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1// SPDX-License-Identifier: GPL-2.0-or-later2/*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 are20 * the integer part of a temperature value or limit, and "_DEC" registers are21 * 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 533 34#define SBTSI_TEMP_MIN 035#define SBTSI_TEMP_MAX 25587536 37/* Each client has this additional data */38struct 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 the45 * 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 of47 * the "low byte" encode in base-2 the decimal portion.48 *49 * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius50 *51 * Therefore temperature in millidegree Celsius =52 * (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 12553 */54static 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 Celsius61 * INT = (TEMP / 125) / 862 * DEC = ((TEMP / 125) % 8) * 3263 * Caller have to make sure temp doesn't exceed 255875, the max valid value.64 */65static 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 72static 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 and83 * 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, read86 * order should be reversed.87 */88 err = i2c_smbus_read_byte_data(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(data->client, SBTSI_REG_TEMP_DEC);95 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT);96 } else {97 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT);98 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC);99 }100 mutex_unlock(&data->lock);101 break;102 case hwmon_temp_max:103 mutex_lock(&data->lock);104 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_INT);105 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_DEC);106 mutex_unlock(&data->lock);107 break;108 case hwmon_temp_min:109 mutex_lock(&data->lock);110 temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_INT);111 temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_DEC);112 mutex_unlock(&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(temp_int, temp_dec);125 126 return 0;127}128 129static 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(val, &temp_int, &temp_dec);151 152 mutex_lock(&data->lock);153 err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int);154 if (err)155 goto exit;156 157 err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec);158exit:159 mutex_unlock(&data->lock);160 return err;161}162 163static 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 184static 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 NULL188};189 190static const struct hwmon_ops sbtsi_hwmon_ops = {191 .is_visible = sbtsi_is_visible,192 .read = sbtsi_read,193 .write = sbtsi_write,194};195 196static const struct hwmon_chip_info sbtsi_chip_info = {197 .ops = &sbtsi_hwmon_ops,198 .info = sbtsi_info,199};200 201static 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, 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, client->name, data, &sbtsi_chip_info,215 NULL);216 217 return PTR_ERR_OR_ZERO(hwmon_dev);218}219 220static const struct i2c_device_id sbtsi_id[] = {221 {"sbtsi"},222 {}223};224MODULE_DEVICE_TABLE(i2c, sbtsi_id);225 226static const struct of_device_id __maybe_unused sbtsi_of_match[] = {227 {228 .compatible = "amd,sbtsi",229 },230 { },231};232MODULE_DEVICE_TABLE(of, sbtsi_of_match);233 234static 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 243module_i2c_driver(sbtsi_driver);244 245MODULE_AUTHOR("Kun Yi <kunyi@google.com>");246MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");247MODULE_LICENSE("GPL");248