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1534c3820c
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: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Ralph Wuerthner <rwuerthn@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> |
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ap_bus.c | ||
ap_bus.h | ||
Makefile |