path: root/arch/frv/kernel/entry.S

/* entry.S: FR-V entry
 *
 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 *
 * Entry to the kernel is "interesting":
 *  (1) There are no stack pointers, not even for the kernel
 *  (2) General Registers should not be clobbered
 *  (3) There are no kernel-only data registers
 *  (4) Since all addressing modes are wrt to a General Register, no global
 *      variables can be reached
 *
 * We deal with this by declaring that we shall kill GR28 on entering the
 * kernel from userspace
 *
 * However, since break interrupts can interrupt the CPU even when PSR.ET==0,
 * they can't rely on GR28 to be anything useful, and so need to clobber a
 * separate register (GR31). Break interrupts are managed in break.S
 *
 * GR29 _is_ saved, and holds the current task pointer globally
 *
 */

#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/ptrace.h>
#include <asm/errno.h>
#include <asm/cache.h>
#include <asm/spr-regs.h>

#define nr_syscalls ((syscall_table_size)/4)

	.section	.text..entry
	.balign		4

.macro LEDS val
#	sethi.p		%hi(0xe1200004),gr30
#	setlo		%lo(0xe1200004),gr30
#	setlos		#~\val,gr31
#	st		gr31,@(gr30,gr0)
#	sethi.p		%hi(0xffc00100),gr30
#	setlo		%lo(0xffc00100),gr30
#	sth		gr0,@(gr30,gr0)
#	membar
.endm

.macro LEDS32
#	not		gr31,gr31
#	sethi.p		%hi(0xe1200004),gr30
#	setlo		%lo(0xe1200004),gr30
#	st.p		gr31,@(gr30,gr0)
#	srli		gr31,#16,gr31
#	sethi.p		%hi(0xffc00100),gr30
#	setlo		%lo(0xffc00100),gr30
#	sth		gr31,@(gr30,gr0)
#	membar
.endm

###############################################################################
#
# entry point for External interrupts received whilst executing userspace code
#
###############################################################################
	.globl		__entry_uspace_external_interrupt
        .type		__entry_uspace_external_interrupt,@function
__entry_uspace_external_interrupt:
	LEDS		0x6200
	sethi.p		%hi(__kernel_frame0_ptr),gr28
	setlo		%lo(__kernel_frame0_ptr),gr28
	ldi		@(gr28,#0),gr28

	# handle h/w single-step through exceptions
	sti		gr0,@(gr28,#REG__STATUS)

	.globl		__entry_uspace_external_interrupt_reentry
__entry_uspace_external_interrupt_reentry:
	LEDS		0x6201

	setlos		#REG__END,gr30
	dcpl		gr28,gr30,#0

	# finish building the exception frame
	sti		sp,  @(gr28,#REG_SP)
	stdi		gr2, @(gr28,#REG_GR(2))
	stdi		gr4, @(gr28,#REG_GR(4))
	stdi		gr6, @(gr28,#REG_GR(6))
	stdi		gr8, @(gr28,#REG_GR(8))
	stdi		gr10,@(gr28,#REG_GR(10))
	stdi		gr12,@(gr28,#REG_GR(12))
	stdi		gr14,@(gr28,#REG_GR(14))
	stdi		gr16,@(gr28,#REG_GR(16))
	stdi		gr18,@(gr28,#REG_GR(18))
	stdi		gr20,@(gr28,#REG_GR(20))
	stdi		gr22,@(gr28,#REG_GR(22))
	stdi		gr24,@(gr28,#REG_GR(24))
	stdi		gr26,@(gr28,#REG_GR(26))
	sti		gr0, @(gr28,#REG_GR(28))
	sti		gr29,@(gr28,#REG_GR(29))
	stdi.p		gr30,@(gr28,#REG_GR(30))

	# set up the kernel stack pointer
	ori		gr28,0,sp

	movsg		tbr ,gr20
	movsg		psr ,gr22
	movsg		pcsr,gr21
	movsg		isr ,gr23
	movsg		ccr ,gr24
	movsg		cccr,gr25
	movsg		lr  ,gr26
	movsg		lcr ,gr27

	setlos.p	#-1,gr4
	andi		gr22,#PSR_PS,gr5		/* try to rebuild original PSR value */
	andi.p		gr22,#~(PSR_PS|PSR_S),gr6
	slli		gr5,#1,gr5
	or		gr6,gr5,gr5
	andi		gr5,#~PSR_ET,gr5

	sti		gr20,@(gr28,#REG_TBR)
	sti		gr21,@(gr28,#REG_PC)
	sti		gr5 ,@(gr28,#REG_PSR)
	sti		gr23,@(gr28,#REG_ISR)
	stdi		gr24,@(gr28,#REG_CCR)
	stdi		gr26,@(gr28,#REG_LR)
	sti		gr4 ,@(gr28,#REG_SYSCALLNO)

	movsg		iacc0h,gr4
	movsg		iacc0l,gr5
	stdi		gr4,@(gr28,#REG_IACC0)

	movsg		gner0,gr4
	movsg		gner1,gr5
	stdi.p		gr4,@(gr28,#REG_GNER0)

	# interrupts start off fully disabled in the interrupt handler
	subcc		gr0,gr0,gr0,icc2		/* set Z and clear C */

	# set up kernel global registers
	sethi.p		%hi(__kernel_current_task),gr5
	setlo		%lo(__kernel_current_task),gr5
	sethi.p		%hi(_gp),gr16
	setlo		%lo(_gp),gr16
	ldi		@(gr5,#0),gr29
	ldi.p		@(gr29,#4),gr15		; __current_thread_info = current->thread_info

	# make sure we (the kernel) get div-zero and misalignment exceptions
	setlos		#ISR_EDE|ISR_DTT_DIVBYZERO|ISR_EMAM_EXCEPTION,gr5
	movgs		gr5,isr

	# switch to the kernel trap table
	sethi.p		%hi(__entry_kerneltrap_table),gr6
	setlo		%lo(__entry_kerneltrap_table),gr6
	movgs		gr6,tbr

	# set the return address
	sethi.p		%hi(__entry_return_from_user_interrupt),gr4
	setlo		%lo(__entry_return_from_user_interrupt),gr4
	movgs		gr4,lr

	# raise the minimum interrupt priority to 15 (NMI only) and enable exceptions
	movsg		psr,gr4

	ori		gr4,#PSR_PIL_14,gr4
	movgs		gr4,psr
	ori		gr4,#PSR_PIL_14|PSR_ET,gr4
	movgs		gr4,psr

	LEDS		0x6202
	bra		do_IRQ

	.size		__entry_uspace_external_interrupt,.-__entry_uspace_external_interrupt

###############################################################################
#
# entry point for External interrupts received whilst executing kernel code
# - on arriving here, the following registers should already be set up:
#	GR15	- current thread_info struct pointer
#	GR16	- kernel GP-REL pointer
#	GR29	- current task struct pointer
#	TBR	- kernel trap vector table
#	ISR	- kernel's preferred integer controls
#
###############################################################################
	.globl		__entry_kernel_external_interrupt
        .type		__entry_kernel_external_interrupt,@function
__entry_kernel_external_interrupt:
	LEDS		0x6210
//	sub		sp,gr15,gr31
//	LEDS32

	# set up the stack pointer
	or.p		sp,gr0,gr30
	subi		sp,#REG__END,sp
	sti		gr30,@(sp,#REG_SP)

	# handle h/w single-step through exceptions
	sti		gr0,@(sp,#REG__STATUS)

	.globl		__entry_kernel_external_interrupt_reentry
__entry_kernel_external_interrupt_reentry:
	LEDS		0x6211

	# set up the exception frame
	setlos		#REG__END,gr30
	dcpl		sp,gr30,#0

	sti.p		gr28,@(sp,#REG_GR(28))
	ori		sp,0,gr28

	# finish building the exception frame
	stdi		gr2,@(gr28,#REG_GR(2))
	stdi		gr4,@(gr28,#REG_GR(4))
	stdi		gr6,@(gr28,#REG_GR(6))
	stdi		gr8,@(gr28,#REG_GR(8))
	stdi		gr10,@(gr28,#REG_GR(10))
	stdi		gr12,@(gr28,#REG_GR(12))
	stdi		gr14,@(gr28,#REG_GR(14))
	stdi		gr16,@(gr28,#REG_GR(16))
	stdi		gr18,@(gr28,#REG_GR(18))
	stdi		gr20,@(gr28,#REG_GR(20))
	stdi		gr22,@(gr28,#REG_GR(22))
	stdi		gr24,@(gr28,#REG_GR(24))
	stdi		gr26,@(gr28,#REG_GR(26))
	sti		gr29,@(gr28,#REG_GR(29))
	stdi.p		gr30,@(gr28,#REG_GR(30))

	# note virtual interrupts will be fully enabled upon return
	subicc		gr0,#1,gr0,icc2			/* clear Z, set C */

	movsg		tbr ,gr20
	movsg		psr ,gr22
	movsg		pcsr,gr21
	movsg		isr ,gr23
	movsg		ccr ,gr24
	movsg		cccr,gr25
	movsg		lr  ,gr26
	movsg		lcr ,gr27

	setlos.p	#-1,gr4
	andi		gr22,#PSR_PS,gr5		/* try to rebuild original PSR value */
	andi.p		gr22,#~(PSR_PS|PSR_S),gr6
	slli		gr5,#1,gr5
	or		gr6,gr5,gr5
	andi.p		gr5,#~PSR_ET,gr5

	# set CCCR.CC3 to Undefined to abort atomic-modify completion inside the kernel
	# - for an explanation of how it works, see: Documentation/frv/atomic-ops.txt
	andi		gr25,#~0xc0,gr25

	sti		gr20,@(gr28,#REG_TBR)
	sti		gr21,@(gr28,#REG_PC)
	sti		gr5 ,@(gr28,#REG_PSR)
	sti		gr23,@(gr28,#REG_ISR)
	stdi		gr24,@(gr28,#REG_CCR)
	stdi		gr26,@(gr28,#REG_LR)
	sti		gr4 ,@(gr28,#REG_SYSCALLNO)

	movsg		iacc0h,gr4
	movsg		iacc0l,gr5
	stdi		gr4,@(gr28,#REG_IACC0)

	movsg		gner0,gr4
	movsg		gner1,gr5
	stdi.p		gr4,@(gr28,#REG_GNER0)

	# interrupts start off fully disabled in the interrupt handler
	subcc		gr0,gr0,gr0,icc2			/* set Z and clear C */

	# set the return address
	sethi.p		%hi(__entry_return_from_kernel_interrupt),gr4
	setlo		%lo(__entry_return_from_kernel_interrupt),gr4
	movgs		gr4,lr

	# clear power-saving mode flags
	movsg		hsr0,gr4
	andi		gr4,#~HSR0_PDM,gr4
	movgs		gr4,hsr0

	# raise the minimu