[PATCH] ARM: Implement cpu_v7_reset.

[Russell King - ARM Linux]

On Thu, Sep 02, 2010 at 11:53:41AM +0300, Mika Westerberg wrote:
> On Thu, Sep 02, 2010 at 09:41:01AM +0100, Russell King - ARM Linux wrote:
> > On Thu, Sep 02, 2010 at 11:34:23AM +0300, Mika Westerberg wrote:
> > > 
> > > When the MMU is turned off, should we be running on 1:1 mappings?
> > 
> > Mappings are setup, but not for this code.  This code relies upon the
> > instruction which jumps to already be in the pipeline at the point when
> > the MMU is turned off - and the destination for that jump to be a 1:1
> > mapping.
> 
> OK, thanks.
> 
> Any Idea what might cause the hang on OMAP3? Only way I was able
> to get it working when MMU is disabled was to run cpu_v7_reset()
> also via 1:1 mapping.

Well, as the current v6 and v7 cpu_reset() code is broken, it's hardly
surprising that it doesn't work.  It needs to be something like this
(I haven't tested it yet.)

diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S
index 22aac85..6b873f9 100644
--- a/arch/arm/mm/proc-v6.S
+++ b/arch/arm/mm/proc-v6.S
@@ -59,6 +59,16 @@ ENTRY(cpu_v6_proc_fin)
  */
 	.align	5
 ENTRY(cpu_v6_reset)
+	mov	ip, #0
+	mcr	p15, 0, ip, c7, c7, 0		@ invalidate I,D caches
+	mcr	p15, 0, ip, c7, c10, 4		@ drain WB
+#ifdef CONFIG_MMU
+	mcr	p15, 0, ip, c8, c7, 0		@ invalidate I & D TLBs
+#endif
+	mrc	p15, 0, ip, c1, c0, 0		@ ctrl register
+	bic	ip, ip, #0x000f			@ ............wcam
+	bic	ip, ip, #0x1100			@ ...i...s........
+	mcr	p15, 0, ip, c1, c0, 0		@ ctrl register
 	mov	pc, r0
 
 /*
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 6a8506d..3542ee0 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -63,6 +63,16 @@ ENDPROC(cpu_v7_proc_fin)
  */
 	.align	5
 ENTRY(cpu_v7_reset)
+	mov	ip, #0
+	mcr	p15, 0, ip, c7, c7, 0		@ invalidate I,D caches
+	dsb
+#ifdef CONFIG_MMU
+	mcr	p15, 0, ip, c8, c7, 0		@ invalidate I & D TLBs
+#endif
+	mrc	p15, 0, ip, c1, c0, 0		@ ctrl register
+	bic	ip, ip, #0x000f			@ ............wcam
+	bic	ip, ip, #0x1100			@ ...i...s........
+	mcr	p15, 0, ip, c1, c0, 0		@ ctrl register
 	mov	pc, r0
 ENDPROC(cpu_v7_reset)