linux-kernel - Re: [PATCH 2/2] hwmon: (ina3221) Implement ti,single-shot DT property

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Date:   Fri, 4 Jan 2019 18:37:55 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Nicolin Chen <nicoleotsuka@...il.com>, jdelvare@...e.com,
        robh+dt@...nel.org, mark.rutland@....com
Cc:     linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] hwmon: (ina3221) Implement ti,single-shot DT property

On 1/4/19 4:49 PM, Nicolin Chen wrote:
> By default, ina3221, as a hardware monitor, continuously measures
> the inputs and generates corresponding data. However, for battery
> powered devices, this mode might be power consuming.
> 
> The DT binding doc is updated with a new boolean type property to
> allow changing the default operating mode from consuming mode to
> single-shot mode, which will measure input on demand and then shut
> down to save power.
> 
> So this patch implements the DT property accordingly.
> 
> Signed-off-by: Nicolin Chen <nicoleotsuka@...il.com>
> ---
>   drivers/hwmon/ina3221.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> index e90ccac8bebb..152735659e19 100644
> --- a/drivers/hwmon/ina3221.c
> +++ b/drivers/hwmon/ina3221.c
> @@ -91,6 +91,12 @@ enum ina3221_channels {
>   	INA3221_NUM_CHANNELS
>   };
>   
> +enum ina3221_modes {
> +	INA3221_MODE_SINGLE_SHOT,
> +	INA3221_MODE_CONTINUOUS,
> +	INA3221_NUM_MODES,

Is NUM_MODES used anywhere ? Please drop unless there is a reason to keep it.

Guenter

> +};
> +
>   /**
>    * struct ina3221_input - channel input source specific information
>    * @label: label of channel input source
> @@ -111,6 +117,7 @@ struct ina3221_input {
>    * @inputs: Array of channel input source specific structures
>    * @lock: mutex lock to serialize sysfs attribute accesses
>    * @reg_config: Register value of INA3221_CONFIG
> + * @mode: Operating mode -- continuous or single-shot
>    */
>   struct ina3221_data {
>   	struct device *pm_dev;
> @@ -119,6 +126,7 @@ struct ina3221_data {
>   	struct ina3221_input inputs[INA3221_NUM_CHANNELS];
>   	struct mutex lock;
>   	u32 reg_config;
> +	enum ina3221_modes mode;
>   };
>   
>   static inline bool ina3221_is_enabled(struct ina3221_data *ina, int channel)
> @@ -188,6 +196,11 @@ static int ina3221_read_in(struct device *dev, u32 attr, int channel, long *val)
>   		if (!ina3221_is_enabled(ina, channel))
>   			return -ENODATA;
>   
> +		/* Write CONFIG register to trigger a single-shot measurement */
> +		if (ina->mode == INA3221_MODE_SINGLE_SHOT)
> +			regmap_write(ina->regmap, INA3221_CONFIG,
> +				     ina->reg_config);
> +
>   		ret = ina3221_wait_for_data(ina);
>   		if (ret)
>   			return ret;
> @@ -232,6 +245,11 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
>   		if (!ina3221_is_enabled(ina, channel))
>   			return -ENODATA;
>   
> +		/* Write CONFIG register to trigger a single-shot measurement */
> +		if (ina->mode == INA3221_MODE_SINGLE_SHOT)
> +			regmap_write(ina->regmap, INA3221_CONFIG,
> +				     ina->reg_config);
> +
>   		ret = ina3221_wait_for_data(ina);
>   		if (ret)
>   			return ret;
> @@ -617,6 +635,9 @@ static int ina3221_probe_from_dt(struct device *dev, struct ina3221_data *ina)
>   	if (!np)
>   		return 0;
>   
> +	if (of_property_read_bool(np, "ti,single-shot"))
> +		ina->mode = INA3221_MODE_SINGLE_SHOT;
> +
>   	for_each_child_of_node(np, child) {
>   		ret = ina3221_probe_child_from_dt(dev, child, ina);
>   		if (ret)
> @@ -654,6 +675,9 @@ static int ina3221_probe(struct i2c_client *client,
>   		}
>   	}
>   
> +	/* Hardware default uses the continuous mode */
> +	ina->mode = INA3221_MODE_CONTINUOUS;
> +
>   	for (i = 0; i < INA3221_NUM_CHANNELS; i++)
>   		ina->inputs[i].shunt_resistor = INA3221_RSHUNT_DEFAULT;
>   
> @@ -666,6 +690,10 @@ static int ina3221_probe(struct i2c_client *client,
>   	/* The driver will be reset, so use reset value */
>   	ina->reg_config = INA3221_CONFIG_DEFAULT;
>   
> +	/* Clear continuous bit to use single-shot mode */
> +	if (ina->mode == INA3221_MODE_SINGLE_SHOT)
> +		ina->reg_config &= ~INA3221_CONFIG_MODE_CONTINUOUS;
> +
>   	/* Disable channels if their inputs are disconnected */
>   	for (i = 0; i < INA3221_NUM_CHANNELS; i++) {
>   		if (ina->inputs[i].disconnected)
>