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>

diff --git a/drivers/usb/core/endpoint.c b/drivers/usb/core/endpoint.c
index 3b2d137912beb6dce921d925adccff2873bb6f86..c505b767cee108e7af7af7f2fb0220e75d54c0d5 100644 (file)
--- 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();
        }