tinyalsa: add support for PCM plugins

Update the pcm framework to support plugins. Resolve the pcm device node
to be either kernel device or virtual device and setup function pointers
accordingly. Implement framework functionality for pcm_plugin.c for ease
of plugin development. Plugin itself is compiled as shared object (.so)
and dynamically linked from pcm_plugin.c.

Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>
Signed-off-by: Rohit kumar <rohitkr@codeaurora.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/src/pcm_io.h b/src/pcm_io.h
new file mode 100644
index 0000000..1b68ac8
--- /dev/null
+++ b/src/pcm_io.h
@@ -0,0 +1,47 @@
+/* pcm_io.h
+** Copyright (c) 2019, The Linux Foundation.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above
+**     copyright notice, this list of conditions and the following
+**     disclaimer in the documentation and/or other materials provided
+**     with the distribution.
+**   * Neither the name of The Linux Foundation nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
+** ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
+** BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+** CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+** SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+** BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+** OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
+** IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**/
+
+#ifndef TINYALSA_SRC_PCM_IO_H
+#define TINYALSA_SRC_PCM_IO_H
+
+#include <sound/asound.h>
+
+struct snd_node;
+
+struct pcm_ops {
+    int (*open) (unsigned int card, unsigned int device,
+                 unsigned int flags, void **data, struct snd_node *node);
+    void (*close) (void *data);
+    int (*ioctl) (void *data, unsigned int cmd, ...);
+};
+
+extern const struct pcm_ops hw_ops;
+extern const struct pcm_ops plug_ops;
+
+#endif /* TINYALSA_SRC_PCM_IO_H */