[PATCH 2/2] hwmon: ina3221: Add enable sysfs nodes

[Nicolin Chen <nicoleotsuka@gmail.com>]

The inX_enable interface allows user space to enable or disable
the corresponding channel. Meanwhile, according to hwmon ABI, a
disabled channel/sensor should return -ENODATA as a read result.

However, there're configurable nodes sharing the same __show()
functions. So this change also adds to check if the attribute is
read-only to make sure it's not reading a configuration but the
sensor data.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
 Documentation/hwmon/ina3221 |  1 +
 drivers/hwmon/ina3221.c     | 85 +++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/Documentation/hwmon/ina3221 b/Documentation/hwmon/ina3221
index 6be64b553cd0..1aa32366d8aa 100644
--- a/Documentation/hwmon/ina3221
+++ b/Documentation/hwmon/ina3221
@@ -23,6 +23,7 @@ Sysfs entries
 
 in[123]_input           Bus voltage(mV) channels
 in[123]_label           Voltage channel labels
+in[123]_enable          Voltage channel enable controls
 curr[123]_input         Current(mA) measurement channels
 shunt[123]_resistor     Shunt resistance(uOhm) channels
 curr[123]_crit          Critical alert current(mA) setting, activates the
diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index 5890a2da3bfe..1be2d062a19e 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -78,6 +78,9 @@ enum ina3221_channels {
 };
 
 static const unsigned int register_channel[] = {
+	[INA3221_BUS1] = INA3221_CHANNEL1,
+	[INA3221_BUS2] = INA3221_CHANNEL2,
+	[INA3221_BUS3] = INA3221_CHANNEL3,
 	[INA3221_SHUNT1] = INA3221_CHANNEL1,
 	[INA3221_SHUNT2] = INA3221_CHANNEL2,
 	[INA3221_SHUNT3] = INA3221_CHANNEL3,
@@ -113,6 +116,19 @@ struct ina3221_data {
 	struct ina3221_input inputs[INA3221_NUM_CHANNELS];
 };
 
+static inline bool ina3221_is_enable(struct ina3221_data *ina, int channel)
+{
+	unsigned int config;
+	int ret;
+
+	/* Return false to reject further read */
+	ret = regmap_read(ina->regmap, INA3221_CONFIG, &config);
+	if (ret)
+		return false;
+
+	return (config & INA3221_CONFIG_CHx_EN(channel)) > 0;
+}
+
 static ssize_t ina3221_show_label(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
@@ -124,6 +140,45 @@ static ssize_t ina3221_show_label(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%s\n", input->label);
 }
 
+static ssize_t ina3221_show_enable(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
+	struct ina3221_data *ina = dev_get_drvdata(dev);
+	unsigned int channel = sd_attr->index;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n",
+			ina3221_is_enable(ina, channel));
+}
+
+static ssize_t ina3221_set_enable(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
+	struct ina3221_data *ina = dev_get_drvdata(dev);
+	unsigned int channel = sd_attr->index;
+	unsigned int mask = INA3221_CONFIG_CHx_EN(channel);
+	unsigned int config;
+	int val, ret;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	/* inX_enable only accepts 1 for enabling or 0 for disabling */
+	if (val != 0 && val != 1)
+		return -EINVAL;
+
+	config = val ? mask : 0;
+
+	ret = regmap_update_bits(ina->regmap, INA3221_CONFIG, mask, config);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
 static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
 			      int *val)
 {
@@ -146,8 +201,13 @@ static ssize_t ina3221_show_bus_voltage(struct device *dev,
 	struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
 	struct ina3221_data *ina = dev_get_drvdata(dev);
 	unsigned int reg = sd_attr->index;
+	unsigned int channel = register_channel[reg];
 	int val, voltage_mv, ret;
 
+	/* No data for read-only attribute if channel is disabled */
+	if (!attr->store && !ina3221_is_enable(ina, channel))
+		return -ENODATA;
+
 	ret = ina3221_read_value(ina, reg, &val);
 	if (ret)
 		return ret;
@@ -164,8 +224,13 @@ static ssize_t ina3221_show_shunt_voltage(struct device *dev,
 	struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
 	struct ina3221_data *ina = dev_get_drvdata(dev);
 	unsigned int reg = sd_attr->index;
+	unsigned int channel = register_channel[reg];
 	int val, voltage_uv, ret;
 
+	/* No data for read-only attribute if channel is disabled */
+	if (!attr->store && !ina3221_is_enable(ina, channel))
+		return -ENODATA;
+
 	ret = ina3221_read_value(ina, reg, &val);
 	if (ret)
 		return ret;
@@ -201,8 +266,13 @@ static ssize_t ina3221_show_current(struct device *dev,
 	struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
 	struct ina3221_data *ina = dev_get_drvdata(dev);
 	unsigned int reg = sd_attr->index;
+	unsigned int channel = register_channel[reg];
 	int current_ma, ret;
 
+	/* No data for read-only attribute if channel is disabled */
+	if (!attr->store && !ina3221_is_enable(ina, channel))
+		return -ENODATA;
+
 	ret = __ina3221_show_current(ina, reg, &current_ma);
 	if (ret)
 		return ret;
@@ -318,6 +388,10 @@ static ssize_t ina3221_show_power(struct device *dev,
 	int val, current_ma, voltage_mv, ret;
 	s64 power_uw;
 
+	/* No data for read-only attribute if channel is disabled */
+	if (!attr->store && !ina3221_is_enable(ina, channel))
+		return -ENODATA;
+
 	/* Read bus voltage */
 	ret = ina3221_read_value(ina, reg_bus, &val);
 	if (ret)
@@ -377,6 +451,14 @@ static SENSOR_DEVICE_ATTR(in2_label, 0444,
 static SENSOR_DEVICE_ATTR(in3_label, 0444,
 		ina3221_show_label, NULL, INA3221_CHANNEL3);
 
+/* voltage channel enable */
+static SENSOR_DEVICE_ATTR(in1_enable, 0644,
+		ina3221_show_enable, ina3221_set_enable, INA3221_CHANNEL1);
+static SENSOR_DEVICE_ATTR(in2_enable, 0644,
+		ina3221_show_enable, ina3221_set_enable, INA3221_CHANNEL2);
+static SENSOR_DEVICE_ATTR(in3_enable, 0644,
+		ina3221_show_enable, ina3221_set_enable, INA3221_CHANNEL3);
+
 /* bus voltage */
 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO,
 		ina3221_show_bus_voltage, NULL, INA3221_BUS1);
@@ -460,6 +542,7 @@ static SENSOR_DEVICE_ATTR(power3_crit, 0644,
 static struct attribute *ina3221_attrs[] = {
 	/* channel 1 -- make sure label at first */
 	&sensor_dev_attr_in1_label.dev_attr.attr,
+	&sensor_dev_attr_in1_enable.dev_attr.attr,
 	&sensor_dev_attr_in1_input.dev_attr.attr,
 	&sensor_dev_attr_curr1_input.dev_attr.attr,
 	&sensor_dev_attr_shunt1_resistor.dev_attr.attr,
@@ -473,6 +556,7 @@ static struct attribute *ina3221_attrs[] = {
 
 	/* channel 2 -- make sure label at first */
 	&sensor_dev_attr_in2_label.dev_attr.attr,
+	&sensor_dev_attr_in2_enable.dev_attr.attr,
 	&sensor_dev_attr_in2_input.dev_attr.attr,
 	&sensor_dev_attr_curr2_input.dev_attr.attr,
 	&sensor_dev_attr_shunt2_resistor.dev_attr.attr,
@@ -486,6 +570,7 @@ static struct attribute *ina3221_attrs[] = {
 
 	/* channel 3 -- make sure label at first */
 	&sensor_dev_attr_in3_label.dev_attr.attr,
+	&sensor_dev_attr_in3_enable.dev_attr.attr,
 	&sensor_dev_attr_in3_input.dev_attr.attr,
 	&sensor_dev_attr_curr3_input.dev_attr.attr,
 	&sensor_dev_attr_shunt3_resistor.dev_attr.attr,
-- 
2.17.1