1/* $Id: locks.S,v 1.1.1.1 2007-08-03 18:52:17 $
2 * locks.S: SMP low-level lock primitives on Sparc.
3 *
4 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
5 * Copyright (C) 1998 Anton Blanchard (anton@progsoc.uts.edu.au)
6 * Copyright (C) 1998 Jakub Jelinek   (jj@ultra.linux.cz)
7 */
8
9#include <asm/ptrace.h>
10#include <asm/psr.h>
11#include <asm/smp.h>
12#include <asm/spinlock.h>
13
14	.text
15	.align	4
16
17	/* Read/writer locks, as usual this is overly clever to make it
18	 * as fast as possible.
19	 */
20
21	/* caches... */
22___rw_read_enter_spin_on_wlock:
23	orcc	%g2, 0x0, %g0
24	be,a	___rw_read_enter
25	 ldstub	[%g1 + 3], %g2
26	b	___rw_read_enter_spin_on_wlock
27	 ldub	[%g1 + 3], %g2
28___rw_read_try_spin_on_wlock:
29	andcc	%g2, 0xff, %g0
30	be,a	___rw_read_try
31	 ldstub	[%g1 + 3], %g2
32	xnorcc	%g2, 0x0, %o0	/* if g2 is ~0, set o0 to 0 and bugger off */
33	bne,a	___rw_read_enter_spin_on_wlock
34	 ld	[%g1], %g2
35	retl
36	 mov	%g4, %o7
37___rw_read_exit_spin_on_wlock:
38	orcc	%g2, 0x0, %g0
39	be,a	___rw_read_exit
40	 ldstub	[%g1 + 3], %g2
41	b	___rw_read_exit_spin_on_wlock
42	 ldub	[%g1 + 3], %g2
43___rw_write_enter_spin_on_wlock:
44	orcc	%g2, 0x0, %g0
45	be,a	___rw_write_enter
46	 ldstub	[%g1 + 3], %g2
47	b	___rw_write_enter_spin_on_wlock
48	 ld	[%g1], %g2
49
50	.globl	___rw_read_enter
51___rw_read_enter:
52	orcc	%g2, 0x0, %g0
53	bne,a	___rw_read_enter_spin_on_wlock
54	 ldub	[%g1 + 3], %g2
55	ld	[%g1], %g2
56	add	%g2, 1, %g2
57	st	%g2, [%g1]
58	retl
59	 mov	%g4, %o7
60
61	.globl	___rw_read_exit
62___rw_read_exit:
63	orcc	%g2, 0x0, %g0
64	bne,a	___rw_read_exit_spin_on_wlock
65	 ldub	[%g1 + 3], %g2
66	ld	[%g1], %g2
67	sub	%g2, 0x1ff, %g2
68	st	%g2, [%g1]
69	retl
70	 mov	%g4, %o7
71
72	.globl	___rw_read_try
73___rw_read_try:
74	orcc	%g2, 0x0, %g0
75	bne	___rw_read_try_spin_on_wlock
76	 ld	[%g1], %g2
77	add	%g2, 1, %g2
78	st	%g2, [%g1]
79	set	1, %o1
80	retl
81	 mov	%g4, %o7
82
83	.globl	___rw_write_enter
84___rw_write_enter:
85	orcc	%g2, 0x0, %g0
86	bne	___rw_write_enter_spin_on_wlock
87	 ld	[%g1], %g2
88	andncc	%g2, 0xff, %g0
89	bne,a	___rw_write_enter_spin_on_wlock
90	 stb	%g0, [%g1 + 3]
91	retl
92	 mov	%g4, %o7
93