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- // 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 <[email protected]>
- */
- #include <linux/err.h>
- #include <linux/i2c.h>
- #include <linux/init.h>
- #include <linux/hwmon.h>
- #include <linux/module.h>
- #include <linux/mutex.h>
- #include <linux/of_device.h>
- #include <linux/of.h>
- /*
- * 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 <[email protected]>");
- MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
- MODULE_LICENSE("GPL");
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