linux-kernel - Re: [PATCH v2] adp5588-keys: Support for dedicated gpio operation

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Date: Fri, 28 Jun 2024 15:15:57 +0200
From: Nuno Sá <noname.nuno@...il.com>
To: "Agarwal, Utsav" <Utsav.Agarwal@...log.com>, "Hennerich, Michael"
	 <Michael.Hennerich@...log.com>, "dmitry.torokhov@...il.com"
	 <dmitry.torokhov@...il.com>, "linux-input@...r.kernel.org"
	 <linux-input@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	 <linux-kernel@...r.kernel.org>
Cc: "Artamonovs, Arturs" <Arturs.Artamonovs@...log.com>, "Bimpikas,
 Vasileios" <Vasileios.Bimpikas@...log.com>, "Gaskell, Oliver"
 <Oliver.Gaskell@...log.com>
Subject: Re: [PATCH v2] adp5588-keys: Support for dedicated gpio operation

Hi Utsav,

On Fri, 2024-06-28 at 12:57 +0000, Agarwal, Utsav wrote:
> From: Utsav Agarwal <utsav.agarwal@...log.com>
> 
> Current state of the driver for the ADP5588/87 only allows partial
> I/O to be used as GPIO. This support was previously present as a
> separate gpio driver, which was dropped with the commit
> 5ddc896088b0 ("gpio: gpio-adp5588: drop the driver") since the
> functionality was deemed to have been merged with adp5588-keys.
> 
> To restore this, keypad specific checks in the probe
> function are relaxed if the following conditions are met:
> 	1) "gpio-only" property has been specified for the node
> 	2) No keypad rows/columns are specified
> 
> The "gpio-only" property is introduced to simplify usage since it
> serves as a clear indication of the user's intention as opposed to being
> inferred from the number of rows and columns specified. This 
> also adds simplicity for the accompanying dt binding update as well
> as interpretation of the same. 
> 
> In such a case, additional checks are also introduced to make sure 
> that keypad and pure GPIO operation are mutually exclusive by 
> checking for keypad specific properties (keypad,num-rows and 
> keypad,num-columns).
> 
> Signed-off-by: Utsav Agarwal <utsav.agarwal@...log.com>
> ---
>  drivers/input/keyboard/adp5588-keys.c | 33 +++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/drivers/input/keyboard/adp5588-keys.c
> b/drivers/input/keyboard/adp5588-keys.c
> index 1b0279393df4..6bfe748797df 100644
> --- a/drivers/input/keyboard/adp5588-keys.c
> +++ b/drivers/input/keyboard/adp5588-keys.c
> @@ -188,6 +188,7 @@ struct adp5588_kpad {
>  	u32 cols;
>  	u32 unlock_keys[2];
>  	int nkeys_unlock;
> +	bool gpio_only;
>  	unsigned short keycode[ADP5588_KEYMAPSIZE];
>  	unsigned char gpiomap[ADP5588_MAXGPIO];
>  	struct gpio_chip gc;
> @@ -647,6 +648,25 @@ static int adp5588_fw_parse(struct adp5588_kpad *kpad)
>  	struct i2c_client *client = kpad->client;
>  	int ret, i;
>  
> +	/*
> +	 * Check if the device is to be operated purely in GPIO mode. If
> +	 * so, confirm that no keypad rows or columns have been specified,
> since
> +	 * all GPINS should be configured as GPIO.
> +	 */
> +	if (kpad->gpio_only) {
> +		ret = device_property_present(&client->dev,
> +				"keypad,num-rows");

Should align with open parenthesis...

> +		if (ret)
> +			return -EINVAL;
> +

dev_err_probe() with a message should be helpful...

> +		ret = device_property_present(&client->dev,
> +				"keypad,num-columns");
> +		if (ret)
> +			return -EINVAL;

Alternatively, you could just:

if (kpad->gpio_only)
	return 0;

And ignore the other properties...

> +
> +		return 0;
> +	}
> +
>  	ret = matrix_keypad_parse_properties(&client->dev, &kpad->rows,
>  					     &kpad->cols);
>  	if (ret)
> @@ -739,6 +759,7 @@ static int adp5588_probe(struct i2c_client *client)
>  	kpad->client = client;
>  	kpad->input = input;
>  
> +	kpad->gpio_only = device_property_present(&client->dev, "gpio-only");

Since the above is also FW properties it could go inside adp5588_fw_parse().
It's also missing the bindings patch.

>  	error = adp5588_fw_parse(kpad);
>  	if (error)
>  		return error;
> @@ -790,6 +811,11 @@ static int adp5588_probe(struct i2c_client *client)
>  	if (error)
>  		return error;
>  
> +	if (!client->irq && kpad->gpio_only) {
> +		dev_info(&client->dev, "Rev.%d, started as GPIO only\n",
> revid);
> +		return 0;
> +	}
> +

Note that in case there are no IRQ, you should not make the gpiochip an irqchip
capable:

https://elixir.bootlin.com/linux/v6.10-rc5/source/drivers/input/keyboard/adp5588-keys.c#L449


- Nuno Sá