[mirror_ubuntu-eoan-kernel.git] / include / asm-generic / mmiowb.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_GENERIC_MMIOWB_H
#define __ASM_GENERIC_MMIOWB_H

/*
 * Generic implementation of mmiowb() tracking for spinlocks.
 *
 * If your architecture doesn't ensure that writes to an I/O peripheral
 * within two spinlocked sections on two different CPUs are seen by the
 * peripheral in the order corresponding to the lock handover, then you
 * need to follow these FIVE easy steps:
 *
 * 	1. Implement mmiowb() (and arch_mmiowb_state() if you're fancy)
 *	   in asm/mmiowb.h, then #include this file
 *	2. Ensure your I/O write accessors call mmiowb_set_pending()
 *	3. Select ARCH_HAS_MMIOWB
 *	4. Untangle the resulting mess of header files
 *	5. Complain to your architects
 */
#ifdef CONFIG_MMIOWB

#include <linux/compiler.h>
#include <asm-generic/mmiowb_types.h>

#ifndef arch_mmiowb_state
#include <asm/percpu.h>
#include <asm/smp.h>

DECLARE_PER_CPU(struct mmiowb_state, __mmiowb_state);
#define __mmiowb_state()	this_cpu_ptr(&__mmiowb_state)
#else
#define __mmiowb_state()	arch_mmiowb_state()
#endif	/* arch_mmiowb_state */

static inline void mmiowb_set_pending(void)
{
	struct mmiowb_state *ms = __mmiowb_state();
	ms->mmiowb_pending = ms->nesting_count;
}

static inline void mmiowb_spin_lock(void)
{
	struct mmiowb_state *ms = __mmiowb_state();
	ms->nesting_count++;
}

static inline void mmiowb_spin_unlock(void)
{
	struct mmiowb_state *ms = __mmiowb_state();

	if (unlikely(ms->mmiowb_pending)) {
		ms->mmiowb_pending = 0;
		mmiowb();
	}

	ms->nesting_count--;
}
#else
#define mmiowb_set_pending()		do { } while (0)
#define mmiowb_spin_lock()		do { } while (0)
#define mmiowb_spin_unlock()		do { } while (0)
#endif	/* CONFIG_MMIOWB */
#endif	/* __ASM_GENERIC_MMIOWB_H */
Commit	Line	Data
d1be6a28 WD	1	/* SPDX-License-Identifier: GPL-2.0 */
	2	#ifndef __ASM_GENERIC_MMIOWB_H
	3	#define __ASM_GENERIC_MMIOWB_H
	4
	5	/*
	6	* Generic implementation of mmiowb() tracking for spinlocks.
	7	*
	8	* If your architecture doesn't ensure that writes to an I/O peripheral
	9	* within two spinlocked sections on two different CPUs are seen by the
	10	* peripheral in the order corresponding to the lock handover, then you
	11	* need to follow these FIVE easy steps:
	12	*
	13	* 1. Implement mmiowb() (and arch_mmiowb_state() if you're fancy)
	14	* in asm/mmiowb.h, then #include this file
	15	* 2. Ensure your I/O write accessors call mmiowb_set_pending()
	16	* 3. Select ARCH_HAS_MMIOWB
	17	* 4. Untangle the resulting mess of header files
	18	* 5. Complain to your architects
	19	*/
	20	#ifdef CONFIG_MMIOWB
	21
	22	#include <linux/compiler.h>
	23	#include <asm-generic/mmiowb_types.h>
	24
	25	#ifndef arch_mmiowb_state
	26	#include <asm/percpu.h>
	27	#include <asm/smp.h>
	28
	29	DECLARE_PER_CPU(struct mmiowb_state, __mmiowb_state);
	30	#define __mmiowb_state() this_cpu_ptr(&__mmiowb_state)
	31	#else
	32	#define __mmiowb_state() arch_mmiowb_state()
	33	#endif /* arch_mmiowb_state */
	34
	35	static inline void mmiowb_set_pending(void)
	36	{
	37	struct mmiowb_state *ms = __mmiowb_state();
	38	ms->mmiowb_pending = ms->nesting_count;
	39	}
	40
	41	static inline void mmiowb_spin_lock(void)
	42	{
	43	struct mmiowb_state *ms = __mmiowb_state();
	44	ms->nesting_count++;
	45	}
	46
	47	static inline void mmiowb_spin_unlock(void)
	48	{
	49	struct mmiowb_state *ms = __mmiowb_state();
	50
	51	if (unlikely(ms->mmiowb_pending)) {
	52	ms->mmiowb_pending = 0;
	53	mmiowb();
	54	}
	55
	56	ms->nesting_count--;
	57	}
	58	#else
	59	#define mmiowb_set_pending() do { } while (0)
	60	#define mmiowb_spin_lock() do { } while (0)
	61	#define mmiowb_spin_unlock() do { } while (0)
	62	#endif /* CONFIG_MMIOWB */
	63	#endif /* __ASM_GENERIC_MMIOWB_H */