diff options
Diffstat (limited to 'drivers/usb/usb-skeleton.c')
| -rw-r--r-- | drivers/usb/usb-skeleton.c | 646 |
1 files changed, 646 insertions, 0 deletions
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c new file mode 100644 index 000000000..d87deee3e --- /dev/null +++ b/drivers/usb/usb-skeleton.c @@ -0,0 +1,646 @@ +// 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 */ + unsigned long disconnected:1; + 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_intf(dev->interface); + 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 */ + usb_autopm_put_interface(dev->interface); + + /* 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 (!count) + return 0; + + /* no concurrent readers */ + rv = mutex_lock_interruptible(&dev->io_mutex); + if (rv < 0) + return rv; + + if (dev->disconnected) { /* 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_t(size_t, count, 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->disconnected) { /* 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 = usb_get_intf(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->disconnected = 1; + mutex_unlock(&dev->io_mutex); + + usb_kill_urb(dev->bulk_in_urb); + 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"); |