linux-kernel - Re: [PATCH v2 4/5] Input: atkbd: Receive and use physcode->keycode mapping from FW

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Date:   Thu, 26 Mar 2020 14:20:25 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Rajat Jain <rajatja@...gle.com>
Cc:     dtor@...gle.com, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Enrico Weigelt <info@...ux.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Allison Randal <allison@...utok.net>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, furquan@...gle.com,
        dlaurie@...gle.com, bleung@...gle.com, zentaro@...gle.com,
        dbehr@...gle.com, rajatxjain@...il.com
Subject: Re: [PATCH v2 4/5] Input: atkbd: Receive and use physcode->keycode
 mapping from FW

Hi Rajat,

On Tue, Mar 24, 2020 at 05:35:17AM -0700, Rajat Jain wrote:
> Allow the firmware to specify the mapping between the physical
> code and the linux keycode. This takes the form of a "keymap"
> property which is an array of u32 values, each value specifying
> mapping for a key.
> 
> Signed-off-by: Rajat Jain <rajatja@...gle.com>
> ---
> v2: Remove the Change-Id from the commit log
> 
>  drivers/input/keyboard/atkbd.c | 39 ++++++++++++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
> index 7623eebef2593..c8017a5707581 100644
> --- a/drivers/input/keyboard/atkbd.c
> +++ b/drivers/input/keyboard/atkbd.c
> @@ -66,6 +66,9 @@ MODULE_PARM_DESC(terminal, "Enable break codes on an IBM Terminal keyboard conne
>  
>  #define MAX_FUNCTION_ROW_KEYS	24
>  
> +#define PHYSCODE(keymap)	((keymap >> 16) & 0xFFFF)
> +#define KEYCODE(keymap)		(keymap & 0xFFFF)
> +
>  /*
>   * Scancode to keycode tables. These are just the default setting, and
>   * are loadable via a userland utility.
> @@ -236,6 +239,9 @@ struct atkbd {
>  
>  	u16 function_row_physmap[MAX_FUNCTION_ROW_KEYS];
>  	int num_function_row_keys;
> +
> +	unsigned short fw_keymap[ATKBD_KEYMAP_SIZE];
> +	bool use_fw_keymap;

Why do we need to keep firmware-provided keymap in atkbd instance? It is
not going anywhere and can be accessed via device_property_* API
whenever we decide to refresh the keymap.

>  };
>  
>  /*
> @@ -1045,7 +1051,10 @@ static void atkbd_set_keycode_table(struct atkbd *atkbd)
>  	memset(atkbd->keycode, 0, sizeof(atkbd->keycode));
>  	bitmap_zero(atkbd->force_release_mask, ATKBD_KEYMAP_SIZE);
>  
> -	if (atkbd->translated) {
> +	if (atkbd->use_fw_keymap) {
> +		memcpy(atkbd->keycode, atkbd->fw_keymap,
> +		       sizeof(atkbd->keycode));
> +	} else if (atkbd->translated) {
>  		for (i = 0; i < 128; i++) {
>  			scancode = atkbd_unxlate_table[i];
>  			atkbd->keycode[i] = atkbd_set2_keycode[scancode];
> @@ -1163,7 +1172,9 @@ static void atkbd_parse_fwnode_data(struct serio *serio)
>  {
>  	struct atkbd *atkbd = serio_get_drvdata(serio);
>  	struct device *dev = &serio->dev;
> -	int n;
> +	int i, n;
> +	u32 *ptr;
> +	u16 physcode, keycode;
>  
>  	if (!dev_fwnode(dev))
>  		return;
> @@ -1176,6 +1187,30 @@ static void atkbd_parse_fwnode_data(struct serio *serio)
>  		atkbd->num_function_row_keys = n;
>  		dev_info(dev, "FW reported %d function-row key locations\n", n);
>  	}
> +
> +	/* Parse "keymap" property */
> +	n = device_property_count_u32(dev, "keymap");
> +	if (n > 0 && n <= ATKBD_KEYMAP_SIZE) {
> +
> +		ptr = kcalloc(n, sizeof(u32), GFP_KERNEL);
> +		if (!ptr)
> +			return;
> +
> +		if (device_property_read_u32_array(dev, "keymap", ptr, n)) {
> +			dev_err(dev, "problem parsing FW keymap property\n");
> +			kfree(ptr);
> +			return;
> +		}
> +
> +		for (i = 0; i < n; i++) {
> +			physcode = PHYSCODE(ptr[i]);
> +			keycode = KEYCODE(ptr[i]);
> +			atkbd->fw_keymap[physcode] = keycode;
> +		}
> +		dev_info(dev, "Using FW keymap (%d keys)\n", n);

This should be dev_dbg().

> +		atkbd->use_fw_keymap = true;
> +		kfree(ptr);
> +	}
>  }
>  
>  /*
> -- 
> 2.25.1.696.g5e7596f4ac-goog
> 

Thanks.

-- 
Dmitry