diff options
Diffstat (limited to 'drivers/hwmon/sbtsi_temp.c')
| -rw-r--r-- | drivers/hwmon/sbtsi_temp.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/drivers/hwmon/sbtsi_temp.c b/drivers/hwmon/sbtsi_temp.c new file mode 100644 index 000000000000..e35357c48b8e --- /dev/null +++ b/drivers/hwmon/sbtsi_temp.c @@ -0,0 +1,250 @@ +// 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 <kunyi@google.com> + */ + +#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 <kunyi@google.com>"); +MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor"); +MODULE_LICENSE("GPL"); |