cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ac97_bus.c (2946B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Linux driver model AC97 bus interface
      4 *
      5 * Author:	Nicolas Pitre
      6 * Created:	Jan 14, 2005
      7 * Copyright:	(C) MontaVista Software Inc.
      8 */
      9
     10#include <linux/module.h>
     11#include <linux/init.h>
     12#include <linux/device.h>
     13#include <linux/string.h>
     14#include <sound/ac97_codec.h>
     15
     16/*
     17 * snd_ac97_check_id() - Reads and checks the vendor ID of the device
     18 * @ac97: The AC97 device to check
     19 * @id: The ID to compare to
     20 * @id_mask: Mask that is applied to the device ID before comparing to @id
     21 *
     22 * If @id is 0 this function returns true if the read device vendor ID is
     23 * a valid ID. If @id is non 0 this functions returns true if @id
     24 * matches the read vendor ID. Otherwise the function returns false.
     25 */
     26static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id,
     27	unsigned int id_mask)
     28{
     29	ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16;
     30	ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2);
     31
     32	if (ac97->id == 0x0 || ac97->id == 0xffffffff)
     33		return false;
     34
     35	if (id != 0 && id != (ac97->id & id_mask))
     36		return false;
     37
     38	return true;
     39}
     40
     41/**
     42 * snd_ac97_reset() - Reset AC'97 device
     43 * @ac97: The AC'97 device to reset
     44 * @try_warm: Try a warm reset first
     45 * @id: Expected device vendor ID
     46 * @id_mask: Mask that is applied to the device ID before comparing to @id
     47 *
     48 * This function resets the AC'97 device. If @try_warm is true the function
     49 * first performs a warm reset. If the warm reset is successful the function
     50 * returns 1. Otherwise or if @try_warm is false the function issues cold reset
     51 * followed by a warm reset. If this is successful the function returns 0,
     52 * otherwise a negative error code. If @id is 0 any valid device ID will be
     53 * accepted, otherwise only the ID that matches @id and @id_mask is accepted.
     54 */
     55int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id,
     56	unsigned int id_mask)
     57{
     58	const struct snd_ac97_bus_ops *ops = ac97->bus->ops;
     59
     60	if (try_warm && ops->warm_reset) {
     61		ops->warm_reset(ac97);
     62		if (snd_ac97_check_id(ac97, id, id_mask))
     63			return 1;
     64	}
     65
     66	if (ops->reset)
     67		ops->reset(ac97);
     68	if (ops->warm_reset)
     69		ops->warm_reset(ac97);
     70
     71	if (snd_ac97_check_id(ac97, id, id_mask))
     72		return 0;
     73
     74	return -ENODEV;
     75}
     76EXPORT_SYMBOL_GPL(snd_ac97_reset);
     77
     78/*
     79 * Let drivers decide whether they want to support given codec from their
     80 * probe method. Drivers have direct access to the struct snd_ac97
     81 * structure and may  decide based on the id field amongst other things.
     82 */
     83static int ac97_bus_match(struct device *dev, struct device_driver *drv)
     84{
     85	return 1;
     86}
     87
     88struct bus_type ac97_bus_type = {
     89	.name		= "ac97",
     90	.match		= ac97_bus_match,
     91};
     92
     93static int __init ac97_bus_init(void)
     94{
     95	return bus_register(&ac97_bus_type);
     96}
     97
     98subsys_initcall(ac97_bus_init);
     99
    100static void __exit ac97_bus_exit(void)
    101{
    102	bus_unregister(&ac97_bus_type);
    103}
    104
    105module_exit(ac97_bus_exit);
    106
    107EXPORT_SYMBOL(ac97_bus_type);
    108
    109MODULE_LICENSE("GPL");