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