Message-Id: <20250304-initial-support-for-max77705-sensors-v2-1-58d2207c732b@gmail.com>
Date: Tue, 04 Mar 2025 14:08:40 +0300
From: Dzmitry Sankouski <dsankouski@...il.com>
To: Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>, 
 Jonathan Corbet <corbet@....net>
Cc: linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Dzmitry Sankouski <dsankouski@...il.com>
Subject: [PATCH v2] hwmon: (max77705) add initial support

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 v2:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v1: https://lore.kernel.org/r/20250225-initial-support-for-max77705-sensors-v1-1-2be6467628b0@gmail.com
---
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            |  10 ++++++++++
 drivers/hwmon/Makefile           |   1 +
 drivers/hwmon/max77705-hwmon.c   | 250 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 308 insertions(+)

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 874f8fd26325..444c7865f74f 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -158,6 +158,7 @@ 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..9037226c50b9
--- /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 29e1a423eee5..0175f9f89325 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18110,6 +18110,13 @@ 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 56494ab85b83..c86fe094a978 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1287,6 +1287,16 @@ 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 I2C
+	select REGMAP_I2C
+	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 b7ef0f0562d3..ff69f45eca50 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -159,6 +159,7 @@ 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..6d2161421ac7
--- /dev/null
+++ b/drivers/hwmon/max77705-hwmon.c
@@ -0,0 +1,250 @@
+// 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/i2c.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/mfd/max77705-private.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+struct channel_desc {
+	u8 reg;
+	u8 avg_reg;
+	const char *const label;
+	// register resolution. nano Volts for voltage, nano Amperes for current
+	u64 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 const struct regmap_config max77705_hwmon_regmap_config = {
+	.name = "max77705_hwmon",
+	.reg_bits = 8,
+	.val_bits = 16,
+	.rd_table = &max77705_hwmon_readable_table,
+	.max_register = MAX77705_FG_END,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE
+};
+
+static int max77705_read_and_convert(struct regmap *regmap, u8 reg, u64 res, long *val)
+{
+	int ret;
+	u32 regval;
+
+	ret = regmap_read(regmap, reg, &regval);
+	if (ret < 0)
+		return ret;
+	*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 >= ARRAY_SIZE(voltage_channel_desc))
+			return 0;
+
+		switch (attr) {
+		case hwmon_in_input:
+		case hwmon_in_label:
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	case hwmon_curr:
+		if (channel >= ARRAY_SIZE(current_channel_desc))
+			return 0;
+
+		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;
+		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;
+	u64 res;
+
+	switch (type) {
+	case hwmon_curr:
+		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, val);
+		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, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+
+	case hwmon_in:
+		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, val);
+		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 i2c_client *i2c;
+	struct device *hwmon_dev;
+	struct regmap *regmap;
+
+	i2c = to_i2c_client(pdev->dev.parent);
+	regmap = devm_regmap_init_i2c(i2c, &max77705_hwmon_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(&pdev->dev, PTR_ERR(regmap),
+				"Failed to register max77705 hwmon regmap\n");
+
+	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: 20d5c66e1810e6e8805ec0d01373afb2dba9f51a
change-id: 20250123-initial-support-for-max77705-sensors-ad0170ac1ec5

Best regards,
-- 
Dzmitry Sankouski <dsankouski@...il.com>

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