head.s

底层驱动开发

/* $Id: head.S,v 1.87 2002/02/09 19:49:31 davem Exp $
 * head.S: Initial boot code for the Sparc64 port of Linux.
 *
 * Copyright (C) 1996,1997 David S. Miller ([e-mail])
 * Copyright (C) 1996 David Sitsky ([e-mail])
 * Copyright (C) 1997,1998 Jakub Jelinek ([e-mail])
 * Copyright (C) 1997 Miguel de Icaza ([e-mail])
 */

#include <linux/config.h>
#include <linux/version.h>
#include <linux/errno.h>
#include <asm/thread_info.h>
#include <asm/asi.h>
#include <asm/pstate.h>
#include <asm/ptrace.h>
#include <asm/spitfire.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/errno.h>
#include <asm/signal.h>
#include <asm/processor.h>
#include <asm/lsu.h>
#include <asm/dcr.h>
#include <asm/dcu.h>
#include <asm/head.h>
#include <asm/ttable.h>
#include <asm/mmu.h>
	
/* This section from from _start to sparc64_boot_end should fit into
 * 0x0000000000404000 to 0x0000000000408000.
 */
	.text
	.globl	start, _start, stext, _stext
_start:
start:
_stext:
stext:
! 0x0000000000404000
	b	sparc64_boot
	 flushw					/* Flush register file.      */

/* This stuff has to be in sync with SILO and other potential boot loaders
 * Fields should be kept upward compatible and whenever any change is made,
 * HdrS version should be incremented.
 */
        .global root_flags, ram_flags, root_dev
        .global sparc_ramdisk_image, sparc_ramdisk_size
	.global sparc_ramdisk_image64

        .ascii  "HdrS"
        .word   LINUX_VERSION_CODE

	/* History:
	 *
	 * 0x0300 : Supports being located at other than 0x4000
	 * 0x0202 : Supports kernel params string
	 * 0x0201 : Supports reboot_command
	 */
	.half   0x0301          /* HdrS version */

root_flags:
        .half   1
root_dev:
        .half   0
ram_flags:
        .half   0
sparc_ramdisk_image:
        .word   0
sparc_ramdisk_size:
        .word   0
        .xword  reboot_command
	.xword	bootstr_info
sparc_ramdisk_image64:
	.xword	0
	.word	_end

	/* PROM cif handler code address is in %o4.  */
sparc64_boot:
1:	rd	%pc, %g7
	set	1b, %g1
	cmp	%g1, %g7
	be,pn	%xcc, sparc64_boot_after_remap
	 mov	%o4, %l7

	/* We need to remap the kernel.  Use position independant
	 * code to remap us to KERNBASE.
	 *
	 * SILO can invoke us with 32-bit address masking enabled,
	 * so make sure that's clear.
	 */
	rdpr	%pstate, %g1
	andn	%g1, PSTATE_AM, %g1
	wrpr	%g1, 0x0, %pstate
	ba,a,pt	%xcc, 1f

	.globl	prom_finddev_name, prom_chosen_path
	.globl	prom_getprop_name, prom_mmu_name
	.globl	prom_callmethod_name, prom_translate_name
	.globl	prom_map_name, prom_unmap_name, prom_mmu_ihandle_cache
	.globl	prom_boot_mapped_pc, prom_boot_mapping_mode
	.globl	prom_boot_mapping_phys_high, prom_boot_mapping_phys_low
prom_finddev_name:
	.asciz	"finddevice"
prom_chosen_path:
	.asciz	"/chosen"
prom_getprop_name:
	.asciz	"getprop"
prom_mmu_name:
	.asciz	"mmu"
prom_callmethod_name:
	.asciz	"call-method"
prom_translate_name:
	.asciz	"translate"
prom_map_name:
	.asciz	"map"
prom_unmap_name:
	.asciz	"unmap"
	.align	4
prom_mmu_ihandle_cache:
	.word	0
prom_boot_mapped_pc:
	.word	0
prom_boot_mapping_mode:
	.word	0
	.align	8
prom_boot_mapping_phys_high:
	.xword	0
prom_boot_mapping_phys_low:
	.xword	0
1:
	rd	%pc, %l0
	mov	(1b - prom_finddev_name), %l1
	mov	(1b - prom_chosen_path), %l2
	mov	(1b - prom_boot_mapped_pc), %l3
	sub	%l0, %l1, %l1
	sub	%l0, %l2, %l2
	sub	%l0, %l3, %l3
	stw	%l0, [%l3]
	sub	%sp, (192 + 128), %sp

	/* chosen_node = prom_finddevice("/chosen") */
	stx	%l1, [%sp + 2047 + 128 + 0x00]	! service, "finddevice"
	mov	1, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x08]	! num_args, 1
	stx	%l3, [%sp + 2047 + 128 + 0x10]	! num_rets, 1
	stx	%l2, [%sp + 2047 + 128 + 0x18]	! arg1, "/chosen"
	stx	%g0, [%sp + 2047 + 128 + 0x20]	! ret1
	call	%l7
	 add	%sp, (2047 + 128), %o0		! argument array

	ldx	[%sp + 2047 + 128 + 0x20], %l4	! chosen device node

	mov	(1b - prom_getprop_name), %l1
	mov	(1b - prom_mmu_name), %l2
	mov	(1b - prom_mmu_ihandle_cache), %l5
	sub	%l0, %l1, %l1
	sub	%l0, %l2, %l2
	sub	%l0, %l5, %l5

	/* prom_mmu_ihandle_cache = prom_getint(chosen_node, "mmu") */
	stx	%l1, [%sp + 2047 + 128 + 0x00]	! service, "getprop"
	mov	4, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x08]	! num_args, 4
	mov	1, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x10]	! num_rets, 1
	stx	%l4, [%sp + 2047 + 128 + 0x18]	! arg1, chosen_node
	stx	%l2, [%sp + 2047 + 128 + 0x20]	! arg2, "mmu"
	stx	%l5, [%sp + 2047 + 128 + 0x28]	! arg3, &prom_mmu_ihandle_cache
	mov	4, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x30]	! arg4, sizeof(arg3)
	stx	%g0, [%sp + 2047 + 128 + 0x38]	! ret1
	call	%l7
	 add	%sp, (2047 + 128), %o0		! argument array

	mov	(1b - prom_callmethod_name), %l1
	mov	(1b - prom_translate_name), %l2
	sub	%l0, %l1, %l1
	sub	%l0, %l2, %l2
	lduw	[%l5], %l5			! prom_mmu_ihandle_cache

	stx	%l1, [%sp + 2047 + 128 + 0x00]	! service, "call-method"
	mov	3, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x08]	! num_args, 3
	mov	5, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x10]	! num_rets, 5
	stx	%l2, [%sp + 2047 + 128 + 0x18]	! arg1: "translate"
	stx	%l5, [%sp + 2047 + 128 + 0x20]	! arg2: prom_mmu_ihandle_cache
	/* PAGE align */
	srlx	%l0, 13, %l3
	sllx	%l3, 13, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x28]	! arg3: vaddr, our PC
	stx	%g0, [%sp + 2047 + 128 + 0x30]	! res1
	stx	%g0, [%sp + 2047 + 128 + 0x38]	! res2
	stx	%g0, [%sp + 2047 + 128 + 0x40]	! res3
	stx	%g0, [%sp + 2047 + 128 + 0x48]	! res4
	stx	%g0, [%sp + 2047 + 128 + 0x50]	! res5
	call	%l7
	 add	%sp, (2047 + 128), %o0		! argument array

	ldx	[%sp + 2047 + 128 + 0x40], %l1	! translation mode
	mov	(1b - prom_boot_mapping_mode), %l4
	sub	%l0, %l4, %l4
	stw	%l1, [%l4]
	mov	(1b - prom_boot_mapping_phys_high), %l4
	sub	%l0, %l4, %l4
	ldx	[%sp + 2047 + 128 + 0x48], %l2	! physaddr high
	stx	%l2, [%l4 + 0x0]
	ldx	[%sp + 2047 + 128 + 0x50], %l3	! physaddr low
	/* 4MB align */
	srlx	%l3, 22, %l3
	sllx	%l3, 22, %l3
	stx	%l3, [%l4 + 0x8]

	/* Leave service as-is, "call-method" */
	mov	7, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x08]	! num_args, 7
	mov	1, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x10]	! num_rets, 1
	mov	(1b - prom_map_name), %l3
	sub	%l0, %l3, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x18]	! arg1: "map"
	/* Leave arg2 as-is, prom_mmu_ihandle_cache */
	mov	-1, %l3
	stx	%l3, [%sp + 2047 + 128 + 0x28]	! arg3: mode (-1 default)
	sethi	%hi(8 * 1024 * 1024), %l3
	stx	%l3, [%sp + 2047 + 128 + 0x30]	! arg4: size (8MB)
	sethi	%hi(KERNBASE), %l3
	stx	%l3, [%sp + 2047 + 128 + 0x38]	! arg5: vaddr (KERNBASE)
	stx	%g0, [%sp + 2047 + 128 + 0x40]	! arg6: empty
	mov	(1b - prom_boot_mapping_phys_low), %l3
	sub	%l0, %l3, %l3
	ldx	[%l3], %l3
	stx	%l3, [%sp + 2047 + 128 + 0x48]	! arg7: phys addr
	call	%l7
	 add	%sp, (2047 + 128), %o0		! argument array

	add	%sp, (192 + 128), %sp

sparc64_boot_after_remap:
	BRANCH_IF_CHEETAH_BASE(g1,g7,cheetah_boot)
	BRANCH_IF_CHEETAH_PLUS_OR_FOLLOWON(g1,g7,cheetah_plus_boot)
	ba,pt	%xcc, spitfire_boot
	 nop

cheetah_plus_boot:
	/* Preserve OBP chosen DCU and DCR register settings.  */
	ba,pt	%xcc, cheetah_generic_boot
	 nop

cheetah_boot:
	mov	DCR_BPE | DCR_RPE | DCR_SI | DCR_IFPOE | DCR_MS, %g1
	wr	%g1, %asr18

	sethi	%uhi(DCU_ME|DCU_RE|DCU_HPE|DCU_SPE|DCU_SL|DCU_WE), %g7
	or	%g7, %ulo(DCU_ME|DCU_RE|DCU_HPE|DCU_SPE|DCU_SL|DCU_WE), %g7
	sllx	%g7, 32, %g7
	or	%g7, DCU_DM | DCU_IM | DCU_DC | DCU_IC, %g7
	stxa	%g7, [%g0] ASI_DCU_CONTROL_REG
	membar	#Sync

cheetah_generic_boot:
	mov	TSB_EXTENSION_P, %g3
	stxa	%g0, [%g3] ASI_DMMU
	stxa	%g0, [%g3] ASI_IMMU
	membar	#Sync

	mov	TSB_EXTENSION_S, %g3
	stxa	%g0, [%g3] ASI_DMMU
	membar	#Sync

	mov	TSB_EXTENSION_N, %g3
	stxa	%g0, [%g3] ASI_DMMU
	stxa	%g0, [%g3] ASI_IMMU
	membar	#Sync

	ba,a,pt	%xcc, jump_to_sun4u_init

spitfire_boot:
	/* Typically PROM has already enabled both MMU's and both on-chip
	 * caches, but we do it here anyway just to be paranoid.
	 */
	mov	(LSU_CONTROL_IC|LSU_CONTROL_DC|LSU_CONTROL_IM|LSU_CONTROL_DM), %g1
	stxa	%g1, [%g0] ASI_LSU_CONTROL
	membar	#Sync

jump_to_sun4u_init:
	/*
	 * Make sure we are in privileged mode, have address masking,
         * using the ordinary globals and have enabled floating
         * point.
	 *
	 * Again, typically PROM has left %pil at 13 or similar, and
	 * (PSTATE_PRIV | PSTATE_PEF | PSTATE_IE) in %pstate.
         */
	wrpr    %g0, (PSTATE_PRIV|PSTATE_PEF|PSTATE_IE), %pstate
	wr	%g0, 0, %fprs

	set	sun4u_init, %g2
	jmpl    %g2 + %g0, %g0
	 nop

sun4u_init:
	/* Set ctx 0 */
	mov	PRIMARY_CONTEXT, %g7
	stxa	%g0, [%g7] ASI_DMMU
	membar	#Sync

	mov	SECONDARY_CONTEXT, %g7
	stxa	%g0, [%g7] ASI_DMMU
	membar	#Sync

	BRANCH_IF_ANY_CHEETAH(g1,g7,cheetah_tlb_fixup)

	ba,pt	%xcc, spitfire_tlb_fixup
	 nop

cheetah_tlb_fixup:
	mov	2, %g2		/* Set TLB type to cheetah+. */
	BRANCH_IF_CHEETAH_PLUS_OR_FOLLOWON(g1,g7,1f)

	mov	1, %g2		/* Set TLB type to cheetah. */

1:	sethi	%hi(tlb_type), %g1
	stw	%g2, [%g1 + %lo(tlb_type)]

	/* Patch copy/page operations to cheetah optimized versions. */
	call	cheetah_patch_copyops
	 nop
	call	cheetah_patch_copy_page
	 nop
	call	cheetah_patch_cachetlbops
	 nop

	ba,pt	%xcc, tlb_fixup_done
	 nop

spitfire_tlb_fixup:
	/* Set TLB type to spitfire. */
	mov	0, %g2
	sethi	%hi(tlb_type), %g1
	stw	%g2, [%g1 + %lo(tlb_type)]

tlb_fixup_done:
	sethi	%hi(init_thread_union), %g6
	or	%g6, %lo(init_thread_union), %g6
	ldx	[%g6 + TI_TASK], %g4
	mov	%sp, %l6
	mov	%o4, %l7

	wr	%g0, ASI_P, %asi
	mov	1, %g1
	sllx	%g1, THREAD_SHIFT, %g1
	sub	%g1, (STACKFRAME_SZ + STACK_BIAS), %g1
	add	%g6, %g1, %sp
	mov	0, %fp

	/* Set per-cpu pointer initially to zero, this makes
	 * the boot-cpu use the in-kernel-image per-cpu areas
	 * before setup_per_cpu_area() is invoked.
	 */
	clr	%g5

	wrpr	%g0, 0, %wstate
	wrpr	%g0, 0x0, %tl

	/* Clear the bss */
	sethi	%hi(__bss_start), %o0
	or	%o0, %lo(__bss_start), %o0
	sethi	%hi(_end), %o1
	or	%o1, %lo(_end), %o1
	call	__bzero
	 sub	%o1, %o0, %o1

	mov	%l6, %o1			! OpenPROM stack
	call	prom_init
	 mov	%l7, %o0			! OpenPROM cif handler

	/* Off we go.... */
	call	start_kernel
	 nop
	/* Not reached... */

	/* This is meant to allow the sharing of this code between
	 * boot processor invocation (via setup_tba() below) and
	 * secondary processor startup (via trampoline.S).  The
	 * former does use this code, the latter does not yet due
	 * to some complexities.  That should be fixed up at some
	 * point.
	 *
	 * There used to be enormous complexity wrt. transferring
	 * over from the firwmare's trap table to the Linux kernel's.
	 * For example, there was a chicken & egg problem wrt. building
	 * the OBP page tables, yet needing to be on the Linux kernel
	 * trap table (to translate PAGE_OFFSET addresses) in order to
	 * do that.
	 *
	 * We now handle OBP tlb misses differently, via linear lookups
	 * into the prom_trans[] array.  So that specific problem no
	 * longer exists.  Yet, unfortunately there are still some issues
	 * preventing trampoline.S from using this code... ho hum.
	 */
	.globl	setup_trap_table
setup_trap_table:
	save	%sp, -192, %sp

	/* Force interrupts to be disabled. */
	rdpr	%pstate, %o1
	andn	%o1, PSTATE_IE, %o1
	wrpr	%o1, 0x0, %pstate
	wrpr	%g0, 15, %pil

	/* Make the firmware call to jump over to the Linux trap table.  */
	call	prom_set_trap_table
	 sethi	%hi(sparc64_ttable_tl0), %o0

	/* Start using proper page size encodings in ctx register.  */
	sethi	%hi(sparc64_kern_pri_context), %g3
	ldx	[%g3 + %lo(sparc64_kern_pri_context)], %g2
	mov	PRIMARY_CONTEXT, %g1
	stxa	%g2, [%g1] ASI_DMMU
	membar	#Sync

	/* The Linux trap handlers expect various trap global registers
	 * to be setup with some fixed values.  So here we set these
	 * up very carefully.  These globals are:
	 *
	 * Alternate Globals (PSTATE_AG):
	 *
	 * %g6			--> current_thread_info()
	 *
	 * MMU Globals (PSTATE_MG):
	 *
	 * %g1			--> TLB_SFSR
	 * %g2			--> ((_PAGE_VALID | _PAGE_SZ4MB |
	 *			      _PAGE_CP | _PAGE_CV | _PAGE_P | _PAGE_W)
	 *			     ^ 0xfffff80000000000)
	 * (this %g2 value is used for computing the PAGE_OFFSET kernel
	 *  TLB entries quickly, the virtual address of the fault XOR'd
	 *  with this %g2 value is the PTE to load into the TLB)
	 * %g3			--> VPTE_BASE_CHEETAH or VPTE_BASE_SPITFIRE
	 *
	 * Interrupt Globals (PSTATE_IG, setup by init_irqwork_curcpu()):
	 *
	 * %g6			--> __irq_work[smp_processor_id()]
	 */

	rdpr	%pstate, %o1
	mov	%g6, %o2
	wrpr	%o1, PSTATE_AG, %pstate
	mov	%o2, %g6

#define KERN_HIGHBITS		((_PAGE_VALID|_PAGE_SZ4MB)^0xfffff80000000000)
#define KERN_LOWBITS		(_PAGE_CP | _PAGE_CV | _PAGE_P | _PAGE_W)
	wrpr	%o1, PSTATE_MG, %pstate
	mov	TSB_REG, %g1
	stxa	%g0, [%g1] ASI_DMMU
	membar	#Sync
	stxa	%g0, [%g1] ASI_IMMU
	membar	#Sync
	mov	TLB_SFSR, %g1
	sethi	%uhi(KERN_HIGHBITS), %g2
	or	%g2, %ulo(KERN_HIGHBITS), %g2
	sllx	%g2, 32, %g2
	or	%g2, KERN_LOWBITS, %g2

	BRANCH_IF_ANY_CHEETAH(g3,g7,8f)
	ba,pt	%xcc, 9f
	 nop

8:
	sethi		%uhi(VPTE_BASE_CHEETAH), %g3
	or		%g3, %ulo(VPTE_BASE_CHEETAH), %g3
	ba,pt		%xcc, 2f
	 sllx		%g3, 32, %g3

9:
	sethi		%uhi(VPTE_BASE_SPITFIRE), %g3
	or		%g3, %ulo(VPTE_BASE_SPITFIRE), %g3
	sllx		%g3, 32, %g3

2:
	clr	%g7
#undef KERN_HIGHBITS
#undef KERN_LOWBITS

	/* Kill PROM timer */
	sethi	%hi(0x80000000), %o2
	sllx	%o2, 32, %o2
	wr	%o2, 0, %tick_cmpr

	BRANCH_IF_ANY_CHEETAH(o2,o3,1f)

	ba,pt	%xcc, 2f
	 nop

	/* Disable STICK_INT interrupts. */
1:
	sethi	%hi(0x80000000), %o2
	sllx	%o2, 32, %o2
	wr	%o2, %asr25

2:
	wrpr	%g0, %g0, %wstate
	wrpr	%o1, 0x0, %pstate

	call	init_irqwork_curcpu
	 nop

	/* Now we can turn interrupts back on. */
	rdpr	%pstate, %o1
	or	%o1, PSTATE_IE, %o1
	wrpr	%o1, 0, %pstate
	wrpr	%g0, 0x0, %pil

	ret
	 restore

	.globl	setup_tba
setup_tba:	/* i0 = is_starfire */
	save	%sp, -192, %sp

	/* The boot processor is the only cpu which invokes this
	 * routine, the other cpus set things up via trampoline.S.
	 * So save the OBP trap table address here.
	 */
	rdpr	%tba, %g7
	sethi	%hi(prom_tba), %o1
	or	%o1, %lo(prom_tba), %o1
	stx	%g7, [%o1]

	call	setup_trap_table
	 nop

	ret
	 restore
sparc64_boot_end:

#include "systbls.S"
#include "ktlb.S"
#include "etrap.S"
#include "rtrap.S"
#include "winfixup.S"
#include "entry.S"

/*
 * The following skip makes sure the trap table in ttable.S is aligned
 * on a 32K boundary as required by the v9 specs for TBA register.
 */
1:
	.skip	0x4000 + _start - 1b

#ifdef CONFIG_SBUS
/* This is just a hack to fool make depend config.h discovering
   strategy: As the .S files below need config.h, but
   make depend does not find it for them, we include config.h
   in head.S */
#endif

! 0x0000000000408000

#include "ttable.S"

	.data
	.align	8
	.globl	prom_tba, tlb_type
prom_tba:	.xword	0
tlb_type:	.word	0	/* Must NOT end up in BSS */
	.section	".fixup",#alloc,#execinstr

	.globl	__ret_efault, __retl_efault
__ret_efault:
	ret
	 restore %g0, -EFAULT, %o0
__retl_efault:
	retl
	 mov	-EFAULT, %o0