Subject: [PATCH v2] watchdog: imx2_wdt: add support for WDOG_B signal generation

From: [email-masked] (Markus Niebel)
Date: Mon, 21 Jul 2014 09:31:49 +0200

Am 21.07.2014 08:30, wrote Uwe Kleine-K?nig:
> On Fri, Jul 18, 2014 at 01:38:30PM +0200, Markus Niebel wrote:
>> From: Markus Niebel <[email-masked]>
>>
>> Watchdog unit of i.MX supports output of a signal at
>> watchdog shutdown. This feature can be useful to signal an
>> external supevisor that a watchdog reset occured.
> supervisor
> 
>> Support this feature as an option via devicetree.
>>
>> Signed-off-by: Markus Niebel <[email-masked]>
>> ---
>> History
>>
>> v2:
>> Fix incorrect sent patch
>> - add include of.h
>> - fix missing if in probe
>>
>>  .../devicetree/bindings/watchdog/fsl-imx-wdt.txt   |    3 +++
>>  drivers/watchdog/imx2_wdt.c                        |   11 +++++++++--
>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
>> index 2144af1..cb759cd 100644
>> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
>> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
>> @@ -5,6 +5,9 @@ Required properties:
>>  - reg : Should contain WDT registers location and length
>>  - interrupts : Should contain WDT interrupt
>>  
>> +Optional properties:
>> +- fsl,use-wre: set if watchdog reset out (WDOG_B) signal shall be asserted
>> +
>>  Examples:
>>  
>>  wdt at 73f98000 {
>> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
>> index 9d4874f..bde96db 100644
>> --- a/drivers/watchdog/imx2_wdt.c
>> +++ b/drivers/watchdog/imx2_wdt.c

#include linux/of.h is missing here ...

>> @@ -58,6 +58,7 @@ struct imx2_wdt_device {
>>  	struct regmap *regmap;
>>  	struct timer_list timer;	/* Pings the watchdog when closed */
>>  	struct watchdog_device wdog;
>> +	unsigned int use_wre:1;		/* enable WRE feature */
>>  };
>>  
>>  static bool nowayout = WATCHDOG_NOWAYOUT;
>> @@ -88,7 +89,10 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog)
>>  	/* Strip the old watchdog Time-Out value */
>>  	val &= ~IMX2_WDT_WCR_WT;
>>  	/* Generate reset if WDOG times out */
>> -	val &= ~IMX2_WDT_WCR_WRE;
>> +	if (wdev->use_wre)
>> +		val |= IMX2_WDT_WCR_WRE;
>> +	else
>> +		val &= ~IMX2_WDT_WCR_WRE;
>>  	/* Keep Watchdog Disabled */
>>  	val &= ~IMX2_WDT_WCR_WDE;
>>  	/* Set the watchdog's Time-Out value */
>> @@ -219,6 +223,9 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>>  		return PTR_ERR(wdev->clk);
>>  	}
>>  
>> +	if (of_property_read_bool(pdev->dev.of_node, "fsl,use-wre"))
>> +		wdev->use_wre = 1;
>> +
>>  	wdog			= &wdev->wdog;
>>  	wdog->info		= &imx2_wdt_info;
>>  	wdog->ops		= &imx2_wdt_ops;
>> @@ -226,7 +233,7 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>>  	wdog->max_timeout	= IMX2_WDT_MAX_TIME;
>>  
>>  	clk_prepare_enable(wdev->clk);
>> -
>> + 
> Don't add a space here.

Oops

> 
> Did you check that this feature works on all cpus that use this driver?
> On which of them did you test your change?
> 

We tested with i.MX6Q and i.MX6DL. Reading the RM at least i.MX25, i.MX35 and i.MX53
should implement the same behaviour. But you are right - the i.MX21 is slighly different.

Will prepare v3 after my holiday with
- work out SOC differences
- add missing include
- extended binding docu
- fix whitespace error

> Best regards
> Uwe
Best Regards

Markus