mirror of
https://github.com/LineageOS/android_kernel_samsung_msm8226.git
synced 2026-09-29 00:00:25 +02:00
Matt Wagantall
8a28989253
With the previous implementation, pre-emption was possible between reading the register value and evaluating the break condition for the timeout. If jiffies advanced sufficiently to expire the timeout before the polling thread was rescheduled, the macro would return -ETIMEDOUT incorrectly. Fix this by re-reading the register value again after evaluating the timeout condition as true. Change-Id: I58a42798235db3606373a2f689f7d6c95475702e Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
115 lines
3.7 KiB
C
115 lines
3.7 KiB
C
/*
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* Copyright (c) 2012-2013 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/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) \
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break; \
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if (timeout_us && time_after(jiffies, timeout)) { \
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(val) = readl(addr); \
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break; \
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} \
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if (sleep_us) \
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usleep_range(DIV_ROUND_UP(sleep_us, 4), 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_timeout_noirq - 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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* @max_reads: Maximum number of reads before giving up
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* @time_between_us: Time to udelay() between successive reads
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*
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* Returns 0 on success and -ETIMEDOUT upon a timeout.
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*/
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#define readl_poll_timeout_noirq(addr, val, cond, max_reads, time_between_us) \
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({ \
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int count; \
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for (count = (max_reads); count > 0; count--) { \
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(val) = readl(addr); \
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if (cond) \
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break; \
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udelay(time_between_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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