// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015-2021, Linaro Limited
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/arm-smccc.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/tee_core.h>
#include "optee_private.h"

struct notif_entry {
        struct list_head link;
        struct completion c;
        u_int key;
};

static bool have_key(struct optee *optee, u_int key)
{
        struct notif_entry *entry;

        list_for_each_entry(entry, &optee->notif.db, link)
                if (entry->key == key)
                        return true;

        return false;
}

int optee_notif_wait(struct optee *optee, u_int key, u32 timeout)
{
        unsigned long flags;
        struct notif_entry *entry;
        int rc = 0;

        if (key > optee->notif.max_key)
                return -EINVAL;

        entry = kmalloc_obj(*entry);
        if (!entry)
                return -ENOMEM;
        init_completion(&entry->c);
        entry->key = key;

        spin_lock_irqsave(&optee->notif.lock, flags);

        /*
         * If the bit is already set it means that the key has already
         * been posted and we must not wait.
         */
        if (test_bit(key, optee->notif.bitmap)) {
                clear_bit(key, optee->notif.bitmap);
                goto out;
        }

        /*
         * Check if someone is already waiting for this key. If there is
         * it's a programming error.
         */
        if (have_key(optee, key)) {
                rc = -EBUSY;
                goto out;
        }

        list_add_tail(&entry->link, &optee->notif.db);

        /*
         * Unlock temporarily and wait for completion.
         */
        spin_unlock_irqrestore(&optee->notif.lock, flags);
        if (timeout != 0) {
                if (!wait_for_completion_timeout(&entry->c, timeout))
                        rc = -ETIMEDOUT;
        } else {
                wait_for_completion(&entry->c);
        }
        spin_lock_irqsave(&optee->notif.lock, flags);

        list_del(&entry->link);
out:
        spin_unlock_irqrestore(&optee->notif.lock, flags);

        kfree(entry);

        return rc;
}

int optee_notif_send(struct optee *optee, u_int key)
{
        unsigned long flags;
        struct notif_entry *entry;

        if (key > optee->notif.max_key)
                return -EINVAL;

        spin_lock_irqsave(&optee->notif.lock, flags);

        list_for_each_entry(entry, &optee->notif.db, link)
                if (entry->key == key) {
                        complete(&entry->c);
                        goto out;
                }

        /* Only set the bit in case there where nobody waiting */
        set_bit(key, optee->notif.bitmap);
out:
        spin_unlock_irqrestore(&optee->notif.lock, flags);

        return 0;
}

int optee_notif_init(struct optee *optee, u_int max_key)
{
        spin_lock_init(&optee->notif.lock);
        INIT_LIST_HEAD(&optee->notif.db);
        optee->notif.bitmap = bitmap_zalloc(max_key, GFP_KERNEL);
        if (!optee->notif.bitmap)
                return -ENOMEM;

        optee->notif.max_key = max_key;

        return 0;
}

void optee_notif_uninit(struct optee *optee)
{
        bitmap_free(optee->notif.bitmap);
}