1. 根目录:
2. include
3. linux
4. iopoll.h

/*
 * 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 */