linux-kernel - Re: [PATCH v4 5/5] Input: msg2638 - Add support for msg2138 key events

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Message-ID: <Y3LonDibllKkTmPs@google.com>
Date:   Mon, 14 Nov 2022 17:17:16 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Vincent Knecht <vincent.knecht@...loo.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, w.david0@...tonmail.com,
        stephan@...hold.net, phone-devel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH v4 5/5] Input: msg2638 - Add support for msg2138 key
 events

On Thu, Nov 10, 2022 at 06:19:48PM +0100, Vincent Knecht wrote:
> Some devices with msg2138 have back/menu/home keys.
> Add support for them.
> 
> Signed-off-by: Vincent Knecht <vincent.knecht@...loo.org>
> ---
>  drivers/input/touchscreen/msg2638.c | 53 +++++++++++++++++++++++++----
>  1 file changed, 47 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/msg2638.c b/drivers/input/touchscreen/msg2638.c
> index 73e1b4d550fb..36069b30ab9b 100644
> --- a/drivers/input/touchscreen/msg2638.c
> +++ b/drivers/input/touchscreen/msg2638.c
> @@ -29,6 +29,8 @@
>  #define MSG2138_MAX_FINGERS		2
>  #define MSG2638_MAX_FINGERS		5
>  
> +#define MAX_BUTTONS			4
> +
>  #define CHIP_ON_DELAY_MS		15
>  #define FIRMWARE_ON_DELAY_MS		50
>  #define RESET_DELAY_MIN_US		10000
> @@ -72,6 +74,8 @@ struct msg2638_ts_data {
>  	struct regulator_bulk_data supplies[2];
>  	struct gpio_desc *reset_gpiod;
>  	int max_fingers;
> +	u32 keycodes[MAX_BUTTONS];
> +	int num_keycodes;
>  };
>  
>  static u8 msg2638_checksum(u8 *data, u32 length)
> @@ -85,6 +89,19 @@ static u8 msg2638_checksum(u8 *data, u32 length)
>  	return (u8)((-sum) & 0xFF);
>  }
>  
> +static void msg2138_report_keys(struct msg2638_ts_data *msg2638, u8 keys)
> +{
> +	int i;
> +
> +	/* keys can be 0x00 or 0xff when all keys have been released */
> +	if (keys == 0xff)
> +		keys = 0;
> +
> +	for (i = 0; i < msg2638->num_keycodes; ++i)
> +		input_report_key(msg2638->input_dev, msg2638->keycodes[i],
> +				 !!(keys & BIT(i)));

No need to do double-negation here, input_report_key() does it already.

> +}
> +
>  static irqreturn_t msg2138_ts_irq_handler(int irq, void *msg2638_handler)
>  {
>  	struct msg2638_ts_data *msg2638 = msg2638_handler;
> @@ -121,9 +138,12 @@ static irqreturn_t msg2138_ts_irq_handler(int irq, void *msg2638_handler)
>  	p0 = &touch_event.pkt[0];
>  	p1 = &touch_event.pkt[1];
>  
> -	/* Ignore non-pressed finger data */
> -	if (p0->xy_hi == 0xFF && p0->x_low == 0xFF && p0->y_low == 0xFF)
> +	/* Ignore non-pressed finger data, but check for key code */
> +	if (p0->xy_hi == 0xFF && p0->x_low == 0xFF && p0->y_low == 0xFF) {
> +		if (p1->xy_hi == 0xFF && p1->y_low == 0xFF)
> +			msg2138_report_keys(msg2638, p1->x_low);
>  		goto report;
> +	}
>  
>  	x = (((p0->xy_hi & 0xF0) << 4) | p0->x_low);
>  	y = (((p0->xy_hi & 0x0F) << 8) | p0->y_low);
> @@ -283,6 +303,7 @@ static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
>  	struct device *dev = &msg2638->client->dev;
>  	struct input_dev *input_dev;
>  	int error;
> +	int i;
>  
>  	input_dev = devm_input_allocate_device(dev);
>  	if (!input_dev) {
> @@ -299,6 +320,14 @@ static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
>  	input_dev->open = msg2638_input_open;
>  	input_dev->close = msg2638_input_close;
>  
> +	if (msg2638->num_keycodes) {
> +		input_dev->keycode = msg2638->keycodes;
> +		input_dev->keycodemax = msg2638->num_keycodes;
> +		input_dev->keycodesize = sizeof(msg2638->keycodes[0]);
> +		for (i = 0; i < msg2638->num_keycodes; i++)
> +			input_set_capability(input_dev, EV_KEY, msg2638->keycodes[i]);
> +	}
> +
>  	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
>  	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
>  
> @@ -367,10 +396,16 @@ static int msg2638_ts_probe(struct i2c_client *client)
>  		return error;
>  	}
>  
> -	error = msg2638_init_input_dev(msg2638);
> -	if (error) {
> -		dev_err(dev, "Failed to initialize input device: %d\n", error);
> -		return error;
> +	msg2638->num_keycodes =
> +		of_property_read_variable_u32_array(dev->of_node, "linux,keycodes",
> +						    msg2638->keycodes, 0,
> +						    ARRAY_SIZE(msg2638->keycodes));

Please do not use OF-specific API, use generic device property API (yes,
you will need 2 calls, one to get the count, and another to actually
fill the array).

Thanks.

-- 
Dmitry