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s390/ap: ap bus userspace notifications for some bus conditions
This patch adds notifications to userspace for two important conditions of the ap bus: I) Initial ap bus scan done. This indicates that the initial scan of all the ap devices (cards, queues) is complete and ap devices have been build up for all the hardware found. This condition is signaled with 1) An ap bus change uevent send to userspace with an environment key/value pair "INITSCAN=done": # udevadm monitor -k -p ... KERNEL[97.830919] change /devices/ap (ap) ACTION=change DEVPATH=/devices/ap SUBSYSTEM=ap INITSCAN=done SEQNUM=10421 2) A sysfs attribute /sys/bus/ap/scans which shows the number of completed ap bus scans done since bus init. So a value of 1 or greater signals that the initial ap bus scan is complete. Note: The initial ap bus scan complete condition is fulfilled and will be signaled even if there was no ap resource found. II) APQN driver bindings complete. This indicates that all APQNs have been bound to an zcrypt or alternate device driver. Only with the help of an device driver an APQN can be used for crypto load. So the binding complete condition is the starting point for user space to be sure all crypto resources on the ap bus are available for use. This condition is signaled with 1) An ap bus change uevent send to userspace with an environment key/value pair "BINDINGS=complete": # udevadm monitor -k -p ... KERNEL[97.830975] change /devices/ap (ap) ACTION=change DEVPATH=/devices/ap SUBSYSTEM=ap BINDINGS=complete SEQNUM=10422 2) A sysfs attribute /sys/bus/ap/bindings showing "<nr of bound apqns>/<total nr of apqns> (complete)" when all available apqns have been bound to device drivers, or "<nr of bound apqns>/<total nr of apqns>" when there are some apqns not bound to an device driver. Note: The binding complete condition is also fulfilled, when there are no apqns available to bind any device driver. In this case the binding complete will be signaled AFTER init scan is done. Note: This condition may arise multiple times when after initial scan modifications on the bindings take place. For example a manual unbind of an APQN switches the binding complete condition off. When at a later time the unbound APQNs are bound with an device driver the binding is (again) complete resulting in another uevent and marking the bindings sysfs attribute with '(complete)'. There is also a new function to be used within the kernel: int ap_wait_init_apqn_bindings_complete(unsigned long timeout) Interface to wait for the AP bus to have done one initial ap bus scan and all detected APQNs have been bound to device drivers. If these both conditions are not fulfilled, this function blocks on a condition with wait_for_completion_interruptible_timeout(). If these both conditions are fulfilled (before the timeout hits) the return value is 0. If the timeout (in jiffies) hits instead -ETIME is returned. On failures negative return values are returned to the caller. Please note that further unbind/bind actions after initial binding complete is through do not cause this function to block again. Reviewed-by: Ingo Franzki <[email protected]> Signed-off-by: Harald Freudenberger <[email protected]> Signed-off-by: Heiko Carstens <[email protected]>
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