4 files changed, 87 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-eem b/Documentation/ABI/testing/configfs-usb-gadget-eem
new file mode 100644
index 000000000000..10e87d67fa2e
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-eem
@@ -0,0 +1,14 @@
+What:           /config/usb-gadget/gadget/functions/eem.name
+Date:           May 2013
+KenelVersion:   3.11
+Description:
+                The attributes:
+
+                ifname          - network device interface name associated with
+                                this function instance
+                qmult           - queue length multiplier for high and
+                                super speed
+                host_addr       - MAC address of host's end of this
+                                Ethernet over USB link
+                dev_addr        - MAC address of device's end of this
+                                Ethernet over USB link
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 159393d58912..d5b0ffe26118 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -544,6 +544,21 @@ choice
 
 # this first set of drivers all depend on bulk-capable hardware.
 
+config USB_CONFIGFS_EEM
+        bool "Ethernet Emulation Model (EEM)"
+        depends on USB_CONFIGFS
+        depends on NET
+        select USB_U_ETHER
+        select USB_F_EEM
+        help
+          CDC EEM is a newer USB standard that is somewhat simpler than CDC ECM
+          and therefore can be supported by more hardware.  Technically ECM and
+          EEM are designed for different applications.  The ECM model extends
+          the network interface to the target (e.g. a USB cable modem), and the
+          EEM model is for mobile devices to communicate with hosts using
+          ethernet over USB.  For Linux gadgets, however, the interface with
+          the host is the same (a usbX device), so the differences are minimal.
+
 config USB_CONFIGFS_PHONET
         boolean "Phonet protocol"
         depends on USB_CONFIGFS
diff --git a/drivers/usb/gadget/f_eem.c b/drivers/usb/gadget/f_eem.c
index 31a2cb7ebe82..90ee8022e8d8 100644
--- a/drivers/usb/gadget/f_eem.c
+++ b/drivers/usb/gadget/f_eem.c
@@ -19,6 +19,7 @@
 #include <linux/slab.h>
 
 #include "u_ether.h"
+#include "u_ether_configfs.h"
 #include "u_eem.h"
 
 #define EEM_HLEN 2
@@ -263,8 +264,10 @@ static int eem_bind(struct usb_configuration *c, struct usb_function *f)
          * with regard to eem_opts->bound access
          */
         if (!eem_opts->bound) {
+                mutex_lock(&eem_opts->lock);
                 gether_set_gadget(eem_opts->net, cdev->gadget);
                 status = gether_register_netdev(eem_opts->net);
+                mutex_unlock(&eem_opts->lock);
                 if (status)
                         return status;
                 eem_opts->bound = true;
@@ -533,6 +536,41 @@ error:
         return status;
 }
 
+static inline struct f_eem_opts *to_f_eem_opts(struct config_item *item)
+{
+        return container_of(to_config_group(item), struct f_eem_opts,
+                            func_inst.group);
+}
+
+/* f_eem_item_ops */
+USB_ETHERNET_CONFIGFS_ITEM(eem);
+
+/* f_eem_opts_dev_addr */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_DEV_ADDR(eem);
+
+/* f_eem_opts_host_addr */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_HOST_ADDR(eem);
+
+/* f_eem_opts_qmult */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_QMULT(eem);
+
+/* f_eem_opts_ifname */
+USB_ETHERNET_CONFIGFS_ITEM_ATTR_IFNAME(eem);
+
+static struct configfs_attribute *eem_attrs[] = {
+        &f_eem_opts_dev_addr.attr,
+        &f_eem_opts_host_addr.attr,
+        &f_eem_opts_qmult.attr,
+        &f_eem_opts_ifname.attr,
+        NULL,
+};
+
+static struct config_item_type eem_func_type = {
+        .ct_item_ops    = &eem_item_ops,
+        .ct_attrs       = eem_attrs,
+        .ct_owner       = THIS_MODULE,
+};
+
 static void eem_free_inst(struct usb_function_instance *f)
 {
         struct f_eem_opts *opts;
@@ -552,20 +590,28 @@ static struct usb_function_instance *eem_alloc_inst(void)
         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
         if (!opts)
                 return ERR_PTR(-ENOMEM);
+        mutex_init(&opts->lock);
         opts->func_inst.free_func_inst = eem_free_inst;
         opts->net = gether_setup_default();
         if (IS_ERR(opts->net))
                 return ERR_CAST(opts->net);
 
+        config_group_init_type_name(&opts->func_inst.group, "", &eem_func_type);
+
         return &opts->func_inst;
 }
 
 static void eem_free(struct usb_function *f)
 {
         struct f_eem *eem;
+        struct f_eem_opts *opts;
 
         eem = func_to_eem(f);
+        opts = container_of(f->fi, struct f_eem_opts, func_inst);
         kfree(eem);
+        mutex_lock(&opts->lock);
+        opts->refcnt--;
+        mutex_unlock(&opts->lock);
 }
 
 static void eem_unbind(struct usb_configuration *c, struct usb_function *f)
@@ -586,8 +632,11 @@ struct usb_function *eem_alloc(struct usb_function_instance *fi)
                 return ERR_PTR(-ENOMEM);
 
         opts = container_of(fi, struct f_eem_opts, func_inst);
+        mutex_lock(&opts->lock);
+        opts->refcnt++;
 
         eem->port.ioport = netdev_priv(opts->net);
+        mutex_unlock(&opts->lock);
         eem->port.cdc_filter = DEFAULT_FILTER;
 
         eem->port.func.name = "cdc_eem";
diff --git a/drivers/usb/gadget/u_eem.h b/drivers/usb/gadget/u_eem.h
index 8f432f2a5e57..e3ae97874c4f 100644
--- a/drivers/usb/gadget/u_eem.h
+++ b/drivers/usb/gadget/u_eem.h
@@ -22,6 +22,15 @@ struct f_eem_opts {
         struct usb_function_instance    func_inst;
         struct net_device               *net;
         bool                            bound;
+
+        /*
+         * Read/write access to configfs attributes is handled by configfs.
+         *
+         * This is to protect the data from concurrent access by read/write
+         * and create symlink/remove symlink.
+         */
+        struct mutex                    lock;
+        int                             refcnt;
 };
 
 #endif /* U_EEM_H */