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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2024 Inochi Amaoto <inochiama@gmail.com>
*/
#define pr_fmt(fmt) "thead-c900-aclint-sswi: " 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/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/pci.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/string_choices.h>
#include <asm/sbi.h>
#include <asm/vendorid_list.h>
#define THEAD_ACLINT_xSWI_REGISTER_SIZE 4
#define THEAD_C9XX_CSR_SXSTATUS 0x5c0
#define THEAD_C9XX_SXSTATUS_CLINTEE BIT(17)
static int sswi_ipi_virq __ro_after_init;
static DEFINE_PER_CPU(void __iomem *, sswi_cpu_regs);
static void thead_aclint_sswi_ipi_send(unsigned int cpu)
{
writel_relaxed(0x1, per_cpu(sswi_cpu_regs, cpu));
}
static void thead_aclint_sswi_ipi_clear(void)
{
writel_relaxed(0x0, this_cpu_read(sswi_cpu_regs));
}
static void thead_aclint_sswi_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);
thead_aclint_sswi_ipi_clear();
ipi_mux_process();
chained_irq_exit(chip, desc);
}
static int thead_aclint_sswi_starting_cpu(unsigned int cpu)
{
enable_percpu_irq(sswi_ipi_virq, irq_get_trigger_type(sswi_ipi_virq));
return 0;
}
static int thead_aclint_sswi_dying_cpu(unsigned int cpu)
{
thead_aclint_sswi_ipi_clear();
disable_percpu_irq(sswi_ipi_virq);
return 0;
}
static int __init thead_aclint_sswi_parse_irq(struct fwnode_handle *fwnode,
void __iomem *reg)
{
struct of_phandle_args parent;
unsigned long hartid;
u32 contexts, i;
int rc, cpu;
contexts = of_irq_count(to_of_node(fwnode));
if (!(contexts)) {
pr_err("%pfwP: no ACLINT SSWI context available\n", fwnode);
return -EINVAL;
}
for (i = 0; i < contexts; i++) {
rc = of_irq_parse_one(to_of_node(fwnode), i, &parent);
if (rc)
return rc;
rc = riscv_of_parent_hartid(parent.np, &hartid);
if (rc)
return rc;
if (parent.args[0] != RV_IRQ_SOFT)
return -ENOTSUPP;
cpu = riscv_hartid_to_cpuid(hartid);
per_cpu(sswi_cpu_regs, cpu) = reg + i * THEAD_ACLINT_xSWI_REGISTER_SIZE;
}
pr_info("%pfwP: register %u CPU%s\n", fwnode, contexts, str_plural(contexts));
return 0;
}
static int __init thead_aclint_sswi_probe(struct fwnode_handle *fwnode)
{
struct irq_domain *domain;
void __iomem *reg;
int virq, rc;
/* If it is T-HEAD CPU, check whether SSWI is enabled */
if (riscv_cached_mvendorid(0) == THEAD_VENDOR_ID &&
!(csr_read(THEAD_C9XX_CSR_SXSTATUS) & THEAD_C9XX_SXSTATUS_CLINTEE))
return -ENOTSUPP;
if (!is_of_node(fwnode))
return -EINVAL;
reg = of_iomap(to_of_node(fwnode), 0);
if (!reg)
return -ENOMEM;
/* Parse SSWI setting */
rc = thead_aclint_sswi_parse_irq(fwnode, reg);
if (rc < 0)
return rc;
/* If mulitple SSWI devices are present, do not register irq again */
if (sswi_ipi_virq)
return 0;
/* Find riscv intc domain and create IPI irq mapping */
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;
}
sswi_ipi_virq = irq_create_mapping(domain, RV_IRQ_SOFT);
if (!sswi_ipi_virq) {
pr_err("unable to create ACLINT SSWI IRQ mapping\n");
return -ENOMEM;
}
/* Register SSWI irq and handler */
virq = ipi_mux_create(BITS_PER_BYTE, thead_aclint_sswi_ipi_send);
if (virq <= 0) {
pr_err("unable to create muxed IPIs\n");
irq_dispose_mapping(sswi_ipi_virq);
return virq < 0 ? virq : -ENOMEM;
}
irq_set_chained_handler(sswi_ipi_virq, thead_aclint_sswi_ipi_handle);
cpuhp_setup_state(CPUHP_AP_IRQ_THEAD_ACLINT_SSWI_STARTING,
"irqchip/thead-aclint-sswi:starting",
thead_aclint_sswi_starting_cpu,
thead_aclint_sswi_dying_cpu);
riscv_ipi_set_virq_range(virq, BITS_PER_BYTE);
/* Announce that SSWI is providing IPIs */
pr_info("providing IPIs using THEAD ACLINT SSWI\n");
return 0;
}
static int __init thead_aclint_sswi_early_probe(struct device_node *node,
struct device_node *parent)
{
return thead_aclint_sswi_probe(&node->fwnode);
}
IRQCHIP_DECLARE(thead_aclint_sswi, "thead,c900-aclint-sswi", thead_aclint_sswi_early_probe);
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