ARM: Add base support for ARMv7-M

This patch adds the base support for the ARMv7-M
architecture. It consists of the corresponding arch/arm/mm/ files and
various #ifdef's around the kernel. Exception handling is implemented by
a subsequent patch.

[ukleinek: squash in some changes originating from commit

b5717ba (Cortex-M3: Add support for the Microcontroller Prototyping System)

from the v2.6.33-arm1 patch stack, port to post 3.6, drop zImage
support, drop reorganisation of pt_regs, assert CONFIG_CPU_V7M doesn't
leak into installed headers and a few cosmetic changes]

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Jonathan Austin <jonathan.austin@arm.com>
Tested-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

3 files changed, 214 insertions, 0 deletions

diff --git a/arch/arm/mm/cache-nop.S b/arch/arm/mm/cache-nop.S
new file mode 100644
index 000000000000..8e12ddca0031
--- /dev/null
+++ b/arch/arm/mm/cache-nop.S
@@ -0,0 +1,50 @@
+/*
+ * 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>
+
+#include "proc-macros.S"
+
+ENTRY(nop_flush_icache_all)
+	mov	pc, lr
+ENDPROC(nop_flush_icache_all)
+
+	.globl nop_flush_kern_cache_all
+	.equ nop_flush_kern_cache_all, nop_flush_icache_all
+
+	.globl nop_flush_kern_cache_louis
+	.equ nop_flush_kern_cache_louis, nop_flush_icache_all
+
+	.globl nop_flush_user_cache_all
+	.equ nop_flush_user_cache_all, nop_flush_icache_all
+
+	.globl nop_flush_user_cache_range
+	.equ nop_flush_user_cache_range, nop_flush_icache_all
+
+	.globl nop_coherent_kern_range
+	.equ nop_coherent_kern_range, nop_flush_icache_all
+
+ENTRY(nop_coherent_user_range)
+	mov	r0, 0
+	mov	pc, lr
+ENDPROC(nop_coherent_user_range)
+
+	.globl nop_flush_kern_dcache_area
+	.equ nop_flush_kern_dcache_area, nop_flush_icache_all
+
+	.globl nop_dma_flush_range
+	.equ nop_dma_flush_range, nop_flush_icache_all
+
+	.globl nop_dma_map_area
+	.equ nop_dma_map_area, nop_flush_icache_all
+
+	.globl nop_dma_unmap_area
+	.equ nop_dma_unmap_area, nop_flush_icache_all
+
+	__INITDATA
+
+	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
+	define_cache_functions nop
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index d51225f90ae2..dd3a6c670f08 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -20,12 +20,19 @@
 
 void __init arm_mm_memblock_reserve(void)
 {
+#ifndef CONFIG_CPU_V7M
 	/*
 	 * Register the exception vector page.
 	 * some architectures which the DRAM is the exception vector to trap,
 	 * alloc_page breaks with error, although it is not NULL, but "0."
 	 */
 	memblock_reserve(CONFIG_VECTORS_BASE, PAGE_SIZE);
+#else /* ifndef CONFIG_CPU_V7M */
+	/*
+	 * There is no dedicated vector page on V7-M. So nothing needs to be
+	 * reserved here.
+	 */
+#endif
 }
 
 void __init sanity_check_meminfo(void)
diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
new file mode 100644
index 000000000000..000499cfceb3
--- /dev/null
+++ b/arch/arm/mm/proc-v7m.S
@@ -0,0 +1,157 @@
+/*
+ *  linux/arch/arm/mm/proc-v7m.S
+ *
+ *  Copyright (C) 2008 ARM Ltd.
+ *  Copyright (C) 2001 Deep Blue Solutions 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.
+ *
+ *  This is the "shell" of the ARMv7-M processor support.
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/v7m.h>
+#include "proc-macros.S"
+
+ENTRY(cpu_v7m_proc_init)
+	mov	pc, lr
+ENDPROC(cpu_v7m_proc_init)
+
+ENTRY(cpu_v7m_proc_fin)
+	mov	pc, lr
+ENDPROC(cpu_v7m_proc_fin)
+
+/*
+ *	cpu_v7m_reset(loc)
+ *
+ *	Perform a soft reset of the system.  Put the CPU into the
+ *	same state as it would be if it had been reset, and branch
+ *	to what would be the reset vector.
+ *
+ *	- loc   - location to jump to for soft reset
+ */
+	.align	5
+ENTRY(cpu_v7m_reset)
+	mov	pc, r0
+ENDPROC(cpu_v7m_reset)
+
+/*
+ *	cpu_v7m_do_idle()
+ *
+ *	Idle the processor (eg, wait for interrupt).
+ *
+ *	IRQs are already disabled.
+ */
+ENTRY(cpu_v7m_do_idle)
+	wfi
+	mov	pc, lr
+ENDPROC(cpu_v7m_do_idle)
+
+ENTRY(cpu_v7m_dcache_clean_area)
+	mov	pc, lr
+ENDPROC(cpu_v7m_dcache_clean_area)
+
+/*
+ * There is no MMU, so here is nothing to do.
+ */
+ENTRY(cpu_v7m_switch_mm)
+	mov	pc, lr
+ENDPROC(cpu_v7m_switch_mm)
+
+.globl	cpu_v7m_suspend_size
+.equ	cpu_v7m_suspend_size, 0
+
+#ifdef CONFIG_ARM_CPU_SUSPEND
+ENTRY(cpu_v7m_do_suspend)
+	mov	pc, lr
+ENDPROC(cpu_v7m_do_suspend)
+
+ENTRY(cpu_v7m_do_resume)
+	mov	pc, lr
+ENDPROC(cpu_v7m_do_resume)
+#endif
+
+	.section ".text.init", #alloc, #execinstr
+
+/*
+ *	__v7m_setup
+ *
+ *	This should be able to cover all ARMv7-M cores.
+ */
+__v7m_setup:
+	@ Configure the vector table base address
+	ldr	r0, =BASEADDR_V7M_SCB
+	ldr	r12, =vector_table
+	str	r12, [r0, V7M_SCB_VTOR]
+
+	@ enable UsageFault, BusFault and MemManage fault.
+	ldr	r5, [r0, #V7M_SCB_SHCSR]
+	orr	r5, #(V7M_SCB_SHCSR_USGFAULTENA | V7M_SCB_SHCSR_BUSFAULTENA | V7M_SCB_SHCSR_MEMFAULTENA)
+	str	r5, [r0, #V7M_SCB_SHCSR]
+
+	@ Lower the priority of the SVC and PendSV exceptions
+	mov	r5, #0x80000000
+	str	r5, [r0, V7M_SCB_SHPR2]	@ set SVC priority
+	mov	r5, #0x00800000
+	str	r5, [r0, V7M_SCB_SHPR3]	@ set PendSV priority
+
+	@ SVC to run the kernel in this mode
+	adr	r1, BSYM(1f)
+	ldr	r5, [r12, #11 * 4]	@ read the SVC vector entry
+	str	r1, [r12, #11 * 4]	@ write the temporary SVC vector entry
+	mov	r6, lr			@ save LR
+	mov	r7, sp			@ save SP
+	ldr	sp, =__v7m_setup_stack_top
+	cpsie	i
+	svc	#0
+1:	cpsid	i
+	str	r5, [r12, #11 * 4]	@ restore the original SVC vector entry
+	mov	lr, r6			@ restore LR
+	mov	sp, r7			@ restore SP
+
+	@ Special-purpose control register
+	mov	r1, #1
+	msr	control, r1		@ Thread mode has unpriviledged access
+
+	@ Configure the System Control Register to ensure 8-byte stack alignment
+	@ Note the STKALIGN bit is either RW or RAO.
+	ldr	r12, [r0, V7M_SCB_CCR]	@ system control register
+	orr	r12, #V7M_SCB_CCR_STKALIGN
+	str	r12, [r0, V7M_SCB_CCR]
+	mov	pc, lr
+ENDPROC(__v7m_setup)
+
+	define_processor_functions v7m, dabort=nommu_early_abort, pabort=legacy_pabort, nommu=1
+
+	.section ".rodata"
+	string cpu_arch_name, "armv7m"
+	string cpu_elf_name "v7m"
+	string cpu_v7m_name "ARMv7-M"
+
+	.section ".proc.info.init", #alloc, #execinstr
+
+	/*
+	 * Match any ARMv7-M processor core.
+	 */
+	.type	__v7m_proc_info, #object
+__v7m_proc_info:
+	.long	0x000f0000		@ Required ID value
+	.long	0x000f0000		@ Mask for ID
+	.long   0			@ proc_info_list.__cpu_mm_mmu_flags
+	.long   0			@ proc_info_list.__cpu_io_mmu_flags
+	b	__v7m_setup		@ proc_info_list.__cpu_flush
+	.long	cpu_arch_name
+	.long	cpu_elf_name
+	.long	HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_IDIVT
+	.long	cpu_v7m_name
+	.long	v7m_processor_functions	@ proc_info_list.proc
+	.long	0			@ proc_info_list.tlb
+	.long	0			@ proc_info_list.user
+	.long	nop_cache_fns		@ proc_info_list.cache
+	.size	__v7m_proc_info, . - __v7m_proc_info
+
+__v7m_setup_stack:
+	.space	4 * 8				@ 8 registers
+__v7m_setup_stack_top: