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Message-ID: <4405fd59-0cf9-4fc0-92d3-6a639d50c7e6@roeck-us.net>
Date: Sat, 12 Apr 2025 13:10:55 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Dzmitry Sankouski <dsankouski@...il.com>, Jean Delvare
<jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
Chanwoo Choi <cw00.choi@...sung.com>, Krzysztof Kozlowski <krzk@...nel.org>
Cc: linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] hwmon: (max77705) add initial support
On 4/12/25 00:20, Dzmitry Sankouski wrote:
> Add support for max77705 hwmon. Includes charger input, system bus, and
> vbyp measurements.
>
> Signed-off-by: Dzmitry Sankouski <dsankouski@...il.com>
> ---
> Maxim MAX77705 is a Companion Power Management and Type-C interface IC.
> It includes charger and fuel gauge blocks, and is capable of measuring
> charger input current, system bus volatage and current, and bypass
> voltage.
>
> Add support for mentioned measurements.
> ---
> Changes in v4:
> - Fix review comments.
> - Link to v3: https://lore.kernel.org/r/20250405-initial-support-for-max77705-sensors-v3-1-e5f64fccd005@gmail.com
>
> Changes in v3:
> - Fix review comments.
> - Fix v2 changed message.
> - Link to v2: https://lore.kernel.org/r/20250304-initial-support-for-max77705-sensors-v2-1-58d2207c732b@gmail.com
>
> Changes in v2:
> - Fix review comments.
> - Link to v1: https://lore.kernel.org/r/20250225-initial-support-for-max77705-sensors-v1-1-2be6467628b0@gmail.com
> ---
> Changes in v4:
> - documentation: "===" line is as long as the text
> - simplify the dependency to depends on MFD_MAX77705
> - cleanup headers
> - sign_extend current measurements - add 'is_signed' parameter to
> max77705_read_and_convert function
> - replace ARRAY_SIZE(voltage_channel_desc) to 2
> - remove last blank line
>
> Changes in v3:
> - change resolution type to u32
> - pass regmap from parent
> - rebase on latest linux-next, containg max77705 driver
>
> Changes in v2:
> - sort headers alphabetically
> - swap curr channel info, to align indeces with channel_desc struct
> - reword coverletter
> - fix checkpatch --strict warnings
> - remove struct max77705_hwmon, use regmap directly
> - move register validation logic to is_visible function
> - move common register reading and converting logic to separate function
> - remove unnessesary {} in if statement
> - s/i2c->dev/pdev->dev in dev_err_probe
> ---
> Documentation/hwmon/index.rst | 1 +
> Documentation/hwmon/max77705.rst | 39 ++++++++++++++++++++++++++++++++
> MAINTAINERS | 7 ++++++
> drivers/hwmon/Kconfig | 9 ++++++++
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/max77705-hwmon.c | 242 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 6 files changed, 299 insertions(+)
>
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index f0ddf6222c44..764c1c91ed70 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -161,6 +161,7 @@ Hardware Monitoring Kernel Drivers
> max6639
> max6650
> max6697
> + max77705
> max8688
> mc13783-adc
> mc34vr500
> diff --git a/Documentation/hwmon/max77705.rst b/Documentation/hwmon/max77705.rst
> new file mode 100644
> index 000000000000..4a7680a340e1
> --- /dev/null
> +++ b/Documentation/hwmon/max77705.rst
> @@ -0,0 +1,39 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver max77705
> +======================
> +
> +Supported chips:
> +
> + * Maxim Integrated MAX77705
> +
> + Prefix: 'max77705'
> +
> + Addresses scanned: none
> +
> + Datasheet: Not available
> +
> +Authors:
> + - Dzmitry Sankouski <dsankouski@...il.com>
> +
> +Description
> +-----------
> +
> +The MAX77705 PMIC provides current and voltage measurements besides fuelgauge:
> +- chip input current
> +- system bus current and voltage
> +- VBYP voltage
> +
> +Sysfs Attributes
> +----------------
> +
> +================= ========================================
> +in1_label "vbyp"
> +in1_input Measured chip vbyp voltage
> +in2_label "vsys"
> +in2_input Measured chip system bus voltage
> +curr1_label "iin"
> +curr1_input Measured chip input current.
> +curr2_label "isys"
> +curr2_input Measured chip system bus current.
> +================= ========================================
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 78467ad7a8fe..2e1e5233a011 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -18369,6 +18369,13 @@ S: Maintained
> F: Documentation/hwmon/pc87427.rst
> F: drivers/hwmon/pc87427.c
>
> +MAX77705 HARDWARE MONITORING DRIVER
> +M: Dzmitry Sankouski <dsankouski@...il.com>
> +L: linux-hwmon@...r.kernel.org
> +S: Maintained
> +F: Documentation/hwmon/max77705.rst
> +F: drivers/hwmon/max77705-hwmon.c
> +
> PCA9532 LED DRIVER
> M: Riku Voipio <riku.voipio@....fi>
> S: Maintained
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index f91f713b0105..7109f252dab4 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1308,6 +1308,15 @@ config SENSORS_MAX31790
> This driver can also be built as a module. If so, the module
> will be called max31790.
>
> +config SENSORS_MAX77705
> + tristate "MAX77705 current and voltage sensor"
> + depends on MFD_MAX77705
> + help
> + If you say yes here you get support for MAX77705 sensors connected with I2C.
> +
> + This driver can also be built as a module. If so, the module
> + will be called max77705-hwmon.
> +
> config SENSORS_MC34VR500
> tristate "NXP MC34VR500 hardware monitoring driver"
> depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 766c652ef22b..22ceebf10299 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -161,6 +161,7 @@ obj-$(CONFIG_SENSORS_MAX6650) += max6650.o
> obj-$(CONFIG_SENSORS_MAX6697) += max6697.o
> obj-$(CONFIG_SENSORS_MAX31790) += max31790.o
> obj-$(CONFIG_MAX31827) += max31827.o
> +obj-$(CONFIG_SENSORS_MAX77705) += max77705-hwmon.o
> obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
> obj-$(CONFIG_SENSORS_MC34VR500) += mc34vr500.o
> obj-$(CONFIG_SENSORS_MCP3021) += mcp3021.o
> diff --git a/drivers/hwmon/max77705-hwmon.c b/drivers/hwmon/max77705-hwmon.c
> new file mode 100644
> index 000000000000..be0a4bd31d33
> --- /dev/null
> +++ b/drivers/hwmon/max77705-hwmon.c
> @@ -0,0 +1,242 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * MAX77705 voltage and current hwmon driver.
> + *
> + * Copyright (C) 2025 Dzmitry Sankouski <dsankouski@...il.com>
> + */
> +
> +#include <linux/err.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/hwmon.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/max77705-private.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +struct channel_desc {
> + u8 reg;
> + u8 avg_reg;
> + const char *const label;
> + // register resolution. nano Volts for voltage, nano Amperes for current
> + u32 resolution;
> +};
> +
> +static const struct channel_desc current_channel_desc[] = {
> + {
> + .reg = IIN_REG,
> + .label = "IIN_REG",
> + .resolution = 125000
> + },
> + {
> + .reg = ISYS_REG,
> + .avg_reg = AVGISYS_REG,
> + .label = "ISYS_REG",
> + .resolution = 312500
> + }
> +};
> +
> +static const struct channel_desc voltage_channel_desc[] = {
> + {
> + .reg = VBYP_REG,
> + .label = "VBYP_REG",
> + .resolution = 427246
> + },
> + {
> + .reg = VSYS_REG,
> + .label = "VSYS_REG",
> + .resolution = 156250
> + }
> +};
> +
> +static const struct regmap_range max77705_hwmon_readable_ranges[] = {
> + regmap_reg_range(AVGISYS_REG, AVGISYS_REG + 1),
> + regmap_reg_range(IIN_REG, IIN_REG + 1),
> + regmap_reg_range(ISYS_REG, ISYS_REG + 1),
> + regmap_reg_range(VBYP_REG, VBYP_REG + 1),
> + regmap_reg_range(VSYS_REG, VSYS_REG + 1),
> +};
> +
> +static const struct regmap_access_table max77705_hwmon_readable_table = {
> + .yes_ranges = max77705_hwmon_readable_ranges,
> + .n_yes_ranges = ARRAY_SIZE(max77705_hwmon_readable_ranges),
> +};
> +
> +static int max77705_read_and_convert(struct regmap *regmap, u8 reg, u32 res,
> + u8 is_signed, long *val)
is_signed could (and should) be bool.
> +{
> + int ret;
> + u32 regval;
> +
> + ret = regmap_read(regmap, reg, ®val);
> + if (ret < 0)
> + return ret;
> +
> + if (is_signed)
> + *val = mult_frac((long)sign_extend32(regval, 15), res, 1000000);
> + else
> + *val = mult_frac((long)regval, res, 1000000);
> +
> + return 0;
> +}
> +
> +static umode_t max77705_is_visible(const void *data,
> + enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + switch (type) {
> + case hwmon_in:
> + if (channel >= 2)
> + return 0;
> +
This and the same check is just as unnecessary as earlier.
> + switch (attr) {
> + case hwmon_in_input:
> + case hwmon_in_label:
> + return 0444;
> + default:
> + break;
> + }
> + break;
> + case hwmon_curr:
> + if (channel >= 2)
> + return 0;
> +
Same here.
> + switch (attr) {
> + case hwmon_curr_input:
> + case hwmon_in_label:
> + return 0444;
> + case hwmon_curr_average:
> + if (current_channel_desc[channel].avg_reg)
> + return 0444;
> + break;
> + default:
> + break;
> + }
> + break;
> + default:
> + break;
> + }
> + return 0;
> +}
> +
> +static int max77705_read_string(struct device *dev, enum hwmon_sensor_types type, u32 attr,
> + int channel, const char **buf)
> +{
> + switch (type) {
> + case hwmon_curr:
> + switch (attr) {
> + case hwmon_in_label:
> + *buf = current_channel_desc[channel].label;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + case hwmon_in:
> + switch (attr) {
> + case hwmon_in_label:
> + *buf = voltage_channel_desc[channel].label;
> + return 0;
> + default:
> + return -EOPNOTSUPP;
> + }
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +
> +static int max77705_read(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long *val)
> +{
> + struct regmap *regmap = dev_get_drvdata(dev);
> + u8 reg, is_signed;
> + u32 res;
> +
> + switch (type) {
> + case hwmon_curr:
> + is_signed = 1;
> + switch (attr) {
> + case hwmon_curr_input:
> + reg = current_channel_desc[channel].reg;
> + res = current_channel_desc[channel].resolution;
> +
> + return max77705_read_and_convert(regmap, reg, res, is_signed, val);
I fail to understand the need for the is_signed variable. Why not just pass a bool "true" ?
> + case hwmon_curr_average:
> + reg = current_channel_desc[channel].avg_reg;
> + res = current_channel_desc[channel].resolution;
> +
> + return max77705_read_and_convert(regmap, reg, res, is_signed, val);
same here.
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + case hwmon_in:
> + is_signed = 0;
> + switch (attr) {
> + case hwmon_in_input:
> + reg = voltage_channel_desc[channel].reg;
> + res = voltage_channel_desc[channel].resolution;
> +
> + return max77705_read_and_convert(regmap, reg, res, is_signed, val);
... and "false" here.
> + default:
> + return -EOPNOTSUPP;
> + }
> + default:
> + return -EOPNOTSUPP;
> + }
> +
> + return 0;
> +}
> +
> +static const struct hwmon_ops max77705_hwmon_ops = {
> + .is_visible = max77705_is_visible,
> + .read = max77705_read,
> + .read_string = max77705_read_string,
> +};
> +
> +static const struct hwmon_channel_info *max77705_info[] = {
> + HWMON_CHANNEL_INFO(in,
> + HWMON_I_INPUT | HWMON_I_LABEL,
> + HWMON_I_INPUT | HWMON_I_LABEL
> + ),
> + HWMON_CHANNEL_INFO(curr,
> + HWMON_C_INPUT | HWMON_C_LABEL,
> + HWMON_C_INPUT | HWMON_C_AVERAGE | HWMON_C_LABEL
> + ),
> + NULL
> +};
> +
> +static const struct hwmon_chip_info max77705_chip_info = {
> + .ops = &max77705_hwmon_ops,
> + .info = max77705_info,
> +};
> +
> +static int max77705_hwmon_probe(struct platform_device *pdev)
> +{
> + struct device *hwmon_dev;
> + struct regmap *regmap;
> +
> + regmap = dev_get_regmap(pdev->dev.parent, NULL);
> + if (!regmap)
> + return -ENODEV;
> +
> + hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, "max77705", regmap,
> + &max77705_chip_info, NULL);
> + if (IS_ERR(hwmon_dev))
> + return dev_err_probe(&pdev->dev, PTR_ERR(hwmon_dev),
> + "Unable to register hwmon device\n");
> +
> + return 0;
> +};
> +
> +static struct platform_driver max77705_hwmon_driver = {
> + .driver = {
> + .name = "max77705-hwmon",
> + },
> + .probe = max77705_hwmon_probe,
> +};
> +
> +module_platform_driver(max77705_hwmon_driver);
> +
> +MODULE_AUTHOR("Dzmitry Sankouski <dsankouski@...il.com>");
> +MODULE_DESCRIPTION("MAX77705 monitor driver");
> +MODULE_LICENSE("GPL");
>
> ---
> base-commit: a4cda136f021ad44b8b52286aafd613030a6db5f
> change-id: 20250123-initial-support-for-max77705-sensors-ad0170ac1ec5
>
> Best regards,
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