Re: CSA2: User space aspect

On 2012-11-08 14:36, Michael Knudsen wrote:

If anyone else has an ideas or opinions about this, please speak up,
otherwise I'll try coming up with an interface specification with
more details.

This diff shows the direction I'm heading:

diff --git a/include/net/bluetooth/sco.h b/include/net/bluetooth/sco.h
index 1e35c43..a565a4d 100644
--- a/include/net/bluetooth/sco.h
+++ b/include/net/bluetooth/sco.h

@@ -51,6 +51,42 @@ struct sco_conninfo {
 	__u8  dev_class[3];
 };
 
+/* Audio format setting */
+#define SCO_HOST_FORMAT	0x04
+#define SCO_AIR_FORMAT	0x05
+
+#define SCO_FORMAT_ULAW		0x00
+#define SCO_FORMAT_ALAW		0x01
+#define SCO_FORMAT_CVSD		0x02
+#define SCO_FORMAT_TRANSPARENT	0x03 
+#define SCO_FORMAT_PCM		0x05 
+#define SCO_FORMAT_MSBC		0x05 
+#define SCO_FORMAT_VENDOR	0xff
+struct sco_format_vendor {
+	__u16 vendor;
+	__u16 codec;
+};
+
+struct sco_format {
+	__u8                     in_format;
+	struct sco_format_vendor in_vendor;
+
+	__u8                     out_format;
+	struct sco_format_vendor out_vendor;
+};
+
+#define SCO_CODECS		0x06
+struct sco_codecs {
+	__u8  count;
+	__u8 *codec;
+};
+
+#define SCO_CODECS_VENDOR	0x07
+struct sco_codecs_vendor {
+	__u8                      count;
+	struct sco_format_vendor *format;
+};
+
 /* ---- SCO connections ---- */
 struct sco_conn {
 	struct hci_conn	*hcon;

@@ -74,6 +110,8 @@ struct sco_pinfo {
 	struct bt_sock	bt;
 	__u32		flags;
 	struct sco_conn	*conn;
+	struct sco_format host_format;
+	struct sco_format air_format;
 };
 
 #endif /* __SCO_H */

Basically, this adds four socket options (I'll do the audio path
stuff as well once this is done):

	SCO_AIR_FORMAT
	SCO_HOST_FORMAT
	SCO_CODECS (ro)
	SCO_CODECS_VENDOR (ro)

The SCO_CODECS ones provide the application with a list of codecs
supported by the hdev as indicated in the HCI_Read_Local_Supported_Codecs
command response, and if the hdev does not support this command a
default of linear PCM, CVSD, and transparent will be provided.

Because the result length is variable, the idea is that the application-
provided structure is modified by the kernel to hold the actual number
of results so the application can allocate a buffer accordingly, e.g.:

	struct sco_codecs sc;
	
	memset(&sc, 0, sizeof(sc));
	getsockopt(sk, SOL_SCO, SCO_CODECS, &sk);

	sk.codecs = malloc(sk.count);
	getsockopt(sk, SOL_SCO, SCO_CODECS, &sk);

The SCO_*_FORMAT ones allows the application to set the parameters that
are to be used on host-controller and controller-controller paths.  While
the spec requires the pairs (host input/output, air input/output) to be
identical, I don't see a reason to enforce this in the API, thus all are
set independently.

So, before I spend any more time on this.. comments?

-m.