Commit 64e2c673 authored Apr 05, 2018 by Sinan Kaya Committed by Arnd Bergmann Apr 06, 2018

io: define several IO & PIO barrier types for the asm-generic version



Getting ready to harden readX()/writeX() and inX()/outX() semantics for the
generic implementation.

Defining two set of macros as __io_br() and __io_ar() to indicate actions
to be taken before and after MMIO read.

Defining two set of macros as __io_bw() and __io_aw() to indicate actions
to be taken before and after MMIO write.

Defining two set of macros as __io_pbw() and __io_paw() to indicate actions
to be taken before and after Port IO write.

Defining two set of macros as __io_pbr() and __io_par() to indicate actions
to be taken before and after Port IO read.

If rmb() is available for the architecture, prefer rmb() as the default
implementation of __io_ar()/__io_par().

If wmb() is available for the architecture, prefer wmb() as the default
implementation of __io_bw()/__io_pbw().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

parent 0adb3285

include/asm-generic/io.h

+44 −0

Original line number	Diff line number	Diff line
		@@ -25,6 +25,50 @@
		#define mmiowb() do {} while (0)
		#endif

		#ifndef __io_br
		#define __io_br() barrier()
		#endif

		/* prevent prefetching of coherent DMA data ahead of a dma-complete */
		#ifndef __io_ar
		#ifdef rmb
		#define __io_ar() rmb()
		#else
		#define __io_ar() barrier()
		#endif
		#endif

		/* flush writes to coherent DMA data before possibly triggering a DMA read */
		#ifndef __io_bw
		#ifdef wmb
		#define __io_bw() wmb()
		#else
		#define __io_bw() barrier()
		#endif
		#endif

		/* serialize device access against a spin_unlock, usually handled there. */
		#ifndef __io_aw
		#define __io_aw() barrier()
		#endif

		#ifndef __io_pbw
		#define __io_pbw() __io_bw()
		#endif

		#ifndef __io_paw
		#define __io_paw() __io_aw()
		#endif

		#ifndef __io_pbr
		#define __io_pbr() __io_br()
		#endif

		#ifndef __io_par
		#define __io_par() __io_ar()
		#endif


		/*
		* __raw_{read,write}{b,w,l,q}() access memory in native endianness.
		*

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