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