USB: added dynamic major number for USB endpoints

This patch is an update for Greg K-H's proposed usbfs2:
http://sourceforge.net/mailarchive/message.php?msg_id=19295229

It creates a dynamic major for USB endpoints and fixes
the endpoint minor calculation.

Signed-off-by: Sarah Bailey <saharabeara@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 85 insertions, 13 deletions

diff --git a/drivers/usb/core/endpoint.c b/drivers/usb/core/endpoint.c
index 3b2d137912be..c505b767cee1 100644
--- a/drivers/usb/core/endpoint.c
+++ b/drivers/usb/core/endpoint.c
@@ -10,15 +10,20 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/idr.h>
 #include <linux/usb.h>
 #include "usb.h"
 
-/* endpoint stuff */
+#define MAX_ENDPOINT_MINORS (64*128*32)
+static int usb_endpoint_major;
+static DEFINE_IDR(endpoint_idr);
 
 struct ep_device {
         struct usb_endpoint_descriptor *desc;
         struct usb_device *udev;
         struct device dev;
+        int minor;
 };
 #define to_ep_device(_dev) \
         container_of(_dev, struct ep_device, dev)
@@ -152,6 +157,55 @@ static struct attribute_group ep_dev_attr_grp = {
         .attrs = ep_dev_attrs,
 };
 
+static int usb_endpoint_major_init(void)
+{
+        dev_t dev;
+        int error;
+
+        error = alloc_chrdev_region(&dev, 0, MAX_ENDPOINT_MINORS,
+                                    "usb_endpoint");
+        if (error) {
+                err("unable to get a dynamic major for usb endpoints");
+                return error;
+        }
+        usb_endpoint_major = MAJOR(dev);
+
+        return error;
+}
+
+static void usb_endpoint_major_cleanup(void)
+{
+        unregister_chrdev_region(MKDEV(usb_endpoint_major, 0),
+                                 MAX_ENDPOINT_MINORS);
+}
+
+static int endpoint_get_minor(struct ep_device *ep_dev)
+{
+        static DEFINE_MUTEX(minor_lock);
+        int retval = -ENOMEM;
+        int id;
+
+        mutex_lock(&minor_lock);
+        if (idr_pre_get(&endpoint_idr, GFP_KERNEL) == 0)
+                goto exit;
+
+        retval = idr_get_new(&endpoint_idr, ep_dev, &id);
+        if (retval < 0) {
+                if (retval == -EAGAIN)
+                        retval = -ENOMEM;
+                goto exit;
+        }
+        ep_dev->minor = id & MAX_ID_MASK;
+exit:
+        mutex_unlock(&minor_lock);
+        return retval;
+}
+
+static void endpoint_free_minor(struct ep_device *ep_dev)
+{
+        idr_remove(&endpoint_idr, ep_dev->minor);
+}
+
 static struct endpoint_class {
         struct kref kref;
         struct class *class;
@@ -176,11 +230,20 @@ static int init_endpoint_class(void)
         ep_class->class = class_create(THIS_MODULE, "usb_endpoint");
         if (IS_ERR(ep_class->class)) {
                 result = IS_ERR(ep_class->class);
-                kfree(ep_class);
-                ep_class = NULL;
-                goto exit;
+                goto class_create_error;
         }
 
+        result = usb_endpoint_major_init();
+        if (result)
+                goto endpoint_major_error;
+
+        goto exit;
+
+endpoint_major_error:
+        class_destroy(ep_class->class);
+class_create_error:
+        kfree(ep_class);
+        ep_class = NULL;
 exit:
         return result;
 }
@@ -191,6 +254,7 @@ static void release_endpoint_class(struct kref *kref)
         class_destroy(ep_class->class);
         kfree(ep_class);
         ep_class = NULL;
+        usb_endpoint_major_cleanup();
 }
 
 static void destroy_endpoint_class(void)
@@ -213,7 +277,6 @@ int usb_create_ep_files(struct device *parent,
 {
         char name[8];
         struct ep_device *ep_dev;
-        int minor;
         int retval;
 
         retval = init_endpoint_class();
@@ -226,12 +289,16 @@ int usb_create_ep_files(struct device *parent,
                 goto error_alloc;
         }
 
-        /* fun calculation to determine the minor of this endpoint */
-        minor = (((udev->bus->busnum - 1) * 128) * 16) + (udev->devnum - 1);
+        retval = endpoint_get_minor(ep_dev);
+        if (retval) {
+                dev_err(parent, "can not allocate minor number for %s",
+                        ep_dev->dev.bus_id);
+                goto error_register;
+        }
 
         ep_dev->desc = &endpoint->desc;
         ep_dev->udev = udev;
-        ep_dev->dev.devt = MKDEV(442, minor);   // FIXME fake number...
+        ep_dev->dev.devt = MKDEV(usb_endpoint_major, ep_dev->minor);
         ep_dev->dev.class = ep_class->class;
         ep_dev->dev.parent = parent;
         ep_dev->dev.release = ep_device_release;
@@ -241,7 +308,7 @@ int usb_create_ep_files(struct device *parent,
 
         retval = device_register(&ep_dev->dev);
         if (retval)
-                goto error_register;
+                goto error_chrdev;
         retval = sysfs_create_group(&ep_dev->dev.kobj, &ep_dev_attr_grp);
         if (retval)
                 goto error_group;
@@ -261,6 +328,9 @@ error_group:
         destroy_endpoint_class();
         return retval;
 
+error_chrdev:
+        endpoint_free_minor(ep_dev);
+
 error_register:
         kfree(ep_dev);
 error_alloc:
@@ -271,14 +341,16 @@ exit:
 
 void usb_remove_ep_files(struct usb_host_endpoint *endpoint)
 {
+        struct ep_device *ep_dev = endpoint->ep_dev;
 
-        if (endpoint->ep_dev) {
+        if (ep_dev) {
                 char name[8];
 
                 sprintf(name, "ep_%02x", endpoint->desc.bEndpointAddress);
-                sysfs_remove_link(&endpoint->ep_dev->dev.parent->kobj, name);
-                sysfs_remove_group(&endpoint->ep_dev->dev.kobj, &ep_dev_attr_grp);
-                device_unregister(&endpoint->ep_dev->dev);
+                sysfs_remove_link(&ep_dev->dev.parent->kobj, name);
+                sysfs_remove_group(&ep_dev->dev.kobj, &ep_dev_attr_grp);
+                endpoint_free_minor(ep_dev);
+                device_unregister(&ep_dev->dev);
                 endpoint->ep_dev = NULL;
                 destroy_endpoint_class();
         }