mbim: Add MBIM descriptor utilities

Used to find MBIM Functional and MBIM Extended Functional descriptors

Makefile.am

@@ -608,7 +608,9 @@ builtin_libadd += @ELL_LIBS@
 
 if MBIMMODEM
 mbim_sources =	drivers/mbimmodem/mbim.h \
-		drivers/mbimmodem/mbim.c
+		drivers/mbimmodem/mbim.c \
+		drivers/mbimmodem/mbim-desc.h \
+		drivers/mbimmodem/mbim-desc.c
 
 builtin_modules += mbimmodem
 builtin_sources += $(mbim_sources) \

drivers/mbimmodem/mbim-desc.c

@@ -0,0 +1,80 @@
+/*
+ *
+ *  oFono - Open Source Telephony
+ *
+ *  Copyright (C) 2017  Intel Corporation. All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stddef.h>
+
+#include "mbim-desc.h"
+
+/*
+ * Attempts to find MBIM specific descriptors.
+ *
+ * Returns true if the MBIM Function descriptor was found, false otherwise.
+ */
+bool mbim_find_descriptors(const uint8_t *data, size_t data_len,
+				const struct mbim_desc **out_desc,
+				const struct mbim_extended_desc **out_ext_desc)
+{
+	bool r = false;
+
+	while (data_len > 3) {
+		uint8_t len = data[0];
+
+		if (data[1] != 0x24)
+			goto next;
+
+		/* MBIM v1.0, Table 4-3 */
+		switch (data[2]) {
+		case 0x1b:
+			if (!out_desc)
+				break;
+
+			if (len != sizeof(struct mbim_desc) || data_len < len)
+				break;
+
+			*out_desc = (const struct mbim_desc *) data;
+			r = true;
+			break;
+		case 0x1c:
+			if (!out_ext_desc)
+				break;
+
+			if (len != sizeof(struct mbim_extended_desc) ||
+					data_len < len)
+				break;
+
+			*out_ext_desc =
+				(const struct mbim_extended_desc *) data;
+			break;
+		}
+
+next:
+		data_len -= len;
+		data += len;
+	}
+
+	return r;
+}

drivers/mbimmodem/mbim-desc.h

@@ -0,0 +1,49 @@
+/*
+ *
+ *  oFono - Open Source Telephony
+ *
+ *  Copyright (C) 2017  Intel Corporation. All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include <linux/types.h>
+
+/* MBIM v1.0, Section 6.4: MBIM Functional Descriptor */
+struct mbim_desc {
+	uint8_t bFunctionLength;
+	uint8_t bDescriptorType;
+	uint8_t bDescriptorSubtype;
+	__le16 bcdMBIMVersion;
+	__le16 wMaxControlMessage;
+	uint8_t bNumberFilters;
+	uint8_t bMaxFilterSize;
+	__le16 wMaxSegmentSize;
+	uint8_t bmNetworkCapabilities;
+} __attribute__ ((packed));
+
+/* MBIM v1.0, Section 6.5: MBIM Extended Functional Descriptor */
+struct mbim_extended_desc {
+	uint8_t	bFunctionLength;
+	uint8_t	bDescriptorType;
+	uint8_t bDescriptorSubtype;
+	__le16 bcdMBIMExtendedVersion;
+	uint8_t bMaxOutstandingCommandMessages;
+	__le16 wMTU;
+} __attribute__ ((packed));
+
+bool mbim_find_descriptors(const uint8_t *data, size_t data_len,
+				const struct mbim_desc **out_desc,
+				const struct mbim_extended_desc **out_ext_desc);