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

From: Nicolin Chen
Date: Wed Sep 26 2018 - 02:43:12 EST

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@xxxxxxxxx>
---
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