1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Multiplex several IPIs over a single HW IPI.
4 *
5 * Copyright (c) 2022 Ventana Micro Systems Inc.
6 */
7
8#define pr_fmt(fmt) "riscv: " fmt
9#include <linux/cpu.h>
10#include <linux/init.h>
11#include <linux/irq.h>
12#include <linux/irqchip/chained_irq.h>
13#include <linux/irqdomain.h>
14#include <asm/sbi.h>
15
16static int sbi_ipi_virq;
17
18static void sbi_ipi_handle(struct irq_desc *desc)
19{
20	struct irq_chip *chip = irq_desc_get_chip(desc);
21
22	chained_irq_enter(chip, desc);
23
24	csr_clear(CSR_IP, IE_SIE);
25	ipi_mux_process();
26
27	chained_irq_exit(chip, desc);
28}
29
30static int sbi_ipi_starting_cpu(unsigned int cpu)
31{
32	enable_percpu_irq(sbi_ipi_virq, irq_get_trigger_type(sbi_ipi_virq));
33	return 0;
34}
35
36void __init sbi_ipi_init(void)
37{
38	int virq;
39	struct irq_domain *domain;
40
41	if (riscv_ipi_have_virq_range())
42		return;
43
44	domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(),
45					  DOMAIN_BUS_ANY);
46	if (!domain) {
47		pr_err("unable to find INTC IRQ domain\n");
48		return;
49	}
50
51	sbi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT);
52	if (!sbi_ipi_virq) {
53		pr_err("unable to create INTC IRQ mapping\n");
54		return;
55	}
56
57	virq = ipi_mux_create(BITS_PER_BYTE, sbi_send_ipi);
58	if (virq <= 0) {
59		pr_err("unable to create muxed IPIs\n");
60		irq_dispose_mapping(sbi_ipi_virq);
61		return;
62	}
63
64	irq_set_chained_handler(sbi_ipi_virq, sbi_ipi_handle);
65
66	/*
67	 * Don't disable IPI when CPU goes offline because
68	 * the masking/unmasking of virtual IPIs is done
69	 * via generic IPI-Mux
70	 */
71	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
72			  "irqchip/sbi-ipi:starting",
73			  sbi_ipi_starting_cpu, NULL);
74
75	riscv_ipi_set_virq_range(virq, BITS_PER_BYTE, false);
76	pr_info("providing IPIs using SBI IPI extension\n");
77}
78