// SPDX-License-Identifier: GPL-2.0-or-later
/* 
 * Code to handle x86 style IRQs plus some generic interrupt stuff.
 *
 * Copyright (C) 1992 Linus Torvalds
 * Copyright (C) 1994, 1995, 1996, 1997, 1998 Ralf Baechle
 * Copyright (C) 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
 * Copyright (C) 1999-2000 Grant Grundler
 * Copyright (c) 2005 Matthew Wilcox
 */
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <linux/types.h>
#include <linux/sched/task_stack.h>
#include <asm/io.h>

#include <asm/softirq_stack.h>
#include <asm/smp.h>
#include <asm/ldcw.h>

#undef PARISC_IRQ_CR16_COUNTS

#define EIEM_MASK(irq)       (1UL<<(CPU_IRQ_MAX - irq))

/* Bits in EIEM correlate with cpu_irq_action[].
** Numbered *Big Endian*! (ie bit 0 is MSB)
*/
static volatile unsigned long cpu_eiem = 0;

/*
** local ACK bitmap ... habitually set to 1, but reset to zero
** between ->ack() and ->end() of the interrupt to prevent
** re-interruption of a processing interrupt.
*/
static DEFINE_PER_CPU(unsigned long, local_ack_eiem) = ~0UL;

static void cpu_mask_irq(struct irq_data *d)
{
        unsigned long eirr_bit = EIEM_MASK(d->irq);

        cpu_eiem &= ~eirr_bit;
        /* Do nothing on the other CPUs.  If they get this interrupt,
         * The & cpu_eiem in the do_cpu_irq_mask() ensures they won't
         * handle it, and the set_eiem() at the bottom will ensure it
         * then gets disabled */
}

static void __cpu_unmask_irq(unsigned int irq)
{
        unsigned long eirr_bit = EIEM_MASK(irq);

        cpu_eiem |= eirr_bit;

        /* This is just a simple NOP IPI.  But what it does is cause
         * all the other CPUs to do a set_eiem(cpu_eiem) at the end
         * of the interrupt handler */
        smp_send_all_nop();
}

static void cpu_unmask_irq(struct irq_data *d)
{
        __cpu_unmask_irq(d->irq);
}

void cpu_ack_irq(struct irq_data *d)
{
        unsigned long mask = EIEM_MASK(d->irq);
        int cpu = smp_processor_id();

        /* Clear in EIEM so we can no longer process */
        per_cpu(local_ack_eiem, cpu) &= ~mask;

        /* disable the interrupt */
        set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));

        /* and now ack it */
        mtctl(mask, 23);
}

void cpu_eoi_irq(struct irq_data *d)
{
        unsigned long mask = EIEM_MASK(d->irq);
        int cpu = smp_processor_id();

        /* set it in the eiems---it's no longer in process */
        per_cpu(local_ack_eiem, cpu) |= mask;

        /* enable the interrupt */
        set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
}

#ifdef CONFIG_SMP
int cpu_check_affinity(struct irq_data *d, const struct cpumask *dest)
{
        int cpu_dest;

        /* timer and ipi have to always be received on all CPUs */
        if (irqd_is_per_cpu(d))
                return -EINVAL;

        cpu_dest = cpumask_first_and(dest, cpu_online_mask);
        if (cpu_dest >= nr_cpu_ids)
                cpu_dest = cpumask_first(cpu_online_mask);

        return cpu_dest;
}
#endif

static struct irq_chip cpu_interrupt_type = {
        .name                   = "CPU",
        .irq_mask               = cpu_mask_irq,
        .irq_unmask             = cpu_unmask_irq,
        .irq_ack                = cpu_ack_irq,
        .irq_eoi                = cpu_eoi_irq,
        /* XXX: Needs to be written.  We managed without it so far, but
         * we really ought to write it.
         */
        .irq_retrigger  = NULL,
};

DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
#define irq_stats(x)            (&per_cpu(irq_stat, x))

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

#ifdef CONFIG_DEBUG_STACKOVERFLOW
        seq_printf(p, "%*s: ", prec, "STK");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->kernel_stack_usage);
        seq_puts(p, "  Kernel stack usage\n");
# ifdef CONFIG_IRQSTACKS
        seq_printf(p, "%*s: ", prec, "IST");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_stack_usage);
        seq_puts(p, "  Interrupt stack usage\n");
# endif
#endif
#ifdef CONFIG_SMP
        if (num_online_cpus() > 1) {
                seq_printf(p, "%*s: ", prec, "RES");
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ", irq_stats(j)->irq_resched_count);
                seq_puts(p, "  Rescheduling interrupts\n");
                seq_printf(p, "%*s: ", prec, "CAL");
                for_each_online_cpu(j)
                        seq_printf(p, "%10u ", irq_stats(j)->irq_call_count);
                seq_puts(p, "  Function call interrupts\n");
        }
#endif
        seq_printf(p, "%*s: ", prec, "UAH");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_unaligned_count);
        seq_puts(p, "  Unaligned access handler traps\n");
        seq_printf(p, "%*s: ", prec, "FPA");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_fpassist_count);
        seq_puts(p, "  Floating point assist traps\n");
        seq_printf(p, "%*s: ", prec, "TLB");
        for_each_online_cpu(j)
                seq_printf(p, "%10u ", irq_stats(j)->irq_tlb_count);
        seq_puts(p, "  TLB shootdowns\n");
        return 0;
}

int show_interrupts(struct seq_file *p, void *v)
{
        int i = *(loff_t *) v, j;
        unsigned long flags;

        if (i == 0) {
                seq_puts(p, "    ");
                for_each_online_cpu(j)
                        seq_printf(p, "       CPU%d", j);

#ifdef PARISC_IRQ_CR16_COUNTS
                seq_printf(p, " [min/avg/max] (CPU cycle counts)");
#endif
                seq_putc(p, '\n');
        }

        if (i < NR_IRQS) {
                struct irq_desc *desc = irq_to_desc(i);
                struct irqaction *action;

                raw_spin_lock_irqsave(&desc->lock, flags);
                action = desc->action;
                if (!action)
                        goto skip;
                seq_printf(p, "%3d: ", i);

                for_each_online_cpu(j)
                        seq_printf(p, "%10u ", irq_desc_kstat_cpu(desc, j));

                seq_printf(p, " %14s", irq_desc_get_chip(desc)->name);
#ifndef PARISC_IRQ_CR16_COUNTS
                seq_printf(p, "  %s", action->name);

                while ((action = action->next))
                        seq_printf(p, ", %s", action->name);
#else
                for ( ;action; action = action->next) {
                        unsigned int k, avg, min, max;

                        min = max = action->cr16_hist[0];

                        for (avg = k = 0; k < PARISC_CR16_HIST_SIZE; k++) {
                                int hist = action->cr16_hist[k];

                                if (hist) {
                                        avg += hist;
                                } else
                                        break;

                                if (hist > max) max = hist;
                                if (hist < min) min = hist;
                        }

                        avg /= k;
                        seq_printf(p, " %s[%d/%d/%d]", action->name,
                                        min,avg,max);
                }
#endif

                seq_putc(p, '\n');
 skip:
                raw_spin_unlock_irqrestore(&desc->lock, flags);
        }

        if (i == NR_IRQS)
                arch_show_interrupts(p, 3);

        return 0;
}



/*
** The following form a "set": Virtual IRQ, Transaction Address, Trans Data.
** Respectively, these map to IRQ region+EIRR, Processor HPA, EIRR bit.
**
** To use txn_XXX() interfaces, get a Virtual IRQ first.
** Then use that to get the Transaction address and data.
*/

int cpu_claim_irq(unsigned int irq, struct irq_chip *type, void *data)
{
        if (irq_has_action(irq))
                return -EBUSY;
        if (irq_get_chip(irq) != &cpu_interrupt_type)
                return -EBUSY;

        /* for iosapic interrupts */
        if (type) {
                irq_set_chip_and_handler(irq, type, handle_percpu_irq);
                irq_set_chip_data(irq, data);
                __cpu_unmask_irq(irq);
        }
        return 0;
}

int txn_claim_irq(int irq)
{
        return cpu_claim_irq(irq, NULL, NULL) ? -1 : irq;
}

/*
 * The bits_wide parameter accommodates the limitations of the HW/SW which
 * use these bits:
 * Legacy PA I/O (GSC/NIO): 5 bits (architected EIM register)
 * V-class (EPIC):          6 bits
 * N/L/A-class (iosapic):   8 bits
 * PCI 2.2 MSI:            16 bits
 * Some PCI devices:       32 bits (Symbios SCSI/ATM/HyperFabric)
 *
 * On the service provider side:
 * o PA 1.1 (and PA2.0 narrow mode)     5-bits (width of EIR register)
 * o PA 2.0 wide mode                   6-bits (per processor)
 * o IA64                               8-bits (0-256 total)
 *
 * So a Legacy PA I/O device on a PA 2.0 box can't use all the bits supported
 * by the processor...and the N/L-class I/O subsystem supports more bits than
 * PA2.0 has. The first case is the problem.
 */
int txn_alloc_irq(unsigned int bits_wide)
{
        int irq;

        /* never return irq 0 cause that's the interval timer */
        for (irq = CPU_IRQ_BASE + 1; irq <= CPU_IRQ_MAX; irq++) {
                if (cpu_claim_irq(irq, NULL, NULL) < 0)
                        continue;
                if ((irq - CPU_IRQ_BASE) >= (1 << bits_wide))
                        continue;
                return irq;
        }

        /* unlikely, but be prepared */
        return -1;
}


unsigned long txn_affinity_addr(unsigned int irq, int cpu)
{
#ifdef CONFIG_SMP
        struct irq_data *d = irq_get_irq_data(irq);
        irq_data_update_affinity(d, cpumask_of(cpu));
#endif

        return per_cpu(cpu_data, cpu).txn_addr;
}


unsigned long txn_alloc_addr(unsigned int virt_irq)
{
        static int next_cpu = -1;

        next_cpu++; /* assign to "next" CPU we want this bugger on */

        /* validate entry */
        while ((next_cpu < nr_cpu_ids) &&
                (!per_cpu(cpu_data, next_cpu).txn_addr ||
                 !cpu_online(next_cpu)))
                next_cpu++;

        if (next_cpu >= nr_cpu_ids) 
                next_cpu = 0;   /* nothing else, assign monarch */

        return txn_affinity_addr(virt_irq, next_cpu);
}


unsigned int txn_alloc_data(unsigned int virt_irq)
{
        return virt_irq - CPU_IRQ_BASE;
}

static inline int eirr_to_irq(unsigned long eirr)
{
        int bit = fls_long(eirr);
        return (BITS_PER_LONG - bit) + TIMER_IRQ;
}

#ifdef CONFIG_IRQSTACKS
/*
 * IRQ STACK - used for irq handler
 */
#ifdef CONFIG_64BIT
#define IRQ_STACK_SIZE      (4096 << 4) /* 64k irq stack size */
#else
#define IRQ_STACK_SIZE      (4096 << 3) /* 32k irq stack size */
#endif

union irq_stack_union {
        unsigned long stack[IRQ_STACK_SIZE/sizeof(unsigned long)];
        volatile unsigned int slock[4];
        volatile unsigned int lock[1];
};

static DEFINE_PER_CPU(union irq_stack_union, irq_stack_union) = {
                .slock = { 1,1,1,1 },
        };
#endif


int sysctl_panic_on_stackoverflow = 1;

static inline void stack_overflow_check(struct pt_regs *regs)
{
#ifdef CONFIG_DEBUG_STACKOVERFLOW
        #define STACK_MARGIN    (256*6)

        unsigned long stack_start = (unsigned long) task_stack_page(current);
        unsigned long sp = regs->gr[30];
        unsigned long stack_usage;
        unsigned int *last_usage;
        int cpu = smp_processor_id();

        /* if sr7 != 0, we interrupted a userspace process which we do not want
         * to check for stack overflow. We will only check the kernel stack. */
        if (regs->sr[7])
                return;

        /* exit if already in panic */
        if (sysctl_panic_on_stackoverflow < 0)
                return;

        /* calculate kernel stack usage */
        stack_usage = sp - stack_start;
#ifdef CONFIG_IRQSTACKS
        if (likely(stack_usage <= THREAD_SIZE))
                goto check_kernel_stack; /* found kernel stack */

        /* check irq stack usage */
        stack_start = (unsigned long) &per_cpu(irq_stack_union, cpu).stack;
        stack_usage = sp - stack_start;

        last_usage = &per_cpu(irq_stat.irq_stack_usage, cpu);
        if (unlikely(stack_usage > *last_usage))
                *last_usage = stack_usage;

        if (likely(stack_usage < (IRQ_STACK_SIZE - STACK_MARGIN)))
                return;

        pr_emerg("stackcheck: %s will most likely overflow irq stack "
                 "(sp:%lx, stk bottom-top:%lx-%lx)\n",
                current->comm, sp, stack_start, stack_start + IRQ_STACK_SIZE);
        goto panic_check;

check_kernel_stack:
#endif

        /* check kernel stack usage */
        last_usage = &per_cpu(irq_stat.kernel_stack_usage, cpu);

        if (unlikely(stack_usage > *last_usage))
                *last_usage = stack_usage;

        if (likely(stack_usage < (THREAD_SIZE - STACK_MARGIN)))
                return;

        pr_emerg("stackcheck: %s will most likely overflow kernel stack "
                 "(sp:%lx, stk bottom-top:%lx-%lx)\n",
                current->comm, sp, stack_start, stack_start + THREAD_SIZE);

#ifdef CONFIG_IRQSTACKS
panic_check:
#endif
        if (sysctl_panic_on_stackoverflow) {
                sysctl_panic_on_stackoverflow = -1; /* disable further checks */
                panic("low stack detected by irq handler - check messages\n");
        }
#endif
}

#ifdef CONFIG_IRQSTACKS
/* in entry.S: */
void call_on_stack(unsigned long p1, void *func, unsigned long new_stack);

static void execute_on_irq_stack(void *func, unsigned long param1)
{
        union irq_stack_union *union_ptr;
        unsigned long irq_stack;
        volatile unsigned int *irq_stack_in_use;

        union_ptr = &per_cpu(irq_stack_union, smp_processor_id());
        irq_stack = (unsigned long) &union_ptr->stack;
        irq_stack = ALIGN(irq_stack + sizeof(irq_stack_union.slock),
                        FRAME_ALIGN); /* align for stack frame usage */

        /* We may be called recursive. If we are already using the irq stack,
         * just continue to use it. Use spinlocks to serialize
         * the irq stack usage.
         */
        irq_stack_in_use = (volatile unsigned int *)__ldcw_align(union_ptr);
        if (!__ldcw(irq_stack_in_use)) {
                void (*direct_call)(unsigned long p1) = func;

                /* We are using the IRQ stack already.
                 * Do direct call on current stack. */
                direct_call(param1);
                return;
        }

        /* This is where we switch to the IRQ stack. */
        call_on_stack(param1, func, irq_stack);

        /* free up irq stack usage. */
        *irq_stack_in_use = 1;
}

#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
void do_softirq_own_stack(void)
{
        execute_on_irq_stack(__do_softirq, 0);
}
#endif
#endif /* CONFIG_IRQSTACKS */

/* ONLY called from entry.S:intr_extint() */
asmlinkage void do_cpu_irq_mask(struct pt_regs *regs)
{
        struct pt_regs *old_regs;
        unsigned long eirr_val;
        int irq, cpu = smp_processor_id();
        struct irq_data *irq_data;
#ifdef CONFIG_SMP
        cpumask_t dest;
#endif

        old_regs = set_irq_regs(regs);
        local_irq_disable();
        irq_enter_rcu();

        eirr_val = mfctl(23) & cpu_eiem & per_cpu(local_ack_eiem, cpu);
        if (!eirr_val)
                goto set_out;
        irq = eirr_to_irq(eirr_val);

        irq_data = irq_get_irq_data(irq);

        /* Filter out spurious interrupts, mostly from serial port at bootup */
        if (unlikely(!irq_desc_has_action(irq_data_to_desc(irq_data))))
                goto set_out;

#ifdef CONFIG_SMP
        cpumask_copy(&dest, irq_data_get_affinity_mask(irq_data));
        if (irqd_is_per_cpu(irq_data) &&
            !cpumask_test_cpu(smp_processor_id(), &dest)) {
                int cpu = cpumask_first(&dest);

                printk(KERN_DEBUG "redirecting irq %d from CPU %d to %d\n",
                       irq, smp_processor_id(), cpu);
                gsc_writel(irq + CPU_IRQ_BASE,
                           per_cpu(cpu_data, cpu).hpa);
                goto set_out;
        }
#endif
        stack_overflow_check(regs);

#ifdef CONFIG_IRQSTACKS
        execute_on_irq_stack(&generic_handle_irq, irq);
#else
        generic_handle_irq(irq);
#endif /* CONFIG_IRQSTACKS */

 out:
        irq_exit_rcu();
        set_irq_regs(old_regs);
        return;

 set_out:
        set_eiem(cpu_eiem & per_cpu(local_ack_eiem, cpu));
        goto out;
}

static void claim_cpu_irqs(void)
{
        unsigned long flags = IRQF_TIMER | IRQF_PERCPU | IRQF_IRQPOLL;
        int i;

        for (i = CPU_IRQ_BASE; i <= CPU_IRQ_MAX; i++) {
                irq_set_chip_and_handler(i, &cpu_interrupt_type,
                                         handle_percpu_irq);
        }

        irq_set_handler(TIMER_IRQ, handle_percpu_irq);
        if (request_irq(TIMER_IRQ, timer_interrupt, flags, "timer", NULL))
                pr_err("Failed to register timer interrupt\n");
#ifdef CONFIG_SMP
        irq_set_handler(IPI_IRQ, handle_percpu_irq);
        if (request_irq(IPI_IRQ, ipi_interrupt, IRQF_PERCPU, "IPI", NULL))
                pr_err("Failed to register IPI interrupt\n");
#endif
}

void init_IRQ(void)
{
        local_irq_disable();    /* PARANOID - should already be disabled */
        mtctl(~0UL, 23);        /* EIRR : clear all pending external intr */
#ifdef CONFIG_SMP
        if (!cpu_eiem) {
                claim_cpu_irqs();
                cpu_eiem = EIEM_MASK(IPI_IRQ) | EIEM_MASK(TIMER_IRQ);
        }
#else
        claim_cpu_irqs();
        cpu_eiem = EIEM_MASK(TIMER_IRQ);
#endif
        set_eiem(cpu_eiem);     /* EIEM : enable all external intr */
}