linux-kernel - Re: [PATCH v4 02/11] leds: aw200xx: support HWEN hardware control

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Message-ID: <20231123155744.GE1354538@google.com>
Date:   Thu, 23 Nov 2023 15:57:44 +0000
From:   Lee Jones <lee@...nel.org>
To:     Dmitry Rokosov <ddrokosov@...utedevices.com>
Cc:     pavel@....cz, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        andy.shevchenko@...il.com, kernel@...rdevices.ru,
        rockosov@...il.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH v4 02/11] leds: aw200xx: support HWEN hardware control

On Tue, 21 Nov 2023, Dmitry Rokosov wrote:

> HWEN is hardware control, which is used for enable/disable aw200xx chip.
> It's high active, internally pulled down to GND.
> 
> After HWEN pin set high the chip begins to load the OTP information,
> which takes 200us to complete. About 200us wait time is needed for
> internal oscillator startup and display SRAM initialization. After
> display SRAM initialization, the registers in page 1 to page 5 can be
> configured via i2c interface.
> 
> Signed-off-by: Dmitry Rokosov <ddrokosov@...utedevices.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> ---
>  drivers/leds/leds-aw200xx.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/drivers/leds/leds-aw200xx.c b/drivers/leds/leds-aw200xx.c
> index 842a22087b16..7762b3a132ac 100644
> --- a/drivers/leds/leds-aw200xx.c
> +++ b/drivers/leds/leds-aw200xx.c
> @@ -10,6 +10,7 @@
>  #include <linux/bitfield.h>
>  #include <linux/bits.h>
>  #include <linux/container_of.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
>  #include <linux/leds.h>
>  #include <linux/mod_devicetable.h>
> @@ -116,6 +117,7 @@ struct aw200xx {
>  	struct mutex mutex;
>  	u32 num_leds;
>  	u32 display_rows;
> +	struct gpio_desc *hwen;
>  	struct aw200xx_led leds[] __counted_by(num_leds);
>  };
>  
> @@ -358,6 +360,25 @@ static int aw200xx_chip_check(const struct aw200xx *const chip)
>  	return 0;
>  }
>  
> +static void aw200xx_enable(const struct aw200xx *const chip)
> +{
> +	gpiod_set_value_cansleep(chip->hwen, 1);
> +
> +	/*
> +	 * After HWEN pin set high the chip begins to load the OTP information,
> +	 * which takes 200us to complete. About 200us wait time is needed for
> +	 * internal oscillator startup and display SRAM initialization. After
> +	 * display SRAM initialization, the registers in page1 to page5 can be
> +	 * configured via i2c interface.
> +	 */
> +	fsleep(400);
> +}
> +
> +static void aw200xx_disable(const struct aw200xx *const chip)
> +{
> +	return gpiod_set_value_cansleep(chip->hwen, 0);
> +}
> +
>  static int aw200xx_probe_fw(struct device *dev, struct aw200xx *chip)
>  {
>  	struct fwnode_handle *child;
> @@ -517,6 +538,14 @@ static int aw200xx_probe(struct i2c_client *client)
>  	if (IS_ERR(chip->regmap))
>  		return PTR_ERR(chip->regmap);
>  
> +	chip->hwen = devm_gpiod_get_optional(&client->dev, "enable",
> +					     GPIOD_OUT_HIGH);
> +	if (IS_ERR(chip->hwen))
> +		return dev_err_probe(&client->dev, PTR_ERR(chip->hwen),
> +				     "Cannot get enable gpio");

Nit: "GPIO"

> +
> +	aw200xx_enable(chip);
> +
>  	ret = aw200xx_chip_check(chip);
>  	if (ret)
>  		return ret;
> @@ -537,6 +566,9 @@ static int aw200xx_probe(struct i2c_client *client)
>  	ret = aw200xx_chip_init(chip);
>  
>  out_unlock:
> +	if (ret)
> +		aw200xx_disable(chip);
> +
>  	mutex_unlock(&chip->mutex);
>  	return ret;
>  }
> @@ -546,6 +578,7 @@ static void aw200xx_remove(struct i2c_client *client)
>  	struct aw200xx *chip = i2c_get_clientdata(client);
>  
>  	aw200xx_chip_reset(chip);
> +	aw200xx_disable(chip);
>  	mutex_destroy(&chip->mutex);
>  }
>  
> -- 
> 2.36.0
> 

-- 
Lee Jones [李琼斯]