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

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
/*
* 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 */
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