[ARM] tegra: tegra_i2s_audio: allow preloading of the tx fifo with data

Add an ioctl to allow the TX fifo to be loaded with data before playback
starts.  Playback can then be started by calling write() on the FIFO, even
with a length of 0.  This will cause the pending data to be played out.

Signed-off-by: Iliyan Malchev <malchev@google.com>

diff --git a/arch/arm/mach-tegra/tegra_i2s_audio.c b/arch/arm/mach-tegra/tegra_i2s_audio.c
index 40653570f87ab4ce6b7e733e6f3c5906d14847dd..47626e103e8d44545ce21810704a42907a7bc91d 100644 (file)
--- a/arch/arm/mach-tegra/tegra_i2s_audio.c
+++ b/arch/arm/mach-tegra/tegra_i2s_audio.c
@@ -1262,6 +1262,26 @@ static long tegra_audio_out_ioctl(struct file *file,
                if (!rc)
                        aos->errors = 0;
                break;
+       case TEGRA_AUDIO_OUT_PRELOAD_FIFO: {
+               struct tegra_audio_out_preload preload;
+               if (copy_from_user(&preload, (void __user *)arg,
+                               sizeof(preload))) {
+                       rc = -EFAULT;
+                       break;
+               }
+               rc = kfifo_from_user(&ads->out.fifo,
+                               (void __user *)preload.data, preload.len,
+                               &preload.len_written);
+               if (rc < 0) {
+                       pr_err("%s: error copying from user\n", __func__);
+                       break;
+               }
+               if (copy_to_user((void __user *)arg, &preload, sizeof(preload)))
+                       rc = -EFAULT;
+               pr_info("%s: preloaded output fifo with %d bytes\n", __func__,
+                       preload.len_written);
+       }
+               break;
        default:
                rc = -EINVAL;
        }

diff --git a/include/linux/tegra_audio.h b/include/linux/tegra_audio.h
index 48590daa06a5f1e399e205b8f331a30c288e78a4..15139cc31d84e69a5469cd5b39cc161034499c4b 100644 (file)
--- a/include/linux/tegra_audio.h
+++ b/include/linux/tegra_audio.h
@@ -58,5 +58,13 @@ struct tegra_audio_buf_config {
 #define TEGRA_AUDIO_OUT_GET_ERROR_COUNT        _IOR(TEGRA_AUDIO_MAGIC, 9, \
                        unsigned *)
 
+struct tegra_audio_out_preload {
+       void *data;
+       size_t len;
+       size_t len_written;
+};
+
+#define TEGRA_AUDIO_OUT_PRELOAD_FIFO   _IOWR(TEGRA_AUDIO_MAGIC, 10, \
+                       struct tegra_audio_out_preload *)
 
 #endif/*_CPCAP_AUDIO_H*/