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