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iopoll: introduce read_poll_timeout macro

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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: Dejin Zheng <zhengdejin5@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Dejin Zheng 2020-03-23 23:05:51 +08:00 committed by David S. Miller
parent af13b3c338
commit 5f5323a14c
1 changed files with 44 additions and 0 deletions
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44
include/linux/iopoll.h
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@ -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)