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 DEFINE_STATIC_KEY_FALSE(riscv_sbi_for_rfence); 17 EXPORT_SYMBOL_GPL(riscv_sbi_for_rfence); 18 19 static int sbi_ipi_virq; 20 21 static void sbi_ipi_handle(struct irq_desc *desc) 22 { 23 struct irq_chip *chip = irq_desc_get_chip(desc); 24 25 chained_irq_enter(chip, desc); 26 27 csr_clear(CSR_IP, IE_SIE); 28 ipi_mux_process(); 29 30 chained_irq_exit(chip, desc); 31 } 32 33 static int sbi_ipi_starting_cpu(unsigned int cpu) 34 { 35 enable_percpu_irq(sbi_ipi_virq, irq_get_trigger_type(sbi_ipi_virq)); 36 return 0; 37 } 38 39 void __init sbi_ipi_init(void) 40 { 41 int virq; 42 struct irq_domain *domain; 43 44 if (riscv_ipi_have_virq_range()) 45 return; 46 47 domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), 48 DOMAIN_BUS_ANY); 49 if (!domain) { 50 pr_err("unable to find INTC IRQ domain\n"); 51 return; 52 } 53 54 sbi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT); 55 if (!sbi_ipi_virq) { 56 pr_err("unable to create INTC IRQ mapping\n"); 57 return; 58 } 59 60 virq = ipi_mux_create(BITS_PER_BYTE, sbi_send_ipi); 61 if (virq <= 0) { 62 pr_err("unable to create muxed IPIs\n"); 63 irq_dispose_mapping(sbi_ipi_virq); 64 return; 65 } 66 67 irq_set_chained_handler(sbi_ipi_virq, sbi_ipi_handle); 68 69 /* 70 * Don't disable IPI when CPU goes offline because 71 * the masking/unmasking of virtual IPIs is done 72 * via generic IPI-Mux 73 */ 74 cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_SBI_IPI_STARTING, 75 "irqchip/sbi-ipi:starting", 76 sbi_ipi_starting_cpu, NULL); 77 78 riscv_ipi_set_virq_range(virq, BITS_PER_BYTE); 79 pr_info("providing IPIs using SBI IPI extension\n"); 80 81 /* 82 * Use the SBI remote fence extension to avoid 83 * the extra context switch needed to handle IPIs. 84 */ 85 static_branch_enable(&riscv_sbi_for_rfence); 86 } 87