arch/powerpc/kernel/dbell.c

   1 /*
   2  * Author: Kumar Gala <galak@kernel.crashing.org>
   3  *
   4  * Copyright 2009 Freescale Semiconductor Inc.
   5  *
   6  * This program is free software; you can redistribute  it and/or modify it
   7  * under  the terms of  the GNU General  Public License as published by the
   8  * Free Software Foundation;  either version 2 of the  License, or (at your
   9  * option) any later version.
  10  */
  11
  12 #include <linux/stddef.h>
  13 #include <linux/kernel.h>
  14 #include <linux/smp.h>
  15 #include <linux/threads.h>
  16 #include <linux/hardirq.h>
  17
  18 #include <asm/dbell.h>
  19 #include <asm/irq_regs.h>
  20
  21 #ifdef CONFIG_SMP
  22 void doorbell_setup_this_cpu(void)
  23 {
  24         unsigned long tag = mfspr(SPRN_DOORBELL_CPUTAG) & PPC_DBELL_TAG_MASK;
  25
  26         smp_muxed_ipi_set_data(smp_processor_id(), tag);
  27 }
  28
  29 void doorbell_cause_ipi(int cpu, unsigned long data)
  30 {
  31         /* Order previous accesses vs. msgsnd, which is treated as a store */
  32         mb();
  33         ppc_msgsnd(PPC_DBELL_MSGTYPE, 0, data);
  34 }
  35
  36 void doorbell_exception(struct pt_regs *regs)
  37 {
  38         struct pt_regs *old_regs = set_irq_regs(regs);
  39
  40         irq_enter();
  41
  42         may_hard_irq_enable();
  43
  44         __get_cpu_var(irq_stat).doorbell_irqs++;
  45
  46         smp_ipi_demux();
  47
  48         irq_exit();
  49         set_irq_regs(old_regs);
  50 }
  51 #else /* CONFIG_SMP */
  52 void doorbell_exception(struct pt_regs *regs)
  53 {
  54         printk(KERN_WARNING "Received doorbell on non-smp system\n");
  55 }
  56 #endif /* CONFIG_SMP */
  57