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kernel/linux-rt-4.4.41/include/linux/iopoll.h 5.52 KB
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  /*
   * 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 */