ARM: v7 setup function should invalidate L1 cache

All ARMv5 and older CPUs invalidate their caches in the early assembly
setup function, prior to enabling the MMU.  This is because the L1
cache should not contain any data relevant to the execution of the
kernel at this point; all data should have been flushed out to memory.

This requirement should also be true for ARMv6 and ARMv7 CPUs - indeed,
these typically do not search their caches when caching is disabled (as
it needs to be when the MMU is disabled) so this change should be safe.

ARMv7 allows there to be CPUs which search their caches while caching is
disabled, and it's permitted that the cache is uninitialised at boot;
for these, the architecture reference manual requires that an
implementation specific code sequence is used immediately after reset
to ensure that the cache is placed into a sane state.  Such
functionality is definitely outside the remit of the Linux kernel, and
must be done by the SoC's firmware before _any_ CPU gets to the Linux
kernel.

Changing the data cache clean+invalidate to a mere invalidate allows us
to get rid of a lot of platform specific hacks around this issue for
their secondary CPU bringup paths - some of which were buggy.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Thierry Reding <treding@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 2 insertions, 12 deletions

diff --git a/arch/arm/mach-rockchip/core.h b/arch/arm/mach-rockchip/core.h
index 39bca96b555a..492c048813da 100644
--- a/arch/arm/mach-rockchip/core.h
+++ b/arch/arm/mach-rockchip/core.h
@@ -17,4 +17,3 @@ extern char rockchip_secondary_trampoline;
 extern char rockchip_secondary_trampoline_end;
 
 extern unsigned long rockchip_boot_fn;
-extern void rockchip_secondary_startup(void);
diff --git a/arch/arm/mach-rockchip/headsmp.S b/arch/arm/mach-rockchip/headsmp.S
index 46c22dedf632..d69708b07282 100644
--- a/arch/arm/mach-rockchip/headsmp.S
+++ b/arch/arm/mach-rockchip/headsmp.S
@@ -15,14 +15,6 @@
 #include <linux/linkage.h>
 #include <linux/init.h>
 
-ENTRY(rockchip_secondary_startup)
-	mrc	p15, 0, r0, c0, c0, 0	@ read main ID register
-	ldr	r1, =0x00000c09		@ Cortex-A9 primary part number
-	teq	r0, r1
-	beq	v7_invalidate_l1
-	b	secondary_startup
-ENDPROC(rockchip_secondary_startup)
-
 ENTRY(rockchip_secondary_trampoline)
 	ldr	pc, 1f
 ENDPROC(rockchip_secondary_trampoline)
diff --git a/arch/arm/mach-rockchip/platsmp.c b/arch/arm/mach-rockchip/platsmp.c
index 5b4ca3c3c879..2e6ab67e2284 100644
--- a/arch/arm/mach-rockchip/platsmp.c
+++ b/arch/arm/mach-rockchip/platsmp.c
@@ -149,8 +149,7 @@ static int __cpuinit rockchip_boot_secondary(unsigned int cpu,
 		 * sram_base_addr + 8: start address for pc
 		 * */
 		udelay(10);
-		writel(virt_to_phys(rockchip_secondary_startup),
-			sram_base_addr + 8);
+		writel(virt_to_phys(secondary_startup), sram_base_addr + 8);
 		writel(0xDEADBEAF, sram_base_addr + 4);
 		dsb_sev();
 	}
@@ -189,7 +188,7 @@ static int __init rockchip_smp_prepare_sram(struct device_node *node)
 	}
 
 	/* set the boot function for the sram code */
-	rockchip_boot_fn = virt_to_phys(rockchip_secondary_startup);
+	rockchip_boot_fn = virt_to_phys(secondary_startup);
 
 	/* copy the trampoline to sram, that runs during startup of the core */
 	memcpy(sram_base_addr, &rockchip_secondary_trampoline, trampoline_sz);