centos man page for ata_wait_register

ATA_WAIT_REGISTER(9)						  libata Library					      ATA_WAIT_REGISTER(9)

NAME
       ata_wait_register - wait until register value changes

SYNOPSIS
       u32 ata_wait_register(struct ata_port * ap, void __iomem * reg, u32 mask, u32 val, unsigned long interval, unsigned long timeout);

ARGUMENTS
       ap
	   ATA port to wait register for, can be NULL

       reg
	   IO-mapped register

       mask
	   Mask to apply to read register value

       val
	   Wait condition

       interval
	   polling interval in milliseconds

       timeout
	   timeout in milliseconds

DESCRIPTION
       Waiting for some bits of register to change is a common operation for ATA controllers. This function reads 32bit LE IO-mapped register reg
       and tests for the following condition.

       (*reg & mask) != val

       If the condition is met, it returns; otherwise, the process is repeated after interval_msec until timeout.

LOCKING
       Kernel thread context (may sleep)

RETURNS
       The final register value.

AUTHOR
       Jeff Garzik
	   Author.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						      ATA_WAIT_REGISTER(9)