arch/xtensa/include/asm/initialize_mmu.h

Source file repositories/reference/linux-study-clean/arch/xtensa/include/asm/initialize_mmu.h

File Facts

System
Linux kernel
Corpus path
arch/xtensa/include/asm/initialize_mmu.h
Extension
.h
Size
5203 bytes
Lines
246
Domain
Architecture Layer
Bucket
arch/xtensa
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _XTENSA_INITIALIZE_MMU_H
#define _XTENSA_INITIALIZE_MMU_H

#include <linux/init.h>
#include <linux/pgtable.h>
#include <asm/vectors.h>

#if XCHAL_HAVE_PTP_MMU
#define CA_BYPASS	(_PAGE_CA_BYPASS | _PAGE_HW_WRITE | _PAGE_HW_EXEC)
#define CA_WRITEBACK	(_PAGE_CA_WB     | _PAGE_HW_WRITE | _PAGE_HW_EXEC)
#else
#define CA_WRITEBACK	(0x4)
#endif

#ifdef __ASSEMBLER__

#define XTENSA_HWVERSION_RC_2009_0 230000

	.macro	initialize_mmu

#if XCHAL_HAVE_S32C1I && (XCHAL_HW_MIN_VERSION >= XTENSA_HWVERSION_RC_2009_0)
/*
 * We Have Atomic Operation Control (ATOMCTL) Register; Initialize it.
 * For details see Documentation/arch/xtensa/atomctl.rst
 */
#if XCHAL_DCACHE_IS_COHERENT
	movi	a3, 0x25	/* For SMP/MX -- internal for writeback,
				 * RCW otherwise
				 */
#else
	movi	a3, 0x29	/* non-MX -- Most cores use Std Memory
				 * Controlers which usually can't use RCW
				 */
#endif
	wsr	a3, atomctl
#endif  /* XCHAL_HAVE_S32C1I &&
	 * (XCHAL_HW_MIN_VERSION >= XTENSA_HWVERSION_RC_2009_0)
	 */

#if defined(CONFIG_MMU) && XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY
/*
 * Have MMU v3
 */

#if !XCHAL_HAVE_VECBASE
# error "MMU v3 requires reloc vectors"
#endif

	movi	a1, 0
	_call0	1f
	_j	2f

	.align	4
1:

#if CONFIG_KERNEL_LOAD_ADDRESS < 0x40000000ul
#define TEMP_MAPPING_VADDR 0x40000000
#else
#define TEMP_MAPPING_VADDR 0x00000000
#endif

	/* Step 1: invalidate mapping at 0x40000000..0x5FFFFFFF. */

	movi	a2, TEMP_MAPPING_VADDR | XCHAL_SPANNING_WAY
	idtlb	a2
	iitlb	a2
	isync

	/* Step 2: map 0x40000000..0x47FFFFFF to paddr containing this code
	 * and jump to the new mapping.
	 */

	srli	a3, a0, 27
	slli	a3, a3, 27
	addi	a3, a3, CA_BYPASS
	addi	a7, a2, 5 - XCHAL_SPANNING_WAY
	wdtlb	a3, a7
	witlb	a3, a7
	isync

	slli	a4, a0, 5
	srli	a4, a4, 5
	addi	a5, a2, -XCHAL_SPANNING_WAY
	add	a4, a4, a5
	jx	a4

	/* Step 3: unmap everything other than current area.
	 *	   Start at 0x60000000, wrap around, and end with 0x20000000
	 */
2:	movi	a4, 0x20000000

Annotation

Implementation Notes