1 files changed, 1085 insertions, 0 deletions

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
new file mode 100644
index 000000000..f453b3c7e
--- /dev/null
+++ b/drivers/uio/uio.c
@@ -0,0 +1,1085 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * drivers/uio/uio.c
+ *
+ * Copyright(C) 2005, Benedikt Spranger <b.spranger@linutronix.de>
+ * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
+ * Copyright(C) 2006, Hans J. Koch <hjk@hansjkoch.de>
+ * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
+ *
+ * Userspace IO
+ *
+ * Base Functions
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/idr.h>
+#include <linux/sched/signal.h>
+#include <linux/string.h>
+#include <linux/kobject.h>
+#include <linux/cdev.h>
+#include <linux/uio_driver.h>
+
+#define UIO_MAX_DEVICES		(1U << MINORBITS)
+
+static int uio_major;
+static struct cdev *uio_cdev;
+static DEFINE_IDR(uio_idr);
+static const struct file_operations uio_fops;
+
+/* Protect idr accesses */
+static DEFINE_MUTEX(minor_lock);
+
+/*
+ * attributes
+ */
+
+struct uio_map {
+	struct kobject kobj;
+	struct uio_mem *mem;
+};
+#define to_map(map) container_of(map, struct uio_map, kobj)
+
+static ssize_t map_name_show(struct uio_mem *mem, char *buf)
+{
+	if (unlikely(!mem->name))
+		mem->name = "";
+
+	return sprintf(buf, "%s\n", mem->name);
+}
+
+static ssize_t map_addr_show(struct uio_mem *mem, char *buf)
+{
+	return sprintf(buf, "%pa\n", &mem->addr);
+}
+
+static ssize_t map_size_show(struct uio_mem *mem, char *buf)
+{
+	return sprintf(buf, "%pa\n", &mem->size);
+}
+
+static ssize_t map_offset_show(struct uio_mem *mem, char *buf)
+{
+	return sprintf(buf, "0x%llx\n", (unsigned long long)mem->offs);
+}
+
+struct map_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct uio_mem *, char *);
+	ssize_t (*store)(struct uio_mem *, const char *, size_t);
+};
+
+static struct map_sysfs_entry name_attribute =
+	__ATTR(name, S_IRUGO, map_name_show, NULL);
+static struct map_sysfs_entry addr_attribute =
+	__ATTR(addr, S_IRUGO, map_addr_show, NULL);
+static struct map_sysfs_entry size_attribute =
+	__ATTR(size, S_IRUGO, map_size_show, NULL);
+static struct map_sysfs_entry offset_attribute =
+	__ATTR(offset, S_IRUGO, map_offset_show, NULL);
+
+static struct attribute *attrs[] = {
+	&name_attribute.attr,
+	&addr_attribute.attr,
+	&size_attribute.attr,
+	&offset_attribute.attr,
+	NULL,	/* need to NULL terminate the list of attributes */
+};
+
+static void map_release(struct kobject *kobj)
+{
+	struct uio_map *map = to_map(kobj);
+	kfree(map);
+}
+
+static ssize_t map_type_show(struct kobject *kobj, struct attribute *attr,
+			     char *buf)
+{
+	struct uio_map *map = to_map(kobj);
+	struct uio_mem *mem = map->mem;
+	struct map_sysfs_entry *entry;
+
+	entry = container_of(attr, struct map_sysfs_entry, attr);
+
+	if (!entry->show)
+		return -EIO;
+
+	return entry->show(mem, buf);
+}
+
+static const struct sysfs_ops map_sysfs_ops = {
+	.show = map_type_show,
+};
+
+static struct kobj_type map_attr_type = {
+	.release	= map_release,
+	.sysfs_ops	= &map_sysfs_ops,
+	.default_attrs	= attrs,
+};
+
+struct uio_portio {
+	struct kobject kobj;
+	struct uio_port *port;
+};
+#define to_portio(portio) container_of(portio, struct uio_portio, kobj)
+
+static ssize_t portio_name_show(struct uio_port *port, char *buf)
+{
+	if (unlikely(!port->name))
+		port->name = "";
+
+	return sprintf(buf, "%s\n", port->name);
+}
+
+static ssize_t portio_start_show(struct uio_port *port, char *buf)
+{
+	return sprintf(buf, "0x%lx\n", port->start);
+}
+
+static ssize_t portio_size_show(struct uio_port *port, char *buf)
+{
+	return sprintf(buf, "0x%lx\n", port->size);
+}
+
+static ssize_t portio_porttype_show(struct uio_port *port, char *buf)
+{
+	const char *porttypes[] = {"none", "x86", "gpio", "other"};
+
+	if ((port->porttype < 0) || (port->porttype > UIO_PORT_OTHER))
+		return -EINVAL;
+
+	return sprintf(buf, "port_%s\n", porttypes[port->porttype]);
+}
+
+struct portio_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct uio_port *, char *);
+	ssize_t (*store)(struct uio_port *, const char *, size_t);
+};
+
+static struct portio_sysfs_entry portio_name_attribute =
+	__ATTR(name, S_IRUGO, portio_name_show, NULL);
+static struct portio_sysfs_entry portio_start_attribute =
+	__ATTR(start, S_IRUGO, portio_start_show, NULL);
+static struct portio_sysfs_entry portio_size_attribute =
+	__ATTR(size, S_IRUGO, portio_size_show, NULL);
+static struct portio_sysfs_entry portio_porttype_attribute =
+	__ATTR(porttype, S_IRUGO, portio_porttype_show, NULL);
+
+static struct attribute *portio_attrs[] = {
+	&portio_name_attribute.attr,
+	&portio_start_attribute.attr,
+	&portio_size_attribute.attr,
+	&portio_porttype_attribute.attr,
+	NULL,
+};
+
+static void portio_release(struct kobject *kobj)
+{
+	struct uio_portio *portio = to_portio(kobj);
+	kfree(portio);
+}
+
+static ssize_t portio_type_show(struct kobject *kobj, struct attribute *attr,
+			     char *buf)
+{
+	struct uio_portio *portio = to_portio(kobj);
+	struct uio_port *port = portio->port;
+	struct portio_sysfs_entry *entry;
+
+	entry = container_of(attr, struct portio_sysfs_entry, attr);
+
+	if (!entry->show)
+		return -EIO;
+
+	return entry->show(port, buf);
+}
+
+static const struct sysfs_ops portio_sysfs_ops = {
+	.show = portio_type_show,
+};
+
+static struct kobj_type portio_attr_type = {
+	.release	= portio_release,
+	.sysfs_ops	= &portio_sysfs_ops,
+	.default_attrs	= portio_attrs,
+};
+
+static ssize_t name_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct uio_device *idev = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info) {
+		ret = -EINVAL;
+		dev_err(dev, "the device has been unregistered\n");
+		goto out;
+	}
+
+	ret = sprintf(buf, "%s\n", idev->info->name);
+
+out:
+	mutex_unlock(&idev->info_lock);
+	return ret;
+}
+static DEVICE_ATTR_RO(name);
+
+static ssize_t version_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	struct uio_device *idev = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info) {
+		ret = -EINVAL;
+		dev_err(dev, "the device has been unregistered\n");
+		goto out;
+	}
+
+	ret = sprintf(buf, "%s\n", idev->info->version);
+
+out:
+	mutex_unlock(&idev->info_lock);
+	return ret;
+}
+static DEVICE_ATTR_RO(version);
+
+static ssize_t event_show(struct device *dev,
+			  struct device_attribute *attr, char *buf)
+{
+	struct uio_device *idev = dev_get_drvdata(dev);
+	return sprintf(buf, "%u\n", (unsigned int)atomic_read(&idev->event));
+}
+static DEVICE_ATTR_RO(event);
+
+static struct attribute *uio_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_version.attr,
+	&dev_attr_event.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(uio);
+
+/* UIO class infrastructure */
+static struct class uio_class = {
+	.name = "uio",
+	.dev_groups = uio_groups,
+};
+
+static bool uio_class_registered;
+
+/*
+ * device functions
+ */
+static int uio_dev_add_attributes(struct uio_device *idev)
+{
+	int ret;
+	int mi, pi;
+	int map_found = 0;
+	int portio_found = 0;
+	struct uio_mem *mem;
+	struct uio_map *map;
+	struct uio_port *port;
+	struct uio_portio *portio;
+
+	for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
+		mem = &idev->info->mem[mi];
+		if (mem->size == 0)
+			break;
+		if (!map_found) {
+			map_found = 1;
+			idev->map_dir = kobject_create_and_add("maps",
+							&idev->dev.kobj);
+			if (!idev->map_dir) {
+				ret = -ENOMEM;
+				goto err_map;
+			}
+		}
+		map = kzalloc(sizeof(*map), GFP_KERNEL);
+		if (!map) {
+			ret = -ENOMEM;
+			goto err_map;
+		}
+		kobject_init(&map->kobj, &map_attr_type);
+		map->mem = mem;
+		mem->map = map;
+		ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
+		if (ret)
+			goto err_map_kobj;
+		ret = kobject_uevent(&map->kobj, KOBJ_ADD);
+		if (ret)
+			goto err_map_kobj;
+	}
+
+	for (pi = 0; pi < MAX_UIO_PORT_REGIONS; pi++) {
+		port = &idev->info->port[pi];
+		if (port->size == 0)
+			break;
+		if (!portio_found) {
+			portio_found = 1;
+			idev->portio_dir = kobject_create_and_add("portio",
+							&idev->dev.kobj);
+			if (!idev->portio_dir) {
+				ret = -ENOMEM;
+				goto err_portio;
+			}
+		}
+		portio = kzalloc(sizeof(*portio), GFP_KERNEL);
+		if (!portio) {
+			ret = -ENOMEM;
+			goto err_portio;
+		}
+		kobject_init(&portio->kobj, &portio_attr_type);
+		portio->port = port;
+		port->portio = portio;
+		ret = kobject_add(&portio->kobj, idev->portio_dir,
+							"port%d", pi);
+		if (ret)
+			goto err_portio_kobj;
+		ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
+		if (ret)
+			goto err_portio_kobj;
+	}
+
+	return 0;
+
+err_portio:
+	pi--;
+err_portio_kobj:
+	for (; pi >= 0; pi--) {
+		port = &idev->info->port[pi];
+		portio = port->portio;
+		kobject_put(&portio->kobj);
+	}
+	kobject_put(idev->portio_dir);
+err_map:
+	mi--;
+err_map_kobj:
+	for (; mi >= 0; mi--) {
+		mem = &idev->info->mem[mi];
+		map = mem->map;
+		kobject_put(&map->kobj);
+	}
+	kobject_put(idev->map_dir);
+	dev_err(&idev->dev, "error creating sysfs files (%d)\n", ret);
+	return ret;
+}
+
+static void uio_dev_del_attributes(struct uio_device *idev)
+{
+	int i;
+	struct uio_mem *mem;
+	struct uio_port *port;
+
+	for (i = 0; i < MAX_UIO_MAPS; i++) {
+		mem = &idev->info->mem[i];
+		if (mem->size == 0)
+			break;
+		kobject_put(&mem->map->kobj);
+	}
+	kobject_put(idev->map_dir);
+
+	for (i = 0; i < MAX_UIO_PORT_REGIONS; i++) {
+		port = &idev->info->port[i];
+		if (port->size == 0)
+			break;
+		kobject_put(&port->portio->kobj);
+	}
+	kobject_put(idev->portio_dir);
+}
+
+static int uio_get_minor(struct uio_device *idev)
+{
+	int retval;
+
+	mutex_lock(&minor_lock);
+	retval = idr_alloc(&uio_idr, idev, 0, UIO_MAX_DEVICES, GFP_KERNEL);
+	if (retval >= 0) {
+		idev->minor = retval;
+		retval = 0;
+	} else if (retval == -ENOSPC) {
+		dev_err(&idev->dev, "too many uio devices\n");
+		retval = -EINVAL;
+	}
+	mutex_unlock(&minor_lock);
+	return retval;
+}
+
+static void uio_free_minor(unsigned long minor)
+{
+	mutex_lock(&minor_lock);
+	idr_remove(&uio_idr, minor);
+	mutex_unlock(&minor_lock);
+}
+
+/**
+ * uio_event_notify - trigger an interrupt event
+ * @info: UIO device capabilities
+ */
+void uio_event_notify(struct uio_info *info)
+{
+	struct uio_device *idev = info->uio_dev;
+
+	atomic_inc(&idev->event);
+	wake_up_interruptible(&idev->wait);
+	kill_fasync(&idev->async_queue, SIGIO, POLL_IN);
+}
+EXPORT_SYMBOL_GPL(uio_event_notify);
+
+/**
+ * uio_interrupt - hardware interrupt handler
+ * @irq: IRQ number, can be UIO_IRQ_CYCLIC for cyclic timer
+ * @dev_id: Pointer to the devices uio_device structure
+ */
+static irqreturn_t uio_interrupt(int irq, void *dev_id)
+{
+	struct uio_device *idev = (struct uio_device *)dev_id;
+	irqreturn_t ret;
+
+	ret = idev->info->handler(irq, idev->info);
+	if (ret == IRQ_HANDLED)
+		uio_event_notify(idev->info);
+
+	return ret;
+}
+
+struct uio_listener {
+	struct uio_device *dev;
+	s32 event_count;
+};
+
+static int uio_open(struct inode *inode, struct file *filep)
+{
+	struct uio_device *idev;
+	struct uio_listener *listener;
+	int ret = 0;
+
+	mutex_lock(&minor_lock);
+	idev = idr_find(&uio_idr, iminor(inode));
+	if (!idev) {
+		ret = -ENODEV;
+		mutex_unlock(&minor_lock);
+		goto out;
+	}
+	get_device(&idev->dev);
+	mutex_unlock(&minor_lock);
+
+	if (!try_module_get(idev->owner)) {
+		ret = -ENODEV;
+		goto err_module_get;
+	}
+
+	listener = kmalloc(sizeof(*listener), GFP_KERNEL);
+	if (!listener) {
+		ret = -ENOMEM;
+		goto err_alloc_listener;
+	}
+
+	listener->dev = idev;
+	listener->event_count = atomic_read(&idev->event);
+	filep->private_data = listener;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info) {
+		mutex_unlock(&idev->info_lock);
+		ret = -EINVAL;
+		goto err_infoopen;
+	}
+
+	if (idev->info->open)
+		ret = idev->info->open(idev->info, inode);
+	mutex_unlock(&idev->info_lock);
+	if (ret)
+		goto err_infoopen;
+
+	return 0;
+
+err_infoopen:
+	kfree(listener);
+
+err_alloc_listener:
+	module_put(idev->owner);
+
+err_module_get:
+	put_device(&idev->dev);
+
+out:
+	return ret;
+}
+
+static int uio_fasync(int fd, struct file *filep, int on)
+{
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+
+	return fasync_helper(fd, filep, on, &idev->async_queue);
+}
+
+static int uio_release(struct inode *inode, struct file *filep)
+{
+	int ret = 0;
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+
+	mutex_lock(&idev->info_lock);
+	if (idev->info && idev->info->release)
+		ret = idev->info->release(idev->info, inode);
+	mutex_unlock(&idev->info_lock);
+
+	module_put(idev->owner);
+	kfree(listener);
+	put_device(&idev->dev);
+	return ret;
+}
+
+static __poll_t uio_poll(struct file *filep, poll_table *wait)
+{
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+	__poll_t ret = 0;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info || !idev->info->irq)
+		ret = -EIO;
+	mutex_unlock(&idev->info_lock);
+
+	if (ret)
+		return ret;
+
+	poll_wait(filep, &idev->wait, wait);
+	if (listener->event_count != atomic_read(&idev->event))
+		return EPOLLIN | EPOLLRDNORM;
+	return 0;
+}
+
+static ssize_t uio_read(struct file *filep, char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+	DECLARE_WAITQUEUE(wait, current);
+	ssize_t retval = 0;
+	s32 event_count;
+
+	if (count != sizeof(s32))
+		return -EINVAL;
+
+	add_wait_queue(&idev->wait, &wait);
+
+	do {
+		mutex_lock(&idev->info_lock);
+		if (!idev->info || !idev->info->irq) {
+			retval = -EIO;
+			mutex_unlock(&idev->info_lock);
+			break;
+		}
+		mutex_unlock(&idev->info_lock);
+
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		event_count = atomic_read(&idev->event);
+		if (event_count != listener->event_count) {
+			__set_current_state(TASK_RUNNING);
+			if (copy_to_user(buf, &event_count, count))
+				retval = -EFAULT;
+			else {
+				listener->event_count = event_count;
+				retval = count;
+			}
+			break;
+		}
+
+		if (filep->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			break;
+		}
+
+		if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			break;
+		}
+		schedule();
+	} while (1);
+
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(&idev->wait, &wait);
+
+	return retval;
+}
+
+static ssize_t uio_write(struct file *filep, const char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+	ssize_t retval;
+	s32 irq_on;
+
+	if (count != sizeof(s32))
+		return -EINVAL;
+
+	if (copy_from_user(&irq_on, buf, count))
+		return -EFAULT;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info) {
+		retval = -EINVAL;
+		goto out;
+	}
+
+	if (!idev->info->irq) {
+		retval = -EIO;
+		goto out;
+	}
+
+	if (!idev->info->irqcontrol) {
+		retval = -ENOSYS;
+		goto out;
+	}
+
+	retval = idev->info->irqcontrol(idev->info, irq_on);
+
+out:
+	mutex_unlock(&idev->info_lock);
+	return retval ? retval : sizeof(s32);
+}
+
+static int uio_find_mem_index(struct vm_area_struct *vma)
+{
+	struct uio_device *idev = vma->vm_private_data;
+
+	if (vma->vm_pgoff < MAX_UIO_MAPS) {
+		if (idev->info->mem[vma->vm_pgoff].size == 0)
+			return -1;
+		return (int)vma->vm_pgoff;
+	}
+	return -1;
+}
+
+static vm_fault_t uio_vma_fault(struct vm_fault *vmf)
+{
+	struct uio_device *idev = vmf->vma->vm_private_data;
+	struct page *page;
+	unsigned long offset;
+	void *addr;
+	vm_fault_t ret = 0;
+	int mi;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info) {
+		ret = VM_FAULT_SIGBUS;
+		goto out;
+	}
+
+	mi = uio_find_mem_index(vmf->vma);
+	if (mi < 0) {
+		ret = VM_FAULT_SIGBUS;
+		goto out;
+	}
+
+	/*
+	 * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
+	 * to use mem[N].
+	 */
+	offset = (vmf->pgoff - mi) << PAGE_SHIFT;
+
+	addr = (void *)(unsigned long)idev->info->mem[mi].addr + offset;
+	if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
+		page = virt_to_page(addr);
+	else
+		page = vmalloc_to_page(addr);
+	get_page(page);
+	vmf->page = page;
+
+out:
+	mutex_unlock(&idev->info_lock);
+
+	return ret;
+}
+
+static const struct vm_operations_struct uio_logical_vm_ops = {
+	.fault = uio_vma_fault,
+};
+
+static int uio_mmap_logical(struct vm_area_struct *vma)
+{
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_ops = &uio_logical_vm_ops;
+	return 0;
+}
+
+static const struct vm_operations_struct uio_physical_vm_ops = {
+#ifdef CONFIG_HAVE_IOREMAP_PROT
+	.access = generic_access_phys,
+#endif
+};
+
+static int uio_mmap_physical(struct vm_area_struct *vma)
+{
+	struct uio_device *idev = vma->vm_private_data;
+	int mi = uio_find_mem_index(vma);
+	struct uio_mem *mem;
+
+	if (mi < 0)
+		return -EINVAL;
+	mem = idev->info->mem + mi;
+
+	if (mem->addr & ~PAGE_MASK)
+		return -ENODEV;
+	if (vma->vm_end - vma->vm_start > mem->size)
+		return -EINVAL;
+
+	vma->vm_ops = &uio_physical_vm_ops;
+	if (idev->info->mem[mi].memtype == UIO_MEM_PHYS)
+		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	/*
+	 * We cannot use the vm_iomap_memory() helper here,
+	 * because vma->vm_pgoff is the map index we looked
+	 * up above in uio_find_mem_index(), rather than an
+	 * actual page offset into the mmap.
+	 *
+	 * So we just do the physical mmap without a page
+	 * offset.
+	 */
+	return remap_pfn_range(vma,
+			       vma->vm_start,
+			       mem->addr >> PAGE_SHIFT,
+			       vma->vm_end - vma->vm_start,
+			       vma->vm_page_prot);
+}
+
+static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
+{
+	struct uio_listener *listener = filep->private_data;
+	struct uio_device *idev = listener->dev;
+	int mi;
+	unsigned long requested_pages, actual_pages;
+	int ret = 0;
+
+	if (vma->vm_end < vma->vm_start)
+		return -EINVAL;
+
+	vma->vm_private_data = idev;
+
+	mutex_lock(&idev->info_lock);
+	if (!idev->info) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mi = uio_find_mem_index(vma);
+	if (mi < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	requested_pages = vma_pages(vma);
+	actual_pages = ((idev->info->mem[mi].addr & ~PAGE_MASK)
+			+ idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
+	if (requested_pages > actual_pages) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (idev->info->mmap) {
+		ret = idev->info->mmap(idev->info, vma);
+		goto out;
+	}
+
+	switch (idev->info->mem[mi].memtype) {
+	case UIO_MEM_IOVA:
+	case UIO_MEM_PHYS:
+		ret = uio_mmap_physical(vma);
+		break;
+	case UIO_MEM_LOGICAL:
+	case UIO_MEM_VIRTUAL:
+		ret = uio_mmap_logical(vma);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+ out:
+	mutex_unlock(&idev->info_lock);
+	return ret;
+}
+
+static const struct file_operations uio_fops = {
+	.owner		= THIS_MODULE,
+	.open		= uio_open,
+	.release	= uio_release,
+	.read		= uio_read,
+	.write		= uio_write,
+	.mmap		= uio_mmap,
+	.poll		= uio_poll,
+	.fasync		= uio_fasync,
+	.llseek		= noop_llseek,
+};
+
+static int uio_major_init(void)
+{
+	static const char name[] = "uio";
+	struct cdev *cdev = NULL;
+	dev_t uio_dev = 0;
+	int result;
+
+	result = alloc_chrdev_region(&uio_dev, 0, UIO_MAX_DEVICES, name);
+	if (result)
+		goto out;
+
+	result = -ENOMEM;
+	cdev = cdev_alloc();
+	if (!cdev)
+		goto out_unregister;
+
+	cdev->owner = THIS_MODULE;
+	cdev->ops = &uio_fops;
+	kobject_set_name(&cdev->kobj, "%s", name);
+
+	result = cdev_add(cdev, uio_dev, UIO_MAX_DEVICES);
+	if (result)
+		goto out_put;
+
+	uio_major = MAJOR(uio_dev);
+	uio_cdev = cdev;
+	return 0;
+out_put:
+	kobject_put(&cdev->kobj);
+out_unregister:
+	unregister_chrdev_region(uio_dev, UIO_MAX_DEVICES);
+out:
+	return result;
+}
+
+static void uio_major_cleanup(void)
+{
+	unregister_chrdev_region(MKDEV(uio_major, 0), UIO_MAX_DEVICES);
+	cdev_del(uio_cdev);
+}
+
+static int init_uio_class(void)
+{
+	int ret;
+
+	/* This is the first time in here, set everything up properly */
+	ret = uio_major_init();
+	if (ret)
+		goto exit;
+
+	ret = class_register(&uio_class);
+	if (ret) {
+		printk(KERN_ERR "class_register failed for uio\n");
+		goto err_class_register;
+	}
+
+	uio_class_registered = true;
+
+	return 0;
+
+err_class_register:
+	uio_major_cleanup();
+exit:
+	return ret;
+}
+
+static void release_uio_class(void)
+{
+	uio_class_registered = false;
+	class_unregister(&uio_class);
+	uio_major_cleanup();
+}
+
+static void uio_device_release(struct device *dev)
+{
+	struct uio_device *idev = dev_get_drvdata(dev);
+
+	kfree(idev);
+}
+
+/**
+ * uio_register_device - register a new userspace IO device
+ * @owner:	module that creates the new device
+ * @parent:	parent device
+ * @info:	UIO device capabilities
+ *
+ * returns zero on success or a negative error code.
+ */
+int __uio_register_device(struct module *owner,
+			  struct device *parent,
+			  struct uio_info *info)
+{
+	struct uio_device *idev;
+	int ret = 0;
+
+	if (!uio_class_registered)
+		return -EPROBE_DEFER;
+
+	if (!parent || !info || !info->name || !info->version)
+		return -EINVAL;
+
+	info->uio_dev = NULL;
+
+	idev = kzalloc(sizeof(*idev), GFP_KERNEL);
+	if (!idev) {
+		return -ENOMEM;
+	}
+
+	idev->owner = owner;
+	idev->info = info;
+	mutex_init(&idev->info_lock);
+	init_waitqueue_head(&idev->wait);
+	atomic_set(&idev->event, 0);
+
+	ret = uio_get_minor(idev);
+	if (ret) {
+		kfree(idev);
+		return ret;
+	}
+
+	device_initialize(&idev->dev);
+	idev->dev.devt = MKDEV(uio_major, idev->minor);
+	idev->dev.class = &uio_class;
+	idev->dev.parent = parent;
+	idev->dev.release = uio_device_release;
+	dev_set_drvdata(&idev->dev, idev);
+
+	ret = dev_set_name(&idev->dev, "uio%d", idev->minor);
+	if (ret)
+		goto err_device_create;
+
+	ret = device_add(&idev->dev);
+	if (ret)
+		goto err_device_create;
+
+	ret = uio_dev_add_attributes(idev);
+	if (ret)
+		goto err_uio_dev_add_attributes;
+
+	info->uio_dev = idev;
+
+	if (info->irq && (info->irq != UIO_IRQ_CUSTOM)) {
+		/*
+		 * Note that we deliberately don't use devm_request_irq
+		 * here. The parent module can unregister the UIO device
+		 * and call pci_disable_msi, which requires that this
+		 * irq has been freed. However, the device may have open
+		 * FDs at the time of unregister and therefore may not be
+		 * freed until they are released.
+		 */
+		ret = request_irq(info->irq, uio_interrupt,
+				  info->irq_flags, info->name, idev);
+		if (ret) {
+			info->uio_dev = NULL;
+			goto err_request_irq;
+		}
+	}
+
+	return 0;
+
+err_request_irq:
+	uio_dev_del_attributes(idev);
+err_uio_dev_add_attributes:
+	device_del(&idev->dev);
+err_device_create:
+	uio_free_minor(idev->minor);
+	put_device(&idev->dev);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__uio_register_device);
+
+static void devm_uio_unregister_device(struct device *dev, void *res)
+{
+	uio_unregister_device(*(struct uio_info **)res);
+}
+
+/**
+ * devm_uio_register_device - Resource managed uio_register_device()
+ * @owner:	module that creates the new device
+ * @parent:	parent device
+ * @info:	UIO device capabilities
+ *
+ * returns zero on success or a negative error code.
+ */
+int __devm_uio_register_device(struct module *owner,
+			       struct device *parent,
+			       struct uio_info *info)
+{
+	struct uio_info **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_uio_unregister_device, sizeof(*ptr),
+			   GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	*ptr = info;
+	ret = __uio_register_device(owner, parent, info);
+	if (ret) {
+		devres_free(ptr);
+		return ret;
+	}
+
+	devres_add(parent, ptr);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__devm_uio_register_device);
+
+/**
+ * uio_unregister_device - unregister a industrial IO device
+ * @info:	UIO device capabilities
+ *
+ */
+void uio_unregister_device(struct uio_info *info)
+{
+	struct uio_device *idev;
+	unsigned long minor;
+
+	if (!info || !info->uio_dev)
+		return;
+
+	idev = info->uio_dev;
+	minor = idev->minor;
+
+	mutex_lock(&idev->info_lock);
+	uio_dev_del_attributes(idev);
+
+	if (info->irq && info->irq != UIO_IRQ_CUSTOM)
+		free_irq(info->irq, idev);
+
+	idev->info = NULL;
+	mutex_unlock(&idev->info_lock);
+
+	wake_up_interruptible(&idev->wait);
+	kill_fasync(&idev->async_queue, SIGIO, POLL_HUP);
+
+	uio_free_minor(minor);
+	device_unregister(&idev->dev);
+
+	return;
+}
+EXPORT_SYMBOL_GPL(uio_unregister_device);
+
+static int __init uio_init(void)
+{
+	return init_uio_class();
+}
+
+static void __exit uio_exit(void)
+{
+	release_uio_class();
+	idr_destroy(&uio_idr);
+}
+
+module_init(uio_init)
+module_exit(uio_exit)
+MODULE_LICENSE("GPL v2");