usb: gadget: f_mass_storage: make sysfs interface optional

When configfs is in place, the luns will not be represented in sysfs,
so there will be no struct device associated with a lun.
In order to maintain compatibility and allow configfs adoption
sysfs is made optional in this patch.

As a consequence some debug macros need to be adjusted. Two new
fields are added to struct fsg_lun: name and name_pfx.
The "name" is for storing a string which is presented to the user
instead of the dev_name. The "name_pfx", if non-NULL, is prepended
to the "name" at printing time.

The name_pfx is for a future lun.0, which will be a default group in
mass_storage.<name>. By design at USB function configfs group's creation
time its name is not known (but instead set a bit later in
drivers/usb/gadget/configfs.c:function_make) and it is this name that
serves the purpose of the said name prefix. So instead of copying
a yet-unknown string a pointer to it is stored in struct fsg_lun.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/drivers/usb/gadget/storage_common.h b/drivers/usb/gadget/storage_common.h
index 1fcda2b..d8cc090 100644
--- a/drivers/usb/gadget/storage_common.h
+++ b/drivers/usb/gadget/storage_common.h
@@ -17,10 +17,20 @@
 #define VLDBG(lun, fmt, args...) do { } while (0)
 #endif /* VERBOSE_DEBUG */
 
-#define LDBG(lun, fmt, args...)   dev_dbg(&(lun)->dev, fmt, ## args)
-#define LERROR(lun, fmt, args...) dev_err(&(lun)->dev, fmt, ## args)
-#define LWARN(lun, fmt, args...)  dev_warn(&(lun)->dev, fmt, ## args)
-#define LINFO(lun, fmt, args...)  dev_info(&(lun)->dev, fmt, ## args)
+#define _LMSG(func, lun, fmt, args...)					\
+	do {								\
+		if ((lun)->name_pfx && *(lun)->name_pfx)		\
+			func("%s/%s: " fmt, *(lun)->name_pfx,		\
+				 (lun)->name, ## args);			\
+		else							\
+			func("%s: " fmt, (lun)->name, ## args);		\
+	} while (0)
+
+#define LDBG(lun, fmt, args...)		_LMSG(pr_debug, lun, fmt, ## args)
+#define LERROR(lun, fmt, args...)	_LMSG(pr_err, lun, fmt, ## args)
+#define LWARN(lun, fmt, args...)	_LMSG(pr_warn, lun, fmt, ## args)
+#define LINFO(lun, fmt, args...)	_LMSG(pr_info, lun, fmt, ## args)
+
 
 #ifdef DUMP_MSGS
 
@@ -100,6 +110,8 @@ struct fsg_lun {
 						       of bound block device */
 	unsigned int	blksize; /* logical block size of bound block device */
 	struct device	dev;
+	const char	*name;		/* "lun.name" */
+	const char	**name_pfx;	/* "function.name" */
 };
 
 static inline bool fsg_lun_is_open(struct fsg_lun *curlun)