sound/xen/xen_snd_front.c

   1 // SPDX-License-Identifier: GPL-2.0 OR MIT
   2
   3 /*
   4  * Xen para-virtual sound device
   5  *
   6  * Copyright (C) 2016-2018 EPAM Systems Inc.
   7  *
   8  * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
   9  */
  10
  11 #include <linux/delay.h>
  12 #include <linux/module.h>
  13
  14 #include <xen/page.h>
  15 #include <xen/platform_pci.h>
  16 #include <xen/xen.h>
  17 #include <xen/xenbus.h>
  18
  19 #include <xen/xen-front-pgdir-shbuf.h>
  20 #include <xen/interface/io/sndif.h>
  21
  22 #include "xen_snd_front.h"
  23 #include "xen_snd_front_alsa.h"
  24 #include "xen_snd_front_evtchnl.h"
  25
  26 static struct xensnd_req *
  27 be_stream_prepare_req(struct xen_snd_front_evtchnl *evtchnl, u8 operation)
  28 {
  29         struct xensnd_req *req;
  30
  31         req = RING_GET_REQUEST(&evtchnl->u.req.ring,
  32                                evtchnl->u.req.ring.req_prod_pvt);
  33         req->operation = operation;
  34         req->id = evtchnl->evt_next_id++;
  35         evtchnl->evt_id = req->id;
  36         return req;
  37 }
  38
  39 static int be_stream_do_io(struct xen_snd_front_evtchnl *evtchnl)
  40 {
  41         if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
  42                 return -EIO;
  43
  44         reinit_completion(&evtchnl->u.req.completion);
  45         xen_snd_front_evtchnl_flush(evtchnl);
  46         return 0;
  47 }
  48
  49 static int be_stream_wait_io(struct xen_snd_front_evtchnl *evtchnl)
  50 {
  51         if (wait_for_completion_timeout(&evtchnl->u.req.completion,
  52                         msecs_to_jiffies(VSND_WAIT_BACK_MS)) <= 0)
  53                 return -ETIMEDOUT;
  54
  55         return evtchnl->u.req.resp_status;
  56 }
  57
  58 int xen_snd_front_stream_query_hw_param(struct xen_snd_front_evtchnl *evtchnl,
  59                                         struct xensnd_query_hw_param *hw_param_req,
  60                                         struct xensnd_query_hw_param *hw_param_resp)
  61 {
  62         struct xensnd_req *req;
  63         int ret;
  64
  65         mutex_lock(&evtchnl->u.req.req_io_lock);
  66
  67         mutex_lock(&evtchnl->ring_io_lock);
  68         req = be_stream_prepare_req(evtchnl, XENSND_OP_HW_PARAM_QUERY);
  69         req->op.hw_param = *hw_param_req;
  70         mutex_unlock(&evtchnl->ring_io_lock);
  71
  72         ret = be_stream_do_io(evtchnl);
  73
  74         if (ret == 0)
  75                 ret = be_stream_wait_io(evtchnl);
  76
  77         if (ret == 0)
  78                 *hw_param_resp = evtchnl->u.req.resp.hw_param;
  79
  80         mutex_unlock(&evtchnl->u.req.req_io_lock);
  81         return ret;
  82 }
  83
  84 int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl *evtchnl,
  85                                  struct xen_front_pgdir_shbuf *shbuf,
  86                                  u8 format, unsigned int channels,
  87                                  unsigned int rate, u32 buffer_sz,
  88                                  u32 period_sz)
  89 {
  90         struct xensnd_req *req;
  91         int ret;
  92
  93         mutex_lock(&evtchnl->u.req.req_io_lock);
  94
  95         mutex_lock(&evtchnl->ring_io_lock);
  96         req = be_stream_prepare_req(evtchnl, XENSND_OP_OPEN);
  97         req->op.open.pcm_format = format;
  98         req->op.open.pcm_channels = channels;
  99         req->op.open.pcm_rate = rate;
 100         req->op.open.buffer_sz = buffer_sz;
 101         req->op.open.period_sz = period_sz;
 102         req->op.open.gref_directory =
 103                 xen_front_pgdir_shbuf_get_dir_start(shbuf);
 104         mutex_unlock(&evtchnl->ring_io_lock);
 105
 106         ret = be_stream_do_io(evtchnl);
 107
 108         if (ret == 0)
 109                 ret = be_stream_wait_io(evtchnl);
 110
 111         mutex_unlock(&evtchnl->u.req.req_io_lock);
 112         return ret;
 113 }
 114
 115 int xen_snd_front_stream_close(struct xen_snd_front_evtchnl *evtchnl)
 116 {
 117         __always_unused struct xensnd_req *req;
 118         int ret;
 119
 120         mutex_lock(&evtchnl->u.req.req_io_lock);
 121
 122         mutex_lock(&evtchnl->ring_io_lock);
 123         req = be_stream_prepare_req(evtchnl, XENSND_OP_CLOSE);
 124         mutex_unlock(&evtchnl->ring_io_lock);
 125
 126         ret = be_stream_do_io(evtchnl);
 127
 128         if (ret == 0)
 129                 ret = be_stream_wait_io(evtchnl);
 130
 131         mutex_unlock(&evtchnl->u.req.req_io_lock);
 132         return ret;
 133 }
 134
 135 int xen_snd_front_stream_write(struct xen_snd_front_evtchnl *evtchnl,
 136                                unsigned long pos, unsigned long count)
 137 {
 138         struct xensnd_req *req;
 139         int ret;
 140
 141         mutex_lock(&evtchnl->u.req.req_io_lock);
 142
 143         mutex_lock(&evtchnl->ring_io_lock);
 144         req = be_stream_prepare_req(evtchnl, XENSND_OP_WRITE);
 145         req->op.rw.length = count;
 146         req->op.rw.offset = pos;
 147         mutex_unlock(&evtchnl->ring_io_lock);
 148
 149         ret = be_stream_do_io(evtchnl);
 150
 151         if (ret == 0)
 152                 ret = be_stream_wait_io(evtchnl);
 153
 154         mutex_unlock(&evtchnl->u.req.req_io_lock);
 155         return ret;
 156 }
 157
 158 int xen_snd_front_stream_read(struct xen_snd_front_evtchnl *evtchnl,
 159                               unsigned long pos, unsigned long count)
 160 {
 161         struct xensnd_req *req;
 162         int ret;
 163
 164         mutex_lock(&evtchnl->u.req.req_io_lock);
 165
 166         mutex_lock(&evtchnl->ring_io_lock);
 167         req = be_stream_prepare_req(evtchnl, XENSND_OP_READ);
 168         req->op.rw.length = count;
 169         req->op.rw.offset = pos;
 170         mutex_unlock(&evtchnl->ring_io_lock);
 171
 172         ret = be_stream_do_io(evtchnl);
 173
 174         if (ret == 0)
 175                 ret = be_stream_wait_io(evtchnl);
 176
 177         mutex_unlock(&evtchnl->u.req.req_io_lock);
 178         return ret;
 179 }
 180
 181 int xen_snd_front_stream_trigger(struct xen_snd_front_evtchnl *evtchnl,
 182                                  int type)
 183 {
 184         struct xensnd_req *req;
 185         int ret;
 186
 187         mutex_lock(&evtchnl->u.req.req_io_lock);
 188
 189         mutex_lock(&evtchnl->ring_io_lock);
 190         req = be_stream_prepare_req(evtchnl, XENSND_OP_TRIGGER);
 191         req->op.trigger.type = type;
 192         mutex_unlock(&evtchnl->ring_io_lock);
 193
 194         ret = be_stream_do_io(evtchnl);
 195
 196         if (ret == 0)
 197                 ret = be_stream_wait_io(evtchnl);
 198
 199         mutex_unlock(&evtchnl->u.req.req_io_lock);
 200         return ret;
 201 }
 202
 203 static void xen_snd_drv_fini(struct xen_snd_front_info *front_info)
 204 {
 205         xen_snd_front_alsa_fini(front_info);
 206         xen_snd_front_evtchnl_free_all(front_info);
 207 }
 208
 209 static int sndback_initwait(struct xen_snd_front_info *front_info)
 210 {
 211         int num_streams;
 212         int ret;
 213
 214         ret = xen_snd_front_cfg_card(front_info, &num_streams);
 215         if (ret < 0)
 216                 return ret;
 217
 218         /* create event channels for all streams and publish */
 219         ret = xen_snd_front_evtchnl_create_all(front_info, num_streams);
 220         if (ret < 0)
 221                 return ret;
 222
 223         return xen_snd_front_evtchnl_publish_all(front_info);
 224 }
 225
 226 static int sndback_connect(struct xen_snd_front_info *front_info)
 227 {
 228         return xen_snd_front_alsa_init(front_info);
 229 }
 230
 231 static void sndback_disconnect(struct xen_snd_front_info *front_info)
 232 {
 233         xen_snd_drv_fini(front_info);
 234         xenbus_switch_state(front_info->xb_dev, XenbusStateInitialising);
 235 }
 236
 237 static void sndback_changed(struct xenbus_device *xb_dev,
 238                             enum xenbus_state backend_state)
 239 {
 240         struct xen_snd_front_info *front_info = dev_get_drvdata(&xb_dev->dev);
 241         int ret;
 242
 243         dev_dbg(&xb_dev->dev, "Backend state is %s, front is %s\n",
 244                 xenbus_strstate(backend_state),
 245                 xenbus_strstate(xb_dev->state));
 246
 247         switch (backend_state) {
 248         case XenbusStateReconfiguring:
 249         case XenbusStateReconfigured:
 250         case XenbusStateInitialised:
 251                 break;
 252
 253         case XenbusStateInitialising:
 254                 /* Recovering after backend unexpected closure. */
 255                 sndback_disconnect(front_info);
 256                 break;
 257
 258         case XenbusStateInitWait:
 259                 /* Recovering after backend unexpected closure. */
 260                 sndback_disconnect(front_info);
 261
 262                 ret = sndback_initwait(front_info);
 263                 if (ret < 0)
 264                         xenbus_dev_fatal(xb_dev, ret, "initializing frontend");
 265                 else
 266                         xenbus_switch_state(xb_dev, XenbusStateInitialised);
 267                 break;
 268
 269         case XenbusStateConnected:
 270                 if (xb_dev->state != XenbusStateInitialised)
 271                         break;
 272
 273                 ret = sndback_connect(front_info);
 274                 if (ret < 0)
 275                         xenbus_dev_fatal(xb_dev, ret, "initializing frontend");
 276                 else
 277                         xenbus_switch_state(xb_dev, XenbusStateConnected);
 278                 break;
 279
 280         case XenbusStateClosing:
 281                 /*
 282                  * In this state backend starts freeing resources,
 283                  * so let it go into closed state first, so we can also
 284                  * remove ours.
 285                  */
 286                 break;
 287
 288         case XenbusStateUnknown:
 289         case XenbusStateClosed:
 290                 if (xb_dev->state == XenbusStateClosed)
 291                         break;
 292
 293                 sndback_disconnect(front_info);
 294                 break;
 295         }
 296 }
 297
 298 static int xen_drv_probe(struct xenbus_device *xb_dev,
 299                          const struct xenbus_device_id *id)
 300 {
 301         struct xen_snd_front_info *front_info;
 302
 303         front_info = devm_kzalloc(&xb_dev->dev,
 304                                   sizeof(*front_info), GFP_KERNEL);
 305         if (!front_info)
 306                 return -ENOMEM;
 307
 308         front_info->xb_dev = xb_dev;
 309         dev_set_drvdata(&xb_dev->dev, front_info);
 310
 311         return xenbus_switch_state(xb_dev, XenbusStateInitialising);
 312 }
 313
 314 static int xen_drv_remove(struct xenbus_device *dev)
 315 {
 316         struct xen_snd_front_info *front_info = dev_get_drvdata(&dev->dev);
 317         int to = 100;
 318
 319         xenbus_switch_state(dev, XenbusStateClosing);
 320
 321         /*
 322          * On driver removal it is disconnected from XenBus,
 323          * so no backend state change events come via .otherend_changed
 324          * callback. This prevents us from exiting gracefully, e.g.
 325          * signaling the backend to free event channels, waiting for its
 326          * state to change to XenbusStateClosed and cleaning at our end.
 327          * Normally when front driver removed backend will finally go into
 328          * XenbusStateInitWait state.
 329          *
 330          * Workaround: read backend's state manually and wait with time-out.
 331          */
 332         while ((xenbus_read_unsigned(front_info->xb_dev->otherend, "state",
 333                                      XenbusStateUnknown) != XenbusStateInitWait) &&
 334                --to)
 335                 msleep(10);
 336
 337         if (!to) {
 338                 unsigned int state;
 339
 340                 state = xenbus_read_unsigned(front_info->xb_dev->otherend,
 341                                              "state", XenbusStateUnknown);
 342                 pr_err("Backend state is %s while removing driver\n",
 343                        xenbus_strstate(state));
 344         }
 345
 346         xen_snd_drv_fini(front_info);
 347         xenbus_frontend_closed(dev);
 348         return 0;
 349 }
 350
 351 static const struct xenbus_device_id xen_drv_ids[] = {
 352         { XENSND_DRIVER_NAME },
 353         { "" }
 354 };
 355
 356 static struct xenbus_driver xen_driver = {
 357         .ids = xen_drv_ids,
 358         .probe = xen_drv_probe,
 359         .remove = xen_drv_remove,
 360         .otherend_changed = sndback_changed,
 361 };
 362
 363 static int __init xen_drv_init(void)
 364 {
 365         if (!xen_domain())
 366                 return -ENODEV;
 367
 368         if (!xen_has_pv_devices())
 369                 return -ENODEV;
 370
 371         /* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */
 372         if (XEN_PAGE_SIZE != PAGE_SIZE) {
 373                 pr_err(XENSND_DRIVER_NAME ": different kernel and Xen page sizes are not supported: XEN_PAGE_SIZE (%lu) != PAGE_SIZE (%lu)\n",
 374                        XEN_PAGE_SIZE, PAGE_SIZE);
 375                 return -ENODEV;
 376         }
 377
 378         pr_info("Initialising Xen " XENSND_DRIVER_NAME " frontend driver\n");
 379         return xenbus_register_frontend(&xen_driver);
 380 }
 381
 382 static void __exit xen_drv_fini(void)
 383 {
 384         pr_info("Unregistering Xen " XENSND_DRIVER_NAME " frontend driver\n");
 385         xenbus_unregister_driver(&xen_driver);
 386 }
 387
 388 module_init(xen_drv_init);
 389 module_exit(xen_drv_fini);
 390
 391 MODULE_DESCRIPTION("Xen virtual sound device frontend");
 392 MODULE_LICENSE("GPL");
 393 MODULE_ALIAS("xen:" XENSND_DRIVER_NAME);
 394 MODULE_SUPPORTED_DEVICE("{{ALSA,Virtual soundcard}}");