1 files changed, 46 insertions, 9 deletions
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 7bcdaed15703..0cfac48a1272 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -1,21 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2012 Regents of the University of California
  * Copyright (C) 2017 SiFive
- *
- *   This program is free software; you can redistribute it and/or
- *   modify it under the terms of the GNU General Public License
- *   as published by the Free Software Foundation, version 2.
- *
- *   This program is distributed in the hope that it will be useful,
- *   but WITHOUT ANY WARRANTY; without even the implied warranty of
- *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *   GNU General Public License for more details.
+ * Copyright (C) 2018 Christoph Hellwig
  */
 
 #include <linux/interrupt.h>
 #include <linux/irqchip.h>
 #include <linux/irqdomain.h>
 
+/*
+ * Possible interrupt causes:
+ */
+#define INTERRUPT_CAUSE_SOFTWARE    1
+#define INTERRUPT_CAUSE_TIMER       5
+#define INTERRUPT_CAUSE_EXTERNAL    9
+
+/*
+ * The high order bit of the trap cause register is always set for
+ * interrupts, which allows us to differentiate them from exceptions
+ * quickly.  The INTERRUPT_CAUSE_* macros don't contain that bit, so we
+ * need to mask it off.
+ */
+#define INTERRUPT_CAUSE_FLAG	(1UL << (__riscv_xlen - 1))
+
+asmlinkage void __irq_entry do_IRQ(struct pt_regs *regs, unsigned long cause)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+
+	irq_enter();
+	switch (cause & ~INTERRUPT_CAUSE_FLAG) {
+	case INTERRUPT_CAUSE_TIMER:
+		riscv_timer_interrupt();
+		break;
+#ifdef CONFIG_SMP
+	case INTERRUPT_CAUSE_SOFTWARE:
+		/*
+		 * We only use software interrupts to pass IPIs, so if a non-SMP
+		 * system gets one, then we don't know what to do.
+		 */
+		riscv_software_interrupt();
+		break;
+#endif
+	case INTERRUPT_CAUSE_EXTERNAL:
+		handle_arch_irq(regs);
+		break;
+	default:
+		panic("unexpected interrupt cause");
+	}
+	irq_exit();
+
+	set_irq_regs(old_regs);
+}
+
 void __init init_IRQ(void)
 {
 	irqchip_init();