LXR linux/sound/core/seq

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *  ALSA sequencer device management
   4 *  Copyright (c) 1999 by Takashi Iwai <tiwai@suse.de>
   5 *
   6 *----------------------------------------------------------------
   7 *
   8 * This device handler separates the card driver module from sequencer
   9 * stuff (sequencer core, synth drivers, etc), so that user can avoid
  10 * to spend unnecessary resources e.g. if he needs only listening to
  11 * MP3s.
  12 *
  13 * The card (or lowlevel) driver creates a sequencer device entry
  14 * via snd_seq_device_new().  This is an entry pointer to communicate
  15 * with the sequencer device "driver", which is involved with the
  16 * actual part to communicate with the sequencer core.
  17 * Each sequencer device entry has an id string and the corresponding
  18 * driver with the same id is loaded when required.  For example,
  19 * lowlevel codes to access emu8000 chip on sbawe card are included in
  20 * emu8000-synth module.  To activate this module, the hardware
  21 * resources like i/o port are passed via snd_seq_device argument.
  22 */
  23
  24#include <linux/device.h>
  25#include <linux/init.h>
  26#include <linux/module.h>
  27#include <sound/core.h>
  28#include <sound/info.h>
  29#include <sound/seq_device.h>
  30#include <sound/seq_kernel.h>
  31#include <sound/initval.h>
  32#include <linux/kmod.h>
  33#include <linux/slab.h>
  34#include <linux/mutex.h>
  35
  36MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
  37MODULE_DESCRIPTION("ALSA sequencer device management");
  38MODULE_LICENSE("GPL");
  39
  40/*
  41 * bus definition
  42 */
  43static int snd_seq_bus_match(struct device *dev, struct device_driver *drv)
  44{
  45        struct snd_seq_device *sdev = to_seq_dev(dev);
  46        struct snd_seq_driver *sdrv = to_seq_drv(drv);
  47
  48        return strcmp(sdrv->id, sdev->id) == 0 &&
  49                sdrv->argsize == sdev->argsize;
  50}
  51
  52static struct bus_type snd_seq_bus_type = {
  53        .name = "snd_seq",
  54        .match = snd_seq_bus_match,
  55};
  56
  57/*
  58 * proc interface -- just for compatibility
  59 */
  60#ifdef CONFIG_SND_PROC_FS
  61static struct snd_info_entry *info_entry;
  62
  63static int print_dev_info(struct device *dev, void *data)
  64{
  65        struct snd_seq_device *sdev = to_seq_dev(dev);
  66        struct snd_info_buffer *buffer = data;
  67
  68        snd_iprintf(buffer, "snd-%s,%s,%d\n", sdev->id,
  69                    dev->driver ? "loaded" : "empty",
  70                    dev->driver ? 1 : 0);
  71        return 0;
  72}
  73
  74static void snd_seq_device_info(struct snd_info_entry *entry,
  75                                struct snd_info_buffer *buffer)
  76{
  77        bus_for_each_dev(&snd_seq_bus_type, NULL, buffer, print_dev_info);
  78}
  79#endif
  80
  81/*
  82 * load all registered drivers (called from seq_clientmgr.c)
  83 */
  84
  85#ifdef CONFIG_MODULES
  86/* flag to block auto-loading */
  87static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
  88
  89static int request_seq_drv(struct device *dev, void *data)
  90{
  91        struct snd_seq_device *sdev = to_seq_dev(dev);
  92
  93        if (!dev->driver)
  94                request_module("snd-%s", sdev->id);
  95        return 0;
  96}
  97
  98static void autoload_drivers(struct work_struct *work)
  99{
 100        /* avoid reentrance */
 101        if (atomic_inc_return(&snd_seq_in_init) == 1)
 102                bus_for_each_dev(&snd_seq_bus_type, NULL, NULL,
 103                                 request_seq_drv);
 104        atomic_dec(&snd_seq_in_init);
 105}
 106
 107static DECLARE_WORK(autoload_work, autoload_drivers);
 108
 109static void queue_autoload_drivers(void)
 110{
 111        schedule_work(&autoload_work);
 112}
 113
 114void snd_seq_autoload_init(void)
 115{
 116        atomic_dec(&snd_seq_in_init);
 117#ifdef CONFIG_SND_SEQUENCER_MODULE
 118        /* initial autoload only when snd-seq is a module */
 119        queue_autoload_drivers();
 120#endif
 121}
 122EXPORT_SYMBOL(snd_seq_autoload_init);
 123
 124void snd_seq_autoload_exit(void)
 125{
 126        atomic_inc(&snd_seq_in_init);
 127}
 128EXPORT_SYMBOL(snd_seq_autoload_exit);
 129
 130void snd_seq_device_load_drivers(void)
 131{
 132        queue_autoload_drivers();
 133        flush_work(&autoload_work);
 134}
 135EXPORT_SYMBOL(snd_seq_device_load_drivers);
 136#define cancel_autoload_drivers()       cancel_work_sync(&autoload_work)
 137#else
 138#define queue_autoload_drivers() /* NOP */
 139#define cancel_autoload_drivers() /* NOP */
 140#endif
 141
 142/*
 143 * device management
 144 */
 145static int snd_seq_device_dev_free(struct snd_device *device)
 146{
 147        struct snd_seq_device *dev = device->device_data;
 148
 149        cancel_autoload_drivers();
 150        put_device(&dev->dev);
 151        return 0;
 152}
 153
 154static int snd_seq_device_dev_register(struct snd_device *device)
 155{
 156        struct snd_seq_device *dev = device->device_data;
 157        int err;
 158
 159        err = device_add(&dev->dev);
 160        if (err < 0)
 161                return err;
 162        if (!dev->dev.driver)
 163                queue_autoload_drivers();
 164        return 0;
 165}
 166
 167static int snd_seq_device_dev_disconnect(struct snd_device *device)
 168{
 169        struct snd_seq_device *dev = device->device_data;
 170
 171        device_del(&dev->dev);
 172        return 0;
 173}
 174
 175static void snd_seq_dev_release(struct device *dev)
 176{
 177        struct snd_seq_device *sdev = to_seq_dev(dev);
 178
 179        if (sdev->private_free)
 180                sdev->private_free(sdev);
 181        kfree(sdev);
 182}
 183
 184/*
 185 * register a sequencer device
 186 * card = card info
 187 * device = device number (if any)
 188 * id = id of driver
 189 * result = return pointer (NULL allowed if unnecessary)
 190 */
 191int snd_seq_device_new(struct snd_card *card, int device, const char *id,
 192                       int argsize, struct snd_seq_device **result)
 193{
 194        struct snd_seq_device *dev;
 195        int err;
 196        static const struct snd_device_ops dops = {
 197                .dev_free = snd_seq_device_dev_free,
 198                .dev_register = snd_seq_device_dev_register,
 199                .dev_disconnect = snd_seq_device_dev_disconnect,
 200        };
 201
 202        if (result)
 203                *result = NULL;
 204
 205        if (snd_BUG_ON(!id))
 206                return -EINVAL;
 207
 208        dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
 209        if (!dev)
 210                return -ENOMEM;
 211
 212        /* set up device info */
 213        dev->card = card;
 214        dev->device = device;
 215        dev->id = id;
 216        dev->argsize = argsize;
 217
 218        device_initialize(&dev->dev);
 219        dev->dev.parent = &card->card_dev;
 220        dev->dev.bus = &snd_seq_bus_type;
 221        dev->dev.release = snd_seq_dev_release;
 222        dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device);
 223
 224        /* add this device to the list */
 225        err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);
 226        if (err < 0) {
 227                put_device(&dev->dev);
 228                return err;
 229        }
 230        
 231        if (result)
 232                *result = dev;
 233
 234        return 0;
 235}
 236EXPORT_SYMBOL(snd_seq_device_new);
 237
 238/*
 239 * driver registration
 240 */
 241int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod)
 242{
 243        if (WARN_ON(!drv->driver.name || !drv->id))
 244                return -EINVAL;
 245        drv->driver.bus = &snd_seq_bus_type;
 246        drv->driver.owner = mod;
 247        return driver_register(&drv->driver);
 248}
 249EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
 250
 251void snd_seq_driver_unregister(struct snd_seq_driver *drv)
 252{
 253        driver_unregister(&drv->driver);
 254}
 255EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
 256
 257/*
 258 * module part
 259 */
 260
 261static int __init seq_dev_proc_init(void)
 262{
 263#ifdef CONFIG_SND_PROC_FS
 264        info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers",
 265                                                  snd_seq_root);
 266        if (info_entry == NULL)
 267                return -ENOMEM;
 268        info_entry->content = SNDRV_INFO_CONTENT_TEXT;
 269        info_entry->c.text.read = snd_seq_device_info;
 270        if (snd_info_register(info_entry) < 0) {
 271                snd_info_free_entry(info_entry);
 272                return -ENOMEM;
 273        }
 274#endif
 275        return 0;
 276}
 277
 278static int __init alsa_seq_device_init(void)
 279{
 280        int err;
 281
 282        err = bus_register(&snd_seq_bus_type);
 283        if (err < 0)
 284                return err;
 285        err = seq_dev_proc_init();
 286        if (err < 0)
 287                bus_unregister(&snd_seq_bus_type);
 288        return err;
 289}
 290
 291static void __exit alsa_seq_device_exit(void)
 292{
 293#ifdef CONFIG_MODULES
 294        cancel_work_sync(&autoload_work);
 295#endif
 296#ifdef CONFIG_SND_PROC_FS
 297        snd_info_free_entry(info_entry);
 298#endif
 299        bus_unregister(&snd_seq_bus_type);
 300}
 301
 302subsys_initcall(alsa_seq_device_init)
 303module_exit(alsa_seq_device_exit)
 304