[U-Boot] [PATCH v2] drivers: watchdog: add MAX6373 WDT support

[Andrea Scian <rnd4@dave-tech.it>]

Il 18/08/2015 15:33, Michael Trimarchi ha scritto:
> Hi
>
> On Tue, Aug 18, 2015 at 3:22 PM,  <rnd4@dave-tech.it> wrote:
>> From: Andrea Scian <andrea.scian@dave.eu>
>>
>> MAX6373 is a simple WDT which is programmed its configuration pins
>> and reset via another pin, which is usually connected to a GPIO
>>
>> Signed-off-by: Andrea Scian <andrea.scian@dave.eu>
>> ---
>>
>> Changes for v2:
>>          - add Kconfig support
>>
>>   drivers/watchdog/Kconfig       |   17 +++++++++++++++++
>>   drivers/watchdog/Makefile      |    1 +
>>   drivers/watchdog/max6373_wdt.c |   34 ++++++++++++++++++++++++++++++++++
>>   3 files changed, 52 insertions(+)
>>   create mode 100644 drivers/watchdog/max6373_wdt.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index e69de29..c7c2011 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -0,0 +1,17 @@
>> +menu "Watchdog Timer Support"
>> +
>> +config MAX6373_WATCHDOG
>> +       bool "Maxim MAX6373 Watchdog"
>> +       depends on DM_GPIO
>> +       default n
>> +       help
>> +         Enable MAX6373 Watchdog timer driver. This is a simple WDT which is reset
>> +         via GPIO
>> +
>> +config MAX6373_WDT_GPIO
>> +       int "Maxim MAX6373 WDT Reset GPIO"
>> +       depends on MAX6373_WATCHDOG
>> +       help
>> +         GPIO number used by the MAX6373 driver to reset the WDT at runtime
>> +
>> +endmenu # menu "Watchdog Timer Support"
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 482a4bd..5bb5f5b 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -15,3 +15,4 @@ obj-$(CONFIG_XILINX_TB_WATCHDOG) += xilinx_tb_wdt.o
>>   obj-$(CONFIG_BFIN_WATCHDOG)  += bfin_wdt.o
>>   obj-$(CONFIG_OMAP_WATCHDOG) += omap_wdt.o
>>   obj-$(CONFIG_DESIGNWARE_WATCHDOG) += designware_wdt.o
>> +obj-$(CONFIG_MAX6373_WATCHDOG) += max6373_wdt.o
>> diff --git a/drivers/watchdog/max6373_wdt.c b/drivers/watchdog/max6373_wdt.c
>> new file mode 100644
>> index 0000000..cda46af
>> --- /dev/null
>> +++ b/drivers/watchdog/max6373_wdt.c
>> @@ -0,0 +1,34 @@
>> +/*
>> + * Copyright (c) 2015 DAVE Embedded Systems <devel@dave.eu>
>> + *
>> + * SPDX-License-Identifier:    GPL-2.0+
>> + *
>> + * MAX6373 is a WDT which uses a simple GPIO to reset its timeout
>> + *
>> + * Use CONFIG_MAX6373_WDT_GPIO to define the GPIO number to use
>> + */
>> +
>> +#include <common.h>
>> +#include <asm/io.h>
>> +#include <asm/gpio.h>
>> +#include <watchdog.h>
>> +
>> +#ifndef CONFIG_MAX6373_WDT_GPIO
>> +#error "Please use CONFIG_MAX6373_WDT_GPIO to define which GPIO to use"
>> +#endif
>> +
>> +void hw_watchdog_reset(void)
>> +{
>> +       gpio_set_value(CONFIG_MAX6373_WDT_GPIO,
>> +               !gpio_get_value(CONFIG_MAX6373_WDT_GPIO));
>> +}
>> +
>
> According to the datasheet timeout can be select from 3 additional pin. Plus
> if a timeout is defined you can avoid to change the value always. For example
> if the gpio pin is on an expander you avoid to send an i2c message always.
> Half of timeout is always enough.

Understood. I think we can add the WDT timeout or WDT ping timeout (in 
ms?) as an additional Kconfig entry.

Can you please give me some clues about the best way to safely calculate 
such a timeout in this scenario?

Then I can elaborate on it and test it on hardware (as soon as I find 
some spare time ;-) )

> Even because this invest a family of device
> I don't think that we require a name. Can be watchdog-gpio?

I didn't think about writing a general purpose GPIO WDT driver, but I 
think it's a nice idea. It may be useful as heartbeat too.

I think we can call it as you suggest.
I can rewrite the code and make it more reusable, if there's no other 
comments on this.

>
> Michael

Thanks for your feedback,

-- 

Andrea SCIAN

DAVE Embedded Systems
>
>> +void hw_watchdog_init(void)
>> +{
>> +       if (gpio_request(CONFIG_MAX6373_WDT_GPIO, "MAX6373 WDT")) {
>> +               printf("Cannot request GPIO %d for MAX6373 WDT\n",
>> +                       CONFIG_MAX6373_WDT_GPIO);
>> +               return;
>> +       }
>> +       gpio_direction_output(CONFIG_MAX6373_WDT_GPIO, 1);
>> +}
>> --
>> 1.7.9.5
>>
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