ENGR00221135: imx6x: clear PowerDown Enable bit of WDOG1_WMCR

From IC spec:
---
The Power down Counter inside WDOG-1 will be enabled out of reset.
This counter has a fixed time-out value of 16 seconds, after which
it will drive the WDOG-1 signal low.

To prevent this, the software must disable this counter by clearing
the PDE bit of Watchdog Miscellaneous Control Register (WDOG_WMCR)
within 16 seconds of reset de-assertion. Once disabled, this counter
cannot be enabled again until the next system reset occurs. This
feature is provided to prevent the hanging up of cores after reset, as
WDOG-1 is not enabled out of reset.
---

NOTE for the last sentence:
This feature requires a dedicated WDOG_B pin for it. The fact that changing
the IOMUX configuration can alter the WDOG_B functionality (GPIO by default)
is not ideal as it defeats the purpose of this feature. But it still
takes effect when the muxed pin is configured as WDOG_B within 16 seconds.

Clear PDE bit to avoid WDOG_B (aka, WDOG-1) assertion.

Tested on MX6SL. May add this for other MX6x.

Signed-off-by: Robby Cai <R63905@freescale.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/include/imx_wdog.h b/include/imx_wdog.h
new file mode 100644
index 0000000..40920f7
--- /dev/null
+++ b/include/imx_wdog.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2012 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef	_IMX_WDOG_H
+#define	_IMX_WDOG_H
+
+#include <asm/io.h>
+
+#define WDOGx_WMCR	0x8
+static inline void wdog_preconfig(int base_addr)
+{
+	/*
+	 * From IC spec:
+	 * The Power down Counter inside WDOG-1 will be enabled out of reset.
+	 * This counter has a fixed time-out value of 16 seconds, after which
+	 * it will drive the WDOG-1 signal low.
+	 *
+	 * To prevent this, the software must disable this counter by clearing
+	 * the PDE bit of Watchdog Miscellaneous Control Register (WDOG_WMCR).
+	 */
+	writew(0, base_addr + WDOGx_WMCR);
+}
+
+#endif