110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Linux driver model AC97 bus interface
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*
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* Author: Nicolas Pitre
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* Created: Jan 14, 2005
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* Copyright: (C) MontaVista Software Inc.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/device.h>
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#include <linux/string.h>
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#include <sound/ac97_codec.h>
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/*
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* snd_ac97_check_id() - Reads and checks the vendor ID of the device
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* @ac97: The AC97 device to check
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* @id: The ID to compare to
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* @id_mask: Mask that is applied to the device ID before comparing to @id
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*
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* If @id is 0 this function returns true if the read device vendor ID is
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* a valid ID. If @id is non 0 this functions returns true if @id
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* matches the read vendor ID. Otherwise the function returns false.
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*/
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static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id,
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unsigned int id_mask)
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{
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ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16;
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ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2);
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if (ac97->id == 0x0 || ac97->id == 0xffffffff)
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return false;
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if (id != 0 && id != (ac97->id & id_mask))
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return false;
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return true;
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}
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/**
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* snd_ac97_reset() - Reset AC'97 device
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* @ac97: The AC'97 device to reset
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* @try_warm: Try a warm reset first
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* @id: Expected device vendor ID
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* @id_mask: Mask that is applied to the device ID before comparing to @id
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*
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* This function resets the AC'97 device. If @try_warm is true the function
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* first performs a warm reset. If the warm reset is successful the function
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* returns 1. Otherwise or if @try_warm is false the function issues cold reset
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* followed by a warm reset. If this is successful the function returns 0,
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* otherwise a negative error code. If @id is 0 any valid device ID will be
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* accepted, otherwise only the ID that matches @id and @id_mask is accepted.
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*/
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int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id,
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unsigned int id_mask)
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{
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const struct snd_ac97_bus_ops *ops = ac97->bus->ops;
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if (try_warm && ops->warm_reset) {
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ops->warm_reset(ac97);
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if (snd_ac97_check_id(ac97, id, id_mask))
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return 1;
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}
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if (ops->reset)
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ops->reset(ac97);
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if (ops->warm_reset)
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ops->warm_reset(ac97);
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if (snd_ac97_check_id(ac97, id, id_mask))
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return 0;
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return -ENODEV;
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}
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EXPORT_SYMBOL_GPL(snd_ac97_reset);
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/*
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* Let drivers decide whether they want to support given codec from their
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* probe method. Drivers have direct access to the struct snd_ac97
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* structure and may decide based on the id field amongst other things.
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*/
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static int ac97_bus_match(struct device *dev, struct device_driver *drv)
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{
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return 1;
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}
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struct bus_type ac97_bus_type = {
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.name = "ac97",
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.match = ac97_bus_match,
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};
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static int __init ac97_bus_init(void)
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{
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return bus_register(&ac97_bus_type);
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}
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subsys_initcall(ac97_bus_init);
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static void __exit ac97_bus_exit(void)
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{
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bus_unregister(&ac97_bus_type);
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}
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module_exit(ac97_bus_exit);
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EXPORT_SYMBOL(ac97_bus_type);
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MODULE_LICENSE("GPL");
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