Commit 54c52312 authored by Matt Wagantall's avatar Matt Wagantall Committed by Will Deacon
Browse files

iopoll: Introduce memory-mapped IO polling macros 



It is sometimes necessary to poll a memory-mapped register until its value
satisfies some condition. Introduce a family of convenience macros that do
this. Tight-looping, sleeping, and timing out can all be accomplished using
these macros.

Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Robert Elliott <elliott@hp.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarMatt Wagantall <mattw@codeaurora.org>
Signed-off-by: default avatarMitchel Humpherys <mitchelh@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 3c8567d1

include/linux/iopoll.h

0 → 100644
+144 −0
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2012-2014 The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only 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.

 *

 */



#ifndef _LINUX_IOPOLL_H

#define _LINUX_IOPOLL_H



#include <linux/kernel.h>

#include <linux/types.h>

#include <linux/hrtimer.h>

#include <linux/delay.h>

#include <linux/errno.h>

#include <linux/io.h>



/**

 * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs

 * @op: accessor function (takes @addr as its only argument)

 * @addr: Address to poll

 * @val: Variable to read the value into

 * @cond: Break condition (usually involving @val)

 * @sleep_us: Maximum time to sleep between reads in us (0

 *            tight-loops).  Should be less than ~20ms since usleep_range

 *            is used (see Documentation/timers/timers-howto.txt).

 * @timeout_us: Timeout in us, 0 means never timeout

 *

 * Returns 0 on success and -ETIMEDOUT upon a timeout. In either

 * case, the last read value at @addr is stored in @val. Must not

 * be called from atomic context if sleep_us or timeout_us are used.

 *

 * When available, you'll probably want to use one of the specialized

 * macros defined below rather than this macro directly.

 */

#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us)	\

({ \

	ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \

	might_sleep_if(sleep_us); \

	for (;;) { \

		(val) = op(addr); \

		if (cond) \

			break; \

		if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \

			(val) = op(addr); \

			break; \

		} \

		if (sleep_us) \

			usleep_range((sleep_us >> 2) + 1, sleep_us); \

	} \

	(cond) ? 0 : -ETIMEDOUT; \

})



/**

 * readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs

 * @op: accessor function (takes @addr as its only argument)

 * @addr: Address to poll

 * @val: Variable to read the value into

 * @cond: Break condition (usually involving @val)

 * @delay_us: Time to udelay between reads in us (0 tight-loops).  Should

 *            be less than ~10us since udelay is used (see

 *            Documentation/timers/timers-howto.txt).

 * @timeout_us: Timeout in us, 0 means never timeout

 *

 * Returns 0 on success and -ETIMEDOUT upon a timeout. In either

 * case, the last read value at @addr is stored in @val.

 *

 * When available, you'll probably want to use one of the specialized

 * macros defined below rather than this macro directly.

 */

#define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \

({ \

	ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \

	for (;;) { \

		(val) = op(addr); \

		if (cond) \

			break; \

		if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \

			(val) = op(addr); \

			break; \

		} \

		if (delay_us) \

			udelay(delay_us);	\

	} \

	(cond) ? 0 : -ETIMEDOUT; \

})





#define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us)



#define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us)



#define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us)



#define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us)



#define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us)



#define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us)



#define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us)



#define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us)



#define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us)



#define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us)



#define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us)



#define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us)



#define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us)



#define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us)



#define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us)



#define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \

	readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us)



#endif /* _LINUX_IOPOLL_H */

CRA Git | Maintained and supported by SUSTech CRA and CCSE