arch/sh/kernel/head_32.S - maze/linux - Git at Google

 /* $Id: head.S,v 1.7 2003/09/01 17:58:19 lethal Exp $
  *
  *  arch/sh/kernel/head.S
  *
  *  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
  *  Copyright (C) 2010  Matt Fleming
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
  * Head.S contains the SH exception handlers and startup code.
  */
 #include <linux/init.h>
 #include <linux/linkage.h>
 #include <asm/thread_info.h>
 #include <asm/mmu.h>
 #include <cpu/mmu_context.h>

 #ifdef CONFIG_CPU_SH4A
 #define SYNCO()		synco

 #define PREFI(label, reg)	\
 	mov.l	label, reg;	\
 	prefi	@reg
 #else
 #define SYNCO()
 #define PREFI(label, reg)
 #endif

 	.section	.empty_zero_page, "aw"
 ENTRY(empty_zero_page)
 	.long	1		/* MOUNT_ROOT_RDONLY */
 	.long	0		/* RAMDISK_FLAGS */
 	.long	0x0200		/* ORIG_ROOT_DEV */
 	.long	1		/* LOADER_TYPE */
 	.long	0x00000000	/* INITRD_START */
 	.long	0x00000000	/* INITRD_SIZE */
 #ifdef CONFIG_32BIT
 	.long	0x53453f00 + 32	/* "SE?" = 32 bit */
 #else
 	.long	0x53453f00 + 29	/* "SE?" = 29 bit */
 #endif
 1:
 	.skip	PAGE_SIZE - empty_zero_page - 1b

 	__HEAD

 /*
  * Condition at the entry of _stext:
  *
  *   BSC has already been initialized.
  *   INTC may or may not be initialized.
  *   VBR may or may not be initialized.
  *   MMU may or may not be initialized.
  *   Cache may or may not be initialized.
  *   Hardware (including on-chip modules) may or may not be initialized.
  *
  */
 ENTRY(_stext)
 	!			Initialize Status Register
 	mov.l	1f, r0		! MD=1, RB=0, BL=0, IMASK=0xF
 	ldc	r0, sr
 	!			Initialize global interrupt mask
 #ifdef CONFIG_CPU_HAS_SR_RB
 	mov	#0, r0
 	ldc	r0, r6_bank
 #endif

 	/*
 	 * Prefetch if possible to reduce cache miss penalty.
 	 *
 	 * We do this early on for SH-4A as a micro-optimization,
 	 * as later on we will have speculative execution enabled
 	 * and this will become less of an issue.
 	 */
 	PREFI(5f, r0)
 	PREFI(6f, r0)

 	!
 	mov.l	2f, r0
 	mov	r0, r15		! Set initial r15 (stack pointer)
 #ifdef CONFIG_CPU_HAS_SR_RB
 	mov.l	7f, r0
 	ldc	r0, r7_bank	! ... and initial thread_info
 #endif

 #ifdef CONFIG_PMB
 /*
  * Reconfigure the initial PMB mappings setup by the hardware.
  *
  * When we boot in 32-bit MMU mode there are 2 PMB entries already
  * setup for us.
  *
  * Entry       VPN	   PPN	    V	SZ	C	UB	WT
  * ---------------------------------------------------------------
  *   0	    0x80000000 0x00000000   1  512MB	1	0	1
  *   1	    0xA0000000 0x00000000   1  512MB	0	0	0
  *
  * But we reprogram them here because we want complete control over
  * our address space and the initial mappings may not map PAGE_OFFSET
  * to __MEMORY_START (or even map all of our RAM).
  *
  * Once we've setup cached and uncached mappings we clear the rest of the
  * PMB entries. This clearing also deals with the fact that PMB entries
  * can persist across reboots. The PMB could have been left in any state
  * when the reboot occurred, so to be safe we clear all entries and start
  * with with a clean slate.
  *
  * The uncached mapping is constructed using the smallest possible
  * mapping with a single unbufferable page. Only the kernel text needs to
  * be covered via the uncached mapping so that certain functions can be
  * run uncached.
  *
  * Drivers and the like that have previously abused the 1:1 identity
  * mapping are unsupported in 32-bit mode and must specify their caching
  * preference when page tables are constructed.
  *
  * This frees up the P2 space for more nefarious purposes.
  *
  * Register utilization is as follows:
  *
  *	r0 = PMB_DATA data field
  *	r1 = PMB_DATA address field
  *	r2 = PMB_ADDR data field
  *	r3 = PMB_ADDR address field
  *	r4 = PMB_E_SHIFT
  *	r5 = remaining amount of RAM to map
  *	r6 = PMB mapping size we're trying to use
  *	r7 = cached_to_uncached
  *	r8 = scratch register
  *	r9 = scratch register
  *	r10 = number of PMB entries we've setup
  *	r11 = scratch register
  */

 	mov.l	.LMMUCR, r1	/* Flush the TLB */
 	mov.l	@r1, r0
 	or	#MMUCR_TI, r0
 	mov.l	r0, @r1

 	mov.l	.LMEMORY_SIZE, r5

 	mov	#PMB_E_SHIFT, r0
 	mov	#0x1, r4
 	shld	r0, r4

 	mov.l	.LFIRST_DATA_ENTRY, r0
 	mov.l	.LPMB_DATA, r1
 	mov.l	.LFIRST_ADDR_ENTRY, r2
 	mov.l	.LPMB_ADDR, r3

 	/*
 	 * First we need to walk the PMB and figure out if there are any
 	 * existing mappings that match the initial mappings VPN/PPN.
 	 * If these have already been established by the bootloader, we
 	 * don't bother setting up new entries here, and let the late PMB
 	 * initialization take care of things instead.
 	 *
 	 * Note that we may need to coalesce and merge entries in order
 	 * to reclaim more available PMB slots, which is much more than
 	 * we want to do at this early stage.
 	 */
 	mov	#0, r10
 	mov	#NR_PMB_ENTRIES, r9

 	mov	r1, r7		/* temporary PMB_DATA iter */

 .Lvalidate_existing_mappings:

 	mov.l	.LPMB_DATA_MASK, r11
 	mov.l	@r7, r8
 	and	r11, r8
 	cmp/eq	r0, r8		/* Check for valid __MEMORY_START mappings */
 	bt	.Lpmb_done

 	add	#1, r10		/* Increment the loop counter */
 	cmp/eq	r9, r10
 	bf/s	.Lvalidate_existing_mappings
 	 add	r4, r7		/* Increment to the next PMB_DATA entry */

 	/*
 	 * If we've fallen through, continue with setting up the initial
 	 * mappings.
 	 */

 	mov	r5, r7		/* cached_to_uncached */
 	mov	#0, r10

 #ifdef CONFIG_UNCACHED_MAPPING
 	/*
 	 * Uncached mapping
 	 */
 	mov	#(PMB_SZ_16M >> 2), r9
 	shll2	r9

 	mov	#(PMB_UB >> 8), r8
 	shll8	r8

 	or	r0, r8
 	or	r9, r8
 	mov.l	r8, @r1
 	mov	r2, r8
 	add	r7, r8
 	mov.l	r8, @r3

 	add	r4, r1
 	add	r4, r3
 	add	#1, r10
 #endif

 /*
  * Iterate over all of the available sizes from largest to
  * smallest for constructing the cached mapping.
  */
 #define __PMB_ITER_BY_SIZE(size)			\
 .L##size:						\
 	mov	#(size >> 4), r6;			\
 	shll16	r6;					\
 	shll8	r6;					\
 							\
 	cmp/hi	r5, r6;					\
 	bt	9999f;					\
 							\
 	mov	#(PMB_SZ_##size##M >> 2), r9;		\
 	shll2	r9;					\
 							\
 	/*						\
 	 * Cached mapping				\
 	 */						\
 	mov	#PMB_C, r8;				\
 	or	r0, r8;					\
 	or	r9, r8;					\
 	mov.l	r8, @r1;				\
 	mov.l	r2, @r3;				\
 							\
 	/* Increment to the next PMB_DATA entry */	\
 	add	r4, r1;					\
 	/* Increment to the next PMB_ADDR entry */	\
 	add	r4, r3;					\
 	/* Increment number of PMB entries */		\
 	add	#1, r10;				\
 							\
 	sub	r6, r5;					\
 	add	r6, r0;					\
 	add	r6, r2;					\
 							\
 	bra	.L##size;				\
 9999:

 	__PMB_ITER_BY_SIZE(512)
 	__PMB_ITER_BY_SIZE(128)
 	__PMB_ITER_BY_SIZE(64)
 	__PMB_ITER_BY_SIZE(16)

 #ifdef CONFIG_UNCACHED_MAPPING
 	/*
 	 * Now that we can access it, update cached_to_uncached and
 	 * uncached_size.
 	 */
 	mov.l	.Lcached_to_uncached, r0
 	mov.l	r7, @r0

 	mov.l	.Luncached_size, r0
 	mov	#1, r7
 	shll16	r7
 	shll8	r7
 	mov.l	r7, @r0
 #endif

 	/*
 	 * Clear the remaining PMB entries.
 	 *
 	 * r3 = entry to begin clearing from
 	 * r10 = number of entries we've setup so far
 	 */
 	mov	#0, r1
 	mov	#NR_PMB_ENTRIES, r0

 .Lagain:
 	mov.l	r1, @r3		/* Clear PMB_ADDR entry */
 	add	#1, r10		/* Increment the loop counter */
 	cmp/eq	r0, r10
 	bf/s	.Lagain
 	 add	r4, r3		/* Increment to the next PMB_ADDR entry */

 	mov.l	6f, r0
 	icbi	@r0

 .Lpmb_done:
 #endif /* CONFIG_PMB */

 #ifndef CONFIG_SH_NO_BSS_INIT
 	/*
 	 * Don't clear BSS if running on slow platforms such as an RTL simulation,
 	 * remote memory via SHdebug link, etc.  For these the memory can be guaranteed
 	 * to be all zero on boot anyway.
 	 */
 				! Clear BSS area
 #ifdef CONFIG_SMP
 	mov.l	3f, r0
 	cmp/eq	#0, r0		! skip clear if set to zero
 	bt	10f
 #endif

 	mov.l	3f, r1
 	add	#4, r1
 	mov.l	4f, r2
 	mov	#0, r0
 9:	cmp/hs	r2, r1
 	bf/s	9b		! while (r1 < r2)
 	 mov.l	r0,@-r2

 10:
 #endif

 	!			Additional CPU initialization
 	mov.l	6f, r0
 	jsr	@r0
 	 nop

 	SYNCO()			! Wait for pending instructions..

 	!			Start kernel
 	mov.l	5f, r0
 	jmp	@r0
 	 nop

 	.balign 4
 #if defined(CONFIG_CPU_SH2)
 1:	.long	0x000000F0		! IMASK=0xF
 #else
 1:	.long	0x500080F0		! MD=1, RB=0, BL=1, FD=1, IMASK=0xF
 #endif
 ENTRY(stack_start)
 2:	.long	init_thread_union+THREAD_SIZE
 3:	.long	__bss_start
 4:	.long	_end
 5:	.long	start_kernel
 6:	.long	cpu_init
 7:	.long	init_thread_union

 #ifdef CONFIG_PMB
 .LPMB_ADDR:		.long	PMB_ADDR
 .LPMB_DATA:		.long	PMB_DATA
 .LPMB_DATA_MASK:	.long	PMB_PFN_MASK | PMB_V
 .LFIRST_ADDR_ENTRY:	.long	PAGE_OFFSET | PMB_V
 .LFIRST_DATA_ENTRY:	.long	__MEMORY_START | PMB_V
 .LMMUCR:		.long	MMUCR
 .LMEMORY_SIZE:		.long	__MEMORY_SIZE
 #ifdef CONFIG_UNCACHED_MAPPING
 .Lcached_to_uncached:	.long	cached_to_uncached
 .Luncached_size:	.long	uncached_size
 #endif
 #endif
	/* $Id: head.S,v 1.7 2003/09/01 17:58:19 lethal Exp $
	*
	* arch/sh/kernel/head.S
	*
	* Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
	* Copyright (C) 2010 Matt Fleming
	*
	* This file is subject to the terms and conditions of the GNU General Public
	* License. See the file "COPYING" in the main directory of this archive
	* for more details.
	*
	* Head.S contains the SH exception handlers and startup code.
	*/
	#include <linux/init.h>
	#include <linux/linkage.h>
	#include <asm/thread_info.h>
	#include <asm/mmu.h>
	#include <cpu/mmu_context.h>

	#ifdef CONFIG_CPU_SH4A
	#define SYNCO() synco

	#define PREFI(label, reg) \
	mov.l label, reg; \
	prefi @reg
	#else
	#define SYNCO()
	#define PREFI(label, reg)
	#endif

	.section .empty_zero_page, "aw"
	ENTRY(empty_zero_page)
	.long 1 /* MOUNT_ROOT_RDONLY */
	.long 0 /* RAMDISK_FLAGS */
	.long 0x0200 /* ORIG_ROOT_DEV */
	.long 1 /* LOADER_TYPE */
	.long 0x00000000 /* INITRD_START */
	.long 0x00000000 /* INITRD_SIZE */
	#ifdef CONFIG_32BIT
	.long 0x53453f00 + 32 /* "SE?" = 32 bit */
	#else
	.long 0x53453f00 + 29 /* "SE?" = 29 bit */
	#endif
	1:
	.skip PAGE_SIZE - empty_zero_page - 1b

	__HEAD

	/*
	* Condition at the entry of _stext:
	*
	* BSC has already been initialized.
	* INTC may or may not be initialized.
	* VBR may or may not be initialized.
	* MMU may or may not be initialized.
	* Cache may or may not be initialized.
	* Hardware (including on-chip modules) may or may not be initialized.
	*
	*/
	ENTRY(_stext)
	! Initialize Status Register
	mov.l 1f, r0 ! MD=1, RB=0, BL=0, IMASK=0xF
	ldc r0, sr
	! Initialize global interrupt mask
	#ifdef CONFIG_CPU_HAS_SR_RB
	mov #0, r0
	ldc r0, r6_bank
	#endif

	/*
	* Prefetch if possible to reduce cache miss penalty.
	*
	* We do this early on for SH-4A as a micro-optimization,
	* as later on we will have speculative execution enabled
	* and this will become less of an issue.
	*/
	PREFI(5f, r0)
	PREFI(6f, r0)

	!
	mov.l 2f, r0
	mov r0, r15 ! Set initial r15 (stack pointer)
	#ifdef CONFIG_CPU_HAS_SR_RB
	mov.l 7f, r0
	ldc r0, r7_bank ! ... and initial thread_info
	#endif

	#ifdef CONFIG_PMB
	/*
	* Reconfigure the initial PMB mappings setup by the hardware.
	*
	* When we boot in 32-bit MMU mode there are 2 PMB entries already
	* setup for us.
	*
	* Entry VPN PPN V SZ C UB WT
	* ---------------------------------------------------------------
	* 0 0x80000000 0x00000000 1 512MB 1 0 1
	* 1 0xA0000000 0x00000000 1 512MB 0 0 0
	*
	* But we reprogram them here because we want complete control over
	* our address space and the initial mappings may not map PAGE_OFFSET
	* to __MEMORY_START (or even map all of our RAM).
	*
	* Once we've setup cached and uncached mappings we clear the rest of the
	* PMB entries. This clearing also deals with the fact that PMB entries
	* can persist across reboots. The PMB could have been left in any state
	* when the reboot occurred, so to be safe we clear all entries and start
	* with with a clean slate.
	*
	* The uncached mapping is constructed using the smallest possible
	* mapping with a single unbufferable page. Only the kernel text needs to
	* be covered via the uncached mapping so that certain functions can be
	* run uncached.
	*
	* Drivers and the like that have previously abused the 1:1 identity
	* mapping are unsupported in 32-bit mode and must specify their caching
	* preference when page tables are constructed.
	*
	* This frees up the P2 space for more nefarious purposes.
	*
	* Register utilization is as follows:
	*
	* r0 = PMB_DATA data field
	* r1 = PMB_DATA address field
	* r2 = PMB_ADDR data field
	* r3 = PMB_ADDR address field
	* r4 = PMB_E_SHIFT
	* r5 = remaining amount of RAM to map
	* r6 = PMB mapping size we're trying to use
	* r7 = cached_to_uncached
	* r8 = scratch register
	* r9 = scratch register
	* r10 = number of PMB entries we've setup
	* r11 = scratch register
	*/

	mov.l .LMMUCR, r1 /* Flush the TLB */
	mov.l @r1, r0
	or #MMUCR_TI, r0
	mov.l r0, @r1

	mov.l .LMEMORY_SIZE, r5

	mov #PMB_E_SHIFT, r0
	mov #0x1, r4
	shld r0, r4

	mov.l .LFIRST_DATA_ENTRY, r0
	mov.l .LPMB_DATA, r1
	mov.l .LFIRST_ADDR_ENTRY, r2
	mov.l .LPMB_ADDR, r3

	/*
	* First we need to walk the PMB and figure out if there are any
	* existing mappings that match the initial mappings VPN/PPN.
	* If these have already been established by the bootloader, we
	* don't bother setting up new entries here, and let the late PMB
	* initialization take care of things instead.
	*
	* Note that we may need to coalesce and merge entries in order
	* to reclaim more available PMB slots, which is much more than
	* we want to do at this early stage.
	*/
	mov #0, r10
	mov #NR_PMB_ENTRIES, r9

	mov r1, r7 /* temporary PMB_DATA iter */

	.Lvalidate_existing_mappings:

	mov.l .LPMB_DATA_MASK, r11
	mov.l @r7, r8
	and r11, r8
	cmp/eq r0, r8 /* Check for valid __MEMORY_START mappings */
	bt .Lpmb_done

	add #1, r10 /* Increment the loop counter */
	cmp/eq r9, r10
	bf/s .Lvalidate_existing_mappings
	add r4, r7 /* Increment to the next PMB_DATA entry */

	/*
	* If we've fallen through, continue with setting up the initial
	* mappings.
	*/

	mov r5, r7 /* cached_to_uncached */
	mov #0, r10

	#ifdef CONFIG_UNCACHED_MAPPING
	/*
	* Uncached mapping
	*/
	mov #(PMB_SZ_16M >> 2), r9
	shll2 r9

	mov #(PMB_UB >> 8), r8
	shll8 r8

	or r0, r8
	or r9, r8
	mov.l r8, @r1
	mov r2, r8
	add r7, r8
	mov.l r8, @r3

	add r4, r1
	add r4, r3
	add #1, r10
	#endif

	/*
	* Iterate over all of the available sizes from largest to
	* smallest for constructing the cached mapping.
	*/
	#define __PMB_ITER_BY_SIZE(size) \
	.L##size: \
	mov #(size >> 4), r6; \
	shll16 r6; \
	shll8 r6; \
	\
	cmp/hi r5, r6; \
	bt 9999f; \
	\
	mov #(PMB_SZ_##size##M >> 2), r9; \
	shll2 r9; \
	\
	/* \
	* Cached mapping \
	*/ \
	mov #PMB_C, r8; \
	or r0, r8; \
	or r9, r8; \
	mov.l r8, @r1; \
	mov.l r2, @r3; \
	\
	/* Increment to the next PMB_DATA entry */ \
	add r4, r1; \
	/* Increment to the next PMB_ADDR entry */ \
	add r4, r3; \
	/* Increment number of PMB entries */ \
	add #1, r10; \
	\
	sub r6, r5; \
	add r6, r0; \
	add r6, r2; \
	\
	bra .L##size; \
	9999:

	__PMB_ITER_BY_SIZE(512)
	__PMB_ITER_BY_SIZE(128)
	__PMB_ITER_BY_SIZE(64)
	__PMB_ITER_BY_SIZE(16)

	#ifdef CONFIG_UNCACHED_MAPPING
	/*
	* Now that we can access it, update cached_to_uncached and
	* uncached_size.
	*/
	mov.l .Lcached_to_uncached, r0
	mov.l r7, @r0

	mov.l .Luncached_size, r0
	mov #1, r7
	shll16 r7
	shll8 r7
	mov.l r7, @r0
	#endif

	/*
	* Clear the remaining PMB entries.
	*
	* r3 = entry to begin clearing from
	* r10 = number of entries we've setup so far
	*/
	mov #0, r1
	mov #NR_PMB_ENTRIES, r0

	.Lagain:
	mov.l r1, @r3 /* Clear PMB_ADDR entry */
	add #1, r10 /* Increment the loop counter */
	cmp/eq r0, r10
	bf/s .Lagain
	add r4, r3 /* Increment to the next PMB_ADDR entry */

	mov.l 6f, r0
	icbi @r0

	.Lpmb_done:
	#endif /* CONFIG_PMB */

	#ifndef CONFIG_SH_NO_BSS_INIT
	/*
	* Don't clear BSS if running on slow platforms such as an RTL simulation,
	* remote memory via SHdebug link, etc. For these the memory can be guaranteed
	* to be all zero on boot anyway.
	*/
	! Clear BSS area
	#ifdef CONFIG_SMP
	mov.l 3f, r0
	cmp/eq #0, r0 ! skip clear if set to zero
	bt 10f
	#endif

	mov.l 3f, r1
	add #4, r1
	mov.l 4f, r2
	mov #0, r0
	9: cmp/hs r2, r1
	bf/s 9b ! while (r1 < r2)
	mov.l r0,@-r2

	10:
	#endif

	! Additional CPU initialization
	mov.l 6f, r0
	jsr @r0
	nop

	SYNCO() ! Wait for pending instructions..

	! Start kernel
	mov.l 5f, r0
	jmp @r0
	nop

	.balign 4
	#if defined(CONFIG_CPU_SH2)
	1: .long 0x000000F0 ! IMASK=0xF
	#else
	1: .long 0x500080F0 ! MD=1, RB=0, BL=1, FD=1, IMASK=0xF
	#endif
	ENTRY(stack_start)
	2: .long init_thread_union+THREAD_SIZE
	3: .long __bss_start
	4: .long _end
	5: .long start_kernel
	6: .long cpu_init
	7: .long init_thread_union

	#ifdef CONFIG_PMB
	.LPMB_ADDR: .long PMB_ADDR
	.LPMB_DATA: .long PMB_DATA
	.LPMB_DATA_MASK: .long PMB_PFN_MASK \| PMB_V
	.LFIRST_ADDR_ENTRY: .long PAGE_OFFSET \| PMB_V
	.LFIRST_DATA_ENTRY: .long __MEMORY_START \| PMB_V
	.LMMUCR: .long MMUCR
	.LMEMORY_SIZE: .long __MEMORY_SIZE
	#ifdef CONFIG_UNCACHED_MAPPING
	.Lcached_to_uncached: .long cached_to_uncached
	.Luncached_size: .long uncached_size
	#endif
	#endif