USB: gadget: f_audio_source: New gadget driver for audio output

This driver presents a standard USB audio class interface to the host
and an ALSA PCM device to userspace

Signed-off-by: Mike Lockwood <lockwood@google.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/usb/gadget/android.c b/drivers/usb/gadget/android.c
index 74184a5..3abc53a 100644
--- a/drivers/usb/gadget/android.c
+++ b/drivers/usb/gadget/android.c
@@ -45,6 +45,7 @@
 #include "epautoconf.c"
 #include "composite.c"
 
+#include "f_audio_source.c"
 #include "f_mass_storage.c"
 #include "u_serial.c"
 #include "f_acm.c"
@@ -740,6 +741,67 @@ static struct android_usb_function accessory_function = {
 	.ctrlrequest	= accessory_function_ctrlrequest,
 };
 
+static int audio_source_function_init(struct android_usb_function *f,
+			struct usb_composite_dev *cdev)
+{
+	struct audio_source_config *config;
+
+	config = kzalloc(sizeof(struct audio_source_config), GFP_KERNEL);
+	if (!config)
+		return -ENOMEM;
+	config->card = -1;
+	config->device = -1;
+	f->config = config;
+	return 0;
+}
+
+static void audio_source_function_cleanup(struct android_usb_function *f)
+{
+	kfree(f->config);
+}
+
+static int audio_source_function_bind_config(struct android_usb_function *f,
+						struct usb_configuration *c)
+{
+	struct audio_source_config *config = f->config;
+
+	return audio_source_bind_config(c, config);
+}
+
+static void audio_source_function_unbind_config(struct android_usb_function *f,
+						struct usb_configuration *c)
+{
+	struct audio_source_config *config = f->config;
+
+	config->card = -1;
+	config->device = -1;
+}
+
+static ssize_t audio_source_pcm_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct audio_source_config *config = f->config;
+
+	/* print PCM card and device numbers */
+	return sprintf(buf, "%d %d\n", config->card, config->device);
+}
+
+static DEVICE_ATTR(pcm, S_IRUGO | S_IWUSR, audio_source_pcm_show, NULL);
+
+static struct device_attribute *audio_source_function_attributes[] = {
+	&dev_attr_pcm,
+	NULL
+};
+
+static struct android_usb_function audio_source_function = {
+	.name		= "audio_source",
+	.init		= audio_source_function_init,
+	.cleanup	= audio_source_function_cleanup,
+	.bind_config	= audio_source_function_bind_config,
+	.unbind_config	= audio_source_function_unbind_config,
+	.attributes	= audio_source_function_attributes,
+};
 
 static struct android_usb_function *supported_functions[] = {
 	&adb_function,
@@ -749,6 +811,7 @@ static struct android_usb_function *supported_functions[] = {
 	&rndis_function,
 	&mass_storage_function,
 	&accessory_function,
+	&audio_source_function,
 	NULL
 };