usb: gadget: Add per-lun inquiry string

Introduce an attribute "inquiry_string" to the lun.

In some environments, e. g. BIOS boot menus, the inquiry string
is the only information about devices presented to the user. The
default string depends on the "cdrom" bit of the first lun as
well as the kernel version and allows no further customization.
So without access to the client it is not obvious which gadget is
active at a given point and what any of the available luns might
contain.

If "inquiry_string" is ignored or set to the empty string, the
old behavior is preserved.

Signed-off-by: Philipp Gesang <philipp.gesang@intra2net.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/usb/gadget/function/storage_common.c b/drivers/usb/gadget/function/storage_common.c
index 990df22..8fbf686 100644
--- a/drivers/usb/gadget/function/storage_common.c
+++ b/drivers/usb/gadget/function/storage_common.c
@@ -369,6 +369,12 @@ ssize_t fsg_show_removable(struct fsg_lun *curlun, char *buf)
 }
 EXPORT_SYMBOL_GPL(fsg_show_removable);
 
+ssize_t fsg_show_inquiry_string(struct fsg_lun *curlun, char *buf)
+{
+	return sprintf(buf, "%s\n", curlun->inquiry_string);
+}
+EXPORT_SYMBOL_GPL(fsg_show_inquiry_string);
+
 /*
  * The caller must hold fsg->filesem for reading when calling this function.
  */
@@ -499,4 +505,22 @@ ssize_t fsg_store_removable(struct fsg_lun *curlun, const char *buf,
 }
 EXPORT_SYMBOL_GPL(fsg_store_removable);
 
+ssize_t fsg_store_inquiry_string(struct fsg_lun *curlun, const char *buf,
+				 size_t count)
+{
+	const size_t len = min(count, sizeof(curlun->inquiry_string));
+
+	if (len == 0 || buf[0] == '\n') {
+		curlun->inquiry_string[0] = 0;
+	} else {
+		snprintf(curlun->inquiry_string,
+			 sizeof(curlun->inquiry_string), "%-28s", buf);
+		if (curlun->inquiry_string[len-1] == '\n')
+			curlun->inquiry_string[len-1] = ' ';
+	}
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(fsg_store_inquiry_string);
+
 MODULE_LICENSE("GPL");