// SPDX-License-Identifier: GPL-2.0
/*
 *    Support for adapter interruptions
 *
 *    Copyright IBM Corp. 1999, 2007
 *    Author(s): Ingo Adlung <adlung@de.ibm.com>
 *               Cornelia Huck <cornelia.huck@de.ibm.com>
 *               Arnd Bergmann <arndb@de.ibm.com>
 *               Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
 */

#include <linux/init.h>
#include <linux/irq.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/rculist.h>
#include <linux/slab.h>
#include <linux/dmapool.h>

#include <asm/airq.h>
#include <asm/isc.h>
#include <asm/cio.h>

#include "cio.h"
#include "cio_debug.h"
#include "ioasm.h"

static DEFINE_SPINLOCK(airq_lists_lock);
static struct hlist_head airq_lists[MAX_ISC+1];

static struct dma_pool *airq_iv_cache;

/**
 * register_adapter_interrupt() - register adapter interrupt handler
 * @airq: pointer to adapter interrupt descriptor
 *
 * Returns 0 on success, or -EINVAL.
 */
int register_adapter_interrupt(struct airq_struct *airq)
{
        char dbf_txt[32];

        if (!airq->handler || airq->isc > MAX_ISC)
                return -EINVAL;
        if (!airq->lsi_ptr) {
                airq->lsi_ptr = kzalloc(1, GFP_KERNEL);
                if (!airq->lsi_ptr)
                        return -ENOMEM;
                airq->flags |= AIRQ_PTR_ALLOCATED;
        }
        if (!airq->lsi_mask)
                airq->lsi_mask = 0xff;
        snprintf(dbf_txt, sizeof(dbf_txt), "rairq:%p", airq);
        CIO_TRACE_EVENT(4, dbf_txt);
        isc_register(airq->isc);
        spin_lock(&airq_lists_lock);
        hlist_add_head_rcu(&airq->list, &airq_lists[airq->isc]);
        spin_unlock(&airq_lists_lock);
        return 0;
}
EXPORT_SYMBOL(register_adapter_interrupt);

/**
 * unregister_adapter_interrupt - unregister adapter interrupt handler
 * @airq: pointer to adapter interrupt descriptor
 */
void unregister_adapter_interrupt(struct airq_struct *airq)
{
        char dbf_txt[32];

        if (hlist_unhashed(&airq->list))
                return;
        snprintf(dbf_txt, sizeof(dbf_txt), "urairq:%p", airq);
        CIO_TRACE_EVENT(4, dbf_txt);
        spin_lock(&airq_lists_lock);
        hlist_del_rcu(&airq->list);
        spin_unlock(&airq_lists_lock);
        synchronize_rcu();
        isc_unregister(airq->isc);
        if (airq->flags & AIRQ_PTR_ALLOCATED) {
                kfree(airq->lsi_ptr);
                airq->lsi_ptr = NULL;
                airq->flags &= ~AIRQ_PTR_ALLOCATED;
        }
}
EXPORT_SYMBOL(unregister_adapter_interrupt);

static irqreturn_t do_airq_interrupt(int irq, void *dummy)
{
        struct tpi_info *tpi_info;
        struct airq_struct *airq;
        struct hlist_head *head;

        set_cpu_flag(CIF_NOHZ_DELAY);
        tpi_info = (struct tpi_info *) &get_irq_regs()->int_code;
        trace_s390_cio_adapter_int(tpi_info);
        head = &airq_lists[tpi_info->isc];
        rcu_read_lock();
        hlist_for_each_entry_rcu(airq, head, list)
                if ((*airq->lsi_ptr & airq->lsi_mask) != 0)
                        airq->handler(airq, !tpi_info->directed_irq);
        rcu_read_unlock();

        return IRQ_HANDLED;
}

static struct irqaction airq_interrupt = {
        .name    = "AIO",
        .handler = do_airq_interrupt,
};

void __init init_airq_interrupts(void)
{
        irq_set_chip_and_handler(THIN_INTERRUPT,
                                 &dummy_irq_chip, handle_percpu_irq);
        setup_irq(THIN_INTERRUPT, &airq_interrupt);
}

static inline unsigned long iv_size(unsigned long bits)
{
        return BITS_TO_LONGS(bits) * sizeof(unsigned long);
}

/**
 * airq_iv_create - create an interrupt vector
 * @bits: number of bits in the interrupt vector
 * @flags: allocation flags
 *
 * Returns a pointer to an interrupt vector structure
 */
struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
{
        struct airq_iv *iv;
        unsigned long size;

        iv = kzalloc(sizeof(*iv), GFP_KERNEL);
        if (!iv)
                goto out;
        iv->bits = bits;
        iv->flags = flags;
        size = iv_size(bits);

        if (flags & AIRQ_IV_CACHELINE) {
                if ((cache_line_size() * BITS_PER_BYTE) < bits
                                || !airq_iv_cache)
                        goto out_free;

                iv->vector = dma_pool_zalloc(airq_iv_cache, GFP_KERNEL,
                                             &iv->vector_dma);
                if (!iv->vector)
                        goto out_free;
        } else {
                iv->vector = cio_dma_zalloc(size);
                if (!iv->vector)
                        goto out_free;
        }
        if (flags & AIRQ_IV_ALLOC) {
                iv->avail = kmalloc(size, GFP_KERNEL);
                if (!iv->avail)
                        goto out_free;
                memset(iv->avail, 0xff, size);
                iv->end = 0;
        } else
                iv->end = bits;
        if (flags & AIRQ_IV_BITLOCK) {
                iv->bitlock = kzalloc(size, GFP_KERNEL);
                if (!iv->bitlock)
                        goto out_free;
        }
        if (flags & AIRQ_IV_PTR) {
                size = bits * sizeof(unsigned long);
                iv->ptr = kzalloc(size, GFP_KERNEL);
                if (!iv->ptr)
                        goto out_free;
        }
        if (flags & AIRQ_IV_DATA) {
                size = bits * sizeof(unsigned int);
                iv->data = kzalloc(size, GFP_KERNEL);
                if (!iv->data)
                        goto out_free;
        }
        spin_lock_init(&iv->lock);
        return iv;

out_free:
        kfree(iv->ptr);
        kfree(iv->bitlock);
        kfree(iv->avail);
        if (iv->flags & AIRQ_IV_CACHELINE && iv->vector)
                dma_pool_free(airq_iv_cache, iv->vector, iv->vector_dma);
        else
                cio_dma_free(iv->vector, size);
        kfree(iv);
out:
        return NULL;
}
EXPORT_SYMBOL(airq_iv_create);

/**
 * airq_iv_release - release an interrupt vector
 * @iv: pointer to interrupt vector structure
 */
void airq_iv_release(struct airq_iv *iv)
{
        kfree(iv->data);
        kfree(iv->ptr);
        kfree(iv->bitlock);
        if (iv->flags & AIRQ_IV_CACHELINE)
                dma_pool_free(airq_iv_cache, iv->vector, iv->vector_dma);
        else
                cio_dma_free(iv->vector, iv_size(iv->bits));
        kfree(iv->avail);
        kfree(iv);
}
EXPORT_SYMBOL(airq_iv_release);

/**
 * airq_iv_alloc - allocate irq bits from an interrupt vector
 * @iv: pointer to an interrupt vector structure
 * @num: number of consecutive irq bits to allocate
 *
 * Returns the bit number of the first irq in the allocated block of irqs,
 * or -1UL if no bit is available or the AIRQ_IV_ALLOC flag has not been
 * specified
 */
unsigned long airq_iv_alloc(struct airq_iv *iv, unsigned long num)
{
        unsigned long bit, i, flags;

        if (!iv->avail || num == 0)
                return -1UL;
        spin_lock_irqsave(&iv->lock, flags);
        bit = find_first_bit_inv(iv->avail, iv->bits);
        while (bit + num <= iv->bits) {
                for (i = 1; i < num; i++)
                        if (!test_bit_inv(bit + i, iv->avail))
                                break;
                if (i >= num) {
                        /* Found a suitable block of irqs */
                        for (i = 0; i < num; i++)
                                clear_bit_inv(bit + i, iv->avail);
                        if (bit + num >= iv->end)
                                iv->end = bit + num + 1;
                        break;
                }
                bit = find_next_bit_inv(iv->avail, iv->bits, bit + i + 1);
        }
        if (bit + num > iv->bits)
                bit = -1UL;
        spin_unlock_irqrestore(&iv->lock, flags);
        return bit;
}
EXPORT_SYMBOL(airq_iv_alloc);

/**
 * airq_iv_free - free irq bits of an interrupt vector
 * @iv: pointer to interrupt vector structure
 * @bit: number of the first irq bit to free
 * @num: number of consecutive irq bits to free
 */
void airq_iv_free(struct airq_iv *iv, unsigned long bit, unsigned long num)
{
        unsigned long i, flags;

        if (!iv->avail || num == 0)
                return;
        spin_lock_irqsave(&iv->lock, flags);
        for (i = 0; i < num; i++) {
                /* Clear (possibly left over) interrupt bit */
                clear_bit_inv(bit + i, iv->vector);
                /* Make the bit positions available again */
                set_bit_inv(bit + i, iv->avail);
        }
        if (bit + num >= iv->end) {
                /* Find new end of bit-field */
                while (iv->end > 0 && !test_bit_inv(iv->end - 1, iv->avail))
                        iv->end--;
        }
        spin_unlock_irqrestore(&iv->lock, flags);
}
EXPORT_SYMBOL(airq_iv_free);

/**
 * airq_iv_scan - scan interrupt vector for non-zero bits
 * @iv: pointer to interrupt vector structure
 * @start: bit number to start the search
 * @end: bit number to end the search
 *
 * Returns the bit number of the next non-zero interrupt bit, or
 * -1UL if the scan completed without finding any more any non-zero bits.
 */
unsigned long airq_iv_scan(struct airq_iv *iv, unsigned long start,
                           unsigned long end)
{
        unsigned long bit;

        /* Find non-zero bit starting from 'ivs->next'. */
        bit = find_next_bit_inv(iv->vector, end, start);
        if (bit >= end)
                return -1UL;
        clear_bit_inv(bit, iv->vector);
        return bit;
}
EXPORT_SYMBOL(airq_iv_scan);

int __init airq_init(void)
{
        airq_iv_cache = dma_pool_create("airq_iv_cache", cio_get_dma_css_dev(),
                                        cache_line_size(),
                                        cache_line_size(), PAGE_SIZE);
        if (!airq_iv_cache)
                return -ENOMEM;
        return 0;
}