arch/powerpc/kernel/pmc.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  arch/powerpc/kernel/pmc.c
 *
 *  Copyright (C) 2004 David Gibson, IBM Corporation.
 *  Includes code formerly from arch/ppc/kernel/perfmon.c:
 *    Author: Andy Fleming
 *    Copyright (c) 2004 Freescale Semiconductor, Inc
 */

#include <linux/errno.h>
#include <linux/bug.h>
#include <linux/spinlock.h>
#include <linux/export.h>

#include <asm/processor.h>
#include <asm/cputable.h>
#include <asm/pmc.h>

#ifndef MMCR0_PMAO
#define MMCR0_PMAO	0
#endif

static void dummy_perf(struct pt_regs *regs)
{
#if defined(CONFIG_FSL_EMB_PERFMON)
	mtpmr(PMRN_PMGC0, mfpmr(PMRN_PMGC0) & ~PMGC0_PMIE);
#elif defined(CONFIG_PPC64) || defined(CONFIG_PPC_BOOK3S_32)
	if (cur_cpu_spec->pmc_type == PPC_PMC_IBM)
		mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~(MMCR0_PMXE|MMCR0_PMAO));
#else
	mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_PMXE);
#endif
}


static DEFINE_RAW_SPINLOCK(pmc_owner_lock);
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;

	raw_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 ? new_perf_irq : dummy_perf;

 out:
	raw_spin_unlock(&pmc_owner_lock);
	return err;
}
EXPORT_SYMBOL_GPL(reserve_pmc_hardware);

void release_pmc_hardware(void)
{
	raw_spin_lock(&pmc_owner_lock);

	WARN_ON(! pmc_owner_caller);

	pmc_owner_caller = NULL;
	perf_irq = dummy_perf;

	raw_spin_unlock(&pmc_owner_lock);
}
EXPORT_SYMBOL_GPL(release_pmc_hardware);

#ifdef CONFIG_PPC64
void power4_enable_pmcs(void)
{
	unsigned long hid0;

	hid0 = mfspr(SPRN_HID0);
	hid0 |= 1UL << (63 - 20);

	/* POWER4 requires the following sequence */
	asm volatile(
		"sync\n"
		"mtspr     %1, %0\n"
		"mfspr     %0, %1\n"
		"mfspr     %0, %1\n"
		"mfspr     %0, %1\n"
		"mfspr     %0, %1\n"
		"mfspr     %0, %1\n"
		"mfspr     %0, %1\n"
		"isync" : "=&r" (hid0) : "i" (SPRN_HID0), "0" (hid0):
		"memory");
}
#endif /* CONFIG_PPC64 */