1/*
2 * Userland implementation of gettimeofday() for 32 bits processes in a
3 * ppc64 kernel for use in the vDSO
4 *
5 * Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org,
6 *                    IBM Corp.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13#include <asm/processor.h>
14#include <asm/ppc_asm.h>
15#include <asm/vdso.h>
16#include <asm/asm-offsets.h>
17#include <asm/unistd.h>
18
19/* Offset for the low 32-bit part of a field of long type */
20#ifdef CONFIG_PPC64
21#define LOPART	4
22#define TSPEC_TV_SEC	TSPC64_TV_SEC+LOPART
23#else
24#define LOPART	0
25#define TSPEC_TV_SEC	TSPC32_TV_SEC
26#endif
27
28	.text
29/*
30 * Exact prototype of gettimeofday
31 *
32 * int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz);
33 *
34 */
35V_FUNCTION_BEGIN(__kernel_gettimeofday)
36  .cfi_startproc
37	mflr	r12
38  .cfi_register lr,r12
39
40	mr	r10,r3			/* r10 saves tv */
41	mr	r11,r4			/* r11 saves tz */
42	bl	__get_datapage@local	/* get data page */
43	mr	r9, r3			/* datapage ptr in r9 */
44	cmplwi	r10,0			/* check if tv is NULL */
45	beq	3f
46	lis	r7,1000000@ha		/* load up USEC_PER_SEC */
47	addi	r7,r7,1000000@l		/* so we get microseconds in r4 */
48	bl	__do_get_tspec@local	/* get sec/usec from tb & kernel */
49	stw	r3,TVAL32_TV_SEC(r10)
50	stw	r4,TVAL32_TV_USEC(r10)
51
523:	cmplwi	r11,0			/* check if tz is NULL */
53	beq	1f
54	lwz	r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
55	lwz	r5,CFG_TZ_DSTTIME(r9)
56	stw	r4,TZONE_TZ_MINWEST(r11)
57	stw	r5,TZONE_TZ_DSTTIME(r11)
58
591:	mtlr	r12
60	crclr	cr0*4+so
61	li	r3,0
62	blr
63  .cfi_endproc
64V_FUNCTION_END(__kernel_gettimeofday)
65
66/*
67 * Exact prototype of clock_gettime()
68 *
69 * int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp);
70 *
71 */
72V_FUNCTION_BEGIN(__kernel_clock_gettime)
73  .cfi_startproc
74	/* Check for supported clock IDs */
75	cmpli	cr0,r3,CLOCK_REALTIME
76	cmpli	cr1,r3,CLOCK_MONOTONIC
77	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
78	bne	cr0,99f
79
80	mflr	r12			/* r12 saves lr */
81  .cfi_register lr,r12
82	mr	r11,r4			/* r11 saves tp */
83	bl	__get_datapage@local	/* get data page */
84	mr	r9,r3			/* datapage ptr in r9 */
85	lis	r7,NSEC_PER_SEC@h	/* want nanoseconds */
86	ori	r7,r7,NSEC_PER_SEC@l
8750:	bl	__do_get_tspec@local	/* get sec/nsec from tb & kernel */
88	bne	cr1,80f			/* not monotonic -> all done */
89
90	/*
91	 * CLOCK_MONOTONIC
92	 */
93
94	/* now we must fixup using wall to monotonic. We need to snapshot
95	 * that value and do the counter trick again. Fortunately, we still
96	 * have the counter value in r8 that was returned by __do_get_xsec.
97	 * At this point, r3,r4 contain our sec/nsec values, r5 and r6
98	 * can be used, r7 contains NSEC_PER_SEC.
99	 */
100
101	lwz	r5,WTOM_CLOCK_SEC(r9)
102	lwz	r6,WTOM_CLOCK_NSEC(r9)
103
104	/* We now have our offset in r5,r6. We create a fake dependency
105	 * on that value and re-check the counter
106	 */
107	or	r0,r6,r5
108	xor	r0,r0,r0
109	add	r9,r9,r0
110	lwz	r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
111        cmpl    cr0,r8,r0		/* check if updated */
112	bne-	50b
113
114	/* Calculate and store result. Note that this mimics the C code,
115	 * which may cause funny results if nsec goes negative... is that
116	 * possible at all ?
117	 */
118	add	r3,r3,r5
119	add	r4,r4,r6
120	cmpw	cr0,r4,r7
121	cmpwi	cr1,r4,0
122	blt	1f
123	subf	r4,r7,r4
124	addi	r3,r3,1
1251:	bge	cr1,80f
126	addi	r3,r3,-1
127	add	r4,r4,r7
128
12980:	stw	r3,TSPC32_TV_SEC(r11)
130	stw	r4,TSPC32_TV_NSEC(r11)
131
132	mtlr	r12
133	crclr	cr0*4+so
134	li	r3,0
135	blr
136
137	/*
138	 * syscall fallback
139	 */
14099:
141	li	r0,__NR_clock_gettime
142	sc
143	blr
144  .cfi_endproc
145V_FUNCTION_END(__kernel_clock_gettime)
146
147
148/*
149 * Exact prototype of clock_getres()
150 *
151 * int __kernel_clock_getres(clockid_t clock_id, struct timespec *res);
152 *
153 */
154V_FUNCTION_BEGIN(__kernel_clock_getres)
155  .cfi_startproc
156	/* Check for supported clock IDs */
157	cmpwi	cr0,r3,CLOCK_REALTIME
158	cmpwi	cr1,r3,CLOCK_MONOTONIC
159	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
160	bne	cr0,99f
161
162	li	r3,0
163	cmpli	cr0,r4,0
164	crclr	cr0*4+so
165	beqlr
166	lis	r5,CLOCK_REALTIME_RES@h
167	ori	r5,r5,CLOCK_REALTIME_RES@l
168	stw	r3,TSPC32_TV_SEC(r4)
169	stw	r5,TSPC32_TV_NSEC(r4)
170	blr
171
172	/*
173	 * syscall fallback
174	 */
17599:
176	li	r0,__NR_clock_getres
177	sc
178	blr
179  .cfi_endproc
180V_FUNCTION_END(__kernel_clock_getres)
181
182
183/*
184 * Exact prototype of time()
185 *
186 * time_t time(time *t);
187 *
188 */
189V_FUNCTION_BEGIN(__kernel_time)
190  .cfi_startproc
191	mflr	r12
192  .cfi_register lr,r12
193
194	mr	r11,r3			/* r11 holds t */
195	bl	__get_datapage@local
196	mr	r9, r3			/* datapage ptr in r9 */
197
198	lwz	r3,STAMP_XTIME+TSPEC_TV_SEC(r9)
199
200	cmplwi	r11,0			/* check if t is NULL */
201	beq	2f
202	stw	r3,0(r11)		/* store result at *t */
2032:	mtlr	r12
204	crclr	cr0*4+so
205	blr
206  .cfi_endproc
207V_FUNCTION_END(__kernel_time)
208
209/*
210 * This is the core of clock_gettime() and gettimeofday(),
211 * it returns the current time in r3 (seconds) and r4.
212 * On entry, r7 gives the resolution of r4, either USEC_PER_SEC
213 * or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
214 * It expects the datapage ptr in r9 and doesn't clobber it.
215 * It clobbers r0, r5 and r6.
216 * On return, r8 contains the counter value that can be reused.
217 * This clobbers cr0 but not any other cr field.
218 */
219__do_get_tspec:
220  .cfi_startproc
221	/* Check for update count & load values. We use the low
222	 * order 32 bits of the update count
223	 */
2241:	lwz	r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
225	andi.	r0,r8,1			/* pending update ? loop */
226	bne-	1b
227	xor	r0,r8,r8		/* create dependency */
228	add	r9,r9,r0
229
230	/* Load orig stamp (offset to TB) */
231	lwz	r5,CFG_TB_ORIG_STAMP(r9)
232	lwz	r6,(CFG_TB_ORIG_STAMP+4)(r9)
233
234	/* Get a stable TB value */
235#ifdef CONFIG_8xx
2362:	mftbu	r3
237	mftbl	r4
238	mftbu	r0
239#else
2402:	mfspr	r3, SPRN_TBRU
241	mfspr	r4, SPRN_TBRL
242	mfspr	r0, SPRN_TBRU
243#endif
244	cmplw	cr0,r3,r0
245	bne-	2b
246
247	/* Subtract tb orig stamp and shift left 12 bits.
248	 */
249	subfc	r4,r6,r4
250	subfe	r0,r5,r3
251	slwi	r0,r0,12
252	rlwimi.	r0,r4,12,20,31
253	slwi	r4,r4,12
254
255	/*
256	 * Load scale factor & do multiplication.
257	 * We only use the high 32 bits of the tb_to_xs value.
258	 * Even with a 1GHz timebase clock, the high 32 bits of
259	 * tb_to_xs will be at least 4 million, so the error from
260	 * ignoring the low 32 bits will be no more than 0.25ppm.
261	 * The error will just make the clock run very very slightly
262	 * slow until the next time the kernel updates the VDSO data,
263	 * at which point the clock will catch up to the kernel's value,
264	 * so there is no long-term error accumulation.
265	 */
266	lwz	r5,CFG_TB_TO_XS(r9)	/* load values */
267	mulhwu	r4,r4,r5
268	li	r3,0
269
270	beq+	4f			/* skip high part computation if 0 */
271	mulhwu	r3,r0,r5
272	mullw	r5,r0,r5
273	addc	r4,r4,r5
274	addze	r3,r3
2754:
276	/* At this point, we have seconds since the xtime stamp
277	 * as a 32.32 fixed-point number in r3 and r4.
278	 * Load & add the xtime stamp.
279	 */
280	lwz	r5,STAMP_XTIME+TSPEC_TV_SEC(r9)
281	lwz	r6,STAMP_SEC_FRAC(r9)
282	addc	r4,r4,r6
283	adde	r3,r3,r5
284
285	/* We create a fake dependency on the result in r3/r4
286	 * and re-check the counter
287	 */
288	or	r6,r4,r3
289	xor	r0,r6,r6
290	add	r9,r9,r0
291	lwz	r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
292        cmplw	cr0,r8,r0		/* check if updated */
293	bne-	1b
294
295	mulhwu	r4,r4,r7		/* convert to micro or nanoseconds */
296
297	blr
298  .cfi_endproc
299