path: root/arch/arm/mm/proc-xscale.S

/*
 *  linux/arch/arm/mm/proc-xscale.S
 *
 *  Author:	Nicolas Pitre
 *  Created:	November 2000
 *  Copyright:	(C) 2000, 2001 MontaVista Software Inc.
 *
 * 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.
 *
 * MMU functions for the Intel XScale CPUs
 *
 * 2001 Aug 21:
 *	some contributions by Brett Gaines <brett.w.gaines@intel.com>
 *	Copyright 2001 by Intel Corp.
 *
 * 2001 Sep 08:
 *	Completely revisited, many important fixes
 *	Nicolas Pitre <nico@cam.org>
 */

#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/assembler.h>
#include <asm/elf.h>
#include <asm/pgtable.h>
#include <asm/pgtable-hwdef.h>
#include <asm/page.h>
#include <asm/ptrace.h>
#include "proc-macros.S"

/*
 * This is the maximum size of an area which will be flushed.  If the area
 * is larger than this, then we flush the whole cache
 */
#define MAX_AREA_SIZE	32768

/*
 * the cache line size of the I and D cache
 */
#define CACHELINESIZE	32

/*
 * the size of the data cache
 */
#define CACHESIZE	32768

/*
 * Virtual address used to allocate the cache when flushed
 *
 * This must be an address range which is _never_ used.  It should
 * apparently have a mapping in the corresponding page table for
 * compatibility with future CPUs that _could_ require it.  For instance we
 * don't care.
 *
 * This must be aligned on a 2*CACHESIZE boundary.  The code selects one of
 * the 2 areas in alternance each time the clean_d_cache macro is used.
 * Without this the XScale core exhibits cache eviction problems and no one
 * knows why.
 *
 * Reminder: the vector table is located at 0xffff0000-0xffff0fff.
 */
#define CLEAN_ADDR	0xfffe0000

/*
 * This macro is used to wait for a CP15 write and is needed
 * when we have to ensure that the last operation to the co-pro
 * was completed before continuing with operation.
 */
	.macro	cpwait, rd
	mrc	p15, 0, \rd, c2, c0, 0		@ arbitrary read of cp15
	mov	\rd, \rd			@ wait for completion
	sub 	pc, pc, #4			@ flush instruction pipeline
	.endm

	.macro	cpwait_ret, lr, rd
	mrc	p15, 0, \rd, c2, c0, 0		@ arbitrary read of cp15
	sub	pc, \lr, \rd, LSR #32		@ wait for completion and
						@ flush instruction pipeline
	.endm

/*
 * This macro cleans the entire dcache using line allocate.
 * The main loop has been unrolled to reduce loop overhead.
 * rd and rs are two scratch registers.
 */
	.macro  clean_d_cache, rd, rs
	ldr	\rs, =clean_addr
	ldr	\rd, [\rs]
	eor	\rd, \rd, #CACHESIZE
	str	\rd, [\rs]
	add	\rs, \rd, #CACHESIZE
1:	mcr	p15, 0, \rd, c7, c2, 5		@ allocate D cache line
	add	\rd, \rd, #CACHELINESIZE
	mcr	p15, 0, \rd, c7, c2, 5		@ allocate D cache line
	add	\rd, \rd, #CACHELINESIZE
	mcr	p15, 0, \rd, c7, c2, 5		@ allocate D cache line
	add	\rd, \rd, #CACHELINESIZE
	mcr	p15, 0, \rd, c7, c2, 5		@ allocate D cache line
	add	\rd, \rd, #CACHELINESIZE
	teq	\rd, \rs
	bne	1b
	.endm

	.data
clean_addr:	.word	CLEAN_ADDR

	.text

/*
 * cpu_xscale_proc_init()
 *
 * Nothing too exciting at the moment
 */
ENTRY(cpu_xscale_proc_init)
	@ enable write buffer coalescing. Some bootloader disable it
	mrc	p15, 0, r1, c1, c0, 1
	bic	r1, r1, #1
	mcr	p15, 0, r1, c1, c0, 1
	mov	pc, lr

/*
 * cpu_xscale_proc_fin()
 */
ENTRY(cpu_xscale_proc_fin)
	str	lr, [sp, #-4]!
	mov	r0, #PSR_F_BIT|PSR_I_BIT|SVC_MODE
	msr	cpsr_c, r0
	bl	xscale_flush_kern_cache_all	@ clean caches
	mrc	p15, 0, r0, c1, c0, 0		@ ctrl register
	bic	r0, r0, #0x1800			@ ...IZ...........
	bic	r0, r0, #0x0006			@ .............CA.
	mcr	p15, 0, r0, c1, c0, 0		@ disable caches
	ldr	pc, [sp], #4

/*
 * cpu_xscale_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
 *
 * Beware PXA270 erratum E7.
 */
	.align	5
ENTRY(cpu_xscale_reset)
	mov	r1, #PSR_F_BIT|PSR_I_BIT|SVC_MODE
	msr	cpsr_c, r1			@ reset CPSR
	mcr	p15, 0, r1, c10, c4, 1		@ unlock I-TLB
	mcr	p15, 0, r1, c8, c5, 0		@ invalidate I-TLB
	mrc	p15, 0, r1, c1, c0, 0		@ ctrl register
	bic	r1, r1, #0x0086			@ ........B....CA.
	bic	r1, r1, #0x3900			@ ..VIZ..S........
	sub	pc, pc, #4			@ flush pipeline
	@ *** cache line aligned ***
	mcr	p15, 0, r1, c1, c0, 0		@ ctrl register
	bic	r1, r1, #0x0001			@ ...............M
	mcr	p15, 0, ip, c7, c7, 0		@ invalidate I,D caches & BTB
	mcr	p15, 0, r1, c1, c0, 0		@ ctrl register
	@ CAUTION: MMU turned off from this point. We count on the pipeline
	@ already containing those two last instructions to survive.
	mcr	p15, 0, ip, c8, c7, 0		@ invalidate I & D TLBs
	mov	pc, r0

/*
 * cpu_xscale_do_idle()
 *
 * Cause the processor to idle
 *
 * For now we do nothing but go to idle mode for every case
 *
 * XScale supports clock switching, but using idle mode support
 * allows external hardware to react to system state changes.
 */
	.align	5

ENTRY(cpu_xscale_do_idle)
	mov	r0, #1
	mcr	p14, 0, r0, c7, c0, 0		@ Go to IDLE
	mov	pc, lr

/* ================================= CACHE ================================ */

/*
 *	flush_user_cache_all()
 *
 *	Invalidate all cache entries in a particular address
 *	space.
 */
ENTRY(xscale_flush_user_cache_all)
	/* FALLTHROUGH */

/*
 *	flush_kern_cache_all()
 *
 *	Clean and invalidate the entire cache.
 */
ENTRY(xscale_flush_kern_cache_all)
	mov	r2, #VM_EXEC
	mov	ip, #0
__flush_whole_cache:
	clean_d_cache r0, r1
	tst	r2, #VM_EXEC
	mcrne	p15, 0, ip, c7, c5, 0		@ Invalidate I cache & BTB
	mcrne	p15, 0, ip, c7, c10, 4		@ Drain Write (& Fill) Buffer
	mov	pc, lr

/*
 *	flush_user_cache_range(start, end, vm_flags)
 *
 *	Invalidate a range of cache entries in the specified
 *	address space.
 *
 *	- start - start address (may not be aligned)
 *	- end	- end address (exclusive, may not be aligned)
 *	- vma	- vma_area_struct describing address space
 */
	.align	5
ENTRY(xscale_flush_user_cache_range)
	mov	ip, #0
	sub	r3, r1, r0			@ calculate total size
	cmp	r3, #MAX_AREA_SIZE
	bhs	__flush_whole_cache

1:	tst	r2, #VM_EXEC
	mcrne	p15, 0, r0, c7, c5, 1		@ Invalidate I cache line
	mcr	p15, 0, r0, c7, c10, 1		@ Clean D cache line
	mcr	p15, 0, r0, c7, c6, 1		@ Invalidate D cache line
	add	r0, r0, #CACHELINESIZE
	cmp	r0, r1
	blo	1b
	tst	r2, #VM_EXEC
	mcrne	p15, 0, ip, c7, c5, 6		@ Invalidate BTB
	mcrne	p15, 0, ip, c7, c10, 4		@ Drain Write (& Fill) Buffer
	mov	pc, lr

/*
 *	coherent_kern_range(start, end)
 *
 *	Ensure coherency between the Icache and the Dcache in the
 *	region described by start.  If you have non-snooping
 *	Harvard caches, you need to implement this function.
 *
 *	- start  - virtual start address
 *	- end	 - virtual end address
 *
 *	Note: single I-cache line invalidation isn't used here since
 *	it also trashes the mini I-cache used by JTAG debuggers.
 */
ENTRY(xscale_coherent_kern_range)
	bic	r0, r0, #CACHELINESIZE - 1
1:	mcr	p15, 0, r0, c7, c10, 1		@ clean D entry
	add	r0, r0, #CACHELINESIZE
	cmp	r0, r1
	blo	1b
	mov	r0, #0
	mcr	p15, 0, r0, c7, c5, 0		@ Invalidate I cache & BTB
	mcr	p15, 0, r0, c7, c10, 4		@