// 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_obj(*dev); if (!dev) return -ENOMEM; kref_init(&dev->kref);Lines 1–500 of 645. 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// 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_obj(*dev); if (!dev) return -ENOMEM; kref_init(&dev->kref);