1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2012 Regents of the University of California
4 * Copyright (C) 2017-2018 SiFive
5 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
6 */
7
8 #define pr_fmt(fmt) "riscv-intc: " fmt
9 #include <linux/atomic.h>
10 #include <linux/bits.h>
11 #include <linux/cpu.h>
12 #include <linux/irq.h>
13 #include <linux/irqchip.h>
14 #include <linux/irqdomain.h>
15 #include <linux/interrupt.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 #include <linux/smp.h>
19
20 static struct irq_domain *intc_domain;
21
riscv_intc_irq(struct pt_regs * regs)22 static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
23 {
24 unsigned long cause = regs->cause & ~CAUSE_IRQ_FLAG;
25
26 if (unlikely(cause >= BITS_PER_LONG))
27 panic("unexpected interrupt cause");
28
29 switch (cause) {
30 #ifdef CONFIG_SMP
31 case RV_IRQ_SOFT:
32 /*
33 * We only use software interrupts to pass IPIs, so if a
34 * non-SMP system gets one, then we don't know what to do.
35 */
36 handle_IPI(regs);
37 break;
38 #endif
39 default:
40 generic_handle_domain_irq(intc_domain, cause);
41 break;
42 }
43 }
44
45 /*
46 * On RISC-V systems local interrupts are masked or unmasked by writing
47 * the SIE (Supervisor Interrupt Enable) CSR. As CSRs can only be written
48 * on the local hart, these functions can only be called on the hart that
49 * corresponds to the IRQ chip.
50 */
51
riscv_intc_irq_mask(struct irq_data * d)52 static void riscv_intc_irq_mask(struct irq_data *d)
53 {
54 csr_clear(CSR_IE, BIT(d->hwirq));
55 }
56
riscv_intc_irq_unmask(struct irq_data * d)57 static void riscv_intc_irq_unmask(struct irq_data *d)
58 {
59 csr_set(CSR_IE, BIT(d->hwirq));
60 }
61
riscv_intc_cpu_starting(unsigned int cpu)62 static int riscv_intc_cpu_starting(unsigned int cpu)
63 {
64 csr_set(CSR_IE, BIT(RV_IRQ_SOFT));
65 return 0;
66 }
67
riscv_intc_cpu_dying(unsigned int cpu)68 static int riscv_intc_cpu_dying(unsigned int cpu)
69 {
70 csr_clear(CSR_IE, BIT(RV_IRQ_SOFT));
71 return 0;
72 }
73
74 static struct irq_chip riscv_intc_chip = {
75 .name = "RISC-V INTC",
76 .irq_mask = riscv_intc_irq_mask,
77 .irq_unmask = riscv_intc_irq_unmask,
78 };
79
riscv_intc_domain_map(struct irq_domain * d,unsigned int irq,irq_hw_number_t hwirq)80 static int riscv_intc_domain_map(struct irq_domain *d, unsigned int irq,
81 irq_hw_number_t hwirq)
82 {
83 irq_set_percpu_devid(irq);
84 irq_domain_set_info(d, irq, hwirq, &riscv_intc_chip, d->host_data,
85 handle_percpu_devid_irq, NULL, NULL);
86
87 return 0;
88 }
89
90 static const struct irq_domain_ops riscv_intc_domain_ops = {
91 .map = riscv_intc_domain_map,
92 .xlate = irq_domain_xlate_onecell,
93 };
94
riscv_intc_init(struct device_node * node,struct device_node * parent)95 static int __init riscv_intc_init(struct device_node *node,
96 struct device_node *parent)
97 {
98 int rc;
99 unsigned long hartid;
100
101 rc = riscv_of_parent_hartid(node, &hartid);
102 if (rc < 0) {
103 pr_warn("unable to find hart id for %pOF\n", node);
104 return 0;
105 }
106
107 /*
108 * The DT will have one INTC DT node under each CPU (or HART)
109 * DT node so riscv_intc_init() function will be called once
110 * for each INTC DT node. We only need to do INTC initialization
111 * for the INTC DT node belonging to boot CPU (or boot HART).
112 */
113 if (riscv_hartid_to_cpuid(hartid) != smp_processor_id())
114 return 0;
115
116 intc_domain = irq_domain_add_linear(node, BITS_PER_LONG,
117 &riscv_intc_domain_ops, NULL);
118 if (!intc_domain) {
119 pr_err("unable to add IRQ domain\n");
120 return -ENXIO;
121 }
122
123 rc = set_handle_irq(&riscv_intc_irq);
124 if (rc) {
125 pr_err("failed to set irq handler\n");
126 return rc;
127 }
128
129 cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_STARTING,
130 "irqchip/riscv/intc:starting",
131 riscv_intc_cpu_starting,
132 riscv_intc_cpu_dying);
133
134 pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
135
136 return 0;
137 }
138
139 IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init);
140