linux-kernel - Re: [PATCH 02/14] Input: atmel_mxt_ts - switch from OF to generic device properties

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Date:   Wed, 14 Mar 2018 20:51:55 +0000
From:   Nick Dyer <nick@...anahar.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, Benson Leung <bleung@...omium.org>,
        Olof Johansson <olof@...om.net>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/14] Input: atmel_mxt_ts - switch from OF to generic
 device properties

On Mon, Mar 12, 2018 at 12:08:55PM -0700, Dmitry Torokhov wrote:
> Instead of using OF-specific APIs to fecth device properties, let's switch
> to generic device properties API. This will allow us to use device
> properties on legacy ChromeOS devices and get rid of platform data down
> the road.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

Acked-by: Nick Dyer <nick@...anahar.org>

> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c | 59 ++++++++++++------------
>  1 file changed, 30 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 1aabfae1297ba..072b78d3c6e00 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -29,6 +29,7 @@
>  #include <linux/of.h>
>  #include <linux/slab.h>
>  #include <linux/gpio/consumer.h>
> +#include <linux/property.h>
>  #include <asm/unaligned.h>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-ioctl.h>
> @@ -2920,47 +2921,52 @@ static void mxt_input_close(struct input_dev *dev)
>  	mxt_stop(data);
>  }
>  
> -#ifdef CONFIG_OF
> -static const struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
> +static const struct mxt_platform_data *
> +mxt_parse_device_properties(struct i2c_client *client)
>  {
> +	static const char keymap_property[] = "linux,gpio-keymap";
>  	struct mxt_platform_data *pdata;
> -	struct device_node *np = client->dev.of_node;
>  	u32 *keymap;
> -	int proplen, ret;
> -
> -	if (!np)
> -		return ERR_PTR(-ENOENT);
> +	int n_keys;
> +	int error;
>  
>  	pdata = devm_kzalloc(&client->dev, sizeof(*pdata), GFP_KERNEL);
>  	if (!pdata)
>  		return ERR_PTR(-ENOMEM);
>  
> -	if (of_find_property(np, "linux,gpio-keymap", &proplen)) {
> -		pdata->t19_num_keys = proplen / sizeof(u32);
> +	if (device_property_present(&client->dev, keymap_property)) {
> +		n_keys = device_property_read_u32_array(&client->dev,
> +							keymap_property,
> +							NULL, 0);
> +		if (n_keys <= 0) {
> +			error = n_keys < 0 ? n_keys : -EINVAL;
> +			dev_err(&client->dev,
> +				"invalid/malformed '%s' property: %d\n",
> +				keymap_property, error);
> +			return ERR_PTR(error);
> +		}
>  
> -		keymap = devm_kzalloc(&client->dev,
> -				pdata->t19_num_keys * sizeof(keymap[0]),
> -				GFP_KERNEL);
> +		keymap = devm_kmalloc_array(&client->dev, n_keys, sizeof(u32),
> +					    GFP_KERNEL);
>  		if (!keymap)
>  			return ERR_PTR(-ENOMEM);
>  
> -		ret = of_property_read_u32_array(np, "linux,gpio-keymap",
> -						 keymap, pdata->t19_num_keys);
> -		if (ret)
> -			dev_warn(&client->dev,
> -				 "Couldn't read linux,gpio-keymap: %d\n", ret);
> +		error = device_property_read_u32_array(&client->dev,
> +						       keymap_property,
> +						       keymap, n_keys);
> +		if (error) {
> +			dev_err(&client->dev,
> +				"failed to parse '%s' property: %d\n",
> +				keymap_property, error);
> +			return ERR_PTR(error);
> +		}
>  
>  		pdata->t19_keymap = keymap;
> +		pdata->t19_num_keys = n_keys;
>  	}
>  
>  	return pdata;
>  }
> -#else
> -static const struct mxt_platform_data *mxt_parse_dt(struct i2c_client *client)
> -{
> -	return ERR_PTR(-ENOENT);
> -}
> -#endif
>  
>  #ifdef CONFIG_ACPI
>  
> @@ -3094,16 +3100,11 @@ mxt_get_platform_data(struct i2c_client *client)
>  	if (pdata)
>  		return pdata;
>  
> -	pdata = mxt_parse_dt(client);
> -	if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT)
> -		return pdata;
> -
>  	pdata = mxt_parse_acpi(client);
>  	if (!IS_ERR(pdata) || PTR_ERR(pdata) != -ENOENT)
>  		return pdata;
>  
> -	dev_err(&client->dev, "No platform data specified\n");
> -	return ERR_PTR(-EINVAL);
> +	return mxt_parse_device_properties(client);
>  }
>  
>  static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
> -- 
> 2.16.2.660.g709887971b-goog
>