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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: Arnd Bergmann <arnd@arndb.de> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Matt Wagantall <mattw@codeaurora.org> Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
145 lines
5.5 KiB
C
145 lines
5.5 KiB
C
/*
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* Copyright (c) 2012-2014 The Linux Foundation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#ifndef _LINUX_IOPOLL_H
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#define _LINUX_IOPOLL_H
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/hrtimer.h>
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#include <linux/delay.h>
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#include <linux/errno.h>
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#include <linux/io.h>
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/**
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* readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
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* @op: accessor function (takes @addr as its only argument)
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* @addr: Address to poll
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* @val: Variable to read the value into
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* @cond: Break condition (usually involving @val)
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* @sleep_us: Maximum time to sleep between reads in us (0
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* tight-loops). Should be less than ~20ms since usleep_range
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* is used (see Documentation/timers/timers-howto.txt).
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* @timeout_us: Timeout in us, 0 means never timeout
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*
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* Returns 0 on success and -ETIMEDOUT upon a timeout. In either
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* case, the last read value at @addr is stored in @val. Must not
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* be called from atomic context if sleep_us or timeout_us are used.
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*
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* When available, you'll probably want to use one of the specialized
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* macros defined below rather than this macro directly.
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*/
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#define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us) \
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({ \
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ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \
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might_sleep_if(sleep_us); \
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for (;;) { \
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(val) = op(addr); \
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if (cond) \
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break; \
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if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \
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(val) = op(addr); \
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break; \
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} \
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if (sleep_us) \
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usleep_range((sleep_us >> 2) + 1, sleep_us); \
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} \
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(cond) ? 0 : -ETIMEDOUT; \
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})
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/**
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* readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs
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* @op: accessor function (takes @addr as its only argument)
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* @addr: Address to poll
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* @val: Variable to read the value into
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* @cond: Break condition (usually involving @val)
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* @delay_us: Time to udelay between reads in us (0 tight-loops). Should
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* be less than ~10us since udelay is used (see
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* Documentation/timers/timers-howto.txt).
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* @timeout_us: Timeout in us, 0 means never timeout
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*
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* Returns 0 on success and -ETIMEDOUT upon a timeout. In either
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* case, the last read value at @addr is stored in @val.
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*
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* When available, you'll probably want to use one of the specialized
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* macros defined below rather than this macro directly.
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*/
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#define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \
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({ \
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ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \
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for (;;) { \
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(val) = op(addr); \
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if (cond) \
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break; \
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if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \
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(val) = op(addr); \
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break; \
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} \
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if (delay_us) \
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udelay(delay_us); \
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} \
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(cond) ? 0 : -ETIMEDOUT; \
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})
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#define readb_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us)
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#define readb_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us)
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#define readw_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us)
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#define readw_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us)
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#define readl_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us)
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#define readl_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us)
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#define readq_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us)
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#define readq_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us)
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#define readb_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readb_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readw_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readw_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readl_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readl_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readq_relaxed_poll_timeout(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us)
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#define readq_relaxed_poll_timeout_atomic(addr, val, cond, delay_us, timeout_us) \
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readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us)
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#endif /* _LINUX_IOPOLL_H */
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