b3ed9c1138
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-loop and sleeping versions are provided with and without timeouts. Signed-off-by: Matt Wagantall <mattw@codeaurora.org> Change-Id: Ia7db00cbe60ded8b0ed9bbff264aaea0841da92a
89 lines
3.0 KiB
C
89 lines
3.0 KiB
C
/*
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* Copyright (c) 2012 Code Aurora Forum. 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/jiffies.h>
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#include <linux/delay.h>
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#include <asm-generic/errno.h>
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#include <asm/io.h>
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/**
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* readl_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
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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 tight-loops)
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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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#define readl_poll_timeout(addr, val, cond, sleep_us, timeout_us) \
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({ \
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unsigned long timeout = jiffies + usecs_to_jiffies(timeout_us); \
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might_sleep_if(timeout_us); \
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for (;;) { \
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(val) = readl(addr); \
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if ((cond) || (timeout_us && time_after(jiffies, timeout))) \
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break; \
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if (sleep_us) \
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usleep_range(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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* readl_poll - Periodically poll an address until a condition is met
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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 tight-loops)
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*
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* Must not be called from atomic context if sleep_us is used.
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*/
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#define readl_poll(addr, val, cond, sleep_us) \
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readl_poll_timeout(addr, val, cond, sleep_us, 0)
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/**
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* readl_tight_poll_timeout - Tight-loop on an address until a condition is met or a timeout occurs
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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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* @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 timeout_us is used.
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*/
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#define readl_tight_poll_timeout(addr, val, cond, timeout_us) \
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readl_poll_timeout(addr, val, cond, 0, timeout_us)
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/**
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* readl_tight_poll - Tight-loop on an address until a condition is met
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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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*
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* May be called from atomic context.
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*/
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#define readl_tight_poll(addr, val, cond) \
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readl_poll_timeout(addr, val, cond, 0, 0)
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#endif /* _LINUX_IOPOLL_H */
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