Re: [PATCH v5 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

[Guenter Roeck <linux@roeck-us.net>]

Hi,

On 08/06/2015 01:34 AM, Wenyou Yang wrote:
>>From SAMA5D4, the watchdog timer is upgrated with a new feature,

Where does the additional ">" come from ?

> which is describled as in the datasheet, "WDT_MR can be written
> until a LOCKMR command is issued in WDT_CR".
> That is to say, as long as the bootstrap and u-boot don't issue
> a LOCKMR command, WDT_MR can be written more than once in the driver.
>
> So the SAMA5D4 watchdog driver's implementation is different from
> the at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
> The user application open the device file to enable the watchdog timer
> hardware, and close to disable it, and set the watchdog timer timeout
> by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
> by issuing WDRSTT command to WDT_CR register with hard-coded key.
>
> Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> ---
>   drivers/watchdog/Kconfig        |    9 ++
>   drivers/watchdog/Makefile       |    1 +
>   drivers/watchdog/at91sam9_wdt.h |    2 +
>   drivers/watchdog/sama5d4_wdt.c  |  280 +++++++++++++++++++++++++++++++++++++++
>   4 files changed, 292 insertions(+)
>   create mode 100644 drivers/watchdog/sama5d4_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index e5e7c55..47ad39a 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -167,6 +167,15 @@ config AT91SAM9X_WATCHDOG
>   	  Watchdog timer embedded into AT91SAM9X and AT91CAP9 chips. This will
>   	  reboot your system when the timeout is reached.
>
> +config SAMA5D4_WATCHDOG
> +	tristate "Atmel SAMA5D4 Watchdog Timer"
> +	depends on ARCH_AT91
> +	select WATCHDOG_CORE
> +	help
> +	  Atmel SAMA5D4 watchdog timer is embedded into SAMA5D4 chips.
> +	  Its Watchdog Timer Mode Register can be written more than once.
> +	  This will reboot your system when the timeout is reached.
> +
>   config CADENCE_WATCHDOG
>   	tristate "Cadence Watchdog Timer"
>   	select WATCHDOG_CORE
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 5c19294..f24b820 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -41,6 +41,7 @@ obj-$(CONFIG_IXP4XX_WATCHDOG) += ixp4xx_wdt.o
>   obj-$(CONFIG_KS8695_WATCHDOG) += ks8695_wdt.o
>   obj-$(CONFIG_S3C2410_WATCHDOG) += s3c2410_wdt.o
>   obj-$(CONFIG_SA1100_WATCHDOG) += sa1100_wdt.o
> +obj-$(CONFIG_SAMA5D4_WATCHDOG) += sama5d4_wdt.o
>   obj-$(CONFIG_DW_WATCHDOG) += dw_wdt.o
>   obj-$(CONFIG_EP93XX_WATCHDOG) += ep93xx_wdt.o
>   obj-$(CONFIG_PNX4008_WATCHDOG) += pnx4008_wdt.o
> diff --git a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
> index c6fbb2e6..b79a83b 100644
> --- a/drivers/watchdog/at91sam9_wdt.h
> +++ b/drivers/watchdog/at91sam9_wdt.h
> @@ -22,11 +22,13 @@
>
>   #define AT91_WDT_MR		0x04			/* Watchdog Mode Register */
>   #define		AT91_WDT_WDV		(0xfff << 0)		/* Counter Value */
> +#define			AT91_WDT_SET_WDV(x)	((x) & AT91_WDT_WDV)
>   #define		AT91_WDT_WDFIEN		(1     << 12)		/* Fault Interrupt Enable */
>   #define		AT91_WDT_WDRSTEN	(1     << 13)		/* Reset Processor */
>   #define		AT91_WDT_WDRPROC	(1     << 14)		/* Timer Restart */
>   #define		AT91_WDT_WDDIS		(1     << 15)		/* Watchdog Disable */
>   #define		AT91_WDT_WDD		(0xfff << 16)		/* Delta Value */
> +#define			AT91_WDT_SET_WDD(x)	(((x) << 16) & AT91_WDT_WDD)
>   #define		AT91_WDT_WDDBGHLT	(1     << 28)		/* Debug Halt */
>   #define		AT91_WDT_WDIDLEHLT	(1     << 29)		/* Idle Halt */
>
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> new file mode 100644
> index 0000000..a412215
> --- /dev/null
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -0,0 +1,280 @@
> +/*
> + * Driver for Atmel SAMA5D4 Watchdog Timer
> + *
> + * Copyright (C) 2015 Atmel Corporation
> + *
> + * Licensed under GPLv2.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/watchdog.h>
> +
> +#include "at91sam9_wdt.h"
> +
> +/* minimum and maximum watchdog timeout, in seconds */
> +#define MIN_WDT_TIMEOUT		1
> +#define MAX_WDT_TIMEOUT		16
> +#define WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
> +
> +#define WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
> +
> +struct sama5d4_wdt {
> +	struct watchdog_device	wdd;
> +	void __iomem		*reg_base;
> +	u32	config;
> +};
> +
> +static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +
> +module_param(wdt_timeout, int, 0);
> +MODULE_PARM_DESC(wdt_timeout,
> +	"Watchdog timeout in seconds. (default = "
> +	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
> +
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout,
> +	"Watchdog cannot be stopped once started (default="
> +	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +#define wdt_read(wdt, field) \
> +	readl_relaxed((wdt)->reg_base + (field))
> +
> +#define wdt_write(wtd, field, val) \
> +	writel_relaxed((val), (wdt)->reg_base + (field))
> +
> +static int sama5d4_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> +	u32 reg;
> +
> +	reg = wdt_read(wdt, AT91_WDT_MR);
> +	reg &= ~AT91_WDT_WDDIS;
> +	wdt_write(wdt, AT91_WDT_MR, reg);
> +
> +	return 0;
> +}
> +
> +static int sama5d4_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> +	u32 reg;
> +
> +	reg = wdt_read(wdt, AT91_WDT_MR);
> +	reg |= AT91_WDT_WDDIS;
> +	wdt_write(wdt, AT91_WDT_MR, reg);
> +
> +	return 0;
> +}
> +
> +static int sama5d4_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> +	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
> +
> +	return 0;
> +}
> +
> +static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
> +				 unsigned int timeout)
> +{
> +	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> +	u32 value = WDT_SEC2TICKS(timeout);
> +	u32 reg;
> +
> +	reg = wdt_read(wdt, AT91_WDT_MR);
> +	reg &= ~AT91_WDT_WDV;
> +	reg &= ~AT91_WDT_WDD;
> +	reg |= AT91_WDT_SET_WDV(value);
> +	reg |= AT91_WDT_SET_WDD(value);
> +	wdt_write(wdt, AT91_WDT_MR, reg);
> +
> +	wdd->timeout = timeout;
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info sama5d4_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> +	.identity = "Atmel SAMA5D4 Watchdog"
> +};
> +
> +static struct watchdog_ops sama5d4_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = sama5d4_wdt_start,
> +	.stop = sama5d4_wdt_stop,
> +	.ping = sama5d4_wdt_ping,
> +	.set_timeout = sama5d4_wdt_set_timeout

You made another silent change in v4: You dropped the comma here,
and above after .identity. Now, while it makes sense to have no comma
after "{ }", it does make sense to have the comma here, because it
avoids unnecessary conflicts and build errors later on if a member
is added at the end of the list. Please add those commas back in.

Also, please stop making silent changes like this. You are making
it really hard to review your code - now I'll have to go through
it line by line again and compare it with your earlier patches to see
if you made any other unannounced changes.

Thanks,
Guenter