW_DEC 0x14 /* RW */ 29 30 #define SBTSI_TEMP_EXT_RANGE_ADJ 49000 31 32 #define SBTSI_TEMP_MIN 0 33 #define SBTSI_TEMP_MAX 255875 34 35 /* 36 * From SB-TSI spec: CPU temperature readings and limit registers encode the 37 * temperature in increments of 0.125 from 0 to 255.875. The "high byte" 38 * register encodes the base-2 of the integer portion, and the upper 3 bits of 39 * the "low byte" encode in base-2 the decimal portion. 40 * 41 * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius 42 * 43 * Therefore temperature in millidegree Celsius = 44 * (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125 45 */ 46 static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal) 47 { 48 return ((integer << 3) + (decimal >> 5)) * 125; 49 } 50 51 /* 52 * Inversely, given temperature in millidegree Celsius 53 * INT = (TEMP / 125) / 8 54 * DEC = ((TEMP / 125) % 8) * 32 55 * Caller have to make sure temp doesn't exceed 255875, the max valid value. 56 */ 57 static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal) 58 { 59 temp /= 125; 60 *integer = temp >> 3; 61 *decimal = (temp & 0x7) << 5; 62 } 63 64 /* 65 * Read integer and decimal parts of an SB-TSI temperature register pair 66 * The read order is determined by the ReadOrder bit to ensure atomic latching. 67 */ 68 static int sbtsi_temp_read(struct sbtsi_data *data, u8 reg1, u8 reg2, 69 u8 *val1, u8 *val2) 70 { 71 int ret; 72 73 guard(sbtsi)(data); 74 ret = sbtsi_xfer(data, reg1, val1, true); 75 if (!ret) 76 ret = sbtsi_xfer(data, reg2, val2, true); 77 return ret; 78 } 79 80 /* 81 * Write integer and decimal parts of an SB-TSI temperature register pair. 82 */ 83 static int sbtsi_temp_write(struct sbtsi_data *data, u8 reg_int, u8 reg_dec, 84 u8 val_int, u8 val_dec) 85 { 86 int ret; 87 88 guard(sbtsi)(data); 89 ret = sbtsi_xfer(data, reg_int, &val_int, false); 90 if (!ret) 91 ret = sbtsi_xfer(data, reg_dec, &val_dec, false); 92 return ret; 93 } 94 95 static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type, 96 u32 attr, int channel, long *val) 97 { 98 struct sbtsi_data *data = dev_get_drvdata(dev); 99 s32 temp_int, temp_dec; 100 int err; 101 u8 val_int, val_dec; 102 103 switch (attr) { 104 case hwmon_temp_input: 105 if (data->read_order) 106 err = sbtsi_temp_read(data, 107 SBTSI_REG_TEMP_DEC, SBTSI_REG_TEMP_INT, 108 &val_dec, &val_int); 109 else 110 err = sbtsi_temp_read(data, 111 SBTSI_REG_TEMP_INT, SBTSI_REG_TEMP_DEC, 112 &val_int, &val_dec); 113 if (err < 0) 114 return err; 115 break; 116 case hwmon_temp_max: 117 err = sbtsi_temp_read(data, 118 SBTSI_REG_TEMP_HIGH_INT, SBTSI_REG_TEMP_HIGH_DEC, 119 &val_int, &val_dec); 120 if (err < 0) 121 return err; 122 break; 123 case hwmon_temp_min: 124 err = sbtsi_temp_read(data, 125 SBTSI_REG_TEMP_LOW_INT, SBTSI_REG_TEMP_LOW_DEC, 126 &val_int, &val_dec); 127 128 if (err < 0) 129 return err; 130 break; 131 default: 132 return -EINVAL; 133 } 134 135 temp_int = val_int; 136 temp_dec = val_dec; 137 *val = sbtsi_reg_to_mc(temp_int, temp_dec); 138 if (data->ext_range_mode) 139 *val -= SBTSI_TEMP_EXT_RANGE_ADJ; 140 141 return 0; 142 } 143 144 static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type, 145 u32 attr, int channel, long val) 146 { 147 struct sbtsi_data *data = dev_get_drvdata(dev); 148 int reg_int, reg_dec; 149 u8 temp_int, temp_dec; 150 151 switch (attr) { 152 case hwmon_temp_max: 153 reg_int = SBTSI_REG_TEMP_HIGH_INT; 154 reg_dec = SBTSI_REG_TEMP_HIGH_DEC; 155 break; 156 case hwmon_temp_min: 157 reg_int = SBTSI_REG_TEMP_LOW_INT; 158 reg_dec = SBTSI_REG_TEMP_LOW_DEC; 159 break; 160 default: 161 return -EINVAL; 162 } 163 164 if (data->ext_range_mode) 165 val += SBTSI_TEMP_EXT_RANGE_ADJ; 166 val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX); 167 sbtsi_mc_to_reg(val, &temp_int, &temp_dec); 168 169 return sbtsi_temp_write(data, reg_int, reg_dec, temp_int, temp_dec); 170 } 171 172 static umode_t sbtsi_is_visible(const void *data, 173 enum hwmon_sensor_types type, 174 u32 attr, int channel) 175 { 176 switch (type) { 177 case hwmon_temp: 178 switch (attr) { 179 case hwmon_temp_input: 180 return 0444; 181 case hwmon_temp_min: 182 return 0644; 183 case hwmon_temp_max: 184 return 0644; 185 } 186 break; 187 default: 188 break; 189 } 190 return 0; 191 } 192 193 static const struct hwmon_channel_info * const sbtsi_info[] = { 194 HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ), 195 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX), 196 NULL 197 }; 198 199 static const struct hwmon_ops sbtsi_hwmon_ops = { 200 .is_visible = sbtsi_is_visible, 201 .read = sbtsi_read, 202 .write = sbtsi_write, 203 }; 204 205 static const struct hwmon_chip_info sbtsi_chip_info = { 206 .ops = &sbtsi_hwmon_ops, 207 .info = sbtsi_info, 208 }; 209 210 static int sbtsi_probe(struct auxiliary_device *adev, 211 const struct auxiliary_device_id *id) 212 { 213 struct sbtsi_data *data = dev_get_drvdata(adev->dev.parent); 214 struct device *dev = &adev->dev; 215 struct device *hwmon_dev; 216 217 hwmon_dev = devm_hwmon_device_register_with_info(dev, "sbtsi", data, 218 &sbtsi_chip_info, NULL); 219 220 return PTR_ERR_OR_ZERO(hwmon_dev); 221 } 222 223 static const struct auxiliary_device_id sbtsi_id[] = { 224 { .name = AMD_SBTSI_ADEV "." AMD_SBTSI_AUX_HWMON }, 225 { } 226 }; 227 MODULE_DEVICE_TABLE(auxiliary, sbtsi_id); 228 229 static struct auxiliary_driver sbtsi_driver = { 230 .driver = { 231 .name = "sbtsi", 232 }, 233 .probe = sbtsi_probe, 234 .id_table = sbtsi_id, 235 }; 236 module_auxiliary_driver(sbtsi_driver); 237 238 MODULE_AUTHOR("Kun Yi <kunyi@google.com>"); 239 MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor"); 240 MODULE_LICENSE("GPL"); 241