1 files changed, 323 insertions, 0 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
new file mode 100644
index 000000000..f74a8f7e5
--- /dev/null
+++ b/arch/arm/vfp/vfphw.S
@@ -0,0 +1,323 @@
+/*
+ *  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 <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/thread_info.h>
+#include <asm/vfpmacros.h>
+#include <linux/kern_levels.h>
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+
+	.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\n"
+	.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\n"
+	.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\n"
+	.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.
+	dec_preempt_count_ti r10, r4
+	ret	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
+
+	tst	r5, #FPSCR_LENGTH_MASK
+	beq	skip
+	orr	r1, r1, #FPEXC_DEX
+	b	process_exception
+skip:
+
+	@ Fall into hand on to next handler - appropriate coproc instr
+	@ not recognised by VFP
+
+	DBGSTR	"not VFP"
+	dec_preempt_count_ti r10, r4
+	ret	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
+	ret	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
+	ret	\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
+	ret	lr
+	.org	1b + 8
+1:	mrc	p10, 0, r0, c\dr, c0, 4	@ fmrs	r0, s1
+	ret	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
+	ret	lr
+	.org	1b + 8
+1:	mcr	p10, 0, r0, c\dr, c0, 4	@ fmsr	r0, s1
+	ret	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
+	ret	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
+	ret	lr
+	.org	1b + 8
+	.endr
+#endif
+
+	@ virtual register 16 (or 32 if VFPv3) for compare with zero
+	mov	r0, #0
+	mov	r1, #0
+	ret	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
+	ret	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
+	ret	lr
+	.org	1b + 8
+	.endr
+#endif
+ENDPROC(vfp_put_double)