linux-kernel - Re: [PATCH 5/6] wl1251: Parse and use MAC address from supplied NVS data

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Message-ID: <87poj9ndj9.fsf@codeaurora.org>
Date:   Fri, 27 Jan 2017 09:54:34 +0200
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Pali Rohár <pali.rohar@...il.com>
Cc:     Ming Lei <ming.lei@...onical.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        David Gnedt <david.gnedt@...izone.at>,
        Michal Kazior <michal.kazior@...to.com>,
        Daniel Wagner <wagi@...om.org>,
        Tony Lindgren <tony@...mide.com>,
        Sebastian Reichel <sre@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Grazvydas Ignotas <notasas@...il.com>,
        linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH 5/6] wl1251: Parse and use MAC address from supplied NVS data

Pali Rohár <pali.rohar@...il.com> writes:

> This patch implements parsing MAC address from NVS data which are sent to
> wl1251 chip. Calibration NVS data could contain valid MAC address and it
> will be used instead randomly generated.
>
> This patch also move code for requesting NVS data from userspace to driver
> initialization code to make sure that NVS data will be there at time when
> permanent MAC address is needed.
>
> Calibration NVS data for wl1251 are model specific. Every one device with
> wl1251 chip should have been calibrated in factory and needs to provide own
> calibration data.
>
> Default example wl1251-nvs.bin data found in linux-firmware repository and
> contains MAC address 00:00:20:07:03:09. So this MAC address is marked as
> invalid as it is not real device specific address, just example one.
>
> Format of calibration NVS data can be found at:
> http://notaz.gp2x.de/misc/pnd/wl1251/nvs_map.txt
>
> Signed-off-by: Pali Rohár <pali.rohar@...il.com>

[...]

> +static int wl1251_read_nvs_mac(struct wl1251 *wl)
> +{
> +	u8 mac[ETH_ALEN];
> +	int i;
> +
> +	if (wl->nvs_len < 0x24)
> +		return -ENODATA;
> +
> +	/* length is 2 and data address is 0x546c (mask is 0xfffe) */
> +	if (wl->nvs[0x19] != 2 || wl->nvs[0x1a] != 0x6d || wl->nvs[0x1b] != 0x54)
> +		return -EINVAL;
> +
> +	/* MAC is stored in reverse order */
> +	for (i = 0; i < ETH_ALEN; i++)
> +		mac[i] = wl->nvs[0x1c + ETH_ALEN - i - 1];

No magic numbers, please. Replace all nvs offsets with proper defines to
make the code more readable.

-- 
Kalle Valo