/*
   *  linux/arch/arm/vfp/vfphw.S
   *
   *  Copyright (C) 2004 ARM Limited.
   *  Written by Deep Blue Solutions Limited.
   *
   * 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.
   *
   * This code is called from the kernel's undefined instruction trap.
   * r9 holds the return address for successful handling.
   * lr holds the return address for unrecognised instructions.
   * r10 points at the start of the private FP workspace in the thread structure
   * sp points to a struct pt_regs (as defined in include/asm/proc/ptrace.h)
   */
  #include <asm/thread_info.h>
  #include <asm/vfpmacros.h>
  #include <linux/kern_levels.h>
  #include "../kernel/entry-header.S"
  
  	.macro	DBGSTR, str
  #ifdef DEBUG
  	stmfd	sp!, {r0-r3, ip, lr}
  	ldr	r0, =1f
  	bl	printk
  	ldmfd	sp!, {r0-r3, ip, lr}
  
  	.pushsection .rodata, "a"
  1:	.ascii	KERN_DEBUG "VFP: \str
  "
  	.byte	0
  	.previous
  #endif
  	.endm
  
  	.macro  DBGSTR1, str, arg
  #ifdef DEBUG
  	stmfd	sp!, {r0-r3, ip, lr}
  	mov	r1, \arg
  	ldr	r0, =1f
  	bl	printk
  	ldmfd	sp!, {r0-r3, ip, lr}
  
  	.pushsection .rodata, "a"
  1:	.ascii	KERN_DEBUG "VFP: \str
  "
  	.byte	0
  	.previous
  #endif
  	.endm
  
  	.macro  DBGSTR3, str, arg1, arg2, arg3
  #ifdef DEBUG
  	stmfd	sp!, {r0-r3, ip, lr}
  	mov	r3, \arg3
  	mov	r2, \arg2
  	mov	r1, \arg1
  	ldr	r0, =1f
  	bl	printk
  	ldmfd	sp!, {r0-r3, ip, lr}
  
  	.pushsection .rodata, "a"
  1:	.ascii	KERN_DEBUG "VFP: \str
  "
  	.byte	0
  	.previous
  #endif
  	.endm
  
  
  @ VFP hardware support entry point.
  @
  @  r0  = instruction opcode (32-bit ARM or two 16-bit Thumb)
  @  r2  = PC value to resume execution after successful emulation
  @  r9  = normal "successful" return address
  @  r10 = vfp_state union
  @  r11 = CPU number
  @  lr  = unrecognised instruction return address
  @  IRQs enabled.
  ENTRY(vfp_support_entry)
  	DBGSTR3	"instr %08x pc %08x state %p", r0, r2, r10
  
  	ldr	r3, [sp, #S_PSR]	@ Neither lazy restore nor FP exceptions
  	and	r3, r3, #MODE_MASK	@ are supported in kernel mode
  	teq	r3, #USR_MODE
  	bne	vfp_kmode_exception	@ Returns through lr
  
  	VFPFMRX	r1, FPEXC		@ Is the VFP enabled?
  	DBGSTR1	"fpexc %08x", r1
  	tst	r1, #FPEXC_EN
  	bne	look_for_VFP_exceptions	@ VFP is already enabled
  
  	DBGSTR1 "enable %x", r10
  	ldr	r3, vfp_current_hw_state_address
  	orr	r1, r1, #FPEXC_EN	@ user FPEXC has the enable bit set
  	ldr	r4, [r3, r11, lsl #2]	@ vfp_current_hw_state pointer
  	bic	r5, r1, #FPEXC_EX	@ make sure exceptions are disabled
  	cmp	r4, r10			@ this thread owns the hw context?
  #ifndef CONFIG_SMP
  	@ For UP, checking that this thread owns the hw context is
  	@ sufficient to determine that the hardware state is valid.
  	beq	vfp_hw_state_valid
  
  	@ On UP, we lazily save the VFP context.  As a different
  	@ thread wants ownership of the VFP hardware, save the old
  	@ state if there was a previous (valid) owner.
  
  	VFPFMXR	FPEXC, r5		@ enable VFP, disable any pending
  					@ exceptions, so we can get at the
  					@ rest of it
  
  	DBGSTR1	"save old state %p", r4
  	cmp	r4, #0			@ if the vfp_current_hw_state is NULL
  	beq	vfp_reload_hw		@ then the hw state needs reloading
  	VFPFSTMIA r4, r5		@ save the working registers
  	VFPFMRX	r5, FPSCR		@ current status
  #ifndef CONFIG_CPU_FEROCEON
  	tst	r1, #FPEXC_EX		@ is there additional state to save?
  	beq	1f
  	VFPFMRX	r6, FPINST		@ FPINST (only if FPEXC.EX is set)
  	tst	r1, #FPEXC_FP2V		@ is there an FPINST2 to read?
  	beq	1f
  	VFPFMRX	r8, FPINST2		@ FPINST2 if needed (and present)
  1:
  #endif
  	stmia	r4, {r1, r5, r6, r8}	@ save FPEXC, FPSCR, FPINST, FPINST2
  vfp_reload_hw:
  
  #else
  	@ For SMP, if this thread does not own the hw context, then we
  	@ need to reload it.  No need to save the old state as on SMP,
  	@ we always save the state when we switch away from a thread.
  	bne	vfp_reload_hw
  
  	@ This thread has ownership of the current hardware context.
  	@ However, it may have been migrated to another CPU, in which
  	@ case the saved state is newer than the hardware context.
  	@ Check this by looking at the CPU number which the state was
  	@ last loaded onto.
  	ldr	ip, [r10, #VFP_CPU]
  	teq	ip, r11
  	beq	vfp_hw_state_valid
  
  vfp_reload_hw:
  	@ We're loading this threads state into the VFP hardware. Update
  	@ the CPU number which contains the most up to date VFP context.
  	str	r11, [r10, #VFP_CPU]
  
  	VFPFMXR	FPEXC, r5		@ enable VFP, disable any pending
  					@ exceptions, so we can get at the
  					@ rest of it
  #endif
  
  	DBGSTR1	"load state %p", r10
  	str	r10, [r3, r11, lsl #2]	@ update the vfp_current_hw_state pointer
  					@ Load the saved state back into the VFP
  	VFPFLDMIA r10, r5		@ reload the working registers while
  					@ FPEXC is in a safe state
  	ldmia	r10, {r1, r5, r6, r8}	@ load FPEXC, FPSCR, FPINST, FPINST2
  #ifndef CONFIG_CPU_FEROCEON
  	tst	r1, #FPEXC_EX		@ is there additional state to restore?
  	beq	1f
  	VFPFMXR	FPINST, r6		@ restore FPINST (only if FPEXC.EX is set)
  	tst	r1, #FPEXC_FP2V		@ is there an FPINST2 to write?
  	beq	1f
  	VFPFMXR	FPINST2, r8		@ FPINST2 if needed (and present)
  1:
  #endif
  	VFPFMXR	FPSCR, r5		@ restore status
  
  @ The context stored in the VFP hardware is up to date with this thread
  vfp_hw_state_valid:
  	tst	r1, #FPEXC_EX
  	bne	process_exception	@ might as well handle the pending
  					@ exception before retrying branch
  					@ out before setting an FPEXC that
  					@ stops us reading stuff
  	VFPFMXR	FPEXC, r1		@ Restore FPEXC last
  	sub	r2, r2, #4		@ Retry current instruction - if Thumb
  	str	r2, [sp, #S_PC]		@ mode it's two 16-bit instructions,
  					@ else it's one 32-bit instruction, so
  					@ always subtract 4 from the following
  					@ instruction address.
  #ifdef CONFIG_PREEMPT_COUNT
  	get_thread_info	r10
  	ldr	r4, [r10, #TI_PREEMPT]	@ get preempt count
  	sub	r11, r4, #1		@ decrement it
  	str	r11, [r10, #TI_PREEMPT]
  #endif
  	mov	pc, r9			@ we think we have handled things
  
  
  look_for_VFP_exceptions:
  	@ Check for synchronous or asynchronous exception
  	tst	r1, #FPEXC_EX | FPEXC_DEX
  	bne	process_exception
  	@ On some implementations of the VFP subarch 1, setting FPSCR.IXE
  	@ causes all the CDP instructions to be bounced synchronously without
  	@ setting the FPEXC.EX bit
  	VFPFMRX	r5, FPSCR
  	tst	r5, #FPSCR_IXE
  	bne	process_exception
  
  	@ Fall into hand on to next handler - appropriate coproc instr
  	@ not recognised by VFP
  
  	DBGSTR	"not VFP"
  #ifdef CONFIG_PREEMPT_COUNT
  	get_thread_info	r10
  	ldr	r4, [r10, #TI_PREEMPT]	@ get preempt count
  	sub	r11, r4, #1		@ decrement it
  	str	r11, [r10, #TI_PREEMPT]
  #endif
  	mov	pc, lr
  
  process_exception:
  	DBGSTR	"bounce"
  	mov	r2, sp			@ nothing stacked - regdump is at TOS
  	mov	lr, r9			@ setup for a return to the user code.
  
  	@ Now call the C code to package up the bounce to the support code
  	@   r0 holds the trigger instruction
  	@   r1 holds the FPEXC value
  	@   r2 pointer to register dump
  	b	VFP_bounce		@ we have handled this - the support
  					@ code will raise an exception if
  					@ required. If not, the user code will
  					@ retry the faulted instruction
  ENDPROC(vfp_support_entry)
  
  ENTRY(vfp_save_state)
  	@ Save the current VFP state
  	@ r0 - save location
  	@ r1 - FPEXC
  	DBGSTR1	"save VFP state %p", r0
  	VFPFSTMIA r0, r2		@ save the working registers
  	VFPFMRX	r2, FPSCR		@ current status
  	tst	r1, #FPEXC_EX		@ is there additional state to save?
  	beq	1f
  	VFPFMRX	r3, FPINST		@ FPINST (only if FPEXC.EX is set)
  	tst	r1, #FPEXC_FP2V		@ is there an FPINST2 to read?
  	beq	1f
  	VFPFMRX	r12, FPINST2		@ FPINST2 if needed (and present)
  1:
  	stmia	r0, {r1, r2, r3, r12}	@ save FPEXC, FPSCR, FPINST, FPINST2
  	mov	pc, lr
  ENDPROC(vfp_save_state)
  
  	.align
  vfp_current_hw_state_address:
  	.word	vfp_current_hw_state
  
  	.macro	tbl_branch, base, tmp, shift
  #ifdef CONFIG_THUMB2_KERNEL
  	adr	\tmp, 1f
  	add	\tmp, \tmp, \base, lsl \shift
  	mov	pc, \tmp
  #else
  	add	pc, pc, \base, lsl \shift
  	mov	r0, r0
  #endif
  1:
  	.endm
  
  ENTRY(vfp_get_float)
  	tbl_branch r0, r3, #3
  	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
  1:	mrc	p10, 0, r0, c\dr, c0, 0	@ fmrs	r0, s0
  	mov	pc, lr
  	.org	1b + 8
  1:	mrc	p10, 0, r0, c\dr, c0, 4	@ fmrs	r0, s1
  	mov	pc, lr
  	.org	1b + 8
  	.endr
  ENDPROC(vfp_get_float)
  
  ENTRY(vfp_put_float)
  	tbl_branch r1, r3, #3
  	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
  1:	mcr	p10, 0, r0, c\dr, c0, 0	@ fmsr	r0, s0
  	mov	pc, lr
  	.org	1b + 8
  1:	mcr	p10, 0, r0, c\dr, c0, 4	@ fmsr	r0, s1
  	mov	pc, lr
  	.org	1b + 8
  	.endr
  ENDPROC(vfp_put_float)
  
  ENTRY(vfp_get_double)
  	tbl_branch r0, r3, #3
  	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
  1:	fmrrd	r0, r1, d\dr
  	mov	pc, lr
  	.org	1b + 8
  	.endr
  #ifdef CONFIG_VFPv3
  	@ d16 - d31 registers
  	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
  1:	mrrc	p11, 3, r0, r1, c\dr	@ fmrrd	r0, r1, d\dr
  	mov	pc, lr
  	.org	1b + 8
  	.endr
  #endif
  
  	@ virtual register 16 (or 32 if VFPv3) for compare with zero
  	mov	r0, #0
  	mov	r1, #0
  	mov	pc, lr
  ENDPROC(vfp_get_double)
  
  ENTRY(vfp_put_double)
  	tbl_branch r2, r3, #3
  	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
  1:	fmdrr	d\dr, r0, r1
  	mov	pc, lr
  	.org	1b + 8
  	.endr
  #ifdef CONFIG_VFPv3
  	@ d16 - d31 registers
  	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
  1:	mcrr	p11, 3, r0, r1, c\dr	@ fmdrr	r0, r1, d\dr
  	mov	pc, lr
  	.org	1b + 8
  	.endr
  #endif
  ENDPROC(vfp_put_double)