xref: /openbmc/linux/arch/arm/kernel/iwmmxt.S (revision a531b0c2) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 *  linux/arch/arm/kernel/iwmmxt.S
4 *
5 *  XScale iWMMXt (Concan) context switching and handling
6 *
7 *  Initial code:
8 *  Copyright (c) 2003, Intel Corporation
9 *
10 *  Full lazy switching support, optimizations and more, by Nicolas Pitre
11*   Copyright (c) 2003-2004, MontaVista Software, Inc.
12 */
13
14#include <linux/linkage.h>
15#include <asm/ptrace.h>
16#include <asm/thread_info.h>
17#include <asm/asm-offsets.h>
18#include <asm/assembler.h>
19#include "iwmmxt.h"
20
21#if defined(CONFIG_CPU_PJ4) || defined(CONFIG_CPU_PJ4B)
22#define PJ4(code...)		code
23#define XSC(code...)
24#elif defined(CONFIG_CPU_MOHAWK) || \
25	defined(CONFIG_CPU_XSC3) || \
26	defined(CONFIG_CPU_XSCALE)
27#define PJ4(code...)
28#define XSC(code...)		code
29#else
30#error "Unsupported iWMMXt architecture"
31#endif
32
33#define MMX_WR0		 	(0x00)
34#define MMX_WR1		 	(0x08)
35#define MMX_WR2		 	(0x10)
36#define MMX_WR3			(0x18)
37#define MMX_WR4		 	(0x20)
38#define MMX_WR5		 	(0x28)
39#define MMX_WR6		 	(0x30)
40#define MMX_WR7		 	(0x38)
41#define MMX_WR8		 	(0x40)
42#define MMX_WR9		 	(0x48)
43#define MMX_WR10		(0x50)
44#define MMX_WR11		(0x58)
45#define MMX_WR12		(0x60)
46#define MMX_WR13		(0x68)
47#define MMX_WR14		(0x70)
48#define MMX_WR15		(0x78)
49#define MMX_WCSSF		(0x80)
50#define MMX_WCASF		(0x84)
51#define MMX_WCGR0		(0x88)
52#define MMX_WCGR1		(0x8C)
53#define MMX_WCGR2		(0x90)
54#define MMX_WCGR3		(0x94)
55
56#define MMX_SIZE		(0x98)
57
58	.text
59	.arm
60
61/*
62 * Lazy switching of Concan coprocessor context
63 *
64 * r10 = struct thread_info pointer
65 * r9  = ret_from_exception
66 * lr  = undefined instr exit
67 *
68 * called from prefetch exception handler with interrupts enabled
69 */
70
71ENTRY(iwmmxt_task_enable)
72	inc_preempt_count r10, r3
73
74	XSC(mrc	p15, 0, r2, c15, c1, 0)
75	PJ4(mrc p15, 0, r2, c1, c0, 2)
76	@ CP0 and CP1 accessible?
77	XSC(tst	r2, #0x3)
78	PJ4(tst	r2, #0xf)
79	bne	4f				@ if so no business here
80	@ enable access to CP0 and CP1
81	XSC(orr	r2, r2, #0x3)
82	XSC(mcr	p15, 0, r2, c15, c1, 0)
83	PJ4(orr	r2, r2, #0xf)
84	PJ4(mcr	p15, 0, r2, c1, c0, 2)
85
86	ldr	r3, =concan_owner
87	add	r0, r10, #TI_IWMMXT_STATE	@ get task Concan save area
88	ldr	r2, [sp, #60]			@ current task pc value
89	ldr	r1, [r3]			@ get current Concan owner
90	str	r0, [r3]			@ this task now owns Concan regs
91	sub	r2, r2, #4			@ adjust pc back
92	str	r2, [sp, #60]
93
94	mrc	p15, 0, r2, c2, c0, 0
95	mov	r2, r2				@ cpwait
96	bl	concan_save
97
98#ifdef CONFIG_PREEMPT_COUNT
99	get_thread_info r10
100#endif
1014:	dec_preempt_count r10, r3
102	ret	r9				@ normal exit from exception
103
104concan_save:
105
106	teq	r1, #0				@ test for last ownership
107	beq	concan_load			@ no owner, skip save
108
109	tmrc	r2, wCon
110
111	@ CUP? wCx
112	tst	r2, #0x1
113	beq 	1f
114
115concan_dump:
116
117	wstrw	wCSSF, r1, MMX_WCSSF
118	wstrw	wCASF, r1, MMX_WCASF
119	wstrw	wCGR0, r1, MMX_WCGR0
120	wstrw	wCGR1, r1, MMX_WCGR1
121	wstrw	wCGR2, r1, MMX_WCGR2
122	wstrw	wCGR3, r1, MMX_WCGR3
123
1241:	@ MUP? wRn
125	tst	r2, #0x2
126	beq	2f
127
128	wstrd	wR0,  r1, MMX_WR0
129	wstrd	wR1,  r1, MMX_WR1
130	wstrd	wR2,  r1, MMX_WR2
131	wstrd	wR3,  r1, MMX_WR3
132	wstrd	wR4,  r1, MMX_WR4
133	wstrd	wR5,  r1, MMX_WR5
134	wstrd	wR6,  r1, MMX_WR6
135	wstrd	wR7,  r1, MMX_WR7
136	wstrd	wR8,  r1, MMX_WR8
137	wstrd	wR9,  r1, MMX_WR9
138	wstrd	wR10, r1, MMX_WR10
139	wstrd	wR11, r1, MMX_WR11
140	wstrd	wR12, r1, MMX_WR12
141	wstrd	wR13, r1, MMX_WR13
142	wstrd	wR14, r1, MMX_WR14
143	wstrd	wR15, r1, MMX_WR15
144
1452:	teq	r0, #0				@ anything to load?
146	reteq	lr				@ if not, return
147
148concan_load:
149
150	@ Load wRn
151	wldrd	wR0,  r0, MMX_WR0
152	wldrd	wR1,  r0, MMX_WR1
153	wldrd	wR2,  r0, MMX_WR2
154	wldrd	wR3,  r0, MMX_WR3
155	wldrd	wR4,  r0, MMX_WR4
156	wldrd	wR5,  r0, MMX_WR5
157	wldrd	wR6,  r0, MMX_WR6
158	wldrd	wR7,  r0, MMX_WR7
159	wldrd	wR8,  r0, MMX_WR8
160	wldrd	wR9,  r0, MMX_WR9
161	wldrd	wR10, r0, MMX_WR10
162	wldrd	wR11, r0, MMX_WR11
163	wldrd	wR12, r0, MMX_WR12
164	wldrd	wR13, r0, MMX_WR13
165	wldrd	wR14, r0, MMX_WR14
166	wldrd	wR15, r0, MMX_WR15
167
168	@ Load wCx
169	wldrw	wCSSF, r0, MMX_WCSSF
170	wldrw	wCASF, r0, MMX_WCASF
171	wldrw	wCGR0, r0, MMX_WCGR0
172	wldrw	wCGR1, r0, MMX_WCGR1
173	wldrw	wCGR2, r0, MMX_WCGR2
174	wldrw	wCGR3, r0, MMX_WCGR3
175
176	@ clear CUP/MUP (only if r1 != 0)
177	teq	r1, #0
178	mov 	r2, #0
179	reteq	lr
180
181	tmcr	wCon, r2
182	ret	lr
183
184ENDPROC(iwmmxt_task_enable)
185
186/*
187 * Back up Concan regs to save area and disable access to them
188 * (mainly for gdb or sleep mode usage)
189 *
190 * r0 = struct thread_info pointer of target task or NULL for any
191 */
192
193ENTRY(iwmmxt_task_disable)
194
195	stmfd	sp!, {r4, lr}
196
197	mrs	ip, cpsr
198	orr	r2, ip, #PSR_I_BIT		@ disable interrupts
199	msr	cpsr_c, r2
200
201	ldr	r3, =concan_owner
202	add	r2, r0, #TI_IWMMXT_STATE	@ get task Concan save area
203	ldr	r1, [r3]			@ get current Concan owner
204	teq	r1, #0				@ any current owner?
205	beq	1f				@ no: quit
206	teq	r0, #0				@ any owner?
207	teqne	r1, r2				@ or specified one?
208	bne	1f				@ no: quit
209
210	@ enable access to CP0 and CP1
211	XSC(mrc	p15, 0, r4, c15, c1, 0)
212	XSC(orr	r4, r4, #0x3)
213	XSC(mcr	p15, 0, r4, c15, c1, 0)
214	PJ4(mrc p15, 0, r4, c1, c0, 2)
215	PJ4(orr	r4, r4, #0xf)
216	PJ4(mcr	p15, 0, r4, c1, c0, 2)
217
218	mov	r0, #0				@ nothing to load
219	str	r0, [r3]			@ no more current owner
220	mrc	p15, 0, r2, c2, c0, 0
221	mov	r2, r2				@ cpwait
222	bl	concan_save
223
224	@ disable access to CP0 and CP1
225	XSC(bic	r4, r4, #0x3)
226	XSC(mcr	p15, 0, r4, c15, c1, 0)
227	PJ4(bic	r4, r4, #0xf)
228	PJ4(mcr	p15, 0, r4, c1, c0, 2)
229
230	mrc	p15, 0, r2, c2, c0, 0
231	mov	r2, r2				@ cpwait
232
2331:	msr	cpsr_c, ip			@ restore interrupt mode
234	ldmfd	sp!, {r4, pc}
235
236ENDPROC(iwmmxt_task_disable)
237
238/*
239 * Copy Concan state to given memory address
240 *
241 * r0 = struct thread_info pointer of target task
242 * r1 = memory address where to store Concan state
243 *
244 * this is called mainly in the creation of signal stack frames
245 */
246
247ENTRY(iwmmxt_task_copy)
248
249	mrs	ip, cpsr
250	orr	r2, ip, #PSR_I_BIT		@ disable interrupts
251	msr	cpsr_c, r2
252
253	ldr	r3, =concan_owner
254	add	r2, r0, #TI_IWMMXT_STATE	@ get task Concan save area
255	ldr	r3, [r3]			@ get current Concan owner
256	teq	r2, r3				@ does this task own it...
257	beq	1f
258
259	@ current Concan values are in the task save area
260	msr	cpsr_c, ip			@ restore interrupt mode
261	mov	r0, r1
262	mov	r1, r2
263	mov	r2, #MMX_SIZE
264	b	memcpy
265
2661:	@ this task owns Concan regs -- grab a copy from there
267	mov	r0, #0				@ nothing to load
268	mov	r2, #3				@ save all regs
269	mov	r3, lr				@ preserve return address
270	bl	concan_dump
271	msr	cpsr_c, ip			@ restore interrupt mode
272	ret	r3
273
274ENDPROC(iwmmxt_task_copy)
275
276/*
277 * Restore Concan state from given memory address
278 *
279 * r0 = struct thread_info pointer of target task
280 * r1 = memory address where to get Concan state from
281 *
282 * this is used to restore Concan state when unwinding a signal stack frame
283 */
284
285ENTRY(iwmmxt_task_restore)
286
287	mrs	ip, cpsr
288	orr	r2, ip, #PSR_I_BIT		@ disable interrupts
289	msr	cpsr_c, r2
290
291	ldr	r3, =concan_owner
292	add	r2, r0, #TI_IWMMXT_STATE	@ get task Concan save area
293	ldr	r3, [r3]			@ get current Concan owner
294	bic	r2, r2, #0x7			@ 64-bit alignment
295	teq	r2, r3				@ does this task own it...
296	beq	1f
297
298	@ this task doesn't own Concan regs -- use its save area
299	msr	cpsr_c, ip			@ restore interrupt mode
300	mov	r0, r2
301	mov	r2, #MMX_SIZE
302	b	memcpy
303
3041:	@ this task owns Concan regs -- load them directly
305	mov	r0, r1
306	mov	r1, #0				@ don't clear CUP/MUP
307	mov	r3, lr				@ preserve return address
308	bl	concan_load
309	msr	cpsr_c, ip			@ restore interrupt mode
310	ret	r3
311
312ENDPROC(iwmmxt_task_restore)
313
314/*
315 * Concan handling on task switch
316 *
317 * r0 = next thread_info pointer
318 *
319 * Called only from the iwmmxt notifier with task preemption disabled.
320 */
321ENTRY(iwmmxt_task_switch)
322
323	XSC(mrc	p15, 0, r1, c15, c1, 0)
324	PJ4(mrc	p15, 0, r1, c1, c0, 2)
325	@ CP0 and CP1 accessible?
326	XSC(tst	r1, #0x3)
327	PJ4(tst	r1, #0xf)
328	bne	1f				@ yes: block them for next task
329
330	ldr	r2, =concan_owner
331	add	r3, r0, #TI_IWMMXT_STATE	@ get next task Concan save area
332	ldr	r2, [r2]			@ get current Concan owner
333	teq	r2, r3				@ next task owns it?
334	retne	lr				@ no: leave Concan disabled
335
3361:	@ flip Concan access
337	XSC(eor	r1, r1, #0x3)
338	XSC(mcr	p15, 0, r1, c15, c1, 0)
339	PJ4(eor r1, r1, #0xf)
340	PJ4(mcr	p15, 0, r1, c1, c0, 2)
341
342	mrc	p15, 0, r1, c2, c0, 0
343	sub	pc, lr, r1, lsr #32		@ cpwait and return
344
345ENDPROC(iwmmxt_task_switch)
346
347/*
348 * Remove Concan ownership of given task
349 *
350 * r0 = struct thread_info pointer
351 */
352ENTRY(iwmmxt_task_release)
353
354	mrs	r2, cpsr
355	orr	ip, r2, #PSR_I_BIT		@ disable interrupts
356	msr	cpsr_c, ip
357	ldr	r3, =concan_owner
358	add	r0, r0, #TI_IWMMXT_STATE	@ get task Concan save area
359	ldr	r1, [r3]			@ get current Concan owner
360	eors	r0, r0, r1			@ if equal...
361	streq	r0, [r3]			@ then clear ownership
362	msr	cpsr_c, r2			@ restore interrupts
363	ret	lr
364
365ENDPROC(iwmmxt_task_release)
366
367	.data
368	.align	2
369concan_owner:
370	.word	0
371
372