[PATCH] wdog: imx-wd: distinguish for WICR/WMCR support

[Sascha Hauer]

On Sat, Jul 02, 2016 at 04:50:02PM +0200, Alexander Kurz wrote:
> The IMX watchdog driver currently distinguishes two variants: imx1-wdt
> using a 32-bit register interface and imx21-wdt with a 16-bit register
> interface.
> Further distinguishment is required: the i.MX21, i.MX27 and i.MX31 SOC
> do provide a three register interface (WCR, WSR, WRSR) while later SOC
> starting with i.MX25 provide two additional registers (WICR and WMCR).
> The five-register interface is also used on i.MX35, and Cortex-A based
> i.MX SOC.
> 
> With commit 4cc0a3d9c547 ("wdog: imx-wd: Disable watchdog powerdown counter")
> one of the extended registers (WMCR) got used first.
> 
> Make imx-wd distinguish between the three and five register Watchdog Timers
> and introduce the five register support as imx25-wdt.
> 
> Note on DTS: keep the i.MX related DTS in sync with linux and make the
> existing programming model fsl,imx21-wdt behave like fsl,imx25-wdt for
> the mean time until this is addressed upstream in linux.
> 
> fixes: 4cc0a3d9c547 ("wdog: imx-wd: Disable watchdog powerdown counter")

So beginning with 4cc0a3d9c547 i.MX21, i.MX27 and i.MX31 accidently use
the five-register interface. What are the practical consequences? Does
the driver still work properly on these SoCs?

I'm aksing because even with this patch...

>  		.compatible = "fsl,imx21-wdt",
> -		.data = &imx21_wd_ops,
> +		/* FIXME: backward compaibility for imported linux DTS
> +		   Most references to fsl,imx21-wdt from linux imported DTS
> +		   linux actually mean fsl,imx25-wdt. Make fsl,imx21-wdt
> +		   behave like fsl,imx25-wdt for the mean time until
> +		   this is fixed there */
> +		.data = &imx25_wd_ops,
> +	}, {

...device tree based i.MX21/27/31 boards still use the five-register
interface. There are no i.MX21/31 based device tree boards, but there
are some i.MX27 boards with device tree support.

Sascha


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