UIO: Add the User IO core code

This interface allows the ability to write the majority of a driver in
userspace with only a very small shell of a driver in the kernel itself.
It uses a char device and sysfs to interact with a userspace process to
process interrupts and control memory accesses.

See the docbook documentation for more details on how to use this
interface.

From: Hans J. Koch <hjk@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 718 insertions, 0 deletions

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
new file mode 100644
index 000000000000..6b1a62d45e46
--- /dev/null
+++ b/drivers/uio/Kconfig
@@ -0,0 +1,16 @@
+menu "Userspace I/O"
+        depends on !S390
+
+config UIO
+        tristate "Userspace I/O drivers"
+        default n
+        help
+          Enable this to allow the userspace driver core code to be
+          built.  This code allows userspace programs easy access to
+          kernel interrupts and memory locations, allowing some drivers
+          to be written in userspace.  Note that a small kernel driver
+          is also required for interrupt handling to work properly.
+
+          If you don't know what to do here, say N.
+
+endmenu
diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
new file mode 100644
index 000000000000..9b7c83063e15
--- /dev/null
+++ b/drivers/uio/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_UIO) += uio.o
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
new file mode 100644
index 000000000000..865f32b63b5c
--- /dev/null
+++ b/drivers/uio/uio.c
@@ -0,0 +1,701 @@
+/*
+ * 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@linutronix.de>
+ * Copyright(C) 2006, Greg Kroah-Hartman <greg@kroah.com>
+ *
+ * Userspace IO
+ *
+ * Base Functions
+ *
+ * Licensed under the GPLv2 only.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/device.h>
+#include <linux/mm.h>
+#include <linux/idr.h>
+#include <linux/string.h>
+#include <linux/kobject.h>
+#include <linux/uio_driver.h>
+
+#define UIO_MAX_DEVICES 255
+
+struct uio_device {
+        struct module           *owner;
+        struct device           *dev;
+        int                     minor;
+        atomic_t                event;
+        struct fasync_struct    *async_queue;
+        wait_queue_head_t       wait;
+        int                     vma_count;
+        struct uio_info         *info;
+        struct kset             map_attr_kset;
+};
+
+static int uio_major;
+static DEFINE_IDR(uio_idr);
+static struct file_operations uio_fops;
+
+/* UIO class infrastructure */
+static struct uio_class {
+        struct kref kref;
+        struct class *class;
+} *uio_class;
+
+/*
+ * attributes
+ */
+
+static struct attribute attr_addr = {
+        .name  = "addr",
+        .mode  = S_IRUGO,
+};
+
+static struct attribute attr_size = {
+        .name  = "size",
+        .mode  = S_IRUGO,
+};
+
+static struct attribute* map_attrs[] = {
+        &attr_addr, &attr_size, NULL
+};
+
+static ssize_t map_attr_show(struct kobject *kobj, struct attribute *attr,
+                             char *buf)
+{
+        struct uio_mem *mem = container_of(kobj, struct uio_mem, kobj);
+
+        if (strncmp(attr->name,"addr",4) == 0)
+                return sprintf(buf, "0x%lx\n", mem->addr);
+
+        if (strncmp(attr->name,"size",4) == 0)
+                return sprintf(buf, "0x%lx\n", mem->size);
+
+        return -ENODEV;
+}
+
+static void map_attr_release(struct kobject *kobj)
+{
+        /* TODO ??? */
+}
+
+static struct sysfs_ops map_attr_ops = {
+        .show  = map_attr_show,
+};
+
+static struct kobj_type map_attr_type = {
+        .release        = map_attr_release,
+        .sysfs_ops      = &map_attr_ops,
+        .default_attrs  = map_attrs,
+};
+
+static ssize_t show_name(struct device *dev,
+                         struct device_attribute *attr, char *buf)
+{
+        struct uio_device *idev = dev_get_drvdata(dev);
+        if (idev)
+                return sprintf(buf, "%s\n", idev->info->name);
+        else
+                return -ENODEV;
+}
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+
+static ssize_t show_version(struct device *dev,
+                            struct device_attribute *attr, char *buf)
+{
+        struct uio_device *idev = dev_get_drvdata(dev);
+        if (idev)
+                return sprintf(buf, "%s\n", idev->info->version);
+        else
+                return -ENODEV;
+}
+static DEVICE_ATTR(version, S_IRUGO, show_version, NULL);
+
+static ssize_t show_event(struct device *dev,
+                          struct device_attribute *attr, char *buf)
+{
+        struct uio_device *idev = dev_get_drvdata(dev);
+        if (idev)
+                return sprintf(buf, "%u\n",
+                                (unsigned int)atomic_read(&idev->event));
+        else
+                return -ENODEV;
+}
+static DEVICE_ATTR(event, S_IRUGO, show_event, NULL);
+
+static struct attribute *uio_attrs[] = {
+        &dev_attr_name.attr,
+        &dev_attr_version.attr,
+        &dev_attr_event.attr,
+        NULL,
+};
+
+static struct attribute_group uio_attr_grp = {
+        .attrs = uio_attrs,
+};
+
+/*
+ * device functions
+ */
+static int uio_dev_add_attributes(struct uio_device *idev)
+{
+        int ret;
+        int mi;
+        int map_found = 0;
+        struct uio_mem *mem;
+
+        ret = sysfs_create_group(&idev->dev->kobj, &uio_attr_grp);
+        if (ret)
+                goto err_group;
+
+        for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
+                mem = &idev->info->mem[mi];
+                if (mem->size == 0)
+                        break;
+                if (!map_found) {
+                        map_found = 1;
+                        kobject_set_name(&idev->map_attr_kset.kobj,"maps");
+                        idev->map_attr_kset.ktype = &map_attr_type;
+                        idev->map_attr_kset.kobj.parent = &idev->dev->kobj;
+                        ret = kset_register(&idev->map_attr_kset);
+                        if (ret)
+                                goto err_remove_group;
+                }
+                kobject_init(&mem->kobj);
+                kobject_set_name(&mem->kobj,"map%d",mi);
+                mem->kobj.parent = &idev->map_attr_kset.kobj;
+                mem->kobj.kset = &idev->map_attr_kset;
+                ret = kobject_add(&mem->kobj);
+                if (ret)
+                        goto err_remove_maps;
+        }
+
+        return 0;
+
+err_remove_maps:
+        for (mi--; mi>=0; mi--) {
+                mem = &idev->info->mem[mi];
+                kobject_unregister(&mem->kobj);
+        }
+        kset_unregister(&idev->map_attr_kset); /* Needed ? */
+err_remove_group:
+        sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
+err_group:
+        dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
+        return ret;
+}
+
+static void uio_dev_del_attributes(struct uio_device *idev)
+{
+        int mi;
+        struct uio_mem *mem;
+        for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
+                mem = &idev->info->mem[mi];
+                if (mem->size == 0)
+                        break;
+                kobject_unregister(&mem->kobj);
+        }
+        kset_unregister(&idev->map_attr_kset);
+        sysfs_remove_group(&idev->dev->kobj, &uio_attr_grp);
+}
+
+static int uio_get_minor(struct uio_device *idev)
+{
+        static DEFINE_MUTEX(minor_lock);
+        int retval = -ENOMEM;
+        int id;
+
+        mutex_lock(&minor_lock);
+        if (idr_pre_get(&uio_idr, GFP_KERNEL) == 0)
+                goto exit;
+
+        retval = idr_get_new(&uio_idr, idev, &id);
+        if (retval < 0) {
+                if (retval == -EAGAIN)
+                        retval = -ENOMEM;
+                goto exit;
+        }
+        idev->minor = id & MAX_ID_MASK;
+exit:
+        mutex_unlock(&minor_lock);
+        return retval;
+}
+
+static void uio_free_minor(struct uio_device *idev)
+{
+        idr_remove(&uio_idr, idev->minor);
+}
+
+/**
+ * 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 = 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;
+
+        idev = idr_find(&uio_idr, iminor(inode));
+        if (!idev)
+                return -ENODEV;
+
+        listener = kmalloc(sizeof(*listener), GFP_KERNEL);
+        if (!listener)
+                return -ENOMEM;
+
+        listener->dev = idev;
+        listener->event_count = atomic_read(&idev->event);
+        filep->private_data = listener;
+
+        if (idev->info->open) {
+                if (!try_module_get(idev->owner))
+                        return -ENODEV;
+                ret = idev->info->open(idev->info, inode);
+                module_put(idev->owner);
+        }
+
+        if (ret)
+                kfree(listener);
+
+        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;
+
+        if (idev->info->release) {
+                if (!try_module_get(idev->owner))
+                        return -ENODEV;
+                ret = idev->info->release(idev->info, inode);
+                module_put(idev->owner);
+        }
+        if (filep->f_flags & FASYNC)
+                ret = uio_fasync(-1, filep, 0);
+        kfree(listener);
+        return ret;
+}
+
+static unsigned int uio_poll(struct file *filep, poll_table *wait)
+{
+        struct uio_listener *listener = filep->private_data;
+        struct uio_device *idev = listener->dev;
+
+        if (idev->info->irq == UIO_IRQ_NONE)
+                return -EIO;
+
+        poll_wait(filep, &idev->wait, wait);
+        if (listener->event_count != atomic_read(&idev->event))
+                return POLLIN | POLLRDNORM;
+        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;
+        s32 event_count;
+
+        if (idev->info->irq == UIO_IRQ_NONE)
+                return -EIO;
+
+        if (count != sizeof(s32))
+                return -EINVAL;
+
+        add_wait_queue(&idev->wait, &wait);
+
+        do {
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                event_count = atomic_read(&idev->event);
+                if (event_count != listener->event_count) {
+                        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 int uio_find_mem_index(struct vm_area_struct *vma)
+{
+        int mi;
+        struct uio_device *idev = vma->vm_private_data;
+
+        for (mi = 0; mi < MAX_UIO_MAPS; mi++) {
+                if (idev->info->mem[mi].size == 0)
+                        return -1;
+                if (vma->vm_pgoff == mi)
+                        return mi;
+        }
+        return -1;
+}
+
+static void uio_vma_open(struct vm_area_struct *vma)
+{
+        struct uio_device *idev = vma->vm_private_data;
+        idev->vma_count++;
+}
+
+static void uio_vma_close(struct vm_area_struct *vma)
+{
+        struct uio_device *idev = vma->vm_private_data;
+        idev->vma_count--;
+}
+
+static struct page *uio_vma_nopage(struct vm_area_struct *vma,
+                                   unsigned long address, int *type)
+{
+        struct uio_device *idev = vma->vm_private_data;
+        struct page* page = NOPAGE_SIGBUS;
+
+        int mi = uio_find_mem_index(vma);
+        if (mi < 0)
+                return page;
+
+        if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
+                page = virt_to_page(idev->info->mem[mi].addr);
+        else
+                page = vmalloc_to_page((void*)idev->info->mem[mi].addr);
+        get_page(page);
+        if (type)
+                *type = VM_FAULT_MINOR;
+        return page;
+}
+
+static struct vm_operations_struct uio_vm_ops = {
+        .open = uio_vma_open,
+        .close = uio_vma_close,
+        .nopage = uio_vma_nopage,
+};
+
+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);
+        if (mi < 0)
+                return -EINVAL;
+
+        vma->vm_flags |= VM_IO | VM_RESERVED;
+
+        return remap_pfn_range(vma,
+                               vma->vm_start,
+                               idev->info->mem[mi].addr >> PAGE_SHIFT,
+                               vma->vm_end - vma->vm_start,
+                               vma->vm_page_prot);
+}
+
+static int uio_mmap_logical(struct vm_area_struct *vma)
+{
+        vma->vm_flags |= VM_RESERVED;
+        vma->vm_ops = &uio_vm_ops;
+        uio_vma_open(vma);
+        return 0;
+}
+
+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;
+
+        mi = uio_find_mem_index(vma);
+        if (mi < 0)
+                return -EINVAL;
+
+        requested_pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+        actual_pages = (idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
+        if (requested_pages > actual_pages)
+                return -EINVAL;
+
+        if (idev->info->mmap) {
+                if (!try_module_get(idev->owner))
+                        return -ENODEV;
+                ret = idev->info->mmap(idev->info, vma);
+                module_put(idev->owner);
+                return ret;
+        }
+
+        switch (idev->info->mem[mi].memtype) {
+                case UIO_MEM_PHYS:
+                        return uio_mmap_physical(vma);
+                case UIO_MEM_LOGICAL:
+                case UIO_MEM_VIRTUAL:
+                        return uio_mmap_logical(vma);
+                default:
+                        return -EINVAL;
+        }
+}
+
+static struct file_operations uio_fops = {
+        .owner          = THIS_MODULE,
+        .open           = uio_open,
+        .release        = uio_release,
+        .read           = uio_read,
+        .mmap           = uio_mmap,
+        .poll           = uio_poll,
+        .fasync         = uio_fasync,
+};
+
+static int uio_major_init(void)
+{
+        uio_major = register_chrdev(0, "uio", &uio_fops);
+        if (uio_major < 0)
+                return uio_major;
+        return 0;
+}
+
+static void uio_major_cleanup(void)
+{
+        unregister_chrdev(uio_major, "uio");
+}
+
+static int init_uio_class(void)
+{
+        int ret = 0;
+
+        if (uio_class != NULL) {
+                kref_get(&uio_class->kref);
+                goto exit;
+        }
+
+        /* This is the first time in here, set everything up properly */
+        ret = uio_major_init();
+        if (ret)
+                goto exit;
+
+        uio_class = kzalloc(sizeof(*uio_class), GFP_KERNEL);
+        if (!uio_class) {
+                ret = -ENOMEM;
+                goto err_kzalloc;
+        }
+
+        kref_init(&uio_class->kref);
+        uio_class->class = class_create(THIS_MODULE, "uio");
+        if (IS_ERR(uio_class->class)) {
+                ret = IS_ERR(uio_class->class);
+                printk(KERN_ERR "class_create failed for uio\n");
+                goto err_class_create;
+        }
+        return 0;
+
+err_class_create:
+        kfree(uio_class);
+        uio_class = NULL;
+err_kzalloc:
+        uio_major_cleanup();
+exit:
+        return ret;
+}
+
+static void release_uio_class(struct kref *kref)
+{
+        /* Ok, we cheat as we know we only have one uio_class */
+        class_destroy(uio_class->class);
+        kfree(uio_class);
+        uio_major_cleanup();
+        uio_class = NULL;
+}
+
+static void uio_class_destroy(void)
+{
+        if (uio_class)
+                kref_put(&uio_class->kref, release_uio_class);
+}
+
+/**
+ * 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 (!parent || !info || !info->name || !info->version)
+                return -EINVAL;
+
+        info->uio_dev = NULL;
+
+        ret = init_uio_class();
+        if (ret)
+                return ret;
+
+        idev = kzalloc(sizeof(*idev), GFP_KERNEL);
+        if (!idev) {
+                ret = -ENOMEM;
+                goto err_kzalloc;
+        }
+
+        idev->owner = owner;
+        idev->info = info;
+        init_waitqueue_head(&idev->wait);
+        atomic_set(&idev->event, 0);
+
+        ret = uio_get_minor(idev);
+        if (ret)
+                goto err_get_minor;
+
+        idev->dev = device_create(uio_class->class, parent,
+                                  MKDEV(uio_major, idev->minor),
+                                  "uio%d", idev->minor);
+        if (IS_ERR(idev->dev)) {
+                printk(KERN_ERR "UIO: device register failed\n");
+                ret = PTR_ERR(idev->dev);
+                goto err_device_create;
+        }
+        dev_set_drvdata(idev->dev, idev);
+
+        ret = uio_dev_add_attributes(idev);
+        if (ret)
+                goto err_uio_dev_add_attributes;
+
+        info->uio_dev = idev;
+
+        if (idev->info->irq >= 0) {
+                ret = request_irq(idev->info->irq, uio_interrupt,
+                                  idev->info->irq_flags, idev->info->name, idev);
+                if (ret)
+                        goto err_request_irq;
+        }
+
+        return 0;
+
+err_request_irq:
+        uio_dev_del_attributes(idev);
+err_uio_dev_add_attributes:
+        device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
+err_device_create:
+        uio_free_minor(idev);
+err_get_minor:
+        kfree(idev);
+err_kzalloc:
+        uio_class_destroy();
+        return ret;
+}
+EXPORT_SYMBOL_GPL(__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;
+
+        if (!info || !info->uio_dev)
+                return;
+
+        idev = info->uio_dev;
+
+        uio_free_minor(idev);
+
+        if (info->irq >= 0)
+                free_irq(info->irq, idev);
+
+        uio_dev_del_attributes(idev);
+
+        dev_set_drvdata(idev->dev, NULL);
+        device_destroy(uio_class->class, MKDEV(uio_major, idev->minor));
+        kfree(idev);
+        uio_class_destroy();
+
+        return;
+}
+EXPORT_SYMBOL_GPL(uio_unregister_device);
+
+static int __init uio_init(void)
+{
+        return 0;
+}
+
+static void __exit uio_exit(void)
+{
+}
+
+module_init(uio_init)
+module_exit(uio_exit)
+MODULE_LICENSE("GPL v2");