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, 22 insertions, 6 deletions

diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
index 2505117e88e8..8f3659b65f53 100644
--- a/drivers/usb/gadget/function/f_mass_storage.c
+++ b/drivers/usb/gadget/function/f_mass_storage.c
@@ -311,11 +311,7 @@ struct fsg_common {
 	/* Gadget's private data. */
 	void			*private_data;
 
-	/*
-	 * Vendor (8 chars), product (16 chars), release (4
-	 * hexadecimal digits) and NUL byte
-	 */
-	char inquiry_string[8 + 16 + 4 + 1];
+	char inquiry_string[INQUIRY_STRING_LEN];
 
 	struct kref		ref;
 };
@@ -1107,7 +1103,12 @@ static int do_inquiry(struct fsg_common *common, struct fsg_buffhd *bh)
 	buf[5] = 0;		/* No special options */
 	buf[6] = 0;
 	buf[7] = 0;
-	memcpy(buf + 8, common->inquiry_string, sizeof common->inquiry_string);
+	if (curlun->inquiry_string[0])
+		memcpy(buf + 8, curlun->inquiry_string,
+		       sizeof(curlun->inquiry_string));
+	else
+		memcpy(buf + 8, common->inquiry_string,
+		       sizeof(common->inquiry_string));
 	return 36;
 }
 
@@ -3209,12 +3210,27 @@ static ssize_t fsg_lun_opts_nofua_store(struct config_item *item,
 
 CONFIGFS_ATTR(fsg_lun_opts_, nofua);
 
+static ssize_t fsg_lun_opts_inquiry_string_show(struct config_item *item,
+						char *page)
+{
+	return fsg_show_inquiry_string(to_fsg_lun_opts(item)->lun, page);
+}
+
+static ssize_t fsg_lun_opts_inquiry_string_store(struct config_item *item,
+						 const char *page, size_t len)
+{
+	return fsg_store_inquiry_string(to_fsg_lun_opts(item)->lun, page, len);
+}
+
+CONFIGFS_ATTR(fsg_lun_opts_, inquiry_string);
+
 static struct configfs_attribute *fsg_lun_attrs[] = {
 	&fsg_lun_opts_attr_file,
 	&fsg_lun_opts_attr_ro,
 	&fsg_lun_opts_attr_removable,
 	&fsg_lun_opts_attr_cdrom,
 	&fsg_lun_opts_attr_nofua,
+	&fsg_lun_opts_attr_inquiry_string,
 	NULL,
 };