hwmon: (adm1177) Add ADM1177 Hot Swap Controller and Digital Power Monitor driver

ADM1177 is a Hot Swap Controller and Digital Power Monitor with
Soft Start Pin.

Datasheet:
Link: https://www.analog.com/media/en/technical-documentation/data-sheets/ADM1177.pdf

Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
Link: https://lore.kernel.org/r/20200114112159.25998-1-beniamin.bia@analog.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/adm1177.rst

@@ -0,0 +1,36 @@
+Kernel driver adm1177
+=====================
+
+Supported chips:
+  * Analog Devices ADM1177
+    Prefix: 'adm1177'
+    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADM1177.pdf
+
+Author: Beniamin Bia <beniamin.bia@analog.com>
+
+
+Description
+-----------
+
+This driver supports hardware monitoring for Analog Devices ADM1177
+Hot-Swap Controller and Digital Power Monitors with Soft Start Pin.
+
+
+Usage Notes
+-----------
+
+This driver does not auto-detect devices. You will have to instantiate the
+devices explicitly. Please see Documentation/i2c/instantiating-devices for
+details.
+
+
+Sysfs entries
+-------------
+
+The following attributes are supported. Current maxim attribute
+is read-write, all other attributes are read-only.
+
+in0_input		Measured voltage in microvolts.
+
+curr1_input		Measured current in microamperes.
+curr1_max_alarm		Overcurrent alarm in microamperes.

Documentation/hwmon/index.rst

@@ -29,6 +29,7 @@ Hardware Monitoring Kernel Drivers
    adm1025
    adm1026
    adm1031
+   adm1177
    adm1275
    adm9240
    ads7828

drivers/hwmon/Kconfig

@@ -164,6 +164,16 @@ config SENSORS_ADM1031
 	  This driver can also be built as a module. If so, the module
 	  will be called adm1031.
 
+config SENSORS_ADM1177
+	tristate "Analog Devices ADM1177 and compatibles"
+	depends on I2C
+	help
+	  If you say yes here you get support for Analog Devices ADM1177
+	  sensor chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called adm1177.
+
 config SENSORS_ADM9240
 	tristate "Analog Devices ADM9240 and compatibles"
 	depends on I2C

drivers/hwmon/Makefile

@@ -34,6 +34,7 @@ obj-$(CONFIG_SENSORS_ADM1025)	+= adm1025.o
 obj-$(CONFIG_SENSORS_ADM1026)	+= adm1026.o
 obj-$(CONFIG_SENSORS_ADM1029)	+= adm1029.o
 obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
+obj-$(CONFIG_SENSORS_ADM1177)	+= adm1177.o
 obj-$(CONFIG_SENSORS_ADM9240)	+= adm9240.o
 obj-$(CONFIG_SENSORS_ADS7828)	+= ads7828.o
 obj-$(CONFIG_SENSORS_ADS7871)	+= ads7871.o

drivers/hwmon/adm1177.c

@@ -0,0 +1,288 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADM1177 Hot Swap Controller and Digital Power Monitor with Soft Start Pin
+ *
+ * Copyright 2015-2019 Analog Devices Inc.
+ */
+
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+
+/*  Command Byte Operations */
+#define ADM1177_CMD_V_CONT	BIT(0)
+#define ADM1177_CMD_I_CONT	BIT(2)
+#define ADM1177_CMD_VRANGE	BIT(4)
+
+/* Extended Register */
+#define ADM1177_REG_ALERT_TH	2
+
+#define ADM1177_BITS		12
+
+/**
+ * struct adm1177_state - driver instance specific data
+ * @client		pointer to i2c client
+ * @reg			regulator info for the the power supply of the device
+ * @r_sense_uohm	current sense resistor value
+ * @alert_threshold_ua	current limit for shutdown
+ * @vrange_high		internal voltage divider
+ */
+struct adm1177_state {
+	struct i2c_client	*client;
+	struct regulator	*reg;
+	u32			r_sense_uohm;
+	u32			alert_threshold_ua;
+	bool			vrange_high;
+};
+
+static int adm1177_read_raw(struct adm1177_state *st, u8 num, u8 *data)
+{
+	return i2c_master_recv(st->client, data, num);
+}
+
+static int adm1177_write_cmd(struct adm1177_state *st, u8 cmd)
+{
+	return i2c_smbus_write_byte(st->client, cmd);
+}
+
+static int adm1177_write_alert_thr(struct adm1177_state *st,
+				   u32 alert_threshold_ua)
+{
+	u64 val;
+	int ret;
+
+	val = 0xFFULL * alert_threshold_ua * st->r_sense_uohm;
+	val = div_u64(val, 105840000U);
+	val = div_u64(val, 1000U);
+	if (val > 0xFF)
+		val = 0xFF;
+
+	ret = i2c_smbus_write_byte_data(st->client, ADM1177_REG_ALERT_TH,
+					val);
+	if (ret)
+		return ret;
+
+	st->alert_threshold_ua = alert_threshold_ua;
+	return 0;
+}
+
+static int adm1177_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	struct adm1177_state *st = dev_get_drvdata(dev);
+	u8 data[3];
+	long dummy;
+	int ret;
+
+	switch (type) {
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_input:
+			ret = adm1177_read_raw(st, 3, data);
+			if (ret < 0)
+				return ret;
+			dummy = (data[1] << 4) | (data[2] & 0xF);
+			/*
+			 * convert to milliamperes
+			 * ((105.84mV / 4096) x raw) / senseResistor(ohm)
+			 */
+			*val = div_u64((105840000ull * dummy),
+				       4096 * st->r_sense_uohm);
+			return 0;
+		case hwmon_curr_max_alarm:
+			*val = st->alert_threshold_ua;
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+	case hwmon_in:
+		ret = adm1177_read_raw(st, 3, data);
+		if (ret < 0)
+			return ret;
+		dummy = (data[0] << 4) | (data[2] >> 4);
+		/*
+		 * convert to millivolts based on resistor devision
+		 * (V_fullscale / 4096) * raw
+		 */
+		if (st->vrange_high)
+			dummy *= 26350;
+		else
+			dummy *= 6650;
+
+		*val = DIV_ROUND_CLOSEST(dummy, 4096);
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int adm1177_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	struct adm1177_state *st = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_max_alarm:
+			adm1177_write_alert_thr(st, val);
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t adm1177_is_visible(const void *data,
+				  enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	const struct adm1177_state *st = data;
+
+	switch (type) {
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+			return 0444;
+		}
+		break;
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_input:
+			if (st->r_sense_uohm)
+				return 0444;
+			return 0;
+		case hwmon_curr_max_alarm:
+			if (st->r_sense_uohm)
+				return 0644;
+			return 0;
+		}
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static const struct hwmon_channel_info *adm1177_info[] = {
+	HWMON_CHANNEL_INFO(curr,
+			   HWMON_C_INPUT | HWMON_C_MAX_ALARM),
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops adm1177_hwmon_ops = {
+	.is_visible = adm1177_is_visible,
+	.read = adm1177_read,
+	.write = adm1177_write,
+};
+
+static const struct hwmon_chip_info adm1177_chip_info = {
+	.ops = &adm1177_hwmon_ops,
+	.info = adm1177_info,
+};
+
+static void adm1177_remove(void *data)
+{
+	struct adm1177_state *st = data;
+
+	regulator_disable(st->reg);
+}
+
+static int adm1177_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct adm1177_state *st;
+	u32 alert_threshold_ua;
+	int ret;
+
+	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	st->client = client;
+
+	st->reg = devm_regulator_get_optional(&client->dev, "vref");
+	if (IS_ERR(st->reg)) {
+		if (PTR_ERR(st->reg) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		st->reg = NULL;
+	} else {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			return ret;
+		ret = devm_add_action_or_reset(&client->dev, adm1177_remove,
+					       st);
+		if (ret)
+			return ret;
+	}
+
+	if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
+				     &st->r_sense_uohm))
+		st->r_sense_uohm = 0;
+	if (device_property_read_u32(dev, "adi,shutdown-threshold-microamp",
+				     &alert_threshold_ua)) {
+		if (st->r_sense_uohm)
+			/*
+			 * set maximum default value from datasheet based on
+			 * shunt-resistor
+			 */
+			alert_threshold_ua = div_u64(105840000000,
+						     st->r_sense_uohm);
+		else
+			alert_threshold_ua = 0;
+	}
+	st->vrange_high = device_property_read_bool(dev,
+						    "adi,vrange-high-enable");
+	if (alert_threshold_ua && st->r_sense_uohm)
+		adm1177_write_alert_thr(st, alert_threshold_ua);
+
+	ret = adm1177_write_cmd(st, ADM1177_CMD_V_CONT |
+				    ADM1177_CMD_I_CONT |
+				    (st->vrange_high ? 0 : ADM1177_CMD_VRANGE));
+	if (ret)
+		return ret;
+
+	hwmon_dev =
+		devm_hwmon_device_register_with_info(dev, client->name, st,
+						     &adm1177_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id adm1177_id[] = {
+	{"adm1177", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, adm1177_id);
+
+static const struct of_device_id adm1177_dt_ids[] = {
+	{ .compatible = "adi,adm1177" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, adm1177_dt_ids);
+
+static struct i2c_driver adm1177_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "adm1177",
+		.of_match_table = adm1177_dt_ids,
+	},
+	.probe = adm1177_probe,
+	.id_table = adm1177_id,
+};
+module_i2c_driver(adm1177_driver);
+
+MODULE_AUTHOR("Beniamin Bia <beniamin.bia@analog.com>");
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Analog Devices ADM1177 ADC driver");
+MODULE_LICENSE("GPL v2");