// SPDX-License-Identifier: GPL-2.0
/*
 * linux/arch/sh/kernel/irq.c
 *
 *      Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
 *
 *
 * SuperH version:  Copyright (C) 1999  Niibe Yutaka
 */
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <linux/ftrace.h>
#include <linux/delay.h>
#include <linux/ratelimit.h>
#include <asm/processor.h>
#include <asm/machvec.h>
#include <linux/uaccess.h>
#include <asm/thread_info.h>
#include <cpu/mmu_context.h>
#include <asm/softirq_stack.h>

atomic_t irq_err_count;

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves, it doesn't deserve
 * a generic callback i think.
 */
void ack_bad_irq(unsigned int irq)
{
        atomic_inc(&irq_err_count);
        printk("unexpected IRQ trap at vector %02x\n", irq);
}

#if defined(CONFIG_PROC_FS)
/*
 * /proc/interrupts printing for arch specific interrupts
 */
int arch_show_interrupts(struct seq_file *p, int prec)
{
        int j;

        seq_printf(p, "%*s: ", prec, "NMI");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", per_cpu(irq_stat.__nmi_count, j));
        seq_printf(p, "  Non-maskable interrupts\n");

        seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));

        return 0;
}
#endif

#ifdef CONFIG_IRQSTACKS
/*
 * per-CPU IRQ handling contexts (thread information and stack)
 */
union irq_ctx {
        struct thread_info      tinfo;
        u32                     stack[THREAD_SIZE/sizeof(u32)];
};

static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;

static char softirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
static char hardirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;

static inline void handle_one_irq(unsigned int irq)
{
        union irq_ctx *curctx, *irqctx;

        curctx = (union irq_ctx *)current_thread_info();
        irqctx = hardirq_ctx[smp_processor_id()];

        /*
         * this is where we switch to the IRQ stack. However, if we are
         * already using the IRQ stack (because we interrupted a hardirq
         * handler) we can't do that and just have to keep using the
         * current stack (which is the irq stack already after all)
         */
        if (curctx != irqctx) {
                u32 *isp;

                isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
                irqctx->tinfo.task = curctx->tinfo.task;
                irqctx->tinfo.previous_sp = current_stack_pointer;

                /*
                 * Copy the softirq bits in preempt_count so that the
                 * softirq checks work in the hardirq context.
                 */
                irqctx->tinfo.preempt_count =
                        (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
                        (curctx->tinfo.preempt_count & SOFTIRQ_MASK);

                __asm__ __volatile__ (
                        "mov    %0, r4          \n"
                        "mov    r15, r8         \n"
                        "jsr    @%1             \n"
                        /* switch to the irq stack */
                        " mov   %2, r15         \n"
                        /* restore the stack (ring zero) */
                        "mov    r8, r15         \n"
                        : /* no outputs */
                        : "r" (irq), "r" (generic_handle_irq), "r" (isp)
                        : "memory", "r0", "r1", "r2", "r3", "r4",
                          "r5", "r6", "r7", "r8", "t", "pr"
                );
        } else
                generic_handle_irq(irq);
}

/*
 * allocate per-cpu stacks for hardirq and for softirq processing
 */
void irq_ctx_init(int cpu)
{
        union irq_ctx *irqctx;

        if (hardirq_ctx[cpu])
                return;

        irqctx = (union irq_ctx *)&hardirq_stack[cpu * THREAD_SIZE];
        irqctx->tinfo.task              = NULL;
        irqctx->tinfo.cpu               = cpu;
        irqctx->tinfo.preempt_count     = HARDIRQ_OFFSET;
        irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);

        hardirq_ctx[cpu] = irqctx;

        irqctx = (union irq_ctx *)&softirq_stack[cpu * THREAD_SIZE];
        irqctx->tinfo.task              = NULL;
        irqctx->tinfo.cpu               = cpu;
        irqctx->tinfo.preempt_count     = 0;
        irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);

        softirq_ctx[cpu] = irqctx;

        printk("CPU %u irqstacks, hard=%p soft=%p\n",
                cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
}

void irq_ctx_exit(int cpu)
{
        hardirq_ctx[cpu] = NULL;
}

void do_softirq_own_stack(void)
{
        struct thread_info *curctx;
        union irq_ctx *irqctx;
        u32 *isp;

        curctx = current_thread_info();
        irqctx = softirq_ctx[smp_processor_id()];
        irqctx->tinfo.task = curctx->task;
        irqctx->tinfo.previous_sp = current_stack_pointer;

        /* build the stack frame on the softirq stack */
        isp = (u32 *)((char *)irqctx + sizeof(*irqctx));

        __asm__ __volatile__ (
                "mov    r15, r9         \n"
                "jsr    @%0             \n"
                /* switch to the softirq stack */
                " mov   %1, r15         \n"
                /* restore the thread stack */
                "mov    r9, r15         \n"
                : /* no outputs */
                : "r" (__do_softirq), "r" (isp)
                : "memory", "r0", "r1", "r2", "r3", "r4",
                  "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
        );
}
#else
static inline void handle_one_irq(unsigned int irq)
{
        generic_handle_irq(irq);
}
#endif

asmlinkage __irq_entry int do_IRQ(unsigned int irq, struct pt_regs *regs)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        irq_enter();

        irq = irq_demux(irq_lookup(irq));

        if (irq != NO_IRQ_IGNORE) {
                handle_one_irq(irq);
                irq_finish(irq);
        }

        irq_exit();

        set_irq_regs(old_regs);

        return IRQ_HANDLED;
}

void __init init_IRQ(void)
{
        plat_irq_setup();

        /* Perform the machine specific initialisation */
        if (sh_mv.mv_init_irq)
                sh_mv.mv_init_irq();

        intc_finalize();

        irq_ctx_init(smp_processor_id());
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * The CPU has been marked offline.  Migrate IRQs off this CPU.  If
 * the affinity settings do not allow other CPUs, force them onto any
 * available CPU.
 */
void migrate_irqs(void)
{
        unsigned int irq, cpu = smp_processor_id();

        for_each_active_irq(irq) {
                struct irq_data *data = irq_get_irq_data(irq);

                if (irq_data_get_node(data) == cpu) {
                        struct cpumask *mask = irq_data_get_affinity_mask(data);
                        unsigned int newcpu = cpumask_any_and(mask,
                                                              cpu_online_mask);
                        if (newcpu >= nr_cpu_ids) {
                                pr_info_ratelimited("IRQ%u no longer affine to CPU%u\n",
                                                    irq, cpu);

                                cpumask_setall(mask);
                        }
                        irq_set_affinity(irq, mask);
                }
        }
}
#endif