audio: utils: Add PCM start and stop

PCM start and stop is mostly needed for hostless ports, since
they require to be explicitly started/stopped. PCM stop can also
be used to unblock read() or write() calls.

Change-Id: Ie651d90933022df754c582a89733d607101ea585
Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>

4 files changed, 162 insertions, 0 deletions

diff --git a/audio/utils/include/tiaudioutils/ALSAPcm.h b/audio/utils/include/tiaudioutils/ALSAPcm.h
index 830e304..030db84 100644
--- a/audio/utils/include/tiaudioutils/ALSAPcm.h
+++ b/audio/utils/include/tiaudioutils/ALSAPcm.h
@@ -116,6 +116,31 @@ class ALSAInPort : public PcmInPort {
      */
     int read(void *buffer, size_t frames);
 
+    /**
+     * \brief Start the ALSA PCM port
+     *
+     * Starts the ALSA PCM capture port. It's mostly needed to start hostless
+     * ports that don't use read() but instead run without CPU intervention.
+     * Regular PCM read through read() method doesn't need to be explicitly
+     * preceded by start(), since it's done internally.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int start();
+
+    /**
+     * \brief Stop the ALSA PCM port
+     *
+     * Stops the ALSA PCM capture port. It's mostly needed to stop hostless
+     * ports that don't use read() but instead run without CPU intervention.
+     * Regular PCM read through read() method doesn't need to be explicitly
+     * stopped, but if done, it will cause read() to immediately return.
+     * This behavior can be desired to unblock read() calls.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int stop();
+
     /** Default number of periods for the tinyalsa config of the capture port */
     static const uint32_t kDefaultNumPeriods = 3;
 
@@ -215,6 +240,31 @@ class ALSAOutPort : public PcmOutPort {
      */
     int write(const void *buffer, size_t frames);
 
+    /**
+     * \brief Start the ALSA PCM port
+     *
+     * Starts the ALSA PCM playback port. It's mostly needed to start hostless
+     * ports that don't use write() but instead run without CPU intervention.
+     * Regular PCM write through write() method doesn't need to be explicitly
+     * preceded by start(), since it's done internally.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int start();
+
+    /**
+     * \brief Stop the ALSA PCM port
+     *
+     * Stops the ALSA PCM playback port. It's mostly needed to stop hostless
+     * ports that don't use write() but instead run without CPU intervention.
+     * Regular PCM write through write() method doesn't need to be explicitly
+     * stopped, but if done, it will cause write() to immediately return.
+     * This behavior can be desired to unblock write() calls.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int stop();
+
     /** Default number of periods for the tinyalsa config of the playback port */
     static const uint32_t kDefaultNumPeriods = 4;
 
diff --git a/audio/utils/include/tiaudioutils/NullPcm.h b/audio/utils/include/tiaudioutils/NullPcm.h
index 8995759..977faaa 100644
--- a/audio/utils/include/tiaudioutils/NullPcm.h
+++ b/audio/utils/include/tiaudioutils/NullPcm.h
@@ -118,6 +118,26 @@ class NullInPort : public PcmInPort {
      */
     int read(void *buffer, size_t frames);
 
+    /**
+     * \brief Start the null PCM port
+     *
+     * Starts the null PCM capture port. No meaningful action is performed
+     * by this method.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int start() { return 0; }
+
+    /**
+     * \brief Stop the null PCM port
+     *
+     * Stops the null PCM capture port. No meaningful action is performed
+     * by this method.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int stop() { return 0; }
+
  private:
     NullInPort(const NullInPort &port);
     NullInPort& operator=(const NullInPort &port);
@@ -215,6 +235,26 @@ class NullOutPort : public PcmOutPort {
      */
     int write(const void *buffer, size_t frames);
 
+    /**
+     * \brief Start the null PCM port
+     *
+     * Starts the null PCM playback port. No meaningful action is performed
+     * by this method.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int start() { return 0; }
+
+    /**
+     * \brief Stop the null PCM port
+     *
+     * Stops the null PCM playback port. No meaningful action is performed
+     * by this method.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    int stop() { return 0; }
+
  private:
     NullOutPort(const NullOutPort &port);
     NullOutPort& operator=(const NullOutPort &port);
diff --git a/audio/utils/include/tiaudioutils/Pcm.h b/audio/utils/include/tiaudioutils/Pcm.h
index a086d36..7d3ecd8 100644
--- a/audio/utils/include/tiaudioutils/Pcm.h
+++ b/audio/utils/include/tiaudioutils/Pcm.h
@@ -312,6 +312,26 @@ class PcmPort {
      * \return true if port is open, false otherwise
      */
     virtual bool isOpen() const = 0;
+
+    /**
+     * \brief Start the PCM port
+     *
+     * Starts the PCM port. It's mostly needed to start hostless ports that
+     * run without CPU intervention.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    virtual int start() = 0;
+
+    /**
+     * \brief Stop the PCM port
+     *
+     * Stops the PCM capture port. It's mostly needed to stop hostless that
+     * run without CPU intervention.
+     *
+     * \return 0 on success, otherwise negative error code
+     */
+    virtual int stop() = 0;
 };
 
 /**
diff --git a/audio/utils/src/ALSAPcm.cpp b/audio/utils/src/ALSAPcm.cpp
index 37d6833..cea2199 100644
--- a/audio/utils/src/ALSAPcm.cpp
+++ b/audio/utils/src/ALSAPcm.cpp
@@ -115,6 +115,32 @@ int ALSAInPort::read(void *buffer, size_t frames)
     return frames;
 }
 
+int ALSAInPort::start()
+{
+    AutoMutex lock(mLock);
+
+    if (!mPcm || !pcm_is_ready(mPcm)) {
+        ALOGE("ALSAInPort: port hw:%u,%u is closed, cannot start", mCardId, mPortId);
+        return -EAGAIN;
+    }
+
+    return pcm_start(mPcm);
+}
+
+int ALSAInPort::stop()
+{
+    /*
+     * mLock is not acquired here because stop() is mostly needed to break
+     * blocked reads which runs with mLock held
+     */
+    if (!mPcm || !pcm_is_ready(mPcm)) {
+        ALOGE("ALSAInPort: port hw:%u,%u is closed, cannot stop", mCardId, mPortId);
+        return -EAGAIN;
+    }
+
+    return pcm_stop(mPcm);
+}
+
 /* ---------------------------------------------------------------------------------------- */
 
 ALSAOutPort::ALSAOutPort(uint32_t card, uint32_t port, uint32_t period_count)
@@ -207,4 +233,30 @@ int ALSAOutPort::write(const void *buffer, size_t frames)
     return frames;
 }
 
+int ALSAOutPort::start()
+{
+    AutoMutex lock(mLock);
+
+    if (!mPcm || !pcm_is_ready(mPcm)) {
+        ALOGE("ALSAOutPort: port hw:%u,%u is closed, cannot start", mCardId, mPortId);
+        return -EAGAIN;
+    }
+
+    return pcm_start(mPcm);
+}
+
+int ALSAOutPort::stop()
+{
+    /*
+     * mLock is not acquired here because stop() is mostly needed to break
+     * blocked writes which runs with mLock held
+     */
+    if (!mPcm || !pcm_is_ready(mPcm)) {
+        ALOGE("ALSAOutPort: port hw:%u,%u is closed, cannot stop", mCardId, mPortId);
+        return -EAGAIN;
+    }
+
+    return pcm_stop(mPcm);
+}
+
 } /* namespace tiaudioutils */