From: linux@roeck-us•net (Guenter Roeck)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v5 1/2] watchdog: imx2_wdt: add external reset support via dt prop
Date: Thu, 7 Apr 2016 18:09:53 -0700 [thread overview]
Message-ID: <570704E1.6010700@roeck-us.net> (raw)
In-Reply-To: <1459523804-11390-2-git-send-email-tharvey@gateworks.com>
On 04/01/2016 08:16 AM, Tim Harvey wrote:
> The IMX6 watchdog supports assertion of a signal (WDOG_B) which
> can be pinmux'd to an external pin. This is typically used for boards that
> have PMIC's in control of the IMX6 power rails. In fact, failure to use
> such an external reset on boards with external PMIC's can result in various
> hangs due to the IMX6 not being fully reset [1] as well as the board failing
> to reset because its PMIC has not been reset to provide adequate voltage for
> the CPU when coming out of reset at 800Mhz.
>
> This uses a new device-tree property 'fsl,ext-reset-output' to indicate the
> board has such a reset and to cause the watchdog to be configured to assert
> WDOG_B instead of an internal reset both on a watchdog timeout and in
> system_restart.
>
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/333689.html
>
> Cc: Fabio Estevam <festevam@gmail•com>
> Cc: Lucas Stach <l.stach@pengutronix•de>
> Cc: Stefan Roese <sr@denx•de>
> Cc: Iain Paton <ipaton0@gmail•com>
> Cc: Sascha Hauer <s.hauer@pengutronix•de>
> Cc: Akshay Bhat <akshay.bhat@timesys•com>
> Cc: Guenter Roeck <linux@roeck-us•net>
> Signed-off-by: Tim Harvey <tharvey@gateworks•com>
> Reviewed-by: Lucas Stach <l.stach@pengutronix•de>
> Acked-by: Shawn Guo <shawn.guo@linaro•org>
Reviewed-by: Guenter Roeck <linux@roeck-us•net>
> ---
> v5:
> - rename property to 'fsl,ext-reset-output'
> v4:
> - change Property to Properties in documentation
> v3:
> - mandate use of 'either' internal or external reset but not both
> simultaneously
> v2:
> - rename property to 'ext-reset-output' based on ML feedback
> - simplify setting SRS bit if external-reset
> - update comments and commit msg
>
> Signed-off-by: Tim Harvey <tharvey@gateworks•com>
> ---
> .../devicetree/bindings/watchdog/fsl-imx-wdt.txt | 4 +++-
> drivers/watchdog/imx2_wdt.c | 19 +++++++++++++++++--
> 2 files changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
> index 8dab6fd..107280e 100644
> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
> @@ -5,10 +5,12 @@ Required properties:
> - reg : Should contain WDT registers location and length
> - interrupts : Should contain WDT interrupt
>
> -Optional property:
> +Optional properties:
> - big-endian: If present the watchdog device's registers are implemented
> in big endian mode, otherwise in native mode(same with CPU), for more
> detail please see: Documentation/devicetree/bindings/regmap/regmap.txt.
> +- fsl,ext-reset-output: If present the watchdog device is configured to
> + assert its external reset (WDOG_B) instead of issuing a software reset.
>
> Examples:
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index e47966a..cb838be 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -39,6 +39,8 @@
>
> #define IMX2_WDT_WCR 0x00 /* Control Register */
> #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
> +#define IMX2_WDT_WCR_WDA (1 << 5) /* -> External Reset WDOG_B */
> +#define IMX2_WDT_WCR_SRS (1 << 4) /* -> Software Reset Signal */
> #define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */
> #define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */
> #define IMX2_WDT_WCR_WDZST (1 << 0) /* -> Watchdog timer Suspend */
> @@ -62,6 +64,7 @@ struct imx2_wdt_device {
> struct regmap *regmap;
> struct timer_list timer; /* Pings the watchdog when closed */
> struct watchdog_device wdog;
> + bool ext_reset;
> };
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -85,6 +88,12 @@ static int imx2_wdt_restart(struct watchdog_device *wdog)
> struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
> unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
>
> + /* Use internal reset or external - not both */
> + if (wdev->ext_reset)
> + wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */
> + else
> + wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */
> +
> /* Assert SRS signal */
> regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
> /*
> @@ -114,8 +123,12 @@ static inline void imx2_wdt_setup(struct watchdog_device *wdog)
> val |= IMX2_WDT_WCR_WDZST;
> /* Strip the old watchdog Time-Out value */
> val &= ~IMX2_WDT_WCR_WT;
> - /* Generate reset if WDOG times out */
> - val &= ~IMX2_WDT_WCR_WRE;
> + /* Generate internal chip-level reset if WDOG times out */
> + if (!wdev->ext_reset)
> + val &= ~IMX2_WDT_WCR_WRE;
> + /* Or if external-reset assert WDOG_B reset only on time-out */
> + else
> + val |= IMX2_WDT_WCR_WRE;
> /* Keep Watchdog Disabled */
> val &= ~IMX2_WDT_WCR_WDE;
> /* Set the watchdog's Time-Out value */
> @@ -263,6 +276,8 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
> regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
> wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
>
> + wdev->ext_reset = of_property_read_bool(pdev->dev.of_node,
> + "fsl,ext-reset-output");
> wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
> if (wdog->timeout != timeout)
> dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n",
>
next prev parent reply other threads:[~2016-04-08 1:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-01 15:16 [PATCH v5 0/2] imx6: Implement external watchdog reset Tim Harvey
2016-04-01 15:16 ` [PATCH v5 1/2] watchdog: imx2_wdt: add external reset support via dt prop Tim Harvey
2016-04-01 16:31 ` Akshay Bhat
2016-04-08 1:09 ` Guenter Roeck [this message]
2016-04-18 16:05 ` Akshay Bhat
2016-04-01 15:16 ` [PATCH v5 2/2] ARM: dts: imx: ventana: Add wdt ext-reset support Tim Harvey
2016-04-08 1:10 ` Guenter Roeck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=570704E1.6010700@roeck-us.net \
--to=linux@roeck-us$(echo .)net \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox