Re: [PATCH v2 3/4] hwmon: smpro: Add Ampere's Altra smpro-hwmon driver

From: Guenter Roeck
Date: Mon Mar 29 2021 - 21:44:11 EST

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In reply to: Quan Nguyen: "[PATCH v2 3/4] hwmon: smpro: Add Ampere's Altra smpro-hwmon driver"
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On 3/28/21 6:52 PM, Quan Nguyen wrote:
> This commit adds support for Ampere SMpro hwmon driver. This driver
> supports accessing various CPU sensors provided by the SMpro co-processor
> including temperature, power, voltages, and current.
>
> Signed-off-by: Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/hwmon/Kconfig | 8 +
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/smpro-hwmon.c | 494 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 503 insertions(+)
> create mode 100644 drivers/hwmon/smpro-hwmon.c
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 0ddc974b102e..ba4b5a911baf 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -67,6 +67,14 @@ config SENSORS_ABITUGURU3
> This driver can also be built as a module. If so, the module
> will be called abituguru3.
>
> +config SENSORS_SMPRO
> + tristate "Ampere's Altra SMpro hardware monitoring driver"
> + depends on MFD_SMPRO
> + help
> + If you say yes here you get support for the thermal, voltage,
> + current and power sensors of Ampere's Altra processor family SoC
> + with SMpro co-processor.
> +
> config SENSORS_AD7314
> tristate "Analog Devices AD7314 and compatibles"
> depends on SPI
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 59e78bc212cf..b25391f9c651 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -174,6 +174,7 @@ obj-$(CONFIG_SENSORS_SHT3x) += sht3x.o
> obj-$(CONFIG_SENSORS_SHTC1) += shtc1.o
> obj-$(CONFIG_SENSORS_SIS5595) += sis5595.o
> obj-$(CONFIG_SENSORS_SMM665) += smm665.o
> +obj-$(CONFIG_SENSORS_SMPRO) += smpro-hwmon.o
> obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
> obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
> obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
> diff --git a/drivers/hwmon/smpro-hwmon.c b/drivers/hwmon/smpro-hwmon.c
> new file mode 100644
> index 000000000000..4277736ebc6e
> --- /dev/null
> +++ b/drivers/hwmon/smpro-hwmon.c
> @@ -0,0 +1,494 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Ampere Computing SoC's SMPro Hardware Monitoring Driver
> + *
> + * Copyright (c) 2021, Ampere Computing LLC
> + */
> +#include <linux/bitfield.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/kernel.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +
> +/* Identification Registers */
> +#define MANUFACTURER_ID_REG 0x02
> +#define AMPERE_MANUFACTURER_ID 0xCD3A
> +
> +/* Logical Power Sensor Registers */
> +#define SOC_TEMP_REG 0x10
> +#define SOC_VRD_TEMP_REG 0x11
> +#define DIMM_VRD_TEMP_REG 0x12
> +#define CORE_VRD_TEMP_REG 0x13
> +#define CH0_DIMM_TEMP_REG 0x14
> +#define CH1_DIMM_TEMP_REG 0x15
> +#define CH2_DIMM_TEMP_REG 0x16
> +#define CH3_DIMM_TEMP_REG 0x17
> +#define CH4_DIMM_TEMP_REG 0x18
> +#define CH5_DIMM_TEMP_REG 0x19
> +#define CH6_DIMM_TEMP_REG 0x1A
> +#define CH7_DIMM_TEMP_REG 0x1B
> +#define RCA_VRD_TEMP_REG 0x1C
> +
> +#define CORE_VRD_PWR_REG 0x20
> +#define SOC_PWR_REG 0x21
> +#define DIMM_VRD1_PWR_REG 0x22
> +#define DIMM_VRD2_PWR_REG 0x23
> +#define CORE_VRD_PWR_MW_REG 0x26
> +#define SOC_PWR_MW_REG 0x27
> +#define DIMM_VRD1_PWR_MW_REG 0x28
> +#define DIMM_VRD2_PWR_MW_REG 0x29
> +#define RCA_VRD_PWR_REG 0x2A
> +#define RCA_VRD_PWR_MW_REG 0x2B
> +
> +#define MEM_HOT_THRESHOLD_REG 0x32
> +#define SOC_VR_HOT_THRESHOLD_REG 0x33
> +#define CORE_VRD_VOLT_REG 0x34
> +#define SOC_VRD_VOLT_REG 0x35
> +#define DIMM_VRD1_VOLT_REG 0x36
> +#define DIMM_VRD2_VOLT_REG 0x37
> +#define RCA_VRD_VOLT_REG 0x38
> +
> +#define CORE_VRD_CURR_REG 0x39
> +#define SOC_VRD_CURR_REG 0x3A
> +#define DIMM_VRD1_CURR_REG 0x3B
> +#define DIMM_VRD2_CURR_REG 0x3C
> +#define RCA_VRD_CURR_REG 0x3D
> +
> +struct smpro_hwmon {
> + struct regmap *regmap;
> +};
> +
> +struct smpro_sensor {
> + const u8 reg;
> + const u8 reg_ext;
> + const char *label;
> +};
> +
> +static const struct smpro_sensor temperature[] = {
> + {
> + .reg = SOC_TEMP_REG,
> + .label = "temp1 SoC"
> + },
> + {
> + .reg = SOC_VRD_TEMP_REG,
> + .label = "temp2 SoC VRD"
> + },
> + {
> + .reg = DIMM_VRD_TEMP_REG,
> + .label = "temp3 DIMM VRD"
> + },
> + {
> + .reg = CORE_VRD_TEMP_REG,
> + .label = "temp4 CORE VRD"
> + },
> + {
> + .reg = CH0_DIMM_TEMP_REG,
> + .label = "temp5 CH0 DIMM"
> + },
> + {
> + .reg = CH1_DIMM_TEMP_REG,
> + .label = "temp6 CH1 DIMM"
> + },
> + {
> + .reg = CH2_DIMM_TEMP_REG,
> + .label = "temp7 CH2 DIMM"
> + },
> + {
> + .reg = CH3_DIMM_TEMP_REG,
> + .label = "temp8 CH3 DIMM"
> + },
> + {
> + .reg = CH4_DIMM_TEMP_REG,
> + .label = "temp9 CH4 DIMM"
> + },
> + {
> + .reg = CH5_DIMM_TEMP_REG,
> + .label = "temp10 CH5 DIMM"
> + },
> + {
> + .reg = CH6_DIMM_TEMP_REG,
> + .label = "temp11 CH6 DIMM"
> + },
> + {
> + .reg = CH7_DIMM_TEMP_REG,
> + .label = "temp12 CH7 DIMM"
> + },
> + {
> + .reg = RCA_VRD_TEMP_REG,
> + .label = "temp13 RCA VRD"
> + },
> +};
> +
> +static const struct smpro_sensor voltage[] = {
> + {
> + .reg = CORE_VRD_VOLT_REG,
> + .label = "vout0 CORE VRD"
> + },
> + {
> + .reg = SOC_VRD_VOLT_REG,
> + .label = "vout1 SoC VRD"
> + },
> + {
> + .reg = DIMM_VRD1_VOLT_REG,
> + .label = "vout2 DIMM VRD1"
> + },
> + {
> + .reg = DIMM_VRD2_VOLT_REG,
> + .label = "vout3 DIMM VRD2"
> + },
> + {
> + .reg = RCA_VRD_VOLT_REG,
> + .label = "vout4 RCA VRD"
> + },
> +};
> +
> +static const struct smpro_sensor curr_sensor[] = {
> + {
> + .reg = CORE_VRD_CURR_REG,
> + .label = "iout1 CORE VRD"
> + },
> + {
> + .reg = SOC_VRD_CURR_REG,
> + .label = "iout2 SoC VRD"
> + },
> + {
> + .reg = DIMM_VRD1_CURR_REG,
> + .label = "iout3 DIMM VRD1"
> + },
> + {
> + .reg = DIMM_VRD2_CURR_REG,
> + .label = "iout4 DIMM VRD2"
> + },
> + {
> + .reg = RCA_VRD_CURR_REG,
> + .label = "iout5 RCA VRD"
> + },
> +};
> +
> +static const struct smpro_sensor power[] = {
> + {
> + .reg = CORE_VRD_PWR_REG,
> + .reg_ext = CORE_VRD_PWR_MW_REG,
> + .label = "power1 CORE VRD"
> + },
> + {
> + .reg = SOC_PWR_REG,
> + .reg_ext = SOC_PWR_MW_REG,
> + .label = "power2 SoC"
> + },
> + {
> + .reg = DIMM_VRD1_PWR_REG,
> + .reg_ext = DIMM_VRD1_PWR_MW_REG,
> + .label = "power3 DIMM VRD1"
> + },
> + {
> + .reg = DIMM_VRD2_PWR_REG,
> + .reg_ext = DIMM_VRD2_PWR_MW_REG,
> + .label = "power4 DIMM VRD2"
> + },
> + {
> + .reg = RCA_VRD_PWR_REG,
> + .reg_ext = RCA_VRD_PWR_MW_REG,
> + .label = "power5 RCA VRD"
> + },
> +};
> +
> +static int smpro_read_temp(struct device *dev, u32 attr, int channel, long *val)
> +{
> + struct smpro_hwmon *hwmon = dev_get_drvdata(dev);
> + unsigned int value;
> + int ret;
> +
> + switch (attr) {
> + case hwmon_temp_input:
> + ret = regmap_read(hwmon->regmap,
> + temperature[channel].reg, &value);
> + if (ret)
> + return ret;
> + *val = (value & 0x1ff) * 1000;
> + break;
> + case hwmon_temp_crit:
> + if (temperature[channel].reg == SOC_VRD_TEMP_REG) {
> + ret = regmap_read(hwmon->regmap, SOC_VR_HOT_THRESHOLD_REG, &value);
> + if (ret)
> + return ret;
> + *val = (value & 0x1ff) * 1000;
> + } else {
> + /* Report same MEM HOT threshold across DIMM channels */
> + ret = regmap_read(hwmon->regmap, MEM_HOT_THRESHOLD_REG, &value);
> + if (ret)
> + return ret;
> + *val = (value & 0x1ff) * 1000;
> + }

To avoid code duplication:

reg = temperature[channel].reg == SOC_VRD_TEMP_REG ? SOC_VR_HOT_THRESHOLD_REG : MEM_HOT_THRESHOLD_REG;
ret = regmap_read(hwmon->regmap, reg, &value);
if (ret)
return ret;

But then why don't you just use reg_ext to store SOC_VR_HOT_THRESHOLD_REG
or MEM_HOT_THRESHOLD_REG ? It is already available, after all, and with it
the code could be simplified to

ret = regmap_read(hwmon->regmap, temperature[channel].reg_ext, &value);
if (ret)
return ret;

I don't have a datasheet, but I do wonder what is in bit 9..15. Any idea ?
Main question is if there is a sign bit, as theoretic as it may be.

> + break;
> + default:
> + return -EOPNOTSUPP;
> + }
> + return 0;
> +}
> +
> +static int smpro_read_in(struct device *dev, u32 attr, int channel, long *val)
> +{
> + struct smpro_hwmon *hwmon = dev_get_drvdata(dev);
> + unsigned int value;
> + int ret;
> +
> + switch (attr) {
> + case hwmon_in_input:
> + ret = regmap_read(hwmon->regmap, voltage[channel].reg, &value);
> + if (ret < 0)
> + return ret;
> + /* Scale reported by the hardware is 1mV */
> + *val = value & 0x7fff;

What is in bit 15 ?

> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int smpro_read_curr(struct device *dev, u32 attr, int channel, long *val)
> +{
> + struct smpro_hwmon *hwmon = dev_get_drvdata(dev);
> + unsigned int value;
> + int ret;
> +
> + switch (attr) {
> + case hwmon_curr_input:
> + ret = regmap_read(hwmon->regmap, curr_sensor[channel].reg, &value);
> + if (ret < 0)
> + return ret;
> + /* Scale reported by the hardware is 1mA */
> + *val = value & 0x7fff;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int smpro_read_power(struct device *dev, u32 attr, int channel, long *val_pwr)
> +{
> + struct smpro_hwmon *hwmon = dev_get_drvdata(dev);
> + unsigned int val = 0, val_mw = 0;
> + int ret;
> +
> + switch (attr) {
> + case hwmon_power_input:
> + ret = regmap_read(hwmon->regmap, power[channel].reg, &val);
> + if (ret)
> + return ret;
> +
> + ret = regmap_read(hwmon->regmap, power[channel].reg_ext, &val_mw);
> + if (ret)
> + return ret;
> +
> + *val_pwr = val * 1000000 + val_mw * 1000;
> + return 0;
> +
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int smpro_read(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long *val)
> +{
> + switch (type) {
> + case hwmon_temp:
> + return smpro_read_temp(dev, attr, channel, val);
> + case hwmon_in:
> + return smpro_read_in(dev, attr, channel, val);
> + case hwmon_power:
> + return smpro_read_power(dev, attr, channel, val);
> + case hwmon_curr:
> + return smpro_read_curr(dev, attr, channel, val);
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int smpro_write(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long val)
> +{
> + return -EOPNOTSUPP;
> +}

There are no writeable attributes, thus the write function is not needed.

> +
> +static int smpro_read_string(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, const char **str)
> +{
> + switch (type) {
> + case hwmon_temp:
> + switch (attr) {
> + case hwmon_temp_label:
> + *str = temperature[channel].label;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> + break;
> +
> + case hwmon_in:
> + switch (attr) {
> + case hwmon_in_label:
> + *str = voltage[channel].label;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> + break;
> +
> + case hwmon_curr:
> + switch (attr) {
> + case hwmon_curr_label:
> + *str = curr_sensor[channel].label;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> + break;
> +
> + case hwmon_power:
> + switch (attr) {
> + case hwmon_power_label:
> + *str = power[channel].label;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> + break;
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + return -EOPNOTSUPP;

If you are returning -ENOPSUPP by default, might as well replace
all the same returns above with break;

> +}
> +
> +static umode_t smpro_is_visible(const void *data, enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + const struct smpro_hwmon *hwmon = data;
> + unsigned int value;
> + int ret;
> +
> + switch (type) {
> + case hwmon_temp:
> + switch (attr) {
> + case hwmon_temp_input:
> + case hwmon_temp_label:
> + case hwmon_temp_crit:
> + ret = regmap_read(hwmon->regmap, temperature[channel].reg, &value);
> + if (ret || value == 0xFFFF)
> + return 0;
> + break;
> + }
> + default:
> + break;
> + }
> +
> + return 0444;
> +}
> +
> +static const struct hwmon_channel_info *smpro_info[] = {
> + HWMON_CHANNEL_INFO(temp,
> + HWMON_T_INPUT | HWMON_T_LABEL,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL,
> + HWMON_T_INPUT | HWMON_T_LABEL,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL | HWMON_T_CRIT,
> + HWMON_T_INPUT | HWMON_T_LABEL),
> + HWMON_CHANNEL_INFO(in,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL),
> + HWMON_CHANNEL_INFO(power,
> + HWMON_P_INPUT | HWMON_P_LABEL,
> + HWMON_P_INPUT | HWMON_P_LABEL,
> + HWMON_P_INPUT | HWMON_P_LABEL,
> + HWMON_P_INPUT | HWMON_P_LABEL,
> + HWMON_P_INPUT | HWMON_P_LABEL),
> + HWMON_CHANNEL_INFO(curr,
> + HWMON_C_INPUT | HWMON_C_LABEL,
> + HWMON_C_INPUT | HWMON_C_LABEL,
> + HWMON_C_INPUT | HWMON_C_LABEL,
> + HWMON_C_INPUT | HWMON_C_LABEL,
> + HWMON_C_INPUT | HWMON_C_LABEL),
> + NULL
> +};
> +
> +static const struct hwmon_ops smpro_hwmon_ops = {
> + .is_visible = smpro_is_visible,
> + .read = smpro_read,
> + .write = smpro_write,
> + .read_string = smpro_read_string,
> +};
> +
> +static const struct hwmon_chip_info smpro_chip_info = {
> + .ops = &smpro_hwmon_ops,
> + .info = smpro_info,
> +};
> +
> +static bool is_valid_id(struct regmap *regmap)
> +{
> + unsigned int val;
> + int ret;
> +
> + ret = regmap_read(regmap, MANUFACTURER_ID_REG, &val);
> +
> + return (ret || (val != AMPERE_MANUFACTURER_ID)) ? false : true;

I am quite concerned about this: The calling code will translate it to
-EPROBE_DEFER even if the manufacturer ID is wrong. It should return
-ENODEV in that case. There should be a better means to determine if the
controller is not available at all, or not yet.

> +}
> +
> +static int smpro_hwmon_probe(struct platform_device *pdev)
> +{
> + struct smpro_hwmon *hwmon;
> + struct device *hwmon_dev;
> +
> + hwmon = devm_kzalloc(&pdev->dev, sizeof(struct smpro_hwmon), GFP_KERNEL);
> + if (!hwmon)
> + return -ENOMEM;
> +
> + hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> + if (!hwmon->regmap)
> + return -ENODEV;
> +
> + /* Check for valid ID */
> + if (!is_valid_id(hwmon->regmap))
> + return -EPROBE_DEFER;
> +
> + hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, "smpro_hwmon",
> + hwmon, &smpro_chip_info, NULL);
> +
> + return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static const struct of_device_id smpro_hwmon_of_match[] = {
> + { .compatible = "ampere,ac01-hwmon" },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, smpro_hwmon_of_match);
> +
> +static struct platform_driver smpro_hwmon_driver = {
> + .probe = smpro_hwmon_probe,
> + .driver = {
> + .name = "smpro-hwmon",
> + .of_match_table = smpro_hwmon_of_match,
> + },
> +};
> +
> +module_platform_driver(smpro_hwmon_driver);
> +
> +MODULE_AUTHOR("Thu Nguyen <thu@xxxxxxxxxxxxxxxxxxxxxx>");
> +MODULE_AUTHOR("Quan Nguyen <quan@xxxxxxxxxxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Ampere Altra SMPro hwmon driver");
> +MODULE_LICENSE("GPL v2");
>

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