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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021 Western Digital Corporation or its affiliates.
* Copyright (C) 2022 Ventana Micro Systems Inc.
*/
#define pr_fmt(fmt) "riscv-imsic: " fmt
#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include "irq-riscv-imsic-state.h"
static int imsic_parent_irq;
#ifdef CONFIG_SMP
static void imsic_ipi_send(unsigned int cpu)
{
struct imsic_local_config *local = per_cpu_ptr(imsic->global.local, cpu);
writel_relaxed(IMSIC_IPI_ID, local->msi_va);
}
static void imsic_ipi_starting_cpu(void)
{
/* Enable IPIs for current CPU. */
__imsic_id_set_enable(IMSIC_IPI_ID);
}
static void imsic_ipi_dying_cpu(void)
{
/* Disable IPIs for current CPU. */
__imsic_id_clear_enable(IMSIC_IPI_ID);
}
static int __init imsic_ipi_domain_init(void)
{
int virq;
/* Create IMSIC IPI multiplexing */
virq = ipi_mux_create(IMSIC_NR_IPI, imsic_ipi_send);
if (virq <= 0)
return virq < 0 ? virq : -ENOMEM;
/* Set vIRQ range */
riscv_ipi_set_virq_range(virq, IMSIC_NR_IPI, true);
/* Announce that IMSIC is providing IPIs */
pr_info("%pfwP: providing IPIs using interrupt %d\n", imsic->fwnode, IMSIC_IPI_ID);
return 0;
}
#else
static void imsic_ipi_starting_cpu(void) { }
static void imsic_ipi_dying_cpu(void) { }
static int __init imsic_ipi_domain_init(void) { return 0; }
#endif
/*
* To handle an interrupt, we read the TOPEI CSR and write zero in one
* instruction. If TOPEI CSR is non-zero then we translate TOPEI.ID to
* Linux interrupt number and let Linux IRQ subsystem handle it.
*/
static void imsic_handle_irq(struct irq_desc *desc)
{
struct irq_chip *chip = irq_desc_get_chip(desc);
int err, cpu = smp_processor_id();
struct imsic_vector *vec;
unsigned long local_id;
chained_irq_enter(chip, desc);
while ((local_id = csr_swap(CSR_TOPEI, 0))) {
local_id >>= TOPEI_ID_SHIFT;
if (local_id == IMSIC_IPI_ID) {
if (IS_ENABLED(CONFIG_SMP))
ipi_mux_process();
continue;
}
if (unlikely(!imsic->base_domain))
continue;
vec = imsic_vector_from_local_id(cpu, local_id);
if (!vec) {
pr_warn_ratelimited("vector not found for local ID 0x%lx\n", local_id);
continue;
}
err = generic_handle_domain_irq(imsic->base_domain, vec->hwirq);
if (unlikely(err))
pr_warn_ratelimited("hwirq 0x%x mapping not found\n", vec->hwirq);
}
chained_irq_exit(chip, desc);
}
static int imsic_starting_cpu(unsigned int cpu)
{
/* Mark per-CPU IMSIC state as online */
imsic_state_online();
/* Enable per-CPU parent interrupt */
enable_percpu_irq(imsic_parent_irq, irq_get_trigger_type(imsic_parent_irq));
/* Setup IPIs */
imsic_ipi_starting_cpu();
/*
* Interrupts identities might have been enabled/disabled while
* this CPU was not running so sync-up local enable/disable state.
*/
imsic_local_sync_all();
/* Enable local interrupt delivery */
imsic_local_delivery(true);
return 0;
}
static int imsic_dying_cpu(unsigned int cpu)
{
/* Cleanup IPIs */
imsic_ipi_dying_cpu();
/* Mark per-CPU IMSIC state as offline */
imsic_state_offline();
return 0;
}
static int __init imsic_early_probe(struct fwnode_handle *fwnode)
{
struct irq_domain *domain;
int rc;
/* Find parent domain and register chained handler */
domain = irq_find_matching_fwnode(riscv_get_intc_hwnode(), DOMAIN_BUS_ANY);
if (!domain) {
pr_err("%pfwP: Failed to find INTC domain\n", fwnode);
return -ENOENT;
}
imsic_parent_irq = irq_create_mapping(domain, RV_IRQ_EXT);
if (!imsic_parent_irq) {
pr_err("%pfwP: Failed to create INTC mapping\n", fwnode);
return -ENOENT;
}
/* Initialize IPI domain */
rc = imsic_ipi_domain_init();
if (rc) {
pr_err("%pfwP: Failed to initialize IPI domain\n", fwnode);
return rc;
}
/* Setup chained handler to the parent domain interrupt */
irq_set_chained_handler(imsic_parent_irq, imsic_handle_irq);
/*
* Setup cpuhp state (must be done after setting imsic_parent_irq)
*
* Don't disable per-CPU IMSIC file when CPU goes offline
* because this affects IPI and the masking/unmasking of
* virtual IPIs is done via generic IPI-Mux
*/
cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_IMSIC_STARTING, "irqchip/riscv/imsic:starting",
imsic_starting_cpu, imsic_dying_cpu);
return 0;
}
static int __init imsic_early_dt_init(struct device_node *node, struct device_node *parent)
{
struct fwnode_handle *fwnode = &node->fwnode;
int rc;
/* Setup IMSIC state */
rc = imsic_setup_state(fwnode);
if (rc) {
pr_err("%pfwP: failed to setup state (error %d)\n", fwnode, rc);
return rc;
}
/* Do early setup of IPIs */
rc = imsic_early_probe(fwnode);
if (rc)
return rc;
/* Ensure that OF platform device gets probed */
of_node_clear_flag(node, OF_POPULATED);
return 0;
}
IRQCHIP_DECLARE(riscv_imsic, "riscv,imsics", imsic_early_dt_init);
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