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usr
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src
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linux-headers-6.8.0-101
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include
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asm-generic
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mmiowb.h
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/* 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() raw_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(); if (likely(ms->nesting_count)) 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 */