// 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.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 * const 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)
{
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"},
{}
};
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 = {
.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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