ARM: highbank: add reset support for Calxeda Midway machine

The Calxeda Midway part has A15 cores, which do not have the Highbank
A9's SCU used there for resetting the chip.
Add code to distinguish between the A9 and the A15 and invoke the
appropriate register writes to support the newer part.

Andre: rework detection of Highbank vs. Midway
Rob: fix Andre's reworked detection

Signed-off-by: Mark Langsdorf <mark.langsdorf@gmail.com>
Signed-off-by: Andre Przywara <osp@andrep.de>
Signed-off-by: Rob Herring <robh@kernel.org>

board/highbank/highbank.c

@@ -18,6 +18,7 @@
 #define HB_SREG_A9_PWR_REQ		0xfff3cf00
 #define HB_SREG_A9_BOOT_SRC_STAT	0xfff3cf04
 #define HB_SREG_A9_PWRDOM_STAT		0xfff3cf20
+#define HB_SREG_A15_PWR_CTRL		0xfff3c200
 
 #define HB_PWR_SUSPEND			0
 #define HB_PWR_SOFT_RESET		1
@@ -116,10 +117,22 @@ int ft_board_setup(void *fdt, bd_t *bd)
 }
 #endif
 
+static int is_highbank(void)
+{
+	uint32_t midr;
+
+	asm volatile ("mrc p15, 0, %0, c0, c0, 0\n" : "=r"(midr));
+
+	return (midr & 0xfff0) == 0xc090;
+}
+
 void reset_cpu(ulong addr)
 {
 	writel(HB_PWR_HARD_RESET, HB_SREG_A9_PWR_REQ);
-	writeb(HB_SCU_A9_PWR_OFF, HB_SCU_A9_PWR_STATUS);
+	if (is_highbank())
+		writeb(HB_SCU_A9_PWR_OFF, HB_SCU_A9_PWR_STATUS);
+	else
+		writel(0x1, HB_SREG_A15_PWR_CTRL);
 
 	wfi();
 }