v4.19.13 snapshot.
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
new file mode 100644
index 0000000..f101347
--- /dev/null
+++ b/drivers/usb/usb-skeleton.c
@@ -0,0 +1,645 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * USB Skeleton driver - 2.2
+ *
+ * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
+ *
+ * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
+ * but has been rewritten to be easier to read and use.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/kref.h>
+#include <linux/uaccess.h>
+#include <linux/usb.h>
+#include <linux/mutex.h>
+
+
+/* Define these values to match your devices */
+#define USB_SKEL_VENDOR_ID 0xfff0
+#define USB_SKEL_PRODUCT_ID 0xfff0
+
+/* table of devices that work with this driver */
+static const struct usb_device_id skel_table[] = {
+ { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
+ { } /* Terminating entry */
+};
+MODULE_DEVICE_TABLE(usb, skel_table);
+
+
+/* Get a minor range for your devices from the usb maintainer */
+#define USB_SKEL_MINOR_BASE 192
+
+/* our private defines. if this grows any larger, use your own .h file */
+#define MAX_TRANSFER (PAGE_SIZE - 512)
+/* MAX_TRANSFER is chosen so that the VM is not stressed by
+ allocations > PAGE_SIZE and the number of packets in a page
+ is an integer 512 is the largest possible packet on EHCI */
+#define WRITES_IN_FLIGHT 8
+/* arbitrarily chosen */
+
+/* Structure to hold all of our device specific stuff */
+struct usb_skel {
+ struct usb_device *udev; /* the usb device for this device */
+ struct usb_interface *interface; /* the interface for this device */
+ struct semaphore limit_sem; /* limiting the number of writes in progress */
+ struct usb_anchor submitted; /* in case we need to retract our submissions */
+ struct urb *bulk_in_urb; /* the urb to read data with */
+ unsigned char *bulk_in_buffer; /* the buffer to receive data */
+ size_t bulk_in_size; /* the size of the receive buffer */
+ size_t bulk_in_filled; /* number of bytes in the buffer */
+ size_t bulk_in_copied; /* already copied to user space */
+ __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
+ __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
+ int errors; /* the last request tanked */
+ bool ongoing_read; /* a read is going on */
+ spinlock_t err_lock; /* lock for errors */
+ struct kref kref;
+ struct mutex io_mutex; /* synchronize I/O with disconnect */
+ wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */
+};
+#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
+
+static struct usb_driver skel_driver;
+static void skel_draw_down(struct usb_skel *dev);
+
+static void skel_delete(struct kref *kref)
+{
+ struct usb_skel *dev = to_skel_dev(kref);
+
+ usb_free_urb(dev->bulk_in_urb);
+ usb_put_dev(dev->udev);
+ kfree(dev->bulk_in_buffer);
+ kfree(dev);
+}
+
+static int skel_open(struct inode *inode, struct file *file)
+{
+ struct usb_skel *dev;
+ struct usb_interface *interface;
+ int subminor;
+ int retval = 0;
+
+ subminor = iminor(inode);
+
+ interface = usb_find_interface(&skel_driver, subminor);
+ if (!interface) {
+ pr_err("%s - error, can't find device for minor %d\n",
+ __func__, subminor);
+ retval = -ENODEV;
+ goto exit;
+ }
+
+ dev = usb_get_intfdata(interface);
+ if (!dev) {
+ retval = -ENODEV;
+ goto exit;
+ }
+
+ retval = usb_autopm_get_interface(interface);
+ if (retval)
+ goto exit;
+
+ /* increment our usage count for the device */
+ kref_get(&dev->kref);
+
+ /* save our object in the file's private structure */
+ file->private_data = dev;
+
+exit:
+ return retval;
+}
+
+static int skel_release(struct inode *inode, struct file *file)
+{
+ struct usb_skel *dev;
+
+ dev = file->private_data;
+ if (dev == NULL)
+ return -ENODEV;
+
+ /* allow the device to be autosuspended */
+ mutex_lock(&dev->io_mutex);
+ if (dev->interface)
+ usb_autopm_put_interface(dev->interface);
+ mutex_unlock(&dev->io_mutex);
+
+ /* decrement the count on our device */
+ kref_put(&dev->kref, skel_delete);
+ return 0;
+}
+
+static int skel_flush(struct file *file, fl_owner_t id)
+{
+ struct usb_skel *dev;
+ int res;
+
+ dev = file->private_data;
+ if (dev == NULL)
+ return -ENODEV;
+
+ /* wait for io to stop */
+ mutex_lock(&dev->io_mutex);
+ skel_draw_down(dev);
+
+ /* read out errors, leave subsequent opens a clean slate */
+ spin_lock_irq(&dev->err_lock);
+ res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
+ dev->errors = 0;
+ spin_unlock_irq(&dev->err_lock);
+
+ mutex_unlock(&dev->io_mutex);
+
+ return res;
+}
+
+static void skel_read_bulk_callback(struct urb *urb)
+{
+ struct usb_skel *dev;
+ unsigned long flags;
+
+ dev = urb->context;
+
+ spin_lock_irqsave(&dev->err_lock, flags);
+ /* sync/async unlink faults aren't errors */
+ if (urb->status) {
+ if (!(urb->status == -ENOENT ||
+ urb->status == -ECONNRESET ||
+ urb->status == -ESHUTDOWN))
+ dev_err(&dev->interface->dev,
+ "%s - nonzero write bulk status received: %d\n",
+ __func__, urb->status);
+
+ dev->errors = urb->status;
+ } else {
+ dev->bulk_in_filled = urb->actual_length;
+ }
+ dev->ongoing_read = 0;
+ spin_unlock_irqrestore(&dev->err_lock, flags);
+
+ wake_up_interruptible(&dev->bulk_in_wait);
+}
+
+static int skel_do_read_io(struct usb_skel *dev, size_t count)
+{
+ int rv;
+
+ /* prepare a read */
+ usb_fill_bulk_urb(dev->bulk_in_urb,
+ dev->udev,
+ usb_rcvbulkpipe(dev->udev,
+ dev->bulk_in_endpointAddr),
+ dev->bulk_in_buffer,
+ min(dev->bulk_in_size, count),
+ skel_read_bulk_callback,
+ dev);
+ /* tell everybody to leave the URB alone */
+ spin_lock_irq(&dev->err_lock);
+ dev->ongoing_read = 1;
+ spin_unlock_irq(&dev->err_lock);
+
+ /* submit bulk in urb, which means no data to deliver */
+ dev->bulk_in_filled = 0;
+ dev->bulk_in_copied = 0;
+
+ /* do it */
+ rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
+ if (rv < 0) {
+ dev_err(&dev->interface->dev,
+ "%s - failed submitting read urb, error %d\n",
+ __func__, rv);
+ rv = (rv == -ENOMEM) ? rv : -EIO;
+ spin_lock_irq(&dev->err_lock);
+ dev->ongoing_read = 0;
+ spin_unlock_irq(&dev->err_lock);
+ }
+
+ return rv;
+}
+
+static ssize_t skel_read(struct file *file, char *buffer, size_t count,
+ loff_t *ppos)
+{
+ struct usb_skel *dev;
+ int rv;
+ bool ongoing_io;
+
+ dev = file->private_data;
+
+ /* if we cannot read at all, return EOF */
+ if (!dev->bulk_in_urb || !count)
+ return 0;
+
+ /* no concurrent readers */
+ rv = mutex_lock_interruptible(&dev->io_mutex);
+ if (rv < 0)
+ return rv;
+
+ if (!dev->interface) { /* disconnect() was called */
+ rv = -ENODEV;
+ goto exit;
+ }
+
+ /* if IO is under way, we must not touch things */
+retry:
+ spin_lock_irq(&dev->err_lock);
+ ongoing_io = dev->ongoing_read;
+ spin_unlock_irq(&dev->err_lock);
+
+ if (ongoing_io) {
+ /* nonblocking IO shall not wait */
+ if (file->f_flags & O_NONBLOCK) {
+ rv = -EAGAIN;
+ goto exit;
+ }
+ /*
+ * IO may take forever
+ * hence wait in an interruptible state
+ */
+ rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
+ if (rv < 0)
+ goto exit;
+ }
+
+ /* errors must be reported */
+ rv = dev->errors;
+ if (rv < 0) {
+ /* any error is reported once */
+ dev->errors = 0;
+ /* to preserve notifications about reset */
+ rv = (rv == -EPIPE) ? rv : -EIO;
+ /* report it */
+ goto exit;
+ }
+
+ /*
+ * if the buffer is filled we may satisfy the read
+ * else we need to start IO
+ */
+
+ if (dev->bulk_in_filled) {
+ /* we had read data */
+ size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
+ size_t chunk = min(available, count);
+
+ if (!available) {
+ /*
+ * all data has been used
+ * actual IO needs to be done
+ */
+ rv = skel_do_read_io(dev, count);
+ if (rv < 0)
+ goto exit;
+ else
+ goto retry;
+ }
+ /*
+ * data is available
+ * chunk tells us how much shall be copied
+ */
+
+ if (copy_to_user(buffer,
+ dev->bulk_in_buffer + dev->bulk_in_copied,
+ chunk))
+ rv = -EFAULT;
+ else
+ rv = chunk;
+
+ dev->bulk_in_copied += chunk;
+
+ /*
+ * if we are asked for more than we have,
+ * we start IO but don't wait
+ */
+ if (available < count)
+ skel_do_read_io(dev, count - chunk);
+ } else {
+ /* no data in the buffer */
+ rv = skel_do_read_io(dev, count);
+ if (rv < 0)
+ goto exit;
+ else
+ goto retry;
+ }
+exit:
+ mutex_unlock(&dev->io_mutex);
+ return rv;
+}
+
+static void skel_write_bulk_callback(struct urb *urb)
+{
+ struct usb_skel *dev;
+ unsigned long flags;
+
+ dev = urb->context;
+
+ /* sync/async unlink faults aren't errors */
+ if (urb->status) {
+ if (!(urb->status == -ENOENT ||
+ urb->status == -ECONNRESET ||
+ urb->status == -ESHUTDOWN))
+ dev_err(&dev->interface->dev,
+ "%s - nonzero write bulk status received: %d\n",
+ __func__, urb->status);
+
+ spin_lock_irqsave(&dev->err_lock, flags);
+ dev->errors = urb->status;
+ spin_unlock_irqrestore(&dev->err_lock, flags);
+ }
+
+ /* free up our allocated buffer */
+ usb_free_coherent(urb->dev, urb->transfer_buffer_length,
+ urb->transfer_buffer, urb->transfer_dma);
+ up(&dev->limit_sem);
+}
+
+static ssize_t skel_write(struct file *file, const char *user_buffer,
+ size_t count, loff_t *ppos)
+{
+ struct usb_skel *dev;
+ int retval = 0;
+ struct urb *urb = NULL;
+ char *buf = NULL;
+ size_t writesize = min(count, (size_t)MAX_TRANSFER);
+
+ dev = file->private_data;
+
+ /* verify that we actually have some data to write */
+ if (count == 0)
+ goto exit;
+
+ /*
+ * limit the number of URBs in flight to stop a user from using up all
+ * RAM
+ */
+ if (!(file->f_flags & O_NONBLOCK)) {
+ if (down_interruptible(&dev->limit_sem)) {
+ retval = -ERESTARTSYS;
+ goto exit;
+ }
+ } else {
+ if (down_trylock(&dev->limit_sem)) {
+ retval = -EAGAIN;
+ goto exit;
+ }
+ }
+
+ spin_lock_irq(&dev->err_lock);
+ retval = dev->errors;
+ if (retval < 0) {
+ /* any error is reported once */
+ dev->errors = 0;
+ /* to preserve notifications about reset */
+ retval = (retval == -EPIPE) ? retval : -EIO;
+ }
+ spin_unlock_irq(&dev->err_lock);
+ if (retval < 0)
+ goto error;
+
+ /* create a urb, and a buffer for it, and copy the data to the urb */
+ urb = usb_alloc_urb(0, GFP_KERNEL);
+ if (!urb) {
+ retval = -ENOMEM;
+ goto error;
+ }
+
+ buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
+ &urb->transfer_dma);
+ if (!buf) {
+ retval = -ENOMEM;
+ goto error;
+ }
+
+ if (copy_from_user(buf, user_buffer, writesize)) {
+ retval = -EFAULT;
+ goto error;
+ }
+
+ /* this lock makes sure we don't submit URBs to gone devices */
+ mutex_lock(&dev->io_mutex);
+ if (!dev->interface) { /* disconnect() was called */
+ mutex_unlock(&dev->io_mutex);
+ retval = -ENODEV;
+ goto error;
+ }
+
+ /* initialize the urb properly */
+ usb_fill_bulk_urb(urb, dev->udev,
+ usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
+ buf, writesize, skel_write_bulk_callback, dev);
+ urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+ usb_anchor_urb(urb, &dev->submitted);
+
+ /* send the data out the bulk port */
+ retval = usb_submit_urb(urb, GFP_KERNEL);
+ mutex_unlock(&dev->io_mutex);
+ if (retval) {
+ dev_err(&dev->interface->dev,
+ "%s - failed submitting write urb, error %d\n",
+ __func__, retval);
+ goto error_unanchor;
+ }
+
+ /*
+ * release our reference to this urb, the USB core will eventually free
+ * it entirely
+ */
+ usb_free_urb(urb);
+
+
+ return writesize;
+
+error_unanchor:
+ usb_unanchor_urb(urb);
+error:
+ if (urb) {
+ usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
+ usb_free_urb(urb);
+ }
+ up(&dev->limit_sem);
+
+exit:
+ return retval;
+}
+
+static const struct file_operations skel_fops = {
+ .owner = THIS_MODULE,
+ .read = skel_read,
+ .write = skel_write,
+ .open = skel_open,
+ .release = skel_release,
+ .flush = skel_flush,
+ .llseek = noop_llseek,
+};
+
+/*
+ * usb class driver info in order to get a minor number from the usb core,
+ * and to have the device registered with the driver core
+ */
+static struct usb_class_driver skel_class = {
+ .name = "skel%d",
+ .fops = &skel_fops,
+ .minor_base = USB_SKEL_MINOR_BASE,
+};
+
+static int skel_probe(struct usb_interface *interface,
+ const struct usb_device_id *id)
+{
+ struct usb_skel *dev;
+ struct usb_endpoint_descriptor *bulk_in, *bulk_out;
+ int retval;
+
+ /* allocate memory for our device state and initialize it */
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ return -ENOMEM;
+
+ kref_init(&dev->kref);
+ sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
+ mutex_init(&dev->io_mutex);
+ spin_lock_init(&dev->err_lock);
+ init_usb_anchor(&dev->submitted);
+ init_waitqueue_head(&dev->bulk_in_wait);
+
+ dev->udev = usb_get_dev(interface_to_usbdev(interface));
+ dev->interface = interface;
+
+ /* set up the endpoint information */
+ /* use only the first bulk-in and bulk-out endpoints */
+ retval = usb_find_common_endpoints(interface->cur_altsetting,
+ &bulk_in, &bulk_out, NULL, NULL);
+ if (retval) {
+ dev_err(&interface->dev,
+ "Could not find both bulk-in and bulk-out endpoints\n");
+ goto error;
+ }
+
+ dev->bulk_in_size = usb_endpoint_maxp(bulk_in);
+ dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
+ dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
+ if (!dev->bulk_in_buffer) {
+ retval = -ENOMEM;
+ goto error;
+ }
+ dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+ if (!dev->bulk_in_urb) {
+ retval = -ENOMEM;
+ goto error;
+ }
+
+ dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress;
+
+ /* save our data pointer in this interface device */
+ usb_set_intfdata(interface, dev);
+
+ /* we can register the device now, as it is ready */
+ retval = usb_register_dev(interface, &skel_class);
+ if (retval) {
+ /* something prevented us from registering this driver */
+ dev_err(&interface->dev,
+ "Not able to get a minor for this device.\n");
+ usb_set_intfdata(interface, NULL);
+ goto error;
+ }
+
+ /* let the user know what node this device is now attached to */
+ dev_info(&interface->dev,
+ "USB Skeleton device now attached to USBSkel-%d",
+ interface->minor);
+ return 0;
+
+error:
+ /* this frees allocated memory */
+ kref_put(&dev->kref, skel_delete);
+
+ return retval;
+}
+
+static void skel_disconnect(struct usb_interface *interface)
+{
+ struct usb_skel *dev;
+ int minor = interface->minor;
+
+ dev = usb_get_intfdata(interface);
+ usb_set_intfdata(interface, NULL);
+
+ /* give back our minor */
+ usb_deregister_dev(interface, &skel_class);
+
+ /* prevent more I/O from starting */
+ mutex_lock(&dev->io_mutex);
+ dev->interface = NULL;
+ mutex_unlock(&dev->io_mutex);
+
+ usb_kill_anchored_urbs(&dev->submitted);
+
+ /* decrement our usage count */
+ kref_put(&dev->kref, skel_delete);
+
+ dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
+}
+
+static void skel_draw_down(struct usb_skel *dev)
+{
+ int time;
+
+ time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
+ if (!time)
+ usb_kill_anchored_urbs(&dev->submitted);
+ usb_kill_urb(dev->bulk_in_urb);
+}
+
+static int skel_suspend(struct usb_interface *intf, pm_message_t message)
+{
+ struct usb_skel *dev = usb_get_intfdata(intf);
+
+ if (!dev)
+ return 0;
+ skel_draw_down(dev);
+ return 0;
+}
+
+static int skel_resume(struct usb_interface *intf)
+{
+ return 0;
+}
+
+static int skel_pre_reset(struct usb_interface *intf)
+{
+ struct usb_skel *dev = usb_get_intfdata(intf);
+
+ mutex_lock(&dev->io_mutex);
+ skel_draw_down(dev);
+
+ return 0;
+}
+
+static int skel_post_reset(struct usb_interface *intf)
+{
+ struct usb_skel *dev = usb_get_intfdata(intf);
+
+ /* we are sure no URBs are active - no locking needed */
+ dev->errors = -EPIPE;
+ mutex_unlock(&dev->io_mutex);
+
+ return 0;
+}
+
+static struct usb_driver skel_driver = {
+ .name = "skeleton",
+ .probe = skel_probe,
+ .disconnect = skel_disconnect,
+ .suspend = skel_suspend,
+ .resume = skel_resume,
+ .pre_reset = skel_pre_reset,
+ .post_reset = skel_post_reset,
+ .id_table = skel_table,
+ .supports_autosuspend = 1,
+};
+
+module_usb_driver(skel_driver);
+
+MODULE_LICENSE("GPL v2");