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Date: Wed, 26 Sep 2018 06:06:32 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Nicolin Chen <nicoleotsuka@...il.com>, jdelvare@...e.com,
corbet@....net
Cc: afd@...com, linux-hwmon@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH 2/2] hwmon: ina3221: Add enable sysfs nodes
Hi Nicolin,
On 09/25/2018 11:42 PM, Nicolin Chen wrote:
> 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.
>
One necessary high level change I don't see below: With this change,
we should no longer drop a channel entirely if it is disabled from
devicetree. All channels should be visible but report -ENODATA if
disabled. In other words, it should be possible for the 'enable' flag
to override settings in DT.
> Signed-off-by: Nicolin Chen <nicoleotsuka@...il.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)
s/is_enable/is_enabled/, maybe ?
> +{
> + 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;
The "> 0" is unnecessary. Conversion to bool is automatic. If you want to make
it explicit, please use
return !!(config & INA3221_CONFIG_CHx_EN(channel));
It should not be necessary to re-read the value from the chip all the time.
I would suggest to cache the value in the 'disabled' variable.
> +}
> +
> 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;
> +
Just use kstrtobool().
> + 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, ¤t_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,
>
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