usb: gadget: the start of the configfs interface

|# modprobe dummy_hcd num=2
|# modprobe libcomposite

|# lsmod
|Module                  Size  Used by
|libcomposite           31648  0
|dummy_hcd              19871  0

|# mkdir /sys/kernel/config/usb_gadget/oha
|# cd /sys/kernel/config/usb_gadget/oha
|# mkdir configs/def.1
|# mkdir configs/def.2
|# mkdir functions/acm.ttyS1
|# mkdir strings/0x1
|mkdir: cannot create directory `strings/0x1': Invalid argument
|# mkdir strings/0x409
|# mkdir strings/1033
|mkdir: cannot create directory `strings/1033': File exists
|# mkdir strings/1032
|# mkdir configs/def.1/strings/0x409
|# mkdir configs/def.2/strings/0x409

|#find . -ls
|   975    0 drwxr-xr-x   5 root     root            0 Dec 23 17:40 .
|   978    0 drwxr-xr-x   4 root     root            0 Dec 23 17:43 ./strings
|  4100    0 drwxr-xr-x   2 root     root            0 Dec 23 17:43 ./strings/1032
|   995    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./strings/1032/serialnumber
|   996    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./strings/1032/product
|   997    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./strings/1032/manufacturer
|  2002    0 drwxr-xr-x   2 root     root            0 Dec 23 17:41 ./strings/0x409
|   998    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./strings/0x409/serialnumber
|   999    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./strings/0x409/product
|  1000    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./strings/0x409/manufacturer
|   977    0 drwxr-xr-x   4 root     root            0 Dec 23 17:41 ./configs
|  4081    0 drwxr-xr-x   3 root     root            0 Dec 23 17:41 ./configs/def.2
|  4082    0 drwxr-xr-x   3 root     root            0 Dec 23 17:42 ./configs/def.2/strings
|  2016    0 drwxr-xr-x   2 root     root            0 Dec 23 17:42 ./configs/def.2/strings/0x409
|  1001    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./configs/def.2/strings/0x409/configuration
|  1002    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./configs/def.2/bmAttributes
|  1003    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./configs/def.2/MaxPower
|   979    0 drwxr-xr-x   3 root     root            0 Dec 23 17:42 ./configs/def.1
|   980    0 drwxr-xr-x   3 root     root            0 Dec 23 17:42 ./configs/def.1/strings
|  5122    0 drwxr-xr-x   2 root     root            0 Dec 23 17:42 ./configs/def.1/strings/0x409
|  1004    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./configs/def.1/strings/0x409/configuration
|  1005    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./configs/def.1/bmAttributes
|  1006    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./configs/def.1/MaxPower
|   976    0 drwxr-xr-x   3 root     root            0 Dec 23 17:41 ./functions
|   981    0 drwxr-xr-x   2 root     root            0 Dec 23 17:41 ./functions/acm.ttyS1
|  1007    0 -r--r--r--   1 root     root         4096 Dec 23 17:43 ./functions/acm.ttyS1/port_num
|  1008    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./UDC
|  1009    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./bcdUSB
|  1010    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./bcdDevice
|  1011    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./idProduct
|  1012    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./idVendor
|  1013    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./bMaxPacketSize0
|  1014    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./bDeviceProtocol
|  1015    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./bDeviceSubClass
|  1016    0 -rw-r--r--   1 root     root         4096 Dec 23 17:43 ./bDeviceClass

|# cat functions/acm.ttyS1/port_num
|0
|# ls -lah /dev/ttyGS*
|crw-rw---T 1 root dialout 252, 0 Dec 23 17:41 /dev/ttyGS0
|
|# echo 0x1234 > idProduct
|# echo 0xabcd > idVendor
|# echo 1122 > strings/0x409/serialnumber
|# echo "The manufacturer" > strings/0x409/manufacturer
|# echo 1 > strings/1032/manufacturer
|# echo 1sa > strings/1032/product
|# echo tada > strings/1032/serialnumber
|echo "Primary configuration" > configs/def.1/strings/0x409/configuration
|# echo "Secondary configuration" > configs/def.2/strings/0x409/configuration
|# ln -s functions/acm.ttyS1 configs/def.1/
|# ln -s functions/acm.ttyS1 configs/def.2/
|find configs/def.1/ -ls
|   979    0 drwxr-xr-x   3 root     root            0 Dec 23 17:49 configs/def.1/
|  6264    0 lrwxrwxrwx   1 root     root            0 Dec 23 17:48 configs/def.1/acm.ttyS1 -> ../../../../usb_gadget/oha/functions/acm.ttyS1
|   980    0 drwxr-xr-x   3 root     root            0 Dec 23 17:42 configs/def.1/strings
|  5122    0 drwxr-xr-x   2 root     root            0 Dec 23 17:49 configs/def.1/strings/0x409
|  6284    0 -rw-r--r--   1 root     root         4096 Dec 23 17:47 configs/def.1/strings/0x409/configuration
|  6285    0 -rw-r--r--   1 root     root         4096 Dec 23 17:49 configs/def.1/bmAttributes
|  6286    0 -rw-r--r--   1 root     root         4096 Dec 23 17:49 configs/def.1/MaxPower
|
|echo 120 > configs/def.1/MaxPower
|
|# ls -lh /sys/class/udc/
|total 0
|lrwxrwxrwx 1 root root 0 Dec 23 17:50 dummy_udc.0 -> ../../devices/platform/dummy_udc.0/udc/dummy_udc.0
|lrwxrwxrwx 1 root root 0 Dec 23 17:50 dummy_udc.1 -> ../../devices/platform/dummy_udc.1/udc/dummy_udc.1
|# echo dummy_udc.0 > UDC
|# lsusb
|Bus 001 Device 002: ID abcd:1234 Unknown
|
|lsusb -d abcd:1234 -v
|Device Descriptor:
…
|  idVendor           0xabcd Unknown
|  idProduct          0x1234
|  bcdDevice            3.06
|  iManufacturer           1 The manufacturer
|  iProduct                2
|  iSerial                 3 1122
|  bNumConfigurations      2
…
|echo "" > UDC

v5…v6
- wired up strings with usb_gstrings_attach()
- add UDC attribe. Write "udc-name" will bind the gadget. Write an empty
  string (it should contain \n since 0 bytes write get optimzed away)
  will unbind the UDC from the gadget. The name of available UDCs can be
  obtained from /sys/class/udc/

v4…v5
- string rework. This will add a strings folder incl. language code like
    strings/409/manufacturer
  as suggested by Alan.
- rebased ontop reworked functions.c which has usb_function_instance
  which is used prior after "mkdir acm.instance" and can be directly
  used for configuration via configfs.

v3…v4
 - moved functions from the root folde down to the gadget as suggested
   by Michał
 - configs have now their own configs folder as suggested by Michał.
   The folder is still name.bConfigurationValue where name becomes the
   sConfiguration. Is this usefull should we just stilc
   configs/bConfigurationValue/ ?
 - added configfs support to the ACM function. The port_num attribute is
   exported by f_acm. An argument has been added to the USB alloc
   function to distinguish between "old" (use facm_configure() to
   configure and configfs interface (expose a config_node).
   The port_num is currently a dumb counter. It will
   require some function re-work to make it work.

scheduled for v5:
- sym linking function into config.

v2…v3
- replaced one ifndef by ifdef as suggested by Micahał
- strstr()/strchr() function_make as suggested by Micahł
- replace [iSerialNumber|iProduct|iManufacturer] with
  [sSerialNumber|sProduct|sManufacturer] as suggested by Alan
- added creation of config descriptors

v1…v2
- moved gadgets from configfs' root directory into /udcs/ within our
  "usb_gadget" folder. Requested by Andrzej & Michał
- use a dot as a delimiter between function's name and its instance's name
  as suggested by Michał
- renamed all config_item_type, configfs_group_operations, make_group,
  drop_item as suggested by suggested by Andrzej to remain consisten
  within this file and within other configfs users
- Since configfs.c and functions.c are now part of the udc-core module,
  the module itself is now called udc. Also added a tiny ifdef around
  init code becuase udc-core is subsys init and this is too early for
  configfs in the built-in case. In the module case, we can only have
  one init function.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -493,6 +493,7 @@ endmenu
 # composite based drivers
 config USB_LIBCOMPOSITE
 	tristate
+	select CONFIGFS_FS
 	depends on USB_GADGET
 
 config USB_F_ACM

drivers/usb/gadget/Makefile

@@ -6,7 +6,7 @@ ccflags-$(CONFIG_USB_GADGET_DEBUG) := -DDEBUG
 obj-$(CONFIG_USB_GADGET)	+= udc-core.o
 obj-$(CONFIG_USB_LIBCOMPOSITE)	+= libcomposite.o
 libcomposite-y			:= usbstring.o config.o epautoconf.o
-libcomposite-y			+= composite.o functions.o
+libcomposite-y			+= composite.o functions.o configfs.o
 obj-$(CONFIG_USB_DUMMY_HCD)	+= dummy_hcd.o
 obj-$(CONFIG_USB_NET2272)	+= net2272.o
 obj-$(CONFIG_USB_NET2280)	+= net2280.o

drivers/usb/gadget/composite.c

@@ -1637,6 +1637,7 @@ void composite_dev_cleanup(struct usb_composite_dev *cdev)
 		kfree(cdev->req->buf);
 		usb_ep_free_request(cdev->gadget->ep0, cdev->req);
 	}
+	cdev->next_string_id = 0;
 	device_remove_file(&cdev->gadget->dev, &dev_attr_suspended);
 }
 

drivers/usb/gadget/f_acm.c

@@ -763,6 +763,59 @@ static struct usb_function *acm_alloc_func(struct usb_function_instance *fi)
 	return &acm->port.func;
 }
 
+static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_serial_opts,
+			func_inst.group);
+}
+
+CONFIGFS_ATTR_STRUCT(f_serial_opts);
+static ssize_t f_acm_attr_show(struct config_item *item,
+				 struct configfs_attribute *attr,
+				 char *page)
+{
+	struct f_serial_opts *opts = to_f_serial_opts(item);
+	struct f_serial_opts_attribute *f_serial_opts_attr =
+		container_of(attr, struct f_serial_opts_attribute, attr);
+	ssize_t ret = 0;
+
+	if (f_serial_opts_attr->show)
+		ret = f_serial_opts_attr->show(opts, page);
+	return ret;
+}
+
+static void acm_attr_release(struct config_item *item)
+{
+	struct f_serial_opts *opts = to_f_serial_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations acm_item_ops = {
+	.release                = acm_attr_release,
+	.show_attribute		= f_acm_attr_show,
+};
+
+static ssize_t f_acm_port_num_show(struct f_serial_opts *opts, char *page)
+{
+	return sprintf(page, "%u\n", opts->port_num);
+}
+
+static struct f_serial_opts_attribute f_acm_port_num =
+	__CONFIGFS_ATTR_RO(port_num, f_acm_port_num_show);
+
+
+static struct configfs_attribute *acm_attrs[] = {
+	&f_acm_port_num.attr,
+	NULL,
+};
+
+static struct config_item_type acm_func_type = {
+	.ct_item_ops    = &acm_item_ops,
+	.ct_attrs	= acm_attrs,
+	.ct_owner       = THIS_MODULE,
+};
+
 static void acm_free_instance(struct usb_function_instance *fi)
 {
 	struct f_serial_opts *opts;
@@ -786,6 +839,8 @@ static struct usb_function_instance *acm_alloc_instance(void)
 		kfree(opts);
 		return ERR_PTR(ret);
 	}
+	config_group_init_type_name(&opts->func_inst.group, "",
+			&acm_func_type);
 	return &opts->func_inst;
 }
 DECLARE_USB_FUNCTION_INIT(acm, acm_alloc_instance, acm_alloc_func);

include/linux/usb/composite.h

@@ -39,6 +39,7 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/log2.h>
+#include <linux/configfs.h>
 
 /*
  * USB function drivers should return USB_GADGET_DELAYED_STATUS if they
@@ -464,6 +465,8 @@ struct usb_function_driver {
 };
 
 struct usb_function_instance {
+	struct config_group group;
+	struct list_head cfs_list;
 	struct usb_function_driver *fd;
 	void (*free_func_inst)(struct usb_function_instance *inst);
 };

include/linux/usb/gadget_configfs.h

@@ -0,0 +1,110 @@
+#ifndef __GADGET_CONFIGFS__
+#define __GADGET_CONFIGFS__
+
+#include <linux/configfs.h>
+
+int check_user_usb_string(const char *name,
+		struct usb_gadget_strings *stringtab_dev);
+
+#define GS_STRINGS_W(__struct, __name)	\
+	static ssize_t __struct##_##__name##_store(struct __struct *gs, \
+		const char *page, size_t len)		\
+{							\
+	int ret;					\
+							\
+	ret = usb_string_copy(page, &gs->__name);	\
+	if (ret)					\
+		return ret;				\
+	return len;					\
+}
+
+#define GS_STRINGS_R(__struct, __name)	\
+	static ssize_t __struct##_##__name##_show(struct __struct *gs, \
+			char *page)	\
+{	\
+	return sprintf(page, "%s\n", gs->__name ?: "");	\
+}
+
+#define GS_STRING_ITEM_ATTR(struct_name, name)	\
+	static struct struct_name##_attribute struct_name##_##name = \
+		__CONFIGFS_ATTR(name,  S_IRUGO | S_IWUSR,		\
+				struct_name##_##name##_show,		\
+				struct_name##_##name##_store)
+
+#define GS_STRINGS_RW(struct_name, _name)	\
+	GS_STRINGS_R(struct_name, _name)	\
+	GS_STRINGS_W(struct_name, _name)	\
+	GS_STRING_ITEM_ATTR(struct_name, _name)
+
+#define USB_CONFIG_STRING_RW_OPS(struct_in)				\
+	CONFIGFS_ATTR_OPS(struct_in);					\
+									\
+static struct configfs_item_operations struct_in##_langid_item_ops = {	\
+	.release                = struct_in##_attr_release,		\
+	.show_attribute         = struct_in##_attr_show,		\
+	.store_attribute        = struct_in##_attr_store,		\
+};									\
+									\
+static struct config_item_type struct_in##_langid_type = {		\
+	.ct_item_ops	= &struct_in##_langid_item_ops,			\
+	.ct_attrs	= struct_in##_langid_attrs,			\
+	.ct_owner	= THIS_MODULE,					\
+}
+
+#define USB_CONFIG_STRINGS_LANG(struct_in, struct_member)	\
+	static struct config_group *struct_in##_strings_make(		\
+			struct config_group *group,			\
+			const char *name)				\
+	{								\
+	struct struct_member *gi;					\
+	struct struct_in *gs;						\
+	struct struct_in *new;						\
+	int langs = 0;							\
+	int ret;							\
+									\
+	new = kzalloc(sizeof(*new), GFP_KERNEL);			\
+	if (!new)							\
+		return ERR_PTR(-ENOMEM);				\
+									\
+	ret = check_user_usb_string(name, &new->stringtab_dev);		\
+	if (ret)							\
+		goto err;						\
+	config_group_init_type_name(&new->group, name,			\
+			&struct_in##_langid_type);			\
+									\
+	gi = container_of(group, struct struct_member, strings_group);	\
+	ret = -EEXIST;							\
+	list_for_each_entry(gs, &gi->string_list, list) {		\
+		if (gs->stringtab_dev.language == new->stringtab_dev.language) \
+			goto err;					\
+		langs++;						\
+	}								\
+	ret = -EOVERFLOW;						\
+	if (langs >= MAX_USB_STRING_LANGS)				\
+		goto err;						\
+									\
+	list_add_tail(&new->list, &gi->string_list);			\
+	return &new->group;						\
+err:									\
+	kfree(new);							\
+	return ERR_PTR(ret);						\
+}									\
+									\
+static void struct_in##_strings_drop(					\
+		struct config_group *group,				\
+		struct config_item *item)				\
+{									\
+	config_item_put(item);						\
+}									\
+									\
+static struct configfs_group_operations struct_in##_strings_ops = {	\
+	.make_group     = &struct_in##_strings_make,			\
+	.drop_item      = &struct_in##_strings_drop,			\
+};									\
+									\
+static struct config_item_type struct_in##_strings_type = {		\
+	.ct_group_ops   = &struct_in##_strings_ops,			\
+	.ct_owner       = THIS_MODULE,					\
+}
+
+#endif