watchdog: imx2_wdt: add external reset support via dt prop
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>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Akshay Bhat <akshay.bhat@timesys.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index 331aed8..62f346b 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -37,6 +37,8 @@
#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 */
@@ -59,6 +61,7 @@
struct clk *clk;
struct regmap *regmap;
struct watchdog_device wdog;
+ bool ext_reset;
};
static bool nowayout = WATCHDOG_NOWAYOUT;
@@ -83,6 +86,12 @@
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);
/*
@@ -112,8 +121,12 @@
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 */
@@ -230,6 +243,8 @@
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",