summaryrefslogtreecommitdiff
path: root/configfs.c
diff options
context:
space:
mode:
authorKieran Bingham <kieran.bingham@ideasonboard.com>2018-05-25 16:31:32 +0100
committerLaurent Pinchart <laurent.pinchart@ideasonboard.com>2018-05-26 18:27:17 +0300
commit83fa2cb53742f43c3a254d0453bd96048ee29a82 (patch)
tree09896a840707250a4dc3f54b0902d86da3596d82 /configfs.c
parent03f3bc285a33397642c79eb94e366d5e18be53fe (diff)
configfs: Provide configfs support
Parse a configuration name from the commandline, and utilise it to identify the configfs configuration path. Only the short-name (i.e. "uvc.1") is necessary to provide if there is no ambiguity regarding the gadget, otherwise the gadget path should be included ("g1/functions/uvc.1"). If the parameter is not provided then the first function is utilised. Legacy g_webcam is still supported, and the parameter will define the UDC to match against if provided. Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Diffstat (limited to 'configfs.c')
-rw-r--r--configfs.c343
1 files changed, 343 insertions, 0 deletions
diff --git a/configfs.c b/configfs.c
new file mode 100644
index 0000000..8d36a29
--- /dev/null
+++ b/configfs.c
@@ -0,0 +1,343 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * ConfigFS Gadget device handling
+ *
+ * Copyright (C) 2018 Kieran Bingham
+ *
+ * Contact: Kieran Bingham <kieran.bingham@ideasonboard.com>
+ */
+
+/* To provide basename and asprintf from the GNU library. */
+ #define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <glob.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "configfs.h"
+
+/* -----------------------------------------------------------------------------
+ * Path handling and support
+ */
+
+static char *path_join(const char *dirname, const char *name)
+{
+ char *path;
+
+ asprintf(&path, "%s/%s", dirname, name);
+
+ return path;
+}
+
+static char *path_glob_first_match(const char *g)
+{
+ glob_t globbuf;
+ char *match = NULL;
+
+ glob(g, 0, NULL, &globbuf);
+
+ if (globbuf.gl_pathc)
+ match = strdup(globbuf.gl_pathv[0]);
+
+ globfree(&globbuf);
+
+ return match;
+}
+
+/* -----------------------------------------------------------------------------
+ * Attribute handling
+ */
+
+static int attribute_read(const char *path, const char *file, char *buf,
+ unsigned int len)
+{
+ char *f;
+ int ret;
+ int fd;
+
+ f = path_join(path, file);
+ if (!f)
+ return -ENOMEM;
+
+ fd = open(f, O_RDONLY);
+ free(f);
+ if (fd == -1) {
+ printf("Failed to open attribute %s: %s\n", file,
+ strerror(errno));
+ return -ENOENT;
+ }
+
+ ret = read(fd, buf, len - 1);
+ close(fd);
+
+ if (ret < 0) {
+ printf("Failed to read attribute %s: %s\n", file,
+ strerror(errno));
+ return -ENODATA;
+ }
+
+ buf[ret] = '\0';
+
+ return 0;
+}
+
+static int attribute_read_uint(const char *path, const char *file,
+ unsigned int *val)
+{
+ /* 4,294,967,295 */
+ char buf[11];
+ char *endptr;
+ int ret;
+
+ ret = attribute_read(path, file, buf, sizeof(buf));
+ if (ret)
+ return ret;
+
+ errno = 0;
+
+ /* base 0: Autodetect hex, octal, decimal. */
+ *val = strtoul(buf, &endptr, 0);
+ if (errno)
+ return -errno;
+
+ if (endptr == buf)
+ return -ENODATA;
+
+ return 0;
+}
+
+static char *attribute_read_str(const char *path, const char *file)
+{
+ char buf[1024];
+ char *p;
+ int ret;
+
+ ret = attribute_read(path, file, buf, sizeof(buf));
+ if (ret)
+ return NULL;
+
+ p = strrchr(buf, '\n');
+ if (p != buf)
+ *p = '\0';
+
+ return strdup(buf);
+}
+
+/* -----------------------------------------------------------------------------
+ * UDC parsing
+ */
+
+/*
+ * udc_find_video_device - Find the video device node for a UVC function
+ * @udc: The UDC name
+ * @function: The UVC function name
+ *
+ * This function finds the video device node corresponding to a UVC function as
+ * specified by a @function name and @udc name.
+ *
+ * The @function parameter specifies the name of the USB function, usually in
+ * the form "uvc.%u". If NULL the first function found will be used.
+ *
+ * The @udc parameter specifies the name of the UDC. If NULL any UDC that
+ * contains a function matching the @function name will be used.
+ *
+ * Return a pointer to a newly allocated string containing the video device node
+ * full path if the function is found. Otherwise return NULL. The returned
+ * pointer must be freed by the caller with a call to free().
+ */
+static char *udc_find_video_device(const char *udc, const char *function)
+{
+ char *vpath;
+ char *video = NULL;
+ glob_t globbuf;
+ unsigned int i;
+
+ asprintf(&vpath, "/sys/class/udc/%s/device/gadget/video4linux/video*",
+ udc ? udc : "*");
+ if (!vpath)
+ return NULL;
+
+ glob(vpath, 0, NULL, &globbuf);
+ free(vpath);
+
+ for (i = 0; i < globbuf.gl_pathc; ++i) {
+ char *config;
+ bool match;
+
+ /* Match on the first if no search string. */
+ if (!function)
+ break;
+
+ config = attribute_read_str(globbuf.gl_pathv[i],
+ "function_name");
+ match = strcmp(function, config) == 0;
+
+ free(config);
+
+ if (match)
+ break;
+ }
+
+ if (i < globbuf.gl_pathc) {
+ const char *v = basename(globbuf.gl_pathv[i]);
+
+ video = path_join("/dev", v);
+ }
+
+ globfree(&globbuf);
+
+ return video;
+}
+
+/* -----------------------------------------------------------------------------
+ * Legacy g_webcam support
+ */
+
+static const struct uvc_function_config g_webcam_config = {
+ .streaming_interval = 1,
+ .streaming_maxburst = 0,
+ .streaming_maxpacket = 1024,
+};
+
+static int parse_legacy_g_webcam(const char *udc,
+ struct uvc_function_config *fc)
+{
+ *fc = g_webcam_config;
+
+ fc->video = udc_find_video_device(udc, NULL);
+
+ return fc->video ? 0 : -ENODEV;
+}
+
+/* -----------------------------------------------------------------------------
+ * ConfigFS support
+ */
+
+/*
+ * configfs_find_uvc_function - Find the ConfigFS full path for a UVC function
+ * @function: The UVC function name
+ *
+ * Return a pointer to a newly allocated string containing the full ConfigFS
+ * path to the function if the function is found. Otherwise return NULL. The
+ * returned pointer must be freed by the caller with a call to free().
+ */
+static char *configfs_find_uvc_function(const char *function)
+{
+ const char *target = function ? function : "*";
+ const char *root;
+ char *func_path;
+ char *path;
+
+ /*
+ * The function description can be provided as a path from the
+ * usb_gadget root "g1/functions/uvc.0", or if there is no ambiguity
+ * over the gadget name, a shortcut "uvc.0" can be provided.
+ */
+ if (!strchr(target, '/'))
+ root = "/sys/kernel/config/usb_gadget/*/functions";
+ else
+ root = "/sys/kernel/config/usb_gadget";
+
+ path = path_join(root, target);
+
+ func_path = path_glob_first_match(path);
+ free(path);
+
+ return func_path;
+}
+
+/*
+ * configfs_free_uvc_function - Free a uvc_function_config object
+ * @fc: The uvc_function_config to be freed
+ *
+ * Free the given @fc function previously allocated by a call to
+ * configfs_parse_uvc_function().
+ */
+void configfs_free_uvc_function(struct uvc_function_config *fc)
+{
+ free(fc->udc);
+ free(fc->video);
+
+ free(fc);
+}
+
+/*
+ * configfs_parse_uvc_function - Parse a UVC function configuration in ConfigFS
+ * @function: The function name
+ *
+ * This function locates and parse the configuration of a UVC function in
+ * ConfigFS as specified by the @function name argument. The function name can
+ * be fully qualified with a gadget name (e.g. "g%u/functions/uvc.%u"), or as a
+ * shortcut can be an unqualified function name (e.g. "uvc.%u"). When the
+ * function name is unqualified, the first function matching the name in any
+ * UDC will be returned.
+ *
+ * Return a pointer to a newly allocated UVC function configuration structure
+ * that contains configuration parameters for the function, if the function is
+ * found. Otherwise return NULL. The returned pointer must be freed by the
+ * caller with a call to free().
+ */
+struct uvc_function_config *configfs_parse_uvc_function(const char *function)
+{
+ struct uvc_function_config *fc;
+ char *fpath;
+ int ret = 0;
+
+ fc = malloc(sizeof *fc);
+ if (fc == NULL)
+ return NULL;
+
+ memset(fc, 0, sizeof *fc);
+
+ /* Find the function in ConfigFS. */
+ fpath = configfs_find_uvc_function(function);
+ if (!fpath) {
+ /*
+ * If the function can't be found attempt legacy parsing to
+ * support the g_webcam gadget. The function parameter contains
+ * a UDC name in that case.
+ */
+ ret = parse_legacy_g_webcam(function, fc);
+ if (ret) {
+ configfs_free_uvc_function(fc);
+ fc = NULL;
+ }
+
+ return fc;
+ }
+
+ /*
+ * Parse the function configuration. Remove the gadget name qualifier
+ * from the function name, if any.
+ */
+ if (function)
+ function = basename(function);
+
+ fc->udc = attribute_read_str(fpath, "../../UDC");
+ fc->video = udc_find_video_device(fc->udc, function);
+ if (!fc->video)
+ ret = -ENODEV;
+
+ ret = ret ? : attribute_read_uint(fpath, "streaming_interval",
+ &fc->streaming_interval);
+
+ ret = ret ? : attribute_read_uint(fpath, "streaming_maxburst",
+ &fc->streaming_maxburst);
+
+ ret = ret ? : attribute_read_uint(fpath, "streaming_maxpacket",
+ &fc->streaming_maxpacket);
+
+ if (ret) {
+ configfs_free_uvc_function(fc);
+ fc = NULL;
+ }
+
+ free(fpath);
+
+ return fc;
+}