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/*
* linux/arch/ppc64/kernel/pmc.c
*
* Copyright (C) 2004 David Gibson, IBM Corporation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <asm/processor.h>
#include <asm/pmc.h>
/* Ensure exceptions are disabled */
static void dummy_perf(struct pt_regs *regs)
{
unsigned int mmcr0 = mfspr(SPRN_MMCR0);
mmcr0 &= ~(MMCR0_PMXE|MMCR0_PMAO);
mtspr(SPRN_MMCR0, mmcr0);
}
static spinlock_t pmc_owner_lock = SPIN_LOCK_UNLOCKED;
static void *pmc_owner_caller; /* mostly for debugging */
perf_irq_t perf_irq = dummy_perf;
int reserve_pmc_hardware(perf_irq_t new_perf_irq)
{
int err = 0;
spin_lock(&pmc_owner_lock);
if (pmc_owner_caller) {
printk(KERN_WARNING "reserve_pmc_hardware: "
"PMC hardware busy (reserved by caller %p)\n",
pmc_owner_caller);
err = -EBUSY;
goto out;
}
pmc_owner_caller = __builtin_return_address(0);
perf_irq = new_perf_irq ? : dummy_perf;
out:
spin_unlock(&pmc_owner_lock);
return err;
}
EXPORT_SYMBOL_GPL(reserve_pmc_hardware);
void release_pmc_hardware(void)
{
spin_lock(&pmc_owner_lock);
WARN_ON(! pmc_owner_caller);
pmc_owner_caller = NULL;
perf_irq = dummy_perf;
spin_unlock(&pmc_owner_lock);
}
EXPORT_SYMBOL_GPL(release_pmc_hardware);
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