Blackfin arch: Workaround reboot bug, issue SSYNC at the start of bfin_reset

reboot failes on BF533
http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=3500Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

arch/blackfin/kernel/reboot.c

+/*
+ * arch/blackfin/kernel/reboot.c - handle shutdown/reboot
+ *
+ * Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/interrupt.h>
+#include <asm/bfin-global.h>
+#include <asm/reboot.h>
+#include <asm/system.h>
+
+#if defined(BF537_FAMILY) || defined(BF533_FAMILY)
+#define SYSCR_VAL 	0x0
+#elif defined(BF561_FAMILY)
+#define SYSCR_VAL 	0x20
+#elif defined(BF548_FAMILY)
+#define SYSCR_VAL 	0x10
+#endif
+
+/* A system soft reset makes external memory unusable
+ * so force this function into L1.
+ */
+__attribute__((l1_text))
+void bfin_reset(void)
+{
+	/* force BMODE and disable Core B (as needed) */
+	bfin_write_SYSCR(SYSCR_VAL);
+
+	/* we use asm ssync here because it's save and we save some L1 */
+	asm("ssync;");
+
+	while (1) {
+		/* initiate system soft reset with magic 0x7 */
+		bfin_write_SWRST(0x7);
+		asm("ssync;");
+		/* clear system soft reset */
+		bfin_write_SWRST(0);
+		asm("ssync;");
+		/* issue core reset */
+		asm("raise 1");
+	}
+}
+
+__attribute__((weak))
+void native_machine_restart(char *cmd)
+{
+}
+
+void machine_restart(char *cmd)
+{
+	native_machine_restart(cmd);
+	local_irq_disable();
+	bfin_reset();
+}
+
+__attribute__((weak))
+void native_machine_halt(void)
+{
+	idle_with_irq_disabled();
+}
+
+void machine_halt(void)
+{
+	native_machine_halt();
+}
+
+__attribute__((weak))
+void native_machine_power_off(void)
+{
+	idle_with_irq_disabled();
+}
+
+void machine_power_off(void)
+{
+	native_machine_power_off();
+}

include/asm-blackfin/reboot.h

+/*
+ * include/asm-blackfin/reboot.h - shutdown/reboot header
+ *
+ * Copyright 2004-2007 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef __ASM_REBOOT_H__
+#define __ASM_REBOOT_H__
+
+/* optional board specific hooks */
+extern void native_machine_restart(char *cmd);
+extern void native_machine_halt(void);
+extern void native_machine_power_off(void);
+
+/* common reboot workarounds */
+extern void bfin_gpio_reset_spi0_ssel1(void);
+
+#endif