ARM: move VFP init to an earlier boot stage
[deliverable/linux.git] / arch / arm / vfp / vfphw.S
CommitLineData
1da177e4
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1/*
2 * linux/arch/arm/vfp/vfphw.S
3 *
4 * Copyright (C) 2004 ARM Limited.
5 * Written by Deep Blue Solutions Limited.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This code is called from the kernel's undefined instruction trap.
12 * r9 holds the return address for successful handling.
13 * lr holds the return address for unrecognised instructions.
14 * r10 points at the start of the private FP workspace in the thread structure
15 * sp points to a struct pt_regs (as defined in include/asm/proc/ptrace.h)
16 */
17#include <asm/thread_info.h>
18#include <asm/vfpmacros.h>
0cc41e4a 19#include <linux/kern_levels.h>
1da177e4
LT
20#include "../kernel/entry-header.S"
21
22 .macro DBGSTR, str
23#ifdef DEBUG
24 stmfd sp!, {r0-r3, ip, lr}
ded3ef0f 25 ldr r0, =1f
1da177e4 26 bl printk
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RK
27 ldmfd sp!, {r0-r3, ip, lr}
28
29 .pushsection .rodata, "a"
301: .ascii KERN_DEBUG "VFP: \str\n"
31 .byte 0
32 .previous
1da177e4
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33#endif
34 .endm
35
36 .macro DBGSTR1, str, arg
37#ifdef DEBUG
38 stmfd sp!, {r0-r3, ip, lr}
39 mov r1, \arg
ded3ef0f 40 ldr r0, =1f
1da177e4 41 bl printk
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RK
42 ldmfd sp!, {r0-r3, ip, lr}
43
44 .pushsection .rodata, "a"
451: .ascii KERN_DEBUG "VFP: \str\n"
46 .byte 0
47 .previous
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48#endif
49 .endm
50
51 .macro DBGSTR3, str, arg1, arg2, arg3
52#ifdef DEBUG
53 stmfd sp!, {r0-r3, ip, lr}
54 mov r3, \arg3
55 mov r2, \arg2
56 mov r1, \arg1
ded3ef0f 57 ldr r0, =1f
1da177e4 58 bl printk
ded3ef0f
RK
59 ldmfd sp!, {r0-r3, ip, lr}
60
61 .pushsection .rodata, "a"
621: .ascii KERN_DEBUG "VFP: \str\n"
63 .byte 0
64 .previous
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65#endif
66 .endm
67
68
69@ VFP hardware support entry point.
70@
15ac49b6
RK
71@ r0 = instruction opcode (32-bit ARM or two 16-bit Thumb)
72@ r2 = PC value to resume execution after successful emulation
73@ r9 = normal "successful" return address
1da177e4 74@ r10 = vfp_state union
c6428464 75@ r11 = CPU number
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RK
76@ lr = unrecognised instruction return address
77@ IRQs enabled.
93ed3970 78ENTRY(vfp_support_entry)
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LT
79 DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
80
81 VFPFMRX r1, FPEXC @ Is the VFP enabled?
82 DBGSTR1 "fpexc %08x", r1
228adef1 83 tst r1, #FPEXC_EN
1da177e4
LT
84 bne look_for_VFP_exceptions @ VFP is already enabled
85
86 DBGSTR1 "enable %x", r10
af61bdf0 87 ldr r3, vfp_current_hw_state_address
228adef1 88 orr r1, r1, #FPEXC_EN @ user FPEXC has the enable bit set
af61bdf0 89 ldr r4, [r3, r11, lsl #2] @ vfp_current_hw_state pointer
228adef1 90 bic r5, r1, #FPEXC_EX @ make sure exceptions are disabled
08409c33 91 cmp r4, r10 @ this thread owns the hw context?
f8f2a852
RK
92#ifndef CONFIG_SMP
93 @ For UP, checking that this thread owns the hw context is
94 @ sufficient to determine that the hardware state is valid.
08409c33 95 beq vfp_hw_state_valid
1da177e4 96
f8f2a852
RK
97 @ On UP, we lazily save the VFP context. As a different
98 @ thread wants ownership of the VFP hardware, save the old
99 @ state if there was a previous (valid) owner.
100
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101 VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
102 @ exceptions, so we can get at the
103 @ rest of it
104
1da177e4 105 DBGSTR1 "save old state %p", r4
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RK
106 cmp r4, #0 @ if the vfp_current_hw_state is NULL
107 beq vfp_reload_hw @ then the hw state needs reloading
25ebee02 108 VFPFSTMIA r4, r5 @ save the working registers
1da177e4 109 VFPFMRX r5, FPSCR @ current status
85d6943a 110#ifndef CONFIG_CPU_FEROCEON
c98929c0 111 tst r1, #FPEXC_EX @ is there additional state to save?
24b647a0
CM
112 beq 1f
113 VFPFMRX r6, FPINST @ FPINST (only if FPEXC.EX is set)
114 tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
115 beq 1f
116 VFPFMRX r8, FPINST2 @ FPINST2 if needed (and present)
1171:
85d6943a 118#endif
1da177e4 119 stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
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120vfp_reload_hw:
121
122#else
123 @ For SMP, if this thread does not own the hw context, then we
124 @ need to reload it. No need to save the old state as on SMP,
125 @ we always save the state when we switch away from a thread.
126 bne vfp_reload_hw
127
128 @ This thread has ownership of the current hardware context.
129 @ However, it may have been migrated to another CPU, in which
130 @ case the saved state is newer than the hardware context.
131 @ Check this by looking at the CPU number which the state was
132 @ last loaded onto.
133 ldr ip, [r10, #VFP_CPU]
134 teq ip, r11
135 beq vfp_hw_state_valid
136
137vfp_reload_hw:
138 @ We're loading this threads state into the VFP hardware. Update
139 @ the CPU number which contains the most up to date VFP context.
140 str r11, [r10, #VFP_CPU]
141
142 VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
143 @ exceptions, so we can get at the
144 @ rest of it
c6428464 145#endif
1da177e4 146
1da177e4 147 DBGSTR1 "load state %p", r10
af61bdf0 148 str r10, [r3, r11, lsl #2] @ update the vfp_current_hw_state pointer
1da177e4 149 @ Load the saved state back into the VFP
25ebee02 150 VFPFLDMIA r10, r5 @ reload the working registers while
1da177e4 151 @ FPEXC is in a safe state
80ed3547 152 ldmia r10, {r1, r5, r6, r8} @ load FPEXC, FPSCR, FPINST, FPINST2
85d6943a 153#ifndef CONFIG_CPU_FEROCEON
c98929c0 154 tst r1, #FPEXC_EX @ is there additional state to restore?
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CM
155 beq 1f
156 VFPFMXR FPINST, r6 @ restore FPINST (only if FPEXC.EX is set)
157 tst r1, #FPEXC_FP2V @ is there an FPINST2 to write?
158 beq 1f
159 VFPFMXR FPINST2, r8 @ FPINST2 if needed (and present)
1601:
85d6943a 161#endif
1da177e4
LT
162 VFPFMXR FPSCR, r5 @ restore status
163
08409c33
RK
164@ The context stored in the VFP hardware is up to date with this thread
165vfp_hw_state_valid:
228adef1 166 tst r1, #FPEXC_EX
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LT
167 bne process_exception @ might as well handle the pending
168 @ exception before retrying branch
169 @ out before setting an FPEXC that
170 @ stops us reading stuff
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RK
171 VFPFMXR FPEXC, r1 @ Restore FPEXC last
172 sub r2, r2, #4 @ Retry current instruction - if Thumb
173 str r2, [sp, #S_PC] @ mode it's two 16-bit instructions,
174 @ else it's one 32-bit instruction, so
175 @ always subtract 4 from the following
176 @ instruction address.
568dca15 177#ifdef CONFIG_PREEMPT_COUNT
f2255be8
GD
178 get_thread_info r10
179 ldr r4, [r10, #TI_PREEMPT] @ get preempt count
180 sub r11, r4, #1 @ decrement it
181 str r11, [r10, #TI_PREEMPT]
182#endif
1da177e4
LT
183 mov pc, r9 @ we think we have handled things
184
185
186look_for_VFP_exceptions:
c98929c0
CM
187 @ Check for synchronous or asynchronous exception
188 tst r1, #FPEXC_EX | FPEXC_DEX
1da177e4 189 bne process_exception
c98929c0
CM
190 @ On some implementations of the VFP subarch 1, setting FPSCR.IXE
191 @ causes all the CDP instructions to be bounced synchronously without
192 @ setting the FPEXC.EX bit
1da177e4 193 VFPFMRX r5, FPSCR
c98929c0 194 tst r5, #FPSCR_IXE
1da177e4
LT
195 bne process_exception
196
197 @ Fall into hand on to next handler - appropriate coproc instr
198 @ not recognised by VFP
199
200 DBGSTR "not VFP"
568dca15 201#ifdef CONFIG_PREEMPT_COUNT
f2255be8
GD
202 get_thread_info r10
203 ldr r4, [r10, #TI_PREEMPT] @ get preempt count
204 sub r11, r4, #1 @ decrement it
205 str r11, [r10, #TI_PREEMPT]
206#endif
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LT
207 mov pc, lr
208
209process_exception:
210 DBGSTR "bounce"
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211 mov r2, sp @ nothing stacked - regdump is at TOS
212 mov lr, r9 @ setup for a return to the user code.
213
214 @ Now call the C code to package up the bounce to the support code
215 @ r0 holds the trigger instruction
216 @ r1 holds the FPEXC value
217 @ r2 pointer to register dump
c98929c0 218 b VFP_bounce @ we have handled this - the support
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LT
219 @ code will raise an exception if
220 @ required. If not, the user code will
221 @ retry the faulted instruction
93ed3970 222ENDPROC(vfp_support_entry)
1da177e4 223
93ed3970 224ENTRY(vfp_save_state)
c6428464
CM
225 @ Save the current VFP state
226 @ r0 - save location
227 @ r1 - FPEXC
228 DBGSTR1 "save VFP state %p", r0
25ebee02 229 VFPFSTMIA r0, r2 @ save the working registers
c6428464 230 VFPFMRX r2, FPSCR @ current status
c98929c0 231 tst r1, #FPEXC_EX @ is there additional state to save?
24b647a0
CM
232 beq 1f
233 VFPFMRX r3, FPINST @ FPINST (only if FPEXC.EX is set)
234 tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
235 beq 1f
236 VFPFMRX r12, FPINST2 @ FPINST2 if needed (and present)
2371:
c6428464
CM
238 stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2
239 mov pc, lr
93ed3970 240ENDPROC(vfp_save_state)
c6428464 241
7eb25ebe 242 .align
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RK
243vfp_current_hw_state_address:
244 .word vfp_current_hw_state
1da177e4 245
07f33a03
CM
246 .macro tbl_branch, base, tmp, shift
247#ifdef CONFIG_THUMB2_KERNEL
248 adr \tmp, 1f
249 add \tmp, \tmp, \base, lsl \shift
250 mov pc, \tmp
251#else
252 add pc, pc, \base, lsl \shift
1da177e4 253 mov r0, r0
07f33a03
CM
254#endif
2551:
256 .endm
257
258ENTRY(vfp_get_float)
259 tbl_branch r0, r3, #3
1da177e4 260 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
07f33a03 2611: mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0
1da177e4 262 mov pc, lr
07f33a03
CM
263 .org 1b + 8
2641: mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
1da177e4 265 mov pc, lr
07f33a03 266 .org 1b + 8
1da177e4 267 .endr
93ed3970 268ENDPROC(vfp_get_float)
1da177e4 269
93ed3970 270ENTRY(vfp_put_float)
07f33a03 271 tbl_branch r1, r3, #3
1da177e4 272 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
07f33a03 2731: mcr p10, 0, r0, c\dr, c0, 0 @ fmsr r0, s0
1da177e4 274 mov pc, lr
07f33a03
CM
275 .org 1b + 8
2761: mcr p10, 0, r0, c\dr, c0, 4 @ fmsr r0, s1
1da177e4 277 mov pc, lr
07f33a03 278 .org 1b + 8
1da177e4 279 .endr
93ed3970 280ENDPROC(vfp_put_float)
1da177e4 281
93ed3970 282ENTRY(vfp_get_double)
07f33a03 283 tbl_branch r0, r3, #3
1da177e4 284 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
07f33a03 2851: fmrrd r0, r1, d\dr
1da177e4 286 mov pc, lr
07f33a03 287 .org 1b + 8
1da177e4 288 .endr
25ebee02
CM
289#ifdef CONFIG_VFPv3
290 @ d16 - d31 registers
291 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
07f33a03 2921: mrrc p11, 3, r0, r1, c\dr @ fmrrd r0, r1, d\dr
25ebee02 293 mov pc, lr
07f33a03 294 .org 1b + 8
25ebee02
CM
295 .endr
296#endif
1da177e4 297
25ebee02 298 @ virtual register 16 (or 32 if VFPv3) for compare with zero
1da177e4
LT
299 mov r0, #0
300 mov r1, #0
301 mov pc, lr
93ed3970 302ENDPROC(vfp_get_double)
1da177e4 303
93ed3970 304ENTRY(vfp_put_double)
07f33a03 305 tbl_branch r2, r3, #3
1da177e4 306 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
07f33a03 3071: fmdrr d\dr, r0, r1
1da177e4 308 mov pc, lr
07f33a03 309 .org 1b + 8
1da177e4 310 .endr
25ebee02
CM
311#ifdef CONFIG_VFPv3
312 @ d16 - d31 registers
313 .irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
138de1c4 3141: mcrr p11, 3, r0, r1, c\dr @ fmdrr r0, r1, d\dr
25ebee02 315 mov pc, lr
07f33a03 316 .org 1b + 8
25ebee02
CM
317 .endr
318#endif
93ed3970 319ENDPROC(vfp_put_double)
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