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
16 static int sbi_ipi_virq;
17
sbi_ipi_handle(struct irq_desc * desc)18 static 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
sbi_ipi_starting_cpu(unsigned int cpu)30 static 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
sbi_ipi_init(void)36 void __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