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>

4 files changed, 3 insertions, 20 deletions

diff --git a/arch/arm/mach-hisi/Makefile b/arch/arm/mach-hisi/Makefile
index 6b7b3033de0b..659db1933ed3 100644
--- a/arch/arm/mach-hisi/Makefile
+++ b/arch/arm/mach-hisi/Makefile
@@ -6,4 +6,4 @@ CFLAGS_platmcpm.o	:= -march=armv7-a
 
 obj-y	+= hisilicon.o
 obj-$(CONFIG_MCPM)		+= platmcpm.o
-obj-$(CONFIG_SMP)		+= platsmp.o hotplug.o headsmp.o
+obj-$(CONFIG_SMP)		+= platsmp.o hotplug.o
diff --git a/arch/arm/mach-hisi/core.h b/arch/arm/mach-hisi/core.h
index 92a682d8e939..c7648ef1825c 100644
--- a/arch/arm/mach-hisi/core.h
+++ b/arch/arm/mach-hisi/core.h
@@ -12,7 +12,6 @@ extern void hi3xxx_cpu_die(unsigned int cpu);
 extern int hi3xxx_cpu_kill(unsigned int cpu);
 extern void hi3xxx_set_cpu(int cpu, bool enable);
 
-extern void hisi_secondary_startup(void);
 extern struct smp_operations hix5hd2_smp_ops;
 extern void hix5hd2_set_cpu(int cpu, bool enable);
 extern void hix5hd2_cpu_die(unsigned int cpu);
diff --git a/arch/arm/mach-hisi/headsmp.S b/arch/arm/mach-hisi/headsmp.S
deleted file mode 100644
index 81e35b159e75..000000000000
--- a/arch/arm/mach-hisi/headsmp.S
+++ /dev/null
@@ -1,16 +0,0 @@
-/*
- *  Copyright (c) 2014 Hisilicon Limited.
- *  Copyright (c) 2014 Linaro Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-#include <linux/linkage.h>
-#include <linux/init.h>
-
-	__CPUINIT
-
-ENTRY(hisi_secondary_startup)
-	bl	v7_invalidate_l1
-	b	secondary_startup
diff --git a/arch/arm/mach-hisi/platsmp.c b/arch/arm/mach-hisi/platsmp.c
index 8880c8e8b296..51744127db66 100644
--- a/arch/arm/mach-hisi/platsmp.c
+++ b/arch/arm/mach-hisi/platsmp.c
@@ -118,7 +118,7 @@ static int hix5hd2_boot_secondary(unsigned int cpu, struct task_struct *idle)
 {
 	phys_addr_t jumpaddr;
 
-	jumpaddr = virt_to_phys(hisi_secondary_startup);
+	jumpaddr = virt_to_phys(secondary_startup);
 	hix5hd2_set_scu_boot_addr(HIX5HD2_BOOT_ADDRESS, jumpaddr);
 	hix5hd2_set_cpu(cpu, true);
 	arch_send_wakeup_ipi_mask(cpumask_of(cpu));
@@ -156,7 +156,7 @@ static int hip01_boot_secondary(unsigned int cpu, struct task_struct *idle)
 	struct device_node *node;
 
 
-	jumpaddr = virt_to_phys(hisi_secondary_startup);
+	jumpaddr = virt_to_phys(secondary_startup);
 	hip01_set_boot_addr(HIP01_BOOT_ADDRESS, jumpaddr);
 
 	node = of_find_compatible_node(NULL, NULL, "hisilicon,hip01-sysctrl");