ARM: OMAP2+: AM33xx: Add SoC specific restart hook

Add restart hook so that DTS based AM33xx builds can restart
the platform.

Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Jean-Sebastien A. Beaudry <jsabeaudry@handyem.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/am33xx-restart.c

@@ -0,0 +1,34 @@
+/*
+ * am33xx-restart.c - Code common to all AM33xx machines.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+
+#include "common.h"
+#include "prm-regbits-33xx.h"
+#include "prm33xx.h"
+
+/**
+ * am3xx_restart - trigger a software restart of the SoC
+ * @mode: the "reboot mode", see arch/arm/kernel/{setup,process}.c
+ * @cmd: passed from the userspace program rebooting the system (if provided)
+ *
+ * Resets the SoC.  For @cmd, see the 'reboot' syscall in
+ * kernel/sys.c.  No return value.
+ */
+void am33xx_restart(char mode, const char *cmd)
+{
+	/* TODO: Handle mode and cmd if necessary */
+
+	am33xx_prm_rmw_reg_bits(AM33XX_GLOBAL_WARM_SW_RST_MASK,
+				AM33XX_GLOBAL_WARM_SW_RST_MASK,
+				AM33XX_PRM_DEVICE_MOD,
+				AM33XX_PRM_RSTCTRL_OFFSET);
+
+	/* OCP barrier */
+	(void)am33xx_prm_read_reg(AM33XX_PRM_DEVICE_MOD,
+				  AM33XX_PRM_RSTCTRL_OFFSET);
+}