mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-29 15:14:18 +08:00
d1be6a28b1
In preparation for removing all explicit mmiowb() calls from driver code, implement a tracking system in asm-generic based loosely on the PowerPC implementation. This allows architectures with a non-empty mmiowb() definition to have the barrier automatically inserted in spin_unlock() following a critical section containing an I/O write. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
/* 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 */
|