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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2012 Regents of the University of California
* Copyright (C) 2017-2018 SiFive
* Copyright (C) 2020 Western Digital Corporation or its affiliates.
*/
#define pr_fmt(fmt) "riscv-intc: " fmt
#include <linux/atomic.h>
#include <linux/bits.h>
#include <linux/cpu.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/smp.h>
static struct irq_domain *intc_domain;
static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
{
unsigned long cause = regs->cause & ~CAUSE_IRQ_FLAG;
if (unlikely(cause >= BITS_PER_LONG))
panic("unexpected interrupt cause");
generic_handle_domain_irq(intc_domain, cause);
}
/*
* On RISC-V systems local interrupts are masked or unmasked by writing
* the SIE (Supervisor Interrupt Enable) CSR. As CSRs can only be written
* on the local hart, these functions can only be called on the hart that
* corresponds to the IRQ chip.
*/
static void riscv_intc_irq_mask(struct irq_data *d)
{
csr_clear(CSR_IE, BIT(d->hwirq));
}
static void riscv_intc_irq_unmask(struct irq_data *d)
{
csr_set(CSR_IE, BIT(d->hwirq));
}
static void riscv_intc_irq_eoi(struct irq_data *d)
{
/*
* The RISC-V INTC driver uses handle_percpu_devid_irq() flow
* for the per-HART local interrupts and child irqchip drivers
* (such as PLIC, SBI IPI, CLINT, APLIC, IMSIC, etc) implement
* chained handlers for the per-HART local interrupts.
*
* In the absence of irq_eoi(), the chained_irq_enter() and
* chained_irq_exit() functions (used by child irqchip drivers)
* will do unnecessary mask/unmask of per-HART local interrupts
* at the time of handling interrupts. To avoid this, we provide
* an empty irq_eoi() callback for RISC-V INTC irqchip.
*/
}
static struct irq_chip riscv_intc_chip = {
.name = "RISC-V INTC",
.irq_mask = riscv_intc_irq_mask,
.irq_unmask = riscv_intc_irq_unmask,
.irq_eoi = riscv_intc_irq_eoi,
};
static int riscv_intc_domain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hwirq)
{
irq_set_percpu_devid(irq);
irq_domain_set_info(d, irq, hwirq, &riscv_intc_chip, d->host_data,
handle_percpu_devid_irq, NULL, NULL);
return 0;
}
static int riscv_intc_domain_alloc(struct irq_domain *domain,
unsigned int virq, unsigned int nr_irqs,
void *arg)
{
int i, ret;
irq_hw_number_t hwirq;
unsigned int type = IRQ_TYPE_NONE;
struct irq_fwspec *fwspec = arg;
ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type);
if (ret)
return ret;
for (i = 0; i < nr_irqs; i++) {
ret = riscv_intc_domain_map(domain, virq + i, hwirq + i);
if (ret)
return ret;
}
return 0;
}
static const struct irq_domain_ops riscv_intc_domain_ops = {
.map = riscv_intc_domain_map,
.xlate = irq_domain_xlate_onecell,
.alloc = riscv_intc_domain_alloc
};
static struct fwnode_handle *riscv_intc_hwnode(void)
{
return intc_domain->fwnode;
}
static int __init riscv_intc_init(struct device_node *node,
struct device_node *parent)
{
int rc;
unsigned long hartid;
rc = riscv_of_parent_hartid(node, &hartid);
if (rc < 0) {
pr_warn("unable to find hart id for %pOF\n", node);
return 0;
}
/*
* The DT will have one INTC DT node under each CPU (or HART)
* DT node so riscv_intc_init() function will be called once
* for each INTC DT node. We only need to do INTC initialization
* for the INTC DT node belonging to boot CPU (or boot HART).
*/
if (riscv_hartid_to_cpuid(hartid) != smp_processor_id())
return 0;
intc_domain = irq_domain_add_linear(node, BITS_PER_LONG,
&riscv_intc_domain_ops, NULL);
if (!intc_domain) {
pr_err("unable to add IRQ domain\n");
return -ENXIO;
}
rc = set_handle_irq(&riscv_intc_irq);
if (rc) {
pr_err("failed to set irq handler\n");
return rc;
}
riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
return 0;
}
IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init);
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