// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Linux driver model AC97 bus interface
 *
 * Author:      Nicolas Pitre
 * Created:     Jan 14, 2005
 * Copyright:   (C) MontaVista Software Inc.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/string.h>
#include <sound/ac97_codec.h>

/*
 * snd_ac97_check_id() - Reads and checks the vendor ID of the device
 * @ac97: The AC97 device to check
 * @id: The ID to compare to
 * @id_mask: Mask that is applied to the device ID before comparing to @id
 *
 * If @id is 0 this function returns true if the read device vendor ID is
 * a valid ID. If @id is non 0 this functions returns true if @id
 * matches the read vendor ID. Otherwise the function returns false.
 */
static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id,
        unsigned int id_mask)
{
        ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16;
        ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2);

        if (ac97->id == 0x0 || ac97->id == 0xffffffff)
                return false;

        if (id != 0 && id != (ac97->id & id_mask))
                return false;

        return true;
}

/**
 * snd_ac97_reset() - Reset AC'97 device
 * @ac97: The AC'97 device to reset
 * @try_warm: Try a warm reset first
 * @id: Expected device vendor ID
 * @id_mask: Mask that is applied to the device ID before comparing to @id
 *
 * This function resets the AC'97 device. If @try_warm is true the function
 * first performs a warm reset. If @try_warm is false the function issues
 * cold reset followed by a warm reset. If @id is 0 any valid device ID
 * will be accepted, otherwise only the ID that matches @id and @id_mask
 * is accepted.
 * Returns:
 * * %1 - if warm reset is successful
 * * %0 - if cold reset and warm reset is successful
 * * %-ENODEV - if @id and @id_mask not matching
 */
int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id,
        unsigned int id_mask)
{
        const struct snd_ac97_bus_ops *ops = ac97->bus->ops;

        if (try_warm && ops->warm_reset) {
                ops->warm_reset(ac97);
                if (snd_ac97_check_id(ac97, id, id_mask))
                        return 1;
        }

        if (ops->reset)
                ops->reset(ac97);
        if (ops->warm_reset)
                ops->warm_reset(ac97);

        if (snd_ac97_check_id(ac97, id, id_mask))
                return 0;

        return -ENODEV;
}
EXPORT_SYMBOL_GPL(snd_ac97_reset);

const struct bus_type ac97_bus_type = {
        .name           = "ac97",
};

static int __init ac97_bus_init(void)
{
        return bus_register(&ac97_bus_type);
}

subsys_initcall(ac97_bus_init);

static void __exit ac97_bus_exit(void)
{
        bus_unregister(&ac97_bus_type);
}

module_exit(ac97_bus_exit);

EXPORT_SYMBOL(ac97_bus_type);

MODULE_DESCRIPTION("Legacy AC97 bus interface");
MODULE_LICENSE("GPL");