// SPDX-License-Identifier: GPL-2.0+
// Copyright 2017 IBM Corp.
#include <linux/interrupt.h>
#include <linux/eventfd.h>
#include <asm/pnv-ocxl.h>
#include "ocxl_internal.h"
#include "trace.h"

struct afu_irq {
        int id;
        int hw_irq;
        unsigned int virq;
        char *name;
        u64 trigger_page;
        struct eventfd_ctx *ev_ctx;
};

static int irq_offset_to_id(struct ocxl_context *ctx, u64 offset)
{
        return (offset - ctx->afu->irq_base_offset) >> PAGE_SHIFT;
}

static u64 irq_id_to_offset(struct ocxl_context *ctx, int id)
{
        return ctx->afu->irq_base_offset + (id << PAGE_SHIFT);
}

static irqreturn_t afu_irq_handler(int virq, void *data)
{
        struct afu_irq *irq = (struct afu_irq *) data;

        trace_ocxl_afu_irq_receive(virq);
        if (irq->ev_ctx)
                eventfd_signal(irq->ev_ctx, 1);
        return IRQ_HANDLED;
}

static int setup_afu_irq(struct ocxl_context *ctx, struct afu_irq *irq)
{
        int rc;

        irq->virq = irq_create_mapping(NULL, irq->hw_irq);
        if (!irq->virq) {
                pr_err("irq_create_mapping failed\n");
                return -ENOMEM;
        }
        pr_debug("hw_irq %d mapped to virq %u\n", irq->hw_irq, irq->virq);

        irq->name = kasprintf(GFP_KERNEL, "ocxl-afu-%u", irq->virq);
        if (!irq->name) {
                irq_dispose_mapping(irq->virq);
                return -ENOMEM;
        }

        rc = request_irq(irq->virq, afu_irq_handler, 0, irq->name, irq);
        if (rc) {
                kfree(irq->name);
                irq->name = NULL;
                irq_dispose_mapping(irq->virq);
                pr_err("request_irq failed: %d\n", rc);
                return rc;
        }
        return 0;
}

static void release_afu_irq(struct afu_irq *irq)
{
        free_irq(irq->virq, irq);
        irq_dispose_mapping(irq->virq);
        kfree(irq->name);
}

int ocxl_afu_irq_alloc(struct ocxl_context *ctx, u64 *irq_offset)
{
        struct afu_irq *irq;
        int rc;

        irq = kzalloc(sizeof(struct afu_irq), GFP_KERNEL);
        if (!irq)
                return -ENOMEM;

        /*
         * We limit the number of afu irqs per context and per link to
         * avoid a single process or user depleting the pool of IPIs
         */

        mutex_lock(&ctx->irq_lock);

        irq->id = idr_alloc(&ctx->irq_idr, irq, 0, MAX_IRQ_PER_CONTEXT,
                        GFP_KERNEL);
        if (irq->id < 0) {
                rc = -ENOSPC;
                goto err_unlock;
        }

        rc = ocxl_link_irq_alloc(ctx->afu->fn->link, &irq->hw_irq,
                                &irq->trigger_page);
        if (rc)
                goto err_idr;

        rc = setup_afu_irq(ctx, irq);
        if (rc)
                goto err_alloc;

        *irq_offset = irq_id_to_offset(ctx, irq->id);

        trace_ocxl_afu_irq_alloc(ctx->pasid, irq->id, irq->virq, irq->hw_irq,
                                *irq_offset);
        mutex_unlock(&ctx->irq_lock);
        return 0;

err_alloc:
        ocxl_link_free_irq(ctx->afu->fn->link, irq->hw_irq);
err_idr:
        idr_remove(&ctx->irq_idr, irq->id);
err_unlock:
        mutex_unlock(&ctx->irq_lock);
        kfree(irq);
        return rc;
}

static void afu_irq_free(struct afu_irq *irq, struct ocxl_context *ctx)
{
        trace_ocxl_afu_irq_free(ctx->pasid, irq->id);
        if (ctx->mapping)
                unmap_mapping_range(ctx->mapping,
                                irq_id_to_offset(ctx, irq->id),
                                1 << PAGE_SHIFT, 1);
        release_afu_irq(irq);
        if (irq->ev_ctx)
                eventfd_ctx_put(irq->ev_ctx);
        ocxl_link_free_irq(ctx->afu->fn->link, irq->hw_irq);
        kfree(irq);
}

int ocxl_afu_irq_free(struct ocxl_context *ctx, u64 irq_offset)
{
        struct afu_irq *irq;
        int id = irq_offset_to_id(ctx, irq_offset);

        mutex_lock(&ctx->irq_lock);

        irq = idr_find(&ctx->irq_idr, id);
        if (!irq) {
                mutex_unlock(&ctx->irq_lock);
                return -EINVAL;
        }
        idr_remove(&ctx->irq_idr, irq->id);
        afu_irq_free(irq, ctx);
        mutex_unlock(&ctx->irq_lock);
        return 0;
}

void ocxl_afu_irq_free_all(struct ocxl_context *ctx)
{
        struct afu_irq *irq;
        int id;

        mutex_lock(&ctx->irq_lock);
        idr_for_each_entry(&ctx->irq_idr, irq, id)
                afu_irq_free(irq, ctx);
        mutex_unlock(&ctx->irq_lock);
}

int ocxl_afu_irq_set_fd(struct ocxl_context *ctx, u64 irq_offset, int eventfd)
{
        struct afu_irq *irq;
        struct eventfd_ctx *ev_ctx;
        int rc = 0, id = irq_offset_to_id(ctx, irq_offset);

        mutex_lock(&ctx->irq_lock);
        irq = idr_find(&ctx->irq_idr, id);
        if (!irq) {
                rc = -EINVAL;
                goto unlock;
        }

        ev_ctx = eventfd_ctx_fdget(eventfd);
        if (IS_ERR(ev_ctx)) {
                rc = -EINVAL;
                goto unlock;
        }

        irq->ev_ctx = ev_ctx;
unlock:
        mutex_unlock(&ctx->irq_lock);
        return rc;
}

u64 ocxl_afu_irq_get_addr(struct ocxl_context *ctx, u64 irq_offset)
{
        struct afu_irq *irq;
        int id = irq_offset_to_id(ctx, irq_offset);
        u64 addr = 0;

        mutex_lock(&ctx->irq_lock);
        irq = idr_find(&ctx->irq_idr, id);
        if (irq)
                addr = irq->trigger_page;
        mutex_unlock(&ctx->irq_lock);
        return addr;
}