usb: gadget: printer: add configfs support

Add support for configfs interface so that f_printer can be used as a
component of usb gadgets composed with it.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

2 files changed, 56 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-printer b/Documentation/ABI/testing/configfs-usb-gadget-printer
new file mode 100644
index 000000000000..6b0714e3c605
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-printer
@@ -0,0 +1,9 @@
+What:		/config/usb-gadget/gadget/functions/printer.name
+Date:		Apr 2015
+KernelVersion:	4.1
+Description:
+		The attributes:
+
+		pnp_string	- Data to be passed to the host in pnp string
+		q_len		- Number of requests per endpoint
+
diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt
index 076ac7ba7f93..f45b2bf4b41d 100644
--- a/Documentation/usb/gadget-testing.txt
+++ b/Documentation/usb/gadget-testing.txt
@@ -19,6 +19,7 @@ provided by gadgets.
 16. UAC1 function
 17. UAC2 function
 18. UVC function
+19. PRINTER function
 
 
 1. ACM function
@@ -726,3 +727,49 @@ with these patches:
 http://www.spinics.net/lists/linux-usb/msg99220.html
 
 host: luvcview -f yuv
+
+19. PRINTER function
+====================
+
+The function is provided by usb_f_printer.ko module.
+
+Function-specific configfs interface
+------------------------------------
+
+The function name to use when creating the function directory is "printer".
+The printer function provides these attributes in its function directory:
+
+	pnp_string	- Data to be passed to the host in pnp string
+	q_len		- Number of requests per endpoint
+
+Testing the PRINTER function
+----------------------------
+
+The most basic testing:
+
+device: run the gadget
+# ls -l /devices/virtual/usb_printer_gadget/
+
+should show g_printer<number>.
+
+If udev is active, then /dev/g_printer<number> should appear automatically.
+
+host:
+
+If udev is active, then e.g. /dev/usb/lp0 should appear.
+
+host->device transmission:
+
+device:
+# cat /dev/g_printer<number>
+host:
+# cat > /dev/usb/lp0
+
+device->host transmission:
+
+# cat > /dev/g_printer<number>
+host:
+# cat /dev/usb/lp0
+
+More advanced testing can be done with the prn_example
+described in Documentation/usb/gadget-printer.txt.