arch/riscv/kernel/sbi-ipi.c

   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
  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
  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
  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 }