On Wed, Dec 02, 2020 at 08:55:59AM -0800, Kun Yi wrote: > SB Temperature Sensor Interface (SB-TSI) is an SMBus compatible > interface that reports AMD SoC's Ttcl (normalized temperature), > and resembles a typical 8-pin remote temperature sensor's I2C interface > to BMC. > > This commit adds basic support using this interface to read CPU > temperature, and read/write high/low CPU temp thresholds. > > To instantiate this driver on an AMD CPU with SB-TSI > support, the i2c bus number would be the bus connected from the board > management controller (BMC) to the CPU. The i2c address is specified in > Section 6.3.1 of the spec [1]: The SB-TSI address is normally 98h for > socket 0 and 90h for socket 1, but it could vary based on hardware address > select pins. > > [1]: https://www.amd.com/system/files/TechDocs/56255_OSRR.pdf > > Test status: tested reading temp1_input, and reading/writing > temp1_max/min. > > Signed-off-by: Kun Yi <kunyi@xxxxxxxxxx> > --- > drivers/hwmon/Kconfig | 10 ++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/sbtsi_temp.c | 265 +++++++++++++++++++++++++++++++++++++ > 3 files changed, 276 insertions(+) > create mode 100644 drivers/hwmon/sbtsi_temp.c > > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 3c059fc23cd6..3d6a809700ae 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -1522,6 +1522,16 @@ config SENSORS_SL28CPLD > This driver can also be built as a module. If so, the module > will be called sl28cpld-hwmon. > > +config SENSORS_SBTSI > + tristate "Emulated SB-TSI temperature sensor" > + depends on I2C > + help > + If you say yes here you get support for emulated temperature > + sensors on AMD SoCs with SB-TSI interface connected to a BMC device. > + > + This driver can also be built as a module. If so, the module will > + be called sbtsi_temp. > + > config SENSORS_SHT15 > tristate "Sensiron humidity and temperature sensors. SHT15 and compat." > depends on GPIOLIB || COMPILE_TEST > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index 01ca5d3fbad4..ee8c037919da 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -160,6 +160,7 @@ obj-$(CONFIG_SENSORS_POWR1220) += powr1220.o > obj-$(CONFIG_SENSORS_PWM_FAN) += pwm-fan.o > obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON) += raspberrypi-hwmon.o > obj-$(CONFIG_SENSORS_S3C) += s3c-hwmon.o > +obj-$(CONFIG_SENSORS_SBTSI) += sbtsi_temp.o > obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o > obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o > obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o > diff --git a/drivers/hwmon/sbtsi_temp.c b/drivers/hwmon/sbtsi_temp.c > new file mode 100644 > index 000000000000..6b0a7b9df1f3 > --- /dev/null > +++ b/drivers/hwmon/sbtsi_temp.c > @@ -0,0 +1,265 @@ > +// 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@xxxxxxxxxx> > + */ > + > +#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, reg_int, reg_dec; > + bool reading_input; > + > + if (type != hwmon_temp) > + return -EINVAL; Unnecessary check. > + > + reading_input = false; > + switch (attr) { > + case hwmon_temp_input: > + reading_input = true; > + /* > + * 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: > + 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; > + } > + > + if (!reading_input) { > + temp_int = i2c_smbus_read_byte_data(data->client, reg_int); > + temp_dec = i2c_smbus_read_byte_data(data->client, reg_dec); > + } This adds unnecessary complexity. I would suggest to move the calls to the case statements and drop reading_input as well as reg_int, reg_dec. Also, I just realized that the mutex is needed here as well, since the values might be written while being read, which could result in inconsistent read values. Example: Limit is changed from 100 to 99.75. Since the integer value is written first, it is possible that 99.0 is returned. > + > + 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; > + > + if (type != hwmon_temp) > + return -EINVAL; This check is really unnecessary. > + > + 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); > + mutex_lock(&data->lock); > + sbtsi_mc_to_reg(val, &temp_int, &temp_dec); > + 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, Line length limit is now 100 columns, so the above line split is unnecessary. > + &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@xxxxxxxxxx>"); > +MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor"); > +MODULE_LICENSE("GPL"); > -- > 2.29.2.454.gaff20da3a2-goog >
