blob: 52e4bc54c9acac2264be07b2b517e9fbb1608333
1 | /* |
2 | * Linux driver model AC97 bus interface |
3 | * |
4 | * Author: Nicolas Pitre |
5 | * Created: Jan 14, 2005 |
6 | * Copyright: (C) MontaVista Software Inc. |
7 | * |
8 | * This program is free software; you can redistribute it and/or modify |
9 | * it under the terms of the GNU General Public License as published by |
10 | * the Free Software Foundation; either version 2 of the License, or |
11 | * (at your option) any later version. |
12 | */ |
13 | |
14 | #include <linux/module.h> |
15 | #include <linux/init.h> |
16 | #include <linux/device.h> |
17 | #include <linux/string.h> |
18 | #include <sound/ac97_codec.h> |
19 | |
20 | /* |
21 | * snd_ac97_check_id() - Reads and checks the vendor ID of the device |
22 | * @ac97: The AC97 device to check |
23 | * @id: The ID to compare to |
24 | * @id_mask: Mask that is applied to the device ID before comparing to @id |
25 | * |
26 | * If @id is 0 this function returns true if the read device vendor ID is |
27 | * a valid ID. If @id is non 0 this functions returns true if @id |
28 | * matches the read vendor ID. Otherwise the function returns false. |
29 | */ |
30 | static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id, |
31 | unsigned int id_mask) |
32 | { |
33 | ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16; |
34 | ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2); |
35 | |
36 | if (ac97->id == 0x0 || ac97->id == 0xffffffff) |
37 | return false; |
38 | |
39 | if (id != 0 && id != (ac97->id & id_mask)) |
40 | return false; |
41 | |
42 | return true; |
43 | } |
44 | |
45 | /** |
46 | * snd_ac97_reset() - Reset AC'97 device |
47 | * @ac97: The AC'97 device to reset |
48 | * @try_warm: Try a warm reset first |
49 | * @id: Expected device vendor ID |
50 | * @id_mask: Mask that is applied to the device ID before comparing to @id |
51 | * |
52 | * This function resets the AC'97 device. If @try_warm is true the function |
53 | * first performs a warm reset. If the warm reset is successful the function |
54 | * returns 1. Otherwise or if @try_warm is false the function issues cold reset |
55 | * followed by a warm reset. If this is successful the function returns 0, |
56 | * otherwise a negative error code. If @id is 0 any valid device ID will be |
57 | * accepted, otherwise only the ID that matches @id and @id_mask is accepted. |
58 | */ |
59 | int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id, |
60 | unsigned int id_mask) |
61 | { |
62 | struct snd_ac97_bus_ops *ops = ac97->bus->ops; |
63 | |
64 | if (try_warm && ops->warm_reset) { |
65 | ops->warm_reset(ac97); |
66 | if (snd_ac97_check_id(ac97, id, id_mask)) |
67 | return 1; |
68 | } |
69 | |
70 | if (ops->reset) |
71 | ops->reset(ac97); |
72 | if (ops->warm_reset) |
73 | ops->warm_reset(ac97); |
74 | |
75 | if (snd_ac97_check_id(ac97, id, id_mask)) |
76 | return 0; |
77 | |
78 | return -ENODEV; |
79 | } |
80 | EXPORT_SYMBOL_GPL(snd_ac97_reset); |
81 | |
82 | /* |
83 | * Let drivers decide whether they want to support given codec from their |
84 | * probe method. Drivers have direct access to the struct snd_ac97 |
85 | * structure and may decide based on the id field amongst other things. |
86 | */ |
87 | static int ac97_bus_match(struct device *dev, struct device_driver *drv) |
88 | { |
89 | return 1; |
90 | } |
91 | |
92 | struct bus_type ac97_bus_type = { |
93 | .name = "ac97", |
94 | .match = ac97_bus_match, |
95 | }; |
96 | |
97 | static int __init ac97_bus_init(void) |
98 | { |
99 | return bus_register(&ac97_bus_type); |
100 | } |
101 | |
102 | subsys_initcall(ac97_bus_init); |
103 | |
104 | static void __exit ac97_bus_exit(void) |
105 | { |
106 | bus_unregister(&ac97_bus_type); |
107 | } |
108 | |
109 | module_exit(ac97_bus_exit); |
110 | |
111 | EXPORT_SYMBOL(ac97_bus_type); |
112 | |
113 | MODULE_LICENSE("GPL"); |
114 |