kernel.git/arch/powerpc/kernel/dbell.c, branch linux-2.6.37.y

powerpc/book3e: Resend doorbell exceptions to ourself

2010-07-09T06:11:19Z

If we are soft disabled and receive a doorbell exception we don't process it immediately. This means we need to check on the way out of irq restore if there are any doorbell exceptions to process. The problem is at that point we don't know what our regs are, and that in turn makes xmon unhappy. To workaround the problem, instead of checking for and processing doorbells, we check for any doorbells and if there were any we send ourselves another. Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt

powerpc/book3e: Use set_irq_regs() in the msgsnd/msgrcv IPI path

2010-07-09T06:11:18Z

include/asm-generic/irq_regs.h declares per-cpu irq_regs variables and get_irq_regs() and set_irq_regs() helper functions to maintain them. These can be used to access the proper pt_regs structure related to the current interrupt entry (if any). In the powerpc arch code, this is used to maintain irq regs on decrementer and external interrupt exceptions. However, for the doorbell exceptions used by the msgsnd/msgrcv IPI mechanism of newer BookE CPUs, the irq_regs are not kept up to date. In particular this means that xmon will not work properly on SMP, because the secondary xmon instances started by IPI will blow up when they cannot retrieve the irq regs. This patch fixes the problem by adding calls to maintain the irq regs across doorbell exceptions. Signed-off-by: David Gibson Signed-off-by: Benjamin Herrenschmidt

powerpc/book3e: More doorbell cleanups. Sample the PIR register

2010-07-09T05:29:53Z

The doorbells use the content of the PIR register to match messages from other CPUs. This may or may not be the same as our linux CPU number, so using that as the "target" is no right. Instead, we sample the PIR register at boot on every processor and use that value subsequently when sending IPIs. We also use a per-cpu message mask rather than a global array which should limit cache line contention. Note: We could use the CPU number in the device-tree instead of the PIR register, as they are supposed to be equivalent. This might prove useful if doorbells are to be used to kick CPUs out of FW at boot time, thus before we can sample the PIR. This is however not the case now and using the PIR just works. Signed-off-by: Benjamin Herrenschmidt

powerpc/book3e: Move doorbell_exception from traps.c to dbell.c

2010-07-09T05:25:18Z

... where it belongs Signed-off-by: Benjamin Herrenschmidt

powerpc: Add support for using doorbells for SMP IPI

2009-02-23T04:53:03Z

The e500mc supports the new msgsnd/doorbell mechanisms that were added in the Power ISA 2.05 architecture. We use the normal level doorbell for doing SMP IPIs at this point. Signed-off-by: Kumar Gala Signed-off-by: Benjamin Herrenschmidt