arch/riscv/kernel/irq.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2012 Regents of the University of California
   4  * Copyright (C) 2017 SiFive
   5  * Copyright (C) 2018 Christoph Hellwig
   6  */
   7
   8 #include <linux/interrupt.h>
   9 #include <linux/irqchip.h>
  10 #include <linux/irqdomain.h>
  11 #include <linux/seq_file.h>
  12 #include <asm/smp.h>
  13
  14 /*
  15  * Possible interrupt causes:
  16  */
  17 #define INTERRUPT_CAUSE_SOFTWARE    1
  18 #define INTERRUPT_CAUSE_TIMER       5
  19 #define INTERRUPT_CAUSE_EXTERNAL    9
  20
  21 /*
  22  * The high order bit of the trap cause register is always set for
  23  * interrupts, which allows us to differentiate them from exceptions
  24  * quickly.  The INTERRUPT_CAUSE_* macros don't contain that bit, so we
  25  * need to mask it off.
  26  */
  27 #define INTERRUPT_CAUSE_FLAG    (1UL << (__riscv_xlen - 1))
  28
  29 int arch_show_interrupts(struct seq_file *p, int prec)
  30 {
  31         show_ipi_stats(p, prec);
  32         return 0;
  33 }
  34
  35 asmlinkage void __irq_entry do_IRQ(struct pt_regs *regs)
  36 {
  37         struct pt_regs *old_regs = set_irq_regs(regs);
  38
  39         irq_enter();
  40         switch (regs->scause & ~INTERRUPT_CAUSE_FLAG) {
  41         case INTERRUPT_CAUSE_TIMER:
  42                 riscv_timer_interrupt();
  43                 break;
  44 #ifdef CONFIG_SMP
  45         case INTERRUPT_CAUSE_SOFTWARE:
  46                 /*
  47                  * We only use software interrupts to pass IPIs, so if a non-SMP
  48                  * system gets one, then we don't know what to do.
  49                  */
  50                 riscv_software_interrupt();
  51                 break;
  52 #endif
  53         case INTERRUPT_CAUSE_EXTERNAL:
  54                 handle_arch_irq(regs);
  55                 break;
  56         default:
  57                 panic("unexpected interrupt cause");
  58         }
  59         irq_exit();
  60
  61         set_irq_regs(old_regs);
  62 }
  63
  64 void __init init_IRQ(void)
  65 {
  66         irqchip_init();
  67 }