• Martin Schwidefsky's avatar
    [S390] zcrypt adjunct processor bus. · 1534c382
    Martin Schwidefsky authored
    Add a bus for the adjunct processor interface. Up to 64 devices can
    be connect to the ap bus interface, each device with 16 domains. That
    makes 1024 message queues. The interface is asynchronous, the answer
    to a message sent to a queue needs to be received at some later point
    in time. Unfortunately the interface does not provide interrupts when
    a message reply is pending. So the ap bus needs to implement some
    fancy polling, each active queue is polled once per 1/HZ second or
    continuously if an idle cpus exsists and the poll thread is activ
    (see poll_thread parameter).
    
    The ap bus uses the sysfs path /sys/bus/ap and has two bus attributes,
    ap_domain and config_time. The ap_domain selects one of the 16 domains
    to be used for this system. This limits the maximum number of ap devices
    to 64. The config_time attribute contains the number of seconds between
    two ap bus scans to find new devices.
    
    The ap bus uses the modalias entries of the form "ap:tN" to autoload
    the ap driver for hardware type N. Currently known types are:
    3 - PCICC, 4 - PCICA, 5 - PCIXCC, 6 - CEX2A and 7 - CEX2C.
    Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
    Signed-off-by: default avatarRalph Wuerthner <rwuerthn@de.ibm.com>
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    1534c382
ap_bus.h 4.91 KB