// SPDX-License-Identifier: GPL-2.0-or-later /* * sbtsi_temp.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI) * compliant AMD SoC temperature device. * * Copyright (c) 2020, Google Inc. * Copyright (c) 2020, Kun Yi */ #include #include #include #include #include #include #include #include /* * SB-TSI registers only support SMBus byte data access. "_INT" registers are * the integer part of a temperature value or limit, and "_DEC" registers are * corresponding decimal parts. */ #define SBTSI_REG_TEMP_INT 0x01 /* RO */ #define SBTSI_REG_STATUS 0x02 /* RO */ #define SBTSI_REG_CONFIG 0x03 /* RO */ #define SBTSI_REG_TEMP_HIGH_INT 0x07 /* RW */ #define SBTSI_REG_TEMP_LOW_INT 0x08 /* RW */ #define SBTSI_REG_TEMP_DEC 0x10 /* RW */ #define SBTSI_REG_TEMP_HIGH_DEC 0x13 /* RW */ #define SBTSI_REG_TEMP_LOW_DEC 0x14 /* RW */ #define SBTSI_CONFIG_READ_ORDER_SHIFT 5 #define SBTSI_TEMP_MIN 0 #define SBTSI_TEMP_MAX 255875 /* Each client has this additional data */ struct sbtsi_data { struct i2c_client *client; struct mutex lock; }; /* * From SB-TSI spec: CPU temperature readings and limit registers encode the * temperature in increments of 0.125 from 0 to 255.875. The "high byte" * register encodes the base-2 of the integer portion, and the upper 3 bits of * the "low byte" encode in base-2 the decimal portion. * * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius * * Therefore temperature in millidegree Celsius = * (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125 */ static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal) { return ((integer << 3) + (decimal >> 5)) * 125; } /* * Inversely, given temperature in millidegree Celsius * INT = (TEMP / 125) / 8 * DEC = ((TEMP / 125) % 8) * 32 * Caller have to make sure temp doesn't exceed 255875, the max valid value. */ static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal) { temp /= 125; *integer = temp >> 3; *decimal = (temp & 0x7) << 5; } static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val) { struct sbtsi_data *data = dev_get_drvdata(dev); s32 temp_int, temp_dec; int err; switch (attr) { case hwmon_temp_input: /* * ReadOrder bit specifies the reading order of integer and * decimal part of CPU temp for atomic reads. If bit == 0, * reading integer part triggers latching of the decimal part, * so integer part should be read first. If bit == 1, read * order should be reversed. */ err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG); if (err < 0) return err; mutex_lock(&data->lock); if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) { temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC); temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT); } else { temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_INT); temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_DEC); } mutex_unlock(&data->lock); break; case hwmon_temp_max: mutex_lock(&data->lock); temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_INT); temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_HIGH_DEC); mutex_unlock(&data->lock); break; case hwmon_temp_min: mutex_lock(&data->lock); temp_int = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_INT); temp_dec = i2c_smbus_read_byte_data(data->client, SBTSI_REG_TEMP_LOW_DEC); mutex_unlock(&data->lock); break; default: return -EINVAL; } if (temp_int < 0) return temp_int; if (temp_dec < 0) return temp_dec; *val = sbtsi_reg_to_mc(temp_int, temp_dec); return 0; } static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val) { struct sbtsi_data *data = dev_get_drvdata(dev); int reg_int, reg_dec, err; u8 temp_int, temp_dec; switch (attr) { case hwmon_temp_max: reg_int = SBTSI_REG_TEMP_HIGH_INT; reg_dec = SBTSI_REG_TEMP_HIGH_DEC; break; case hwmon_temp_min: reg_int = SBTSI_REG_TEMP_LOW_INT; reg_dec = SBTSI_REG_TEMP_LOW_DEC; break; default: return -EINVAL; } val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX); sbtsi_mc_to_reg(val, &temp_int, &temp_dec); mutex_lock(&data->lock); err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int); if (err) goto exit; err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec); exit: mutex_unlock(&data->lock); return err; } static umode_t sbtsi_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel) { switch (type) { case hwmon_temp: switch (attr) { case hwmon_temp_input: return 0444; case hwmon_temp_min: return 0644; case hwmon_temp_max: return 0644; } break; default: break; } return 0; } static const struct hwmon_channel_info *sbtsi_info[] = { HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ), HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX), NULL }; static const struct hwmon_ops sbtsi_hwmon_ops = { .is_visible = sbtsi_is_visible, .read = sbtsi_read, .write = sbtsi_write, }; static const struct hwmon_chip_info sbtsi_chip_info = { .ops = &sbtsi_hwmon_ops, .info = sbtsi_info, }; static int sbtsi_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct device *dev = &client->dev; struct device *hwmon_dev; struct sbtsi_data *data; data = devm_kzalloc(dev, sizeof(struct sbtsi_data), GFP_KERNEL); if (!data) return -ENOMEM; data->client = client; mutex_init(&data->lock); hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data, &sbtsi_chip_info, NULL); return PTR_ERR_OR_ZERO(hwmon_dev); } static const struct i2c_device_id sbtsi_id[] = { {"sbtsi", 0}, {} }; MODULE_DEVICE_TABLE(i2c, sbtsi_id); static const struct of_device_id __maybe_unused sbtsi_of_match[] = { { .compatible = "amd,sbtsi", }, { }, }; MODULE_DEVICE_TABLE(of, sbtsi_of_match); static struct i2c_driver sbtsi_driver = { .class = I2C_CLASS_HWMON, .driver = { .name = "sbtsi", .of_match_table = of_match_ptr(sbtsi_of_match), }, .probe = sbtsi_probe, .id_table = sbtsi_id, }; module_i2c_driver(sbtsi_driver); MODULE_AUTHOR("Kun Yi "); MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor"); MODULE_LICENSE("GPL");