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1da177e4 LT |
1 | /* |
2 | * linux/arch/ppc64/kernel/pmc.c | |
3 | * | |
4 | * Copyright (C) 2004 David Gibson, IBM Corporation. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/config.h> | |
13 | #include <linux/errno.h> | |
14 | #include <linux/spinlock.h> | |
15 | #include <linux/module.h> | |
16 | ||
17 | #include <asm/processor.h> | |
18 | #include <asm/pmc.h> | |
19 | ||
20 | /* Ensure exceptions are disabled */ | |
21 | static void dummy_perf(struct pt_regs *regs) | |
22 | { | |
23 | unsigned int mmcr0 = mfspr(SPRN_MMCR0); | |
24 | ||
25 | mmcr0 &= ~(MMCR0_PMXE|MMCR0_PMAO); | |
26 | mtspr(SPRN_MMCR0, mmcr0); | |
27 | } | |
28 | ||
29 | static spinlock_t pmc_owner_lock = SPIN_LOCK_UNLOCKED; | |
30 | static void *pmc_owner_caller; /* mostly for debugging */ | |
31 | perf_irq_t perf_irq = dummy_perf; | |
32 | ||
33 | int reserve_pmc_hardware(perf_irq_t new_perf_irq) | |
34 | { | |
35 | int err = 0; | |
36 | ||
37 | spin_lock(&pmc_owner_lock); | |
38 | ||
39 | if (pmc_owner_caller) { | |
40 | printk(KERN_WARNING "reserve_pmc_hardware: " | |
41 | "PMC hardware busy (reserved by caller %p)\n", | |
42 | pmc_owner_caller); | |
43 | err = -EBUSY; | |
44 | goto out; | |
45 | } | |
46 | ||
47 | pmc_owner_caller = __builtin_return_address(0); | |
48 | perf_irq = new_perf_irq ? : dummy_perf; | |
49 | ||
50 | out: | |
51 | spin_unlock(&pmc_owner_lock); | |
52 | return err; | |
53 | } | |
54 | EXPORT_SYMBOL_GPL(reserve_pmc_hardware); | |
55 | ||
56 | void release_pmc_hardware(void) | |
57 | { | |
58 | spin_lock(&pmc_owner_lock); | |
59 | ||
60 | WARN_ON(! pmc_owner_caller); | |
61 | ||
62 | pmc_owner_caller = NULL; | |
63 | perf_irq = dummy_perf; | |
64 | ||
65 | spin_unlock(&pmc_owner_lock); | |
66 | } | |
67 | EXPORT_SYMBOL_GPL(release_pmc_hardware); |