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init: Add symlinks to USB character devices

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Since we now support USB host mode, devices might get a different device
file depending if other devices are connected on the host port. This
patch creates symlinks to USB character devices that depend on the port
devices are connected to, but not on the order they have been probed.
(e.g. /dev/usb/tty2-1:1.0 -> /dev/ttyUSB0)

Change-Id: I285bcc2d59446fbff8a7abbe39c21781f3bb4bd3
This commit is contained in:
Benoit Goby 2010-08-03 14:36:02 -07:00
parent da7723ce90
commit d2278638d6
1 changed files with 52 additions and 0 deletions
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52
init/devices.c
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@ -264,6 +264,57 @@ static void parse_event(const char *msg, struct uevent *uevent)
uevent->firmware, uevent->major, uevent->minor);
}
static char **get_character_device_symlinks(struct uevent *uevent)
{
const char *parent;
char *slash;
char **links;
int link_num = 0;
int width;
if (strncmp(uevent->path, "/devices/platform/", 18))
return NULL;
links = malloc(sizeof(char *) * 2);
if (!links)
return NULL;
memset(links, 0, sizeof(char *) * 2);
/* skip "/devices/platform/<driver>" */
parent = strchr(uevent->path + 18, '/');
if (!*parent)
goto err;
if (!strncmp(parent, "/usb", 4)) {
/* skip root hub name and device. use device interface */
while (*++parent && *parent != '/');
if (*parent)
while (*++parent && *parent != '/');
if (!*parent)
goto err;
slash = strchr(++parent, '/');
if (!slash)
goto err;
width = slash - parent;
if (width <= 0)
goto err;
if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
link_num++;
else
links[link_num] = NULL;
mkdir("/dev/usb", 0755);
}
else {
goto err;
}
return links;
err:
free(links);
return NULL;
}
static char **parse_platform_block_device(struct uevent *uevent)
{
const char *driver;
@ -407,6 +458,7 @@ static void handle_device_event(struct uevent *uevent)
name += 4;
} else
base = "/dev/";
links = get_character_device_symlinks(uevent);
}
if (!devpath_ready)