sunxi: Implement poweroff support for axp209 pmic

Adds poweroff support for axp209 pmic.

Signed-off-by: Michael van Slingerland <michael@deviousops.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

drivers/power/Kconfig

@@ -28,6 +28,7 @@ config AXP152_POWER
 config AXP209_POWER
 	boolean "axp209 pmic support"
 	depends on MACH_SUN4I || MACH_SUN5I || MACH_SUN7I
+	select CMD_POWEROFF
 	---help---
 	Select this to enable support for the axp209 pmic found on most
 	A10, A13 and A20 boards.

drivers/power/axp209.c

@@ -6,6 +6,7 @@
  */
 
 #include <common.h>
+#include <command.h>
 #include <asm/arch/pmic_bus.h>
 #include <axp_pmic.h>
 
@@ -168,3 +169,14 @@ int axp_init(void)
 
 	return 0;
 }
+
+int do_poweroff(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	pmic_bus_write(AXP209_SHUTDOWN, AXP209_POWEROFF);
+
+	/* infinite loop during shutdown */
+	while (1) {}
+
+	/* not reached */
+	return 0;
+}