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// SPDX-License-Identifier: GPL-2.0-only
/*
* Multiplex several IPIs over a single HW IPI.
*
* Copyright (c) 2022 Ventana Micro Systems Inc.
*/
#define pr_fmt(fmt) "riscv: " fmt
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <asm/sbi.h>
DEFINE_STATIC_KEY_FALSE(riscv_sbi_for_rfence);
EXPORT_SYMBOL_GPL(riscv_sbi_for_rfence);
static int sbi_ipi_virq;
static void sbi_ipi_handle(struct irq_desc *desc)
{
struct irq_chip *chip = irq_desc_get_chip(desc);
chained_irq_enter(chip, desc);
csr_clear(CSR_IP, IE_SIE);
ipi_mux_process();
chained_irq_exit(chip, desc);
}
static int sbi_ipi_starting_cpu(unsigned int cpu)
{
enable_percpu_irq(sbi_ipi_virq, irq_get_trigger_type(sbi_ipi_virq));
return 0;
}
void __init sbi_ipi_init(void)
{
int virq;
struct irq_domain *domain;
if (riscv_ipi_have_virq_range())
return;
domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(),
DOMAIN_BUS_ANY);
if (!domain) {
pr_err("unable to find INTC IRQ domain\n");
return;
}
sbi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT);
if (!sbi_ipi_virq) {
pr_err("unable to create INTC IRQ mapping\n");
return;
}
virq = ipi_mux_create(BITS_PER_BYTE, sbi_send_ipi);
if (virq <= 0) {
pr_err("unable to create muxed IPIs\n");
irq_dispose_mapping(sbi_ipi_virq);
return;
}
irq_set_chained_handler(sbi_ipi_virq, sbi_ipi_handle);
/*
* Don't disable IPI when CPU goes offline because
* the masking/unmasking of virtual IPIs is done
* via generic IPI-Mux
*/
cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
"irqchip/sbi-ipi:starting",
sbi_ipi_starting_cpu, NULL);
riscv_ipi_set_virq_range(virq, BITS_PER_BYTE);
pr_info("providing IPIs using SBI IPI extension\n");
/*
* Use the SBI remote fence extension to avoid
* the extra context switch needed to handle IPIs.
*/
static_branch_enable(&riscv_sbi_for_rfence);
}
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