/* SPDX-License-Identifier: GPL-2.0 */
/*
 *
 *  linux/arch/h8300/kernel/entry.S
 *
 *  Yoshinori Sato <ysato@users.sourceforge.jp>
 *  David McCullough <davidm@snapgear.com>
 *
 */

/*
 *  entry.S
 *  include exception/interrupt gateway
 *          system call entry
 */

#include <linux/sys.h>
#include <asm/unistd.h>
#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/errno.h>

#if defined(CONFIG_CPU_H8300H)
#define USERRET 8
INTERRUPTS = 64
	.h8300h
	.macro	SHLL2 reg
	shll.l	\reg
	shll.l	\reg
	.endm
	.macro	SHLR2 reg
	shlr.l	\reg
	shlr.l	\reg
	.endm
	.macro	SAVEREGS
	mov.l	er0,@-sp
	mov.l	er1,@-sp
	mov.l	er2,@-sp
	mov.l	er3,@-sp
	.endm
	.macro	RESTOREREGS
	mov.l	@sp+,er3
	mov.l	@sp+,er2
	.endm
	.macro	SAVEEXR
	.endm
	.macro	RESTOREEXR
	.endm
#endif
#if defined(CONFIG_CPU_H8S)
#define USERRET 10
#define USEREXR 8
INTERRUPTS = 128
	.h8300s
	.macro	SHLL2 reg
	shll.l	#2,\reg
	.endm
	.macro	SHLR2 reg
	shlr.l	#2,\reg
	.endm
	.macro	SAVEREGS
	stm.l	er0-er3,@-sp
	.endm
	.macro	RESTOREREGS
	ldm.l	@sp+,er2-er3
	.endm
	.macro	SAVEEXR
	mov.w	@(USEREXR:16,er0),r1
	mov.w	r1,@(LEXR-LER3:16,sp)		/* copy EXR */
	.endm
	.macro	RESTOREEXR
	mov.w	@(LEXR-LER1:16,sp),r1		/* restore EXR */
	mov.b	r1l,r1h
	mov.w	r1,@(USEREXR:16,er0)
	.endm
#endif


/* CPU context save/restore macros. */

	.macro	SAVE_ALL
	mov.l	er0,@-sp
	stc	ccr,r0l				/* check kernel mode */
	btst	#4,r0l
	bne	5f

	/* user mode */
	mov.l	sp,@_sw_usp
	mov.l	@sp,er0				/* restore saved er0 */
	orc	#0x10,ccr			/* switch kernel stack */
	mov.l	@_sw_ksp,sp
	sub.l	#(LRET-LORIG),sp		/* allocate LORIG - LRET */
	SAVEREGS
	mov.l   @_sw_usp,er0
	mov.l   @(USERRET:16,er0),er1           /* copy the RET addr */
	mov.l   er1,@(LRET-LER3:16,sp)
	SAVEEXR

	mov.l	@(LORIG-LER3:16,sp),er0
	mov.l	er0,@(LER0-LER3:16,sp)		/* copy ER0 */
	mov.w	e1,r1				/* e1 highbyte = ccr */
	and	#0xef,r1h			/* mask mode? flag */
	bra	6f
5:
	/* kernel mode */
	mov.l	@sp,er0				/* restore saved er0 */
	subs	#2,sp				/* set dummy ccr */
	subs	#4,sp				/* set dummp sp */
	SAVEREGS
	mov.w	@(LRET-LER3:16,sp),r1		/* copy old ccr */
6:
	mov.b	r1h,r1l
	mov.b	#0,r1h
	mov.w	r1,@(LCCR-LER3:16,sp)		/* set ccr */
	mov.l	@_sw_usp,er2
	mov.l	er2,@(LSP-LER3:16,sp)		/* set usp */
	mov.l	er6,@-sp			/* syscall arg #6 */
	mov.l	er5,@-sp			/* syscall arg #5 */
	mov.l	er4,@-sp			/* syscall arg #4 */
	.endm					/* r1 = ccr */

	.macro	RESTORE_ALL
	mov.l	@sp+,er4
	mov.l	@sp+,er5
	mov.l	@sp+,er6
	RESTOREREGS
	mov.w	@(LCCR-LER1:16,sp),r0		/* check kernel mode */
	btst	#4,r0l
	bne	7f

	orc	#0xc0,ccr
	mov.l	@(LSP-LER1:16,sp),er0
	mov.l	@(LER0-LER1:16,sp),er1		/* restore ER0 */
	mov.l	er1,@er0
	RESTOREEXR
	mov.w	@(LCCR-LER1:16,sp),r1		/* restore the RET addr */
	mov.b	r1l,r1h
	mov.b	@(LRET+1-LER1:16,sp),r1l
	mov.w	r1,e1
	mov.w	@(LRET+2-LER1:16,sp),r1
	mov.l	er1,@(USERRET:16,er0)

	mov.l	@sp+,er1
	add.l	#(LRET-LER1),sp			/* remove LORIG - LRET */
	mov.l	sp,@_sw_ksp
	andc	#0xef,ccr			/* switch to user mode */
	mov.l	er0,sp
	bra	8f
7:
	mov.l	@sp+,er1
	add.l	#10,sp
8:
	mov.l	@sp+,er0
	adds	#4,sp				/* remove the sw created LVEC */
	rte
	.endm

.globl _system_call
.globl ret_from_exception
.globl ret_from_fork
.globl ret_from_kernel_thread
.globl ret_from_interrupt
.globl _interrupt_redirect_table
.globl _sw_ksp,_sw_usp
.globl _resume
.globl _interrupt_entry
.globl _trace_break
.globl _nmi

#if defined(CONFIG_ROMKERNEL)
	.section .int_redirect,"ax"
_interrupt_redirect_table:
#if defined(CONFIG_CPU_H8300H)
	.rept	7
	.long	0
	.endr
#endif
#if defined(CONFIG_CPU_H8S)
	.rept	5
	.long	0
	.endr
	jmp	@_trace_break
	.long	0
#endif

	jsr	@_interrupt_entry		/* NMI */
	jmp	@_system_call			/* TRAPA #0 (System call) */
	.long	0
#if defined(CONFIG_KGDB)
	jmp	@_kgdb_trap
#else
	.long	0
#endif
	jmp	@_trace_break			/* TRAPA #3 (breakpoint) */
	.rept	INTERRUPTS-12
	jsr	@_interrupt_entry
	.endr
#endif
#if defined(CONFIG_RAMKERNEL)
.globl _interrupt_redirect_table
	.section .bss
_interrupt_redirect_table:
	.space	4
#endif

	.section .text
	.align	2
_interrupt_entry:
	SAVE_ALL
/* r1l is saved ccr */
	mov.l	sp,er0
	add.l	#LVEC,er0
	btst	#4,r1l
	bne	1f
	/* user LVEC */
	mov.l	@_sw_usp,er0
	adds	#4,er0
1:
	mov.l	@er0,er0			/* LVEC address */
#if defined(CONFIG_ROMKERNEL)
	sub.l	#_interrupt_redirect_table,er0
#endif
#if defined(CONFIG_RAMKERNEL)
	mov.l	@_interrupt_redirect_table,er1
	sub.l	er1,er0
#endif
	SHLR2	er0
	dec.l	#1,er0
	mov.l	sp,er1
	subs	#4,er1				/* adjust ret_pc */
#if defined(CONFIG_CPU_H8S)
	orc	#7,exr
#endif
	jsr	@do_IRQ
	jmp	@ret_from_interrupt

_system_call:
	subs	#4,sp				/* dummy LVEC */
	SAVE_ALL
	/* er0: syscall nr */
	andc	#0xbf,ccr
	mov.l	er0,er4

	/* save top of frame */
	mov.l	sp,er0
	jsr	@set_esp0
	andc	#0x3f,ccr
	mov.l	sp,er2
	and.w	#0xe000,r2
	mov.l	@(TI_FLAGS:16,er2),er2
	and.w	#_TIF_WORK_SYSCALL_MASK,r2
	beq	1f
	mov.l	sp,er0
	jsr	@do_syscall_trace_enter
1:
	cmp.l	#__NR_syscalls,er4
	bcc	badsys
	SHLL2	er4
	mov.l	#_sys_call_table,er0
	add.l	er4,er0
	mov.l	@er0,er4
	beq	ret_from_exception:16
	mov.l	@(LER1:16,sp),er0
	mov.l	@(LER2:16,sp),er1
	mov.l	@(LER3:16,sp),er2
	jsr	@er4
	mov.l	er0,@(LER0:16,sp)		/* save the return value */
	mov.l	sp,er2
	and.w	#0xe000,r2
	mov.l	@(TI_FLAGS:16,er2),er2
	and.w	#_TIF_WORK_SYSCALL_MASK,r2
	beq	2f
	mov.l	sp,er0
	jsr	@do_syscall_trace_leave
2:
	orc	#0xc0,ccr
	bra	resume_userspace

badsys:
	mov.l	#-ENOSYS,er0
	mov.l	er0,@(LER0:16,sp)
	bra	resume_userspace

#if !defined(CONFIG_PREEMPT)
#define resume_kernel restore_all
#endif

ret_from_exception:
#if defined(CONFIG_PREEMPT)
	orc	#0xc0,ccr
#endif
ret_from_interrupt:
	mov.b	@(LCCR+1:16,sp),r0l
	btst	#4,r0l
	bne	resume_kernel:16	/* return from kernel */
resume_userspace:
	andc	#0xbf,ccr
	mov.l	sp,er4
	and.w	#0xe000,r4		/* er4 <- current thread info */
	mov.l	@(TI_FLAGS:16,er4),er1
	and.l	#_TIF_WORK_MASK,er1
	beq	restore_all:8
work_pending:
	btst	#TIF_NEED_RESCHED,r1l
	bne	work_resched:8
	/* work notifysig */
	mov.l	sp,er0
	subs	#4,er0			/* er0: pt_regs */
	jsr	@do_notify_resume
	bra	resume_userspace:8
work_resched:
	mov.l	sp,er0
	jsr	@set_esp0
	jsr	@schedule
	bra	resume_userspace:8
restore_all:
	RESTORE_ALL			/* Does RTE */

#if defined(CONFIG_PREEMPT)
resume_kernel:
	mov.l	@(TI_PRE_COUNT:16,er4),er0
	bne	restore_all:8
need_resched:
	mov.l	@(TI_FLAGS:16,er4),er0
	btst	#TIF_NEED_RESCHED,r0l
	beq	restore_all:8
	mov.b	@(LCCR+1:16,sp),r0l	/* Interrupt Enabled? */
	bmi	restore_all:8
	mov.l	sp,er0
	jsr	@set_esp0
	jsr	@preempt_schedule_irq
	bra	need_resched:8
#endif

ret_from_fork:
	mov.l	er2,er0
	jsr	@schedule_tail
	jmp	@ret_from_exception

ret_from_kernel_thread:
	mov.l	er2,er0
	jsr	@schedule_tail
	mov.l	@(LER4:16,sp),er0
	mov.l	@(LER5:16,sp),er1
	jsr	@er1
	jmp	@ret_from_exception

_resume:
	/*
	 * Beware - when entering resume, offset of tss is in d1,
	 * prev (the current task) is in a0, next (the new task)
	 * is in a1 and d2.b is non-zero if the mm structure is
	 * shared between the tasks, so don't change these
	 * registers until their contents are no longer needed.
	 */

	/* save sr */
	sub.w	r3,r3
	stc	ccr,r3l
	mov.w	r3,@(THREAD_CCR+2:16,er0)

	/* disable interrupts */
	orc	#0xc0,ccr
	mov.l	@_sw_usp,er3
	mov.l	er3,@(THREAD_USP:16,er0)
	mov.l	sp,@(THREAD_KSP:16,er0)

	/* Skip address space switching if they are the same. */
	/* FIXME: what did we hack out of here, this does nothing! */

	mov.l	@(THREAD_USP:16,er1),er0
	mov.l	er0,@_sw_usp
	mov.l	@(THREAD_KSP:16,er1),sp

	/* restore status register */
	mov.w	@(THREAD_CCR+2:16,er1),r3

	ldc	r3l,ccr
	rts

_trace_break:
	subs	#4,sp
	SAVE_ALL
	sub.l	er1,er1
	dec.l	#1,er1
	mov.l	er1,@(LORIG,sp)
	mov.l	sp,er0
	jsr	@set_esp0
	mov.l	@_sw_usp,er0
	mov.l	@er0,er1
	mov.w	@(-2:16,er1),r2
	cmp.w	#0x5730,r2
	beq	1f
	subs	#2,er1
	mov.l	er1,@er0
1:
	and.w	#0xff,e1
	mov.l	er1,er0
	jsr	@trace_trap
	jmp	@ret_from_exception

_nmi:
	subs	#4, sp
	mov.l	er0, @-sp
	mov.l	@_interrupt_redirect_table, er0
	add.l	#8*4, er0
	mov.l	er0, @(4,sp)
	mov.l	@sp+, er0
	jmp	@_interrupt_entry

#if defined(CONFIG_KGDB)
_kgdb_trap:
	subs	#4,sp
	SAVE_ALL
	mov.l	sp,er0
	add.l	#LRET,er0
	mov.l	er0,@(LSP,sp)
	jsr	@set_esp0
	mov.l	sp,er0
	subs	#4,er0
	jsr	@h8300_kgdb_trap
	jmp	@ret_from_exception
#endif

	.section	.bss
_sw_ksp:
	.space	4
_sw_usp:
	.space	4

	.end