arm, am335x: add watchdog support

Add TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog support.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Tom Rini <trini@ti.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>

arch/arm/include/asm/arch-am33xx/cpu.h

@@ -46,6 +46,26 @@
 #define PRM_RSTCTRL_RESET		0x01
 #define PRM_RSTST_WARM_RESET_MASK	0x232
 
+/*
+ * Watchdog:
+ * Using the prescaler, the OMAP watchdog could go for many
+ * months before firing.  These limits work without scaling,
+ * with the 60 second default assumed by most tools and docs.
+ */
+#define TIMER_MARGIN_MAX	(24 * 60 * 60)	/* 1 day */
+#define TIMER_MARGIN_DEFAULT	60	/* 60 secs */
+#define TIMER_MARGIN_MIN	1
+
+#define PTV			0	/* prescale */
+#define GET_WLDR_VAL(secs)	(0xffffffff - ((secs) * (32768/(1<<PTV))) + 1)
+#define WDT_WWPS_PEND_WCLR	BIT(0)
+#define WDT_WWPS_PEND_WLDR	BIT(2)
+#define WDT_WWPS_PEND_WTGR	BIT(3)
+#define WDT_WWPS_PEND_WSPR	BIT(4)
+
+#define WDT_WCLR_PRE		BIT(5)
+#define WDT_WCLR_PTV_OFF	2
+
 #ifndef __KERNEL_STRICT_NAMES
 #ifndef __ASSEMBLY__
 struct gpmc_cs {

drivers/watchdog/Makefile

@@ -18,6 +18,7 @@ COBJS-$(CONFIG_TNETV107X_WATCHDOG) += tnetv107x_wdt.o
 COBJS-$(CONFIG_S5P)               += s5p_wdt.o
 COBJS-$(CONFIG_XILINX_TB_WATCHDOG) += xilinx_tb_wdt.o
 COBJS-$(CONFIG_BFIN_WATCHDOG)  += bfin_wdt.o
+COBJS-$(CONFIG_OMAP_WATCHDOG) += omap_wdt.o
 
 COBJS	:= $(COBJS-y)
 SRCS	:= $(COBJS:.o=.c)

drivers/watchdog/omap_wdt.c

@@ -0,0 +1,121 @@
+/*
+ * omap_wdt.c
+ *
+ * (C) Copyright 2013
+ * Heiko Schocher, DENX Software Engineering, hs@denx.de.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ *
+ * Based on:
+ *
+ * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
+ *
+ * commit 2d991a164a61858012651e13c59521975504e260
+ * Author: Bill Pemberton <wfp5p@virginia.edu>
+ * Date:   Mon Nov 19 13:21:41 2012 -0500
+ *
+ * watchdog: remove use of __devinit
+ *
+ * CONFIG_HOTPLUG is going away as an option so __devinit is no longer
+ * needed.
+ *
+ * Author: MontaVista Software, Inc.
+ *	 <gdavis@mvista.com> or <source@mvista.com>
+ *
+ * History:
+ *
+ * 20030527: George G. Davis <gdavis@mvista.com>
+ *	Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
+ *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>
+ *	Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *
+ * Copyright (c) 2004 Texas Instruments.
+ *	1. Modified to support OMAP1610 32-KHz watchdog timer
+ *	2. Ported to 2.6 kernel
+ *
+ * Copyright (c) 2005 David Brownell
+ *	Use the driver model and standard identifiers; handle bigger timeouts.
+ */
+
+#include <common.h>
+#include <watchdog.h>
+#include <asm/arch/hardware.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/arch/cpu.h>
+
+/* Hardware timeout in seconds */
+#define WDT_HW_TIMEOUT 60
+
+static unsigned int wdt_trgr_pattern = 0x1234;
+
+void hw_watchdog_reset(void)
+{
+	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
+
+	/* wait for posted write to complete */
+	while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WTGR)
+		;
+
+	wdt_trgr_pattern = ~wdt_trgr_pattern;
+	writel(wdt_trgr_pattern, &wdt->wdtwtgr);
+
+	/* wait for posted write to complete */
+	while ((readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WTGR))
+		;
+}
+
+static int omap_wdt_set_timeout(unsigned int timeout)
+{
+	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
+	u32 pre_margin = GET_WLDR_VAL(timeout);
+
+	/* just count up at 32 KHz */
+	while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WLDR)
+		;
+
+	writel(pre_margin, &wdt->wdtwldr);
+	while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WLDR)
+		;
+
+	return 0;
+}
+
+void hw_watchdog_init(void)
+{
+	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
+
+	/* initialize prescaler */
+	while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
+		;
+
+	writel(WDT_WCLR_PRE | (PTV << WDT_WCLR_PTV_OFF), &wdt->wdtwclr);
+	while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
+		;
+
+	omap_wdt_set_timeout(WDT_HW_TIMEOUT);
+
+	/* Sequence to enable the watchdog */
+	writel(0xBBBB, &wdt->wdtwspr);
+	while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
+		;
+
+	writel(0x4444, &wdt->wdtwspr);
+	while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
+		;
+}
+
+void hw_watchdog_disable(void)
+{
+	struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
+
+	/*
+	 * Disable watchdog
+	 */
+	writel(0xAAAA, &wdt->wdtwspr);
+	while (readl(&wdt->wdtwwps) != 0x0)
+		;
+	writel(0x5555, &wdt->wdtwspr);
+	while (readl(&wdt->wdtwwps) != 0x0)
+		;
+}