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 */
snd_ac97_check_id(struct snd_ac97 * ac97,unsigned int id,unsigned int id_mask)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 */
snd_ac97_reset(struct snd_ac97 * ac97,bool try_warm,unsigned int id,unsigned int id_mask)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 */
ac97_bus_match(struct device * dev,struct device_driver * drv)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
ac97_bus_init(void)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
ac97_bus_exit(void)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
