bcm2835_wdt: support for the BCM2835/2836 watchdog

Signed-off-by: Paolo Pisati <p.pisati@gmail.com>

arch/arm/mach-bcm283x/reset.c

@@ -21,18 +21,33 @@
  */
 #define BCM2835_WDOG_RSTS_RASPBERRYPI_HALT	0x555
 
+/* max ticks timeout */
+#define BCM2835_WDOG_MAX_TIMEOUT	0x000fffff
+
+#ifdef CONFIG_BCM2835_WDT
+extern void hw_watchdog_disable(void);
+#else
+void hw_watchdog_disable(void) {}
+#endif
+
 __efi_runtime_data struct bcm2835_wdog_regs *wdog_regs =
 	(struct bcm2835_wdog_regs *)BCM2835_WDOG_PHYSADDR;
 
-void __efi_runtime reset_cpu(ulong addr)
+void __efi_runtime reset_cpu(ulong ticks)
 {
-	uint32_t rstc;
+	uint32_t rstc, timeout;
+
+	if (ticks == 0) {
+		hw_watchdog_disable();
+		timeout = RESET_TIMEOUT;
+	} else
+		timeout = ticks & BCM2835_WDOG_MAX_TIMEOUT;
 
 	rstc = readl(&wdog_regs->rstc);
 	rstc &= ~BCM2835_WDOG_RSTC_WRCFG_MASK;
 	rstc |= BCM2835_WDOG_RSTC_WRCFG_FULL_RESET;
 
-	writel(BCM2835_WDOG_PASSWORD | RESET_TIMEOUT, &wdog_regs->wdog);
+	writel(BCM2835_WDOG_PASSWORD | timeout, &wdog_regs->wdog);
 	writel(BCM2835_WDOG_PASSWORD | rstc, &wdog_regs->rstc);
 }
 

board/raspberrypi/rpi/rpi.c

@@ -23,6 +23,7 @@
 #ifdef CONFIG_ARM64
 #include <asm/armv8/mmu.h>
 #endif
+#include <watchdog.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -455,6 +456,9 @@ static void rpi_disable_inactive_uart(void)
 
 int board_init(void)
 {
+#ifdef CONFIG_HW_WATCHDOG
+	hw_watchdog_init();
+#endif
 #ifndef CONFIG_PL01X_SERIAL
 	rpi_disable_inactive_uart();
 #endif

drivers/watchdog/Kconfig

 menu "Watchdog Timer Support"
 
+config HW_WATCHDOG
+	bool
+
+config BCM2835_WDT
+	bool "Enable BCM2835/2836 watchdog driver"
+	select HW_WATCHDOG
+	help
+	  Say Y here to enable the BCM2835/2836 watchdog
+
+	  This provides basic infrastructure to support BCM2835/2836 watchdog
+	  hardware, with a max timeout of ~15secs.
+
 config ULP_WATCHDOG
 	bool "i.MX7ULP watchdog"
 	help

drivers/watchdog/Makefile

@@ -18,3 +18,4 @@ obj-$(CONFIG_ULP_WATCHDOG) += ulp_wdog.o
 obj-$(CONFIG_WDT) += wdt-uclass.o
 obj-$(CONFIG_WDT_SANDBOX) += sandbox_wdt.o
 obj-$(CONFIG_WDT_ASPEED) += ast_wdt.o
+obj-$(CONFIG_BCM2835_WDT)       += bcm2835_wdt.o

drivers/watchdog/bcm2835_wdt.c

+/*
+ * Watchdog driver for Broadcom BCM2835
+ *
+ * Copyright (C) 2017 Paolo Pisati <p.pisati@gmail.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#include <common.h>
+#include <efi_loader.h>
+#include <asm/io.h>
+#include <asm/arch/wdog.h>
+
+#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
+#define MAX_TIMEOUT   0xf /* ~15s */
+
+static __efi_runtime_data bool enabled = true;
+
+extern void reset_cpu(ulong ticks);
+
+void hw_watchdog_reset(void)
+{
+	if (enabled)
+		reset_cpu(SECS_TO_WDOG_TICKS(MAX_TIMEOUT));
+}
+
+void hw_watchdog_init(void)
+{
+	hw_watchdog_reset();
+}
+
+void __efi_runtime hw_watchdog_disable(void)
+{
+	enabled = false;
+}