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authorJoachim Eastwood <manabian@gmail.com>2015-03-25 08:47:18 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-03-28 17:54:53 +0100
commitc20611df13c3e3070607c267cf781ba8645a185e (patch)
treeedd0917670e155eb71a8192556843286aa45e8a8 /arch/arm/boot/compressed
parentARM: 8319/1: advertise availability of v8 Crypto instructions (diff)
downloadlinux-c20611df13c3e3070607c267cf781ba8645a185e.tar.xz
linux-c20611df13c3e3070607c267cf781ba8645a185e.zip
ARM: 8327/1: zImage: add support for ARMv7-M
This patch makes it possible to enter zImage in Thumb mode for ARMv7-M (Cortex-M) CPUs that do not support ARM mode. The kernel entry is also made in Thumb mode. [ukl: fix spelling in commit log, return early in call_cache_fn] Signed-off-by: Joachim Eastwood <manabian@gmail.com> Tested-by: Stefan Agner <stefan@agner.ch> Tested-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> Tested-by: Chanwoo Choi <cw00.choi@samsung.com> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/boot/compressed')
-rw-r--r--arch/arm/boot/compressed/head.S33
1 files changed, 27 insertions, 6 deletions
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 55a353243a90..2c45b5709fa4 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -10,8 +10,11 @@
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/v7m.h>
+
+ AR_CLASS( .arch armv7-a )
+ M_CLASS( .arch armv7-m )
- .arch armv7-a
/*
* Debugging stuff
*
@@ -114,7 +117,12 @@
* sort out different calling conventions
*/
.align
- .arm @ Always enter in ARM state
+ /*
+ * Always enter in ARM state for CPUs that support the ARM ISA.
+ * As of today (2014) that's exactly the members of the A and R
+ * classes.
+ */
+ AR_CLASS( .arm )
start:
.type start,#function
.rept 7
@@ -132,14 +140,15 @@ start:
THUMB( .thumb )
1:
- ARM_BE8( setend be ) @ go BE8 if compiled for BE8
- mrs r9, cpsr
+ ARM_BE8( setend be ) @ go BE8 if compiled for BE8
+ AR_CLASS( mrs r9, cpsr )
#ifdef CONFIG_ARM_VIRT_EXT
bl __hyp_stub_install @ get into SVC mode, reversibly
#endif
mov r7, r1 @ save architecture ID
mov r8, r2 @ save atags pointer
+#ifndef CONFIG_CPU_V7M
/*
* Booting from Angel - need to enter SVC mode and disable
* FIQs/IRQs (numeric definitions from angel arm.h source).
@@ -155,6 +164,7 @@ not_angel:
safe_svcmode_maskall r0
msr spsr_cxsf, r9 @ Save the CPU boot mode in
@ SPSR
+#endif
/*
* Note that some cache flushing and other stuff may
* be needed here - is there an Angel SWI call for this?
@@ -827,6 +837,16 @@ __common_mmu_cache_on:
call_cache_fn: adr r12, proc_types
#ifdef CONFIG_CPU_CP15
mrc p15, 0, r9, c0, c0 @ get processor ID
+#elif defined(CONFIG_CPU_V7M)
+ /*
+ * On v7-M the processor id is located in the V7M_SCB_CPUID
+ * register, but as cache handling is IMPLEMENTATION DEFINED on
+ * v7-M (if existant at all) we just return early here.
+ * If V7M_SCB_CPUID were used the cpu ID functions (i.e.
+ * __armv7_mmu_cache_{on,off,flush}) would be selected which
+ * use cp15 registers that are not implemented on v7-M.
+ */
+ bx lr
#else
ldr r9, =CONFIG_PROCESSOR_ID
#endif
@@ -1327,8 +1347,9 @@ __hyp_reentry_vectors:
__enter_kernel:
mov r0, #0 @ must be 0
- ARM( mov pc, r4 ) @ call kernel
- THUMB( bx r4 ) @ entry point is always ARM
+ ARM( mov pc, r4 ) @ call kernel
+ M_CLASS( add r4, r4, #1 ) @ enter in Thumb mode for M class
+ THUMB( bx r4 ) @ entry point is always ARM for A/R classes
reloc_code_end: