sunxi: Implement reset_cpu

There is no way to reset the cpu, so use the watchdog for this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
diff --git a/arch/arm/cpu/armv7/sunxi/board.c b/arch/arm/cpu/armv7/sunxi/board.c
index 49c9448..c80b421 100644
--- a/arch/arm/cpu/armv7/sunxi/board.c
+++ b/arch/arm/cpu/armv7/sunxi/board.c
@@ -56,6 +56,13 @@
 
 void reset_cpu(ulong addr)
 {
+	static const struct sunxi_wdog *wdog =
+		 &((struct sunxi_timer_reg *)SUNXI_TIMER_BASE)->wdog;
+
+	/* Set the watchdog for its shortest interval (.5s) and wait */
+	writel(WDT_MODE_RESET_EN | WDT_MODE_EN, &wdog->mode);
+	writel(WDT_CTRL_KEY | WDT_CTRL_RESTART, &wdog->ctl);
+	while (1);
 }
 
 /* do some early init */