[PATCH v2] input: touchscreen: silead: Add regulator support

[Hans de Goede]

HI,

On 16-11-16 18:51, Dmitry Torokhov wrote:
> On Wed, Nov 16, 2016 at 12:55:07PM +0100, Hans de Goede wrote:
>> On some tablets the touchscreen controller is powered by separate
>> regulators, add support for this.
>>
>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>> Acked-by: Rob Herring <robh at kernel.org>
>> ---
>> Changes in v2:
>> -Use devm_regulator_bulk_get() and friends
>> -Use devm_add_action_or_reset() to disable the regulator
>> ---
>>  .../bindings/input/touchscreen/silead_gsl1680.txt  |  2 ++
>>  drivers/input/touchscreen/silead.c                 | 29 ++++++++++++++++++++++
>>  2 files changed, 31 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt b/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt
>> index e844c3f..b726823 100644
>> --- a/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt
>> +++ b/Documentation/devicetree/bindings/input/touchscreen/silead_gsl1680.txt
>> @@ -22,6 +22,8 @@ Optional properties:
>>  - touchscreen-inverted-y  : See touchscreen.txt
>>  - touchscreen-swapped-x-y : See touchscreen.txt
>>  - silead,max-fingers	  : maximum number of fingers the touchscreen can detect
>> +- vddio-supply		  : regulator phandle for controller VDDIO
>> +- avdd-supply		  : regulator phandle for controller AVDD
>>
>>  Example:
>>
>> diff --git a/drivers/input/touchscreen/silead.c b/drivers/input/touchscreen/silead.c
>> index f502c84..404830a 100644
>> --- a/drivers/input/touchscreen/silead.c
>> +++ b/drivers/input/touchscreen/silead.c
>> @@ -29,6 +29,7 @@
>>  #include <linux/input/touchscreen.h>
>>  #include <linux/pm.h>
>>  #include <linux/irq.h>
>> +#include <linux/regulator/consumer.h>
>>
>>  #include <asm/unaligned.h>
>>
>> @@ -73,6 +74,7 @@ struct silead_ts_data {
>>  	struct i2c_client *client;
>>  	struct gpio_desc *gpio_power;
>>  	struct input_dev *input;
>> +	struct regulator_bulk_data regulators[2];
>>  	char fw_name[64];
>>  	struct touchscreen_properties prop;
>>  	u32 max_fingers;
>> @@ -433,6 +435,13 @@ static int silead_ts_set_default_fw_name(struct silead_ts_data *data,
>>  }
>>  #endif
>>
>> +static void silead_disable_regulator(void *arg)
>> +{
>> +	struct silead_ts_data *data = arg;
>> +
>> +	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
>> +}
>> +
>>  static int silead_ts_probe(struct i2c_client *client,
>>  			   const struct i2c_device_id *id)
>>  {
>> @@ -465,6 +474,26 @@ static int silead_ts_probe(struct i2c_client *client,
>>  	if (client->irq <= 0)
>>  		return -ENODEV;
>>
>> +	data->regulators[0].supply = "vddio";
>> +	data->regulators[1].supply = "avdd";
>> +	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(data->regulators),
>> +					data->regulators);
>> +	if (error)
>> +		return error;
>> +
>> +	/*
>> +	 * Enable regulators at probe and disable them at remove, we need
>> +	 * to keep the chip powered otherwise it forgets its firmware.
>> +	 */
>
> Hmm, this burns power though. Why can't we reload firmware on resume (it
> should be already cached)?

We already put the device in low-power mode using the power pin. Of the
20 or so different tablets I've with this touchscreen controller only
2 actually have a separate regulator for the controller, so I do not
believe that powering down the regulator will be a big win, otherwise
all tablets would have had this.

 > Does it take too long?

It is a couple of kB written one 32-bit word at a time over i2c, so
it's not fast.

Regards,

Hans


>
> Thanks.
>
>> +	error = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
>> +				      data->regulators);
>> +	if (error)
>> +		return error;
>> +
>> +	error = devm_add_action_or_reset(dev, silead_disable_regulator, data);
>> +	if (error)
>> +		return error;
>> +
>>  	/* Power GPIO pin */
>>  	data->gpio_power = devm_gpiod_get_optional(dev, "power", GPIOD_OUT_LOW);
>>  	if (IS_ERR(data->gpio_power)) {
>> --
>> 2.9.3
>>
>