i5000: enforce hard reset

Not doing a hard reset leaves the BOFL0 register cleared, which
prevents the BSP selection from working. To make sure we start
with known values, use the SPAD0 register for soft reset detection.
If there's a value other than 0, do a hard reset.

Change-Id: I390e3208084cfd32d73cce439ddf2bc9d4436a62
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Reviewed-on: http://review.coreboot.org/1103
Tested-by: build bot (Jenkins)

src/northbridge/intel/i5000/halt_second_bsp.S

@@ -2,6 +2,26 @@
 
 	movl	%eax, %ebp
 
+	/* check if SPAD0 is cleared. If yes, it means this was a hard reset */
+	movl	$0x800080d0, %eax
+	movw	$0xcf8, %dx
+	outl	%eax, %dx
+
+	addw	$4, %dx
+	inl	%dx, %eax
+	cmp	$0, %eax
+	je	no_reset
+
+	/* perform hard reset */
+	movw	$0xcf9, %dx
+	movw	$0x06, %ax
+	outw	%ax, %dx
+
+loop0:	hlt
+	jmp	loop
+
+no_reset:
+
 	/* Read the semaphore register of i5000 (BOFL0).
 	   If it returns zero, it means there was already
 	   another read by another CPU */
@@ -25,5 +45,14 @@
 loop:	hlt
 	jmp	loop
 
-1:	/* Restore BIST */
+1:	/* set magic value for soft reset detection */
+	movl    $0x800080d0, %eax
+	movw    $0xcf8, %dx
+	outl    %eax, %dx
+
+	addw    $4, %dx
+	movl	$0x12345678, %eax
+	outl	%eax, %dx
+
+	/* Restore BIST */
 	mov	%ebp, %eax