irqflags.h

/*
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __ASM_IRQFLAGS_H
#define __ASM_IRQFLAGS_H

#ifdef __KERNEL__

#include <asm/alternative.h>
#include <asm/barrier.h>
#include <asm/ptrace.h>
#include <asm/sysreg.h>

/*
 * Aarch64 has flags for masking: Debug, Asynchronous (serror), Interrupts and
 * FIQ exceptions, in the 'daif' register. We mask and unmask them in 'dai'
 * order:
 * Masking debug exceptions causes all other exceptions to be masked too/
 * Masking SError masks irq, but not debug exceptions. Masking irqs has no
 * side effects for other flags. Keeping to this order makes it easier for
 * entry.S to know which exceptions should be unmasked.
 *
 * FIQ is never expected, but we mask it when we disable debug exceptions, and
 * unmask it at all other times.
 */

/*
 * CPU interrupt mask handling.
 */
static inline void arch_local_irq_enable(void)
{
	if (system_has_prio_mask_debugging()) {
		u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1);

		WARN_ON_ONCE(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF);
	}

	asm volatile(ALTERNATIVE(
		"msr	daifclr, #2		// arch_local_irq_enable",
		__msr_s(SYS_ICC_PMR_EL1, "%0"),
		ARM64_HAS_IRQ_PRIO_MASKING)
		:
		: "r" ((unsigned long) GIC_PRIO_IRQON)
		: "memory");

	pmr_sync();
}

static inline void arch_local_irq_disable(void)
{
	if (system_has_prio_mask_debugging()) {
		u32 pmr = read_sysreg_s(SYS_ICC_PMR_EL1);

		WARN_ON_ONCE(pmr != GIC_PRIO_IRQON && pmr != GIC_PRIO_IRQOFF);
	}

	asm volatile(ALTERNATIVE(
		"msr	daifset, #2		// arch_local_irq_disable",
		__msr_s(SYS_ICC_PMR_EL1, "%0"),
		ARM64_HAS_IRQ_PRIO_MASKING)
		:
		: "r" ((unsigned long) GIC_PRIO_IRQOFF)
		: "memory");
}

/*
 * Save the current interrupt enable state.
 */
static inline unsigned long arch_local_save_flags(void)
{
	unsigned long flags;

	asm volatile(ALTERNATIVE(
		"mrs	%0, daif",
		__mrs_s("%0", SYS_ICC_PMR_EL1),
		ARM64_HAS_IRQ_PRIO_MASKING)
		: "=&r" (flags)
		:
		: "memory");

	return flags;
}

static inline int arch_irqs_disabled_flags(unsigned long flags)
{
	int res;

	asm volatile(ALTERNATIVE(
		"and	%w0, %w1, #" __stringify(PSR_I_BIT),
		"eor	%w0, %w1, #" __stringify(GIC_PRIO_IRQON),
		ARM64_HAS_IRQ_PRIO_MASKING)
		: "=&r" (res)
		: "r" ((int) flags)
		: "memory");

	return res;
}

static inline unsigned long arch_local_irq_save(void)
{
	unsigned long flags;

	flags = arch_local_save_flags();

	/*
	 * There are too many states with IRQs disabled, just keep the current
	 * state if interrupts are already disabled/masked.
	 */
	if (!arch_irqs_disabled_flags(flags))
		arch_local_irq_disable();

	return flags;
}

/*
 * restore saved IRQ state
 */
static inline void arch_local_irq_restore(unsigned long flags)
{
	asm volatile(ALTERNATIVE(
		"msr	daif, %0",
		__msr_s(SYS_ICC_PMR_EL1, "%0"),
		ARM64_HAS_IRQ_PRIO_MASKING)
		:
		: "r" (flags)
		: "memory");

	pmr_sync();
}

#endif
#endif