Commit 5f5323a1 authored by Dejin Zheng's avatar Dejin Zheng Committed by David S. Miller
Browse files

iopoll: introduce read_poll_timeout macro 



this macro is an extension of readx_poll_timeout macro. the accessor
function op just supports only one parameter in the readx_poll_timeout
macro, but this macro can supports multiple variable parameters for
it. so functions like phy_read(struct phy_device *phydev, u32 regnum)
and phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum) can
also use this poll timeout core. and also expand it can sleep some time
before read operation.

Signed-off-by: default avatarDejin Zheng <zhengdejin5@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent af13b3c3

include/linux/iopoll.h

+44 −0
Original line number Diff line number Diff line
@@ -13,6 +13,50 @@ 
#include <linux/errno.h>

#include <linux/io.h>



/**

 * read_poll_timeout - Periodically poll an address until a condition is

 *			met or a timeout occurs

 * @op: accessor function (takes @args as its arguments)

 * @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.rst).

 * @timeout_us: Timeout in us, 0 means never timeout

 * @sleep_before_read: if it is true, sleep @sleep_us before read.

 * @args: arguments for @op poll

 *

 * Returns 0 on success and -ETIMEDOUT upon a timeout. In either

 * case, the last read value at @args 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 read_poll_timeout(op, val, cond, sleep_us, timeout_us, \

				sleep_before_read, args...) \

({ \

	u64 __timeout_us = (timeout_us); \

	unsigned long __sleep_us = (sleep_us); \

	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \

	might_sleep_if((__sleep_us) != 0); \

	if (sleep_before_read && __sleep_us) \

		usleep_range((__sleep_us >> 2) + 1, __sleep_us); \

	for (;;) { \

		(val) = op(args); \

		if (cond) \

			break; \

		if (__timeout_us && \

		    ktime_compare(ktime_get(), __timeout) > 0) { \

			(val) = op(args); \

			break; \

		} \

		if (__sleep_us) \

			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \

	} \

	(cond) ? 0 : -ETIMEDOUT; \

})



/**

 * 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)

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