linux-kernel - Re: [PATCH v2 2/2] hwmon: (ina3221) Implement ti,single-shot DT property

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Message-ID: <20190107193555.GA13547@roeck-us.net>
Date:   Mon, 7 Jan 2019 11:35:55 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Nicolin Chen <nicoleotsuka@...il.com>
Cc:     jdelvare@...e.com, robh+dt@...nel.org, mark.rutland@....com,
        linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] hwmon: (ina3221) Implement ti,single-shot DT
 property

On Fri, Jan 04, 2019 at 07:06:36PM -0800, 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>
> ---
> Changelog
> v1->v2:
>  * Replaced the useless mode defines with a boolean variable.
> 
>  drivers/hwmon/ina3221.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> index e90ccac8bebb..4258a6ebe195 100644
> --- a/drivers/hwmon/ina3221.c
> +++ b/drivers/hwmon/ina3221.c
> @@ -111,6 +111,7 @@ 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
> + * @single_shot: running in single-shot operating mode
>   */
>  struct ina3221_data {
>  	struct device *pm_dev;
> @@ -119,6 +120,8 @@ struct ina3221_data {
>  	struct ina3221_input inputs[INA3221_NUM_CHANNELS];
>  	struct mutex lock;
>  	u32 reg_config;
> +
> +	bool single_shot;
>  };
>  
>  static inline bool ina3221_is_enabled(struct ina3221_data *ina, int channel)
> @@ -188,6 +191,11 @@ 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->single_shot)
> +			regmap_write(ina->regmap, INA3221_CONFIG,
> +				     ina->reg_config);
> +
>  		ret = ina3221_wait_for_data(ina);
>  		if (ret)
>  			return ret;
> @@ -232,6 +240,11 @@ 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->single_shot)
> +			regmap_write(ina->regmap, INA3221_CONFIG,
> +				     ina->reg_config);
> +
>  		ret = ina3221_wait_for_data(ina);
>  		if (ret)
>  			return ret;
> @@ -617,6 +630,9 @@ 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->single_shot = true;
> +
	ina->single_shot = of_property_read_bool(np, "ti,single-shot");

No need to resend right now; let's wait for feedback from Rob.

Guenter

>  	for_each_child_of_node(np, child) {
>  		ret = ina3221_probe_child_from_dt(dev, child, ina);
>  		if (ret)
> @@ -666,6 +682,10 @@ 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->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)