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/percpu.h>
  17
  18 #include <asm/dbell.h>
  19 #include <asm/irq_regs.h>
  20
  21 #ifdef CONFIG_SMP
  22 struct doorbell_cpu_info {
  23         unsigned long   messages;       /* current messages bits */
  24         unsigned int    tag;            /* tag value */
  25 };
  26
  27 static DEFINE_PER_CPU(struct doorbell_cpu_info, doorbell_cpu_info);
  28
  29 void doorbell_setup_this_cpu(void)
  30 {
  31         struct doorbell_cpu_info *info = &__get_cpu_var(doorbell_cpu_info);
  32
  33         info->messages = 0;
  34         info->tag = mfspr(SPRN_PIR) & 0x3fff;
  35 }
  36
  37 void doorbell_message_pass(int target, int msg)
  38 {
  39         struct doorbell_cpu_info *info;
  40         int i;
  41
  42         if (target < NR_CPUS) {
  43                 info = &per_cpu(doorbell_cpu_info, target);
  44                 set_bit(msg, &info->messages);
  45                 ppc_msgsnd(PPC_DBELL, 0, info->tag);
  46         }
  47         else if (target == MSG_ALL_BUT_SELF) {
  48                 for_each_online_cpu(i) {
  49                         if (i == smp_processor_id())
  50                                 continue;
  51                         info = &per_cpu(doorbell_cpu_info, i);
  52                         set_bit(msg, &info->messages);
  53                         ppc_msgsnd(PPC_DBELL, 0, info->tag);
  54                 }
  55         }
  56         else { /* target == MSG_ALL */
  57                 for_each_online_cpu(i) {
  58                         info = &per_cpu(doorbell_cpu_info, i);
  59                         set_bit(msg, &info->messages);
  60                 }
  61                 ppc_msgsnd(PPC_DBELL, PPC_DBELL_MSG_BRDCAST, 0);
  62         }
  63 }
  64
  65 void doorbell_exception(struct pt_regs *regs)
  66 {
  67         struct pt_regs *old_regs = set_irq_regs(regs);
  68         struct doorbell_cpu_info *info = &__get_cpu_var(doorbell_cpu_info);
  69         int msg;
  70
  71         /* Warning: regs can be NULL when called from irq enable */
  72
  73         if (!info->messages || (num_online_cpus() < 2))
  74                 goto out;
  75
  76         for (msg = 0; msg < 4; msg++)
  77                 if (test_and_clear_bit(msg, &info->messages))
  78                         smp_message_recv(msg);
  79
  80 out:
  81         set_irq_regs(old_regs);
  82 }
  83
  84 void doorbell_check_self(void)
  85 {
  86         struct doorbell_cpu_info *info = &__get_cpu_var(doorbell_cpu_info);
  87
  88         if (!info->messages)
  89                 return;
  90
  91         ppc_msgsnd(PPC_DBELL, 0, info->tag);
  92 }
  93
  94 #else /* CONFIG_SMP */
  95 void doorbell_exception(struct pt_regs *regs)
  96 {
  97         printk(KERN_WARNING "Received doorbell on non-smp system\n");
  98 }
  99 #endif /* CONFIG_SMP */
 100