/*
   * arch/score/kernel/entry.S
   *
   * Score Processor version.
   *
   * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   *  Chen Liqin <liqin.chen@sunplusct.com>
   *  Lennox Wu <lennox.wu@sunplusct.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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, see the file COPYING, or write
   * to the Free Software Foundation, Inc.,
   * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */

  #include <linux/err.h>

  #include <linux/init.h>
  #include <linux/linkage.h>
  
  #include <asm/asmmacro.h>
  #include <asm/thread_info.h>
  #include <asm/unistd.h>
  
  /*
   * disable interrupts.
   */
  .macro	disable_irq
  	mfcr	r8, cr0
  	srli	r8, r8, 1
  	slli	r8, r8, 1
  	mtcr	r8, cr0
  	nop
  	nop
  	nop
  	nop
  	nop
  .endm
  
  /*
   * enable interrupts.
   */
  .macro	enable_irq
  	mfcr	r8, cr0
  	ori	r8, 1
  	mtcr	r8, cr0
  	nop
  	nop
  	nop
  	nop
  	nop
  .endm
  
  __INIT
  ENTRY(debug_exception_vector)
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  
  ENTRY(general_exception_vector)			# should move to addr 0x200
  	j	general_exception
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  
  ENTRY(interrupt_exception_vector)		# should move to addr 0x210
  	j	interrupt_exception
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  	nop!
  
  	.section ".text", "ax"
  	.align	2;
  general_exception:
  	mfcr	r31, cr2
  	nop
  	la	r30, exception_handlers
  	andi	r31, 0x1f			# get ecr.exc_code
  	slli	r31, r31, 2
  	add	r30, r30, r31
  	lw	r30, [r30]
  	br	r30
  
  interrupt_exception:
  	SAVE_ALL
  	mfcr	r4, cr2
  	nop
  	lw	r16, [r28, TI_REGS]
  	sw	r0, [r28, TI_REGS]
  	la	r3, ret_from_irq
  	srli	r4, r4, 18			# get ecr.ip[7:2], interrupt No.
  	mv	r5, r0
  	j	do_IRQ
  
  ENTRY(handle_nmi)				# NMI #1
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, nmi_exception_handler
  	brl	r8
  	j	restore_all
  
  ENTRY(handle_adelinsn)				# AdEL-instruction #2
  	SAVE_ALL
  	mfcr	r8, cr6
  	nop
  	nop
  	sw	r8, [r0, PT_EMA]
  	mv	r4, r0
  	la	r8, do_adelinsn
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_ibe)				# BusEL-instruction #5
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_be
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_pel)				# P-EL #6
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_pel
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_ccu)				# CCU #8
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_ccu
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_ri)				# RI #9
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_ri
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_tr)				# Trap #10
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_tr
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_adedata)				# AdES-instruction #12
  	SAVE_ALL
  	mfcr	r8, cr6
  	nop
  	nop
  	sw	r8, [r0, PT_EMA]
  	mv	r4, r0
  	la	r8, do_adedata
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_cee)				# CeE #16
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_cee
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_cpe)				# CpE #17
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_cpe
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_dbe)				# BusEL-data #18
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_be
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  ENTRY(handle_reserved)				# others
  	SAVE_ALL
  	mv	r4, r0
  	la	r8, do_reserved
  	brl	r8
  	mv	r4, r0
  	j	ret_from_exception
  	nop
  
  #ifndef CONFIG_PREEMPT
  #define resume_kernel	restore_all
  #else
  #define __ret_from_irq	ret_from_exception
  #endif
  
  	.align	2
  #ifndef CONFIG_PREEMPT
  ENTRY(ret_from_exception)
  	disable_irq			# preempt stop
  	nop
  	j	__ret_from_irq
  	nop
  #endif
  
  ENTRY(ret_from_irq)
  	sw	r16, [r28, TI_REGS]
  
  ENTRY(__ret_from_irq)
  	lw	r8, [r0, PT_PSR]	# returning to kernel mode?
  	andri.c	r8, r8, KU_USER
  	beq	resume_kernel
  
  resume_userspace:
  	disable_irq
  	lw	r6, [r28, TI_FLAGS]	# current->work
  	li	r8, _TIF_WORK_MASK
  	and.c	r8, r8, r6		# ignoring syscall_trace
  	bne	work_pending
  	nop
  	j	restore_all
  	nop
  
  #ifdef CONFIG_PREEMPT
  resume_kernel:
  	disable_irq
  	lw	r8, [r28, TI_PRE_COUNT]
  	cmpz.c	r8
  	bne	r8, restore_all
  need_resched:
  	lw	r8, [r28, TI_FLAGS]
  	andri.c	r9, r8, _TIF_NEED_RESCHED
  	beq	restore_all
  	lw	r8, [r28, PT_PSR]		# Interrupts off?
  	andri.c	r8, r8, 1
  	beq	restore_all
  	bl	preempt_schedule_irq
  	nop
  	j	need_resched
  	nop
  #endif
  
  ENTRY(ret_from_fork)
  	bl	schedule_tail			# r4=struct task_struct *prev
  
  ENTRY(syscall_exit)
  	nop
  	disable_irq
  	lw	r6, [r28, TI_FLAGS]		# current->work
  	li	r8, _TIF_WORK_MASK
  	and.c	r8, r6, r8
  	bne	syscall_exit_work
  
  ENTRY(restore_all)					# restore full frame
  	RESTORE_ALL_AND_RET
  
  work_pending:
  	andri.c	r8, r6, _TIF_NEED_RESCHED # r6 is preloaded with TI_FLAGS
  	beq	work_notifysig
  work_resched:
  	bl	schedule
  	nop
  	disable_irq
  	lw	r6, [r28, TI_FLAGS]
  	li	r8, _TIF_WORK_MASK
  	and.c	r8, r6, r8	# is there any work to be done
  				# other than syscall tracing?
  	beq	restore_all
  	andri.c	r8, r6, _TIF_NEED_RESCHED
  	bne	work_resched
  
  work_notifysig:
  	mv	r4, r0
  	li	r5, 0
  	bl	do_notify_resume	# r6 already loaded
  	nop
  	j	resume_userspace
  	nop
  
  ENTRY(syscall_exit_work)
  	li	r8, _TIF_SYSCALL_TRACE
  	and.c	r8, r8, r6		# r6 is preloaded with TI_FLAGS
  	beq	work_pending		# trace bit set?
  	nop
  	enable_irq
  	mv	r4, r0
  	li	r5, 1
  	bl	do_syscall_trace
  	nop
  	b	resume_userspace
  	nop
  
  .macro	save_context	reg
  	sw	r12, [\reg, THREAD_REG12];
  	sw	r13, [\reg, THREAD_REG13];
  	sw	r14, [\reg, THREAD_REG14];
  	sw	r15, [\reg, THREAD_REG15];
  	sw	r16, [\reg, THREAD_REG16];
  	sw	r17, [\reg, THREAD_REG17];
  	sw	r18, [\reg, THREAD_REG18];
  	sw	r19, [\reg, THREAD_REG19];
  	sw	r20, [\reg, THREAD_REG20];
  	sw	r21, [\reg, THREAD_REG21];
  	sw	r29, [\reg, THREAD_REG29];
  	sw	r2, [\reg, THREAD_REG2];
  	sw	r0, [\reg, THREAD_REG0]
  .endm
  
  .macro	restore_context	reg
  	lw	r12, [\reg, THREAD_REG12];
  	lw	r13, [\reg, THREAD_REG13];
  	lw	r14, [\reg, THREAD_REG14];
  	lw	r15, [\reg, THREAD_REG15];
  	lw	r16, [\reg, THREAD_REG16];
  	lw	r17, [\reg, THREAD_REG17];
  	lw	r18, [\reg, THREAD_REG18];
  	lw	r19, [\reg, THREAD_REG19];
  	lw	r20, [\reg, THREAD_REG20];
  	lw	r21, [\reg, THREAD_REG21];
  	lw	r29, [\reg, THREAD_REG29];
  	lw	r0, [\reg, THREAD_REG0];
  	lw	r2, [\reg, THREAD_REG2];
  	lw	r3, [\reg, THREAD_REG3]
  .endm
  
  /*
   * task_struct *resume(task_struct *prev, task_struct *next,
   *			struct thread_info *next_ti)
   */
  ENTRY(resume)
  	mfcr	r9, cr0
  	nop
  	nop
  	sw	r9, [r4, THREAD_PSR]
  	save_context	r4
  	sw	r3, [r4, THREAD_REG3]
  
  	mv	r28, r6
  	restore_context	r5
  	mv	r8, r6
  	addi	r8, KERNEL_STACK_SIZE
  	subi	r8, 32
  	la 	r9, kernelsp;
  	sw 	r8, [r9];
  
  	mfcr	r9, cr0
  	ldis	r7, 0x00ff
  	nop
  	and	r9, r9, r7
  	lw	r6, [r5, THREAD_PSR]
  	not	r7, r7
  	and	r6, r6, r7
  	or	r6, r6, r9
  	mtcr	r6, cr0
  	nop; nop; nop; nop; nop
  	br	r3
  
  ENTRY(handle_sys)
  	SAVE_ALL

  	sw	r8, [r0, 16]		# argument 5 from user r8
  	sw	r9, [r0, 20]		# argument 6 from user r9

  	enable_irq
  
  	sw	r4, [r0, PT_ORIG_R4]	#for restart syscall
  	sw	r7, [r0, PT_ORIG_R7]	#for restart syscall
  	sw	r27, [r0, PT_IS_SYSCALL] # it from syscall
  
  	lw	r9, [r0, PT_EPC]	# skip syscall on return
  	addi	r9, 4
  	sw	r9, [r0, PT_EPC]
  
  	cmpi.c	r27, __NR_syscalls 	# check syscall number
  	bgtu	illegal_syscall

  	slli	r8, r27, 2		# get syscall routine

  	la	r11, sys_call_table
  	add	r11, r11, r8
  	lw	r10, [r11]		# get syscall entry

  
  	cmpz.c	r10
  	beq	illegal_syscall

  	lw	r8, [r28, TI_FLAGS]
  	li	r9, _TIF_SYSCALL_TRACE
  	and.c	r8, r8, r9
  	bne	syscall_trace_entry
  
  	brl	r10			# Do The Real system call
  
  	cmpi.c	r4, 0
  	blt	1f
  	ldi	r8, 0
  	sw	r8, [r0, PT_R7]
  	b 2f
  1:

  	cmpi.c	r4, -MAX_ERRNO - 1

  	ble	2f
  	ldi	r8, 0x1;
  	sw	r8, [r0, PT_R7]
  	neg	r4, r4
  2:
  	sw	r4, [r0, PT_R4]		# save result
  
  syscall_return:
  	disable_irq
  	lw	r6, [r28, TI_FLAGS]	# current->work
  	li	r8, _TIF_WORK_MASK
  	and.c	r8, r6, r8
  	bne	syscall_return_work
  	j	restore_all
  
  syscall_return_work:
  	j	syscall_exit_work
  
  syscall_trace_entry:
  	mv	r16, r10
  	mv	r4, r0
  	li	r5, 0
  	bl	do_syscall_trace
  
  	mv	r8, r16
  	lw	r4, [r0, PT_R4]		# Restore argument registers
  	lw	r5, [r0, PT_R5]
  	lw	r6, [r0, PT_R6]
  	lw	r7, [r0, PT_R7]
  	brl	r8

  	li	r8, -MAX_ERRNO - 1

  	sw	r8, [r0, PT_R7]		# set error flag
  
  	neg	r4, r4			# error
  	sw	r4, [r0, PT_R0]		# set flag for syscall
  					# restarting
  1:	sw	r4, [r0, PT_R2]		# result
  	j	syscall_exit

  illegal_syscall:
  	ldi	r4, -ENOSYS		# error
  	sw	r4, [r0, PT_ORIG_R4]
  	sw	r4, [r0, PT_R4]
  	ldi	r9, 1			# set error flag
  	sw	r9, [r0, PT_R7]
  	j	syscall_return
  
  ENTRY(sys_execve)
  	mv	r4, r0
  	la	r8, score_execve
  	br	r8
  
  ENTRY(sys_clone)
  	mv	r4, r0
  	la	r8, score_clone
  	br	r8
  
  ENTRY(sys_rt_sigreturn)
  	mv	r4, r0
  	la	r8, score_rt_sigreturn
  	br	r8
  
  ENTRY(sys_sigaltstack)
  	mv	r4, r0
  	la	r8, score_sigaltstack
  	br	r8

  
  #ifdef __ARCH_WANT_SYSCALL_DEPRECATED
  ENTRY(sys_fork)
  	mv	r4, r0
  	la	r8, score_fork
  	br	r8
  
  ENTRY(sys_vfork)
  	mv	r4, r0
  	la	r8, score_vfork
  	br	r8
  #endif /* __ARCH_WANT_SYSCALL_DEPRECATED */