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 
12 /*
13  * Possible interrupt causes:
14  */
15 #define INTERRUPT_CAUSE_SOFTWARE    1
16 #define INTERRUPT_CAUSE_TIMER       5
17 #define INTERRUPT_CAUSE_EXTERNAL    9
18 
19 /*
20  * The high order bit of the trap cause register is always set for
21  * interrupts, which allows us to differentiate them from exceptions
22  * quickly.  The INTERRUPT_CAUSE_* macros don't contain that bit, so we
23  * need to mask it off.
24  */
25 #define INTERRUPT_CAUSE_FLAG	(1UL << (__riscv_xlen - 1))
26 
do_IRQ(struct pt_regs * regs,unsigned long cause)27 asmlinkage void __irq_entry do_IRQ(struct pt_regs *regs, unsigned long cause)
28 {
29 	struct pt_regs *old_regs = set_irq_regs(regs);
30 
31 	irq_enter();
32 	switch (cause & ~INTERRUPT_CAUSE_FLAG) {
33 	case INTERRUPT_CAUSE_TIMER:
34 		riscv_timer_interrupt();
35 		break;
36 #ifdef CONFIG_SMP
37 	case INTERRUPT_CAUSE_SOFTWARE:
38 		/*
39 		 * We only use software interrupts to pass IPIs, so if a non-SMP
40 		 * system gets one, then we don't know what to do.
41 		 */
42 		riscv_software_interrupt();
43 		break;
44 #endif
45 	case INTERRUPT_CAUSE_EXTERNAL:
46 		handle_arch_irq(regs);
47 		break;
48 	default:
49 		panic("unexpected interrupt cause");
50 	}
51 	irq_exit();
52 
53 	set_irq_regs(old_regs);
54 }
55 
init_IRQ(void)56 void __init init_IRQ(void)
57 {
58 	irqchip_init();
59 }
60