1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Linux driver model AC97 bus interface 4 * 5 * Author: Nicolas Pitre 6 * Created: Jan 14, 2005 7 * Copyright: (C) MontaVista Software Inc. 8 */ 9 10 #include <linux/module.h> 11 #include <linux/init.h> 12 #include <linux/device.h> 13 #include <linux/string.h> 14 #include <sound/ac97_codec.h> 15 16 /* 17 * snd_ac97_check_id() - Reads and checks the vendor ID of the device 18 * @ac97: The AC97 device to check 19 * @id: The ID to compare to 20 * @id_mask: Mask that is applied to the device ID before comparing to @id 21 * 22 * If @id is 0 this function returns true if the read device vendor ID is 23 * a valid ID. If @id is non 0 this functions returns true if @id 24 * matches the read vendor ID. Otherwise the function returns false. 25 */ 26 static bool snd_ac97_check_id(struct snd_ac97 *ac97, unsigned int id, 27 unsigned int id_mask) 28 { 29 ac97->id = ac97->bus->ops->read(ac97, AC97_VENDOR_ID1) << 16; 30 ac97->id |= ac97->bus->ops->read(ac97, AC97_VENDOR_ID2); 31 32 if (ac97->id == 0x0 || ac97->id == 0xffffffff) 33 return false; 34 35 if (id != 0 && id != (ac97->id & id_mask)) 36 return false; 37 38 return true; 39 } 40 41 /** 42 * snd_ac97_reset() - Reset AC'97 device 43 * @ac97: The AC'97 device to reset 44 * @try_warm: Try a warm reset first 45 * @id: Expected device vendor ID 46 * @id_mask: Mask that is applied to the device ID before comparing to @id 47 * 48 * This function resets the AC'97 device. If @try_warm is true the function 49 * first performs a warm reset. If @try_warm is false the function issues 50 * cold reset followed by a warm reset. If @id is 0 any valid device ID 51 * will be accepted, otherwise only the ID that matches @id and @id_mask 52 * is accepted. 53 * Returns: 54 * * %1 - if warm reset is successful 55 * * %0 - if cold reset and warm reset is successful 56 * * %-ENODEV - if @id and @id_mask not matching 57 */ 58 int snd_ac97_reset(struct snd_ac97 *ac97, bool try_warm, unsigned int id, 59 unsigned int id_mask) 60 { 61 const struct snd_ac97_bus_ops *ops = ac97->bus->ops; 62 63 if (try_warm && ops->warm_reset) { 64 ops->warm_reset(ac97); 65 if (snd_ac97_check_id(ac97, id, id_mask)) 66 return 1; 67 } 68 69 if (ops->reset) 70 ops->reset(ac97); 71 if (ops->warm_reset) 72 ops->warm_reset(ac97); 73 74 if (snd_ac97_check_id(ac97, id, id_mask)) 75 return 0; 76 77 return -ENODEV; 78 } 79 EXPORT_SYMBOL_GPL(snd_ac97_reset); 80 81 const struct bus_type ac97_bus_type = { 82 .name = "ac97", 83 }; 84 85 static int __init ac97_bus_init(void) 86 { 87 return bus_register(&ac97_bus_type); 88 } 89 90 subsys_initcall(ac97_bus_init); 91 92 static void __exit ac97_bus_exit(void) 93 { 94 bus_unregister(&ac97_bus_type); 95 } 96 97 module_exit(ac97_bus_exit); 98 99 EXPORT_SYMBOL(ac97_bus_type); 100 101 MODULE_DESCRIPTION("Legacy AC97 bus interface"); 102 MODULE_LICENSE("GPL"); 103