libusbgx: Add function level OS Descriptor support

This adds support for OS Descriptors available on function level,
called "Feature Descriptors".

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
[Fix mem leak in error path, allow multiple ifaces per funciton]
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>

2 files changed, 109 insertions, 0 deletions

diff --git a/include/usbg/usbg.h b/include/usbg/usbg.h
index e5de7af..4b67f4e 100644
--- a/include/usbg/usbg.h
+++ b/include/usbg/usbg.h
@@ -216,6 +216,15 @@ typedef enum
 	USBG_FUNCTION_TYPE_MAX,
 } usbg_function_type;
 
+/**
+ * @brief USB OS Descriptor function attributes
+ */
+struct usbg_function_os_desc
+{
+	char *compatible_id;
+	char *sub_compatible_id;
+};
+
 /* Error codes */
 
 /**
@@ -790,6 +799,42 @@ extern int usbg_get_function_attrs(usbg_function *f, void *f_attrs);
  */
 extern int usbg_set_function_attrs(usbg_function *f, void *f_attrs);
 
+/**
+ * @brief Get OS Descriptor compatibility of given function
+ * @param f Pointer to function
+ * @param iname Interface name
+ * @param f_os_desc OS Descriptor compatibility to be filled
+ * @return 0 on success, usbg_error if error occurred
+ */
+extern int usbg_get_interf_os_desc(usbg_function *f, const char *iname,
+		struct usbg_function_os_desc *f_os_desc);
+
+/**
+ * @brief Free OS Descriptor function attributes
+ * @details This function releases the memory allocated for function
+ *          atrributes for struct usbg_function_os_desc.
+ * @param f_os_desc OS Descriptor function attributes to be released
+ */
+static inline void usbg_free_interf_os_desc(
+			struct usbg_function_os_desc *f_os_desc)
+{
+	if (!f_os_desc)
+		return;
+
+	free(f_os_desc->compatible_id);
+	free(f_os_desc->sub_compatible_id);
+}
+
+/**
+ * @brief Set OS Descriptor compatibility of given function
+ * @param f Pointer to function
+ * @param iname Interface name
+ * @param f_os_desc OS Descriptor compatibility to be set
+ * @return 0 on success, usbg_error if error occurred
+ */
+extern int usbg_set_interf_os_desc(usbg_function *f, const char *iname,
+		const struct usbg_function_os_desc *f_os_desc);
+
 /* USB configurations allocation and configuration */
 
 /**
diff --git a/src/usbg.c b/src/usbg.c
index 1c93f7b..090aea2 100644
--- a/src/usbg.c
+++ b/src/usbg.c
@@ -2009,6 +2009,70 @@ out:
 	return ret;
 }
 
+int usbg_get_interf_os_desc(usbg_function *f, const char *iname,
+			struct usbg_function_os_desc *f_os_desc)
+{
+	int ret = USBG_ERROR_NOT_SUPPORTED;
+	int nmb;
+	char spath[USBG_MAX_PATH_LENGTH];
+
+	if (!iname)
+		return ret;
+
+	nmb = snprintf(spath, sizeof(spath), "%s/%s/%s/interface.%s", f->path,
+			f->name, OS_DESC_DIR, iname);
+	if (nmb >= sizeof(spath)) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	ret = usbg_read_string_alloc(spath, "", "compatible_id",
+				&f_os_desc->compatible_id);
+	if (ret < 0)
+		goto out;
+
+	ret = usbg_read_string_alloc(spath, "", "sub_compatible_id",
+				&f_os_desc->sub_compatible_id);
+	if (ret < 0)
+		goto free_compatible;
+
+	return ret;
+
+free_compatible:
+	free(f_os_desc->compatible_id);
+out:
+	return ret;
+}
+
+int usbg_set_interf_os_desc(usbg_function *f, const char *iname,
+			const struct usbg_function_os_desc *f_os_desc)
+{
+	int ret = USBG_ERROR_NOT_SUPPORTED;
+	int nmb;
+	char spath[USBG_MAX_PATH_LENGTH];
+
+	if (!iname)
+		return ret;
+
+	nmb = snprintf(spath, sizeof(spath), "%s/%s/%s/interface.%s", f->path,
+			f->name, OS_DESC_DIR, iname);
+	if (nmb >= sizeof(spath)) {
+		ret = USBG_ERROR_PATH_TOO_LONG;
+		goto out;
+	}
+
+	ret = usbg_write_string(spath, "", "compatible_id",
+			f_os_desc->compatible_id);
+	if (ret < 0)
+		return ret;
+
+	ret = usbg_write_string(spath, "", "sub_compatible_id",
+			f_os_desc->sub_compatible_id);
+
+out:
+	return ret;
+}
+
 int usbg_create_config(usbg_gadget *g, int id, const char *label,
 		       const struct usbg_config_attrs *c_attrs,
 		       const struct usbg_config_strs *c_strs,