uio.c

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/*
 * drivers/uio/uio.c
 *
 * Copyright(C) 2005, Benedikt Spranger <[email protected]>
 * Copyright(C) 2005, Thomas Gleixner <[email protected]>
 * Copyright(C) 2006, Hans J. Koch <[email protected]>
 * Copyright(C) 2006, Greg Kroah-Hartman <[email protected]>
 *
 * 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/slab.h>
#include <linux/mm.h>
#include <linux/idr.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/kobject.h>
#include <linux/cdev.h>
#include <linux/uio_driver.h>

#define UIO_MAX_DEVICES     (1U << MINORBITS)

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 kobject      *map_dir;
    struct kobject      *portio_dir;
};

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, "0x%llx\n", (unsigned long long)mem->addr);
}

static ssize_t map_size_show(struct uio_mem *mem, char *buf)
{
    return sprintf(buf, "0x%lx\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->addr & ~PAGE_MASK);
}

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 show_name(struct device *dev,
             struct device_attribute *attr, char *buf)
{
    struct uio_device *idev = dev_get_drvdata(dev);
    return sprintf(buf, "%s\n", idev->info->name);
}

static ssize_t show_version(struct device *dev,
                struct device_attribute *attr, char *buf)
{
    struct uio_device *idev = dev_get_drvdata(dev);
    return sprintf(buf, "%s\n", idev->info->version);
}

static ssize_t show_event(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 struct device_attribute uio_class_attributes[] = {
    __ATTR(name, S_IRUGO, show_name, NULL),
    __ATTR(version, S_IRUGO, show_version, NULL),
    __ATTR(event, S_IRUGO, show_event, NULL),
    {}
};

/* UIO class infrastructure */
static struct class uio_class = {
    .name = "uio",
    .dev_attrs = uio_class_attributes,
};

/*
 * 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)
                goto err_map;
        }
        map = kzalloc(sizeof(*map), GFP_KERNEL);
        if (!map)
            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;
        ret = kobject_uevent(&map->kobj, KOBJ_ADD);
        if (ret)
            goto err_map;
    }

    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)
                goto err_portio;
        }
        portio = kzalloc(sizeof(*portio), GFP_KERNEL);
        if (!portio)
            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;
        ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
        if (ret)
            goto err_portio;
    }

    return 0;

err_portio:
    for (pi--; pi >= 0; pi--) {
        port = &idev->info->port[pi];
        portio = port->portio;
        kobject_put(&portio->kobj);
    }
    kobject_put(idev->portio_dir);
err_map:
    for (mi--; 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 = -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;
    }
    if (id < UIO_MAX_DEVICES) {
        idev->minor = id;
    } else {
        dev_err(idev->dev, "too many uio devices\n");
        retval = -EINVAL;
        idr_remove(&uio_idr, id);
    }
exit:
    mutex_unlock(&minor_lock);
    return retval;
}

static void uio_free_minor(struct uio_device *idev)
{
    mutex_lock(&minor_lock);
    idr_remove(&uio_idr, idev->minor);
    mutex_unlock(&minor_lock);
}

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);

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;

    mutex_lock(&minor_lock);
    idev = idr_find(&uio_idr, iminor(inode));
    mutex_unlock(&minor_lock);
    if (!idev) {
        ret = -ENODEV;
        goto out;
    }

    if (!try_module_get(idev->owner)) {
        ret = -ENODEV;
        goto out;
    }

    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;

    if (idev->info->open) {
        ret = idev->info->open(idev->info, inode);
        if (ret)
            goto err_infoopen;
    }
    return 0;

err_infoopen:
    kfree(listener);

err_alloc_listener:
    module_put(idev->owner);

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;

    if (idev->info->release)
        ret = idev->info->release(idev->info, inode);

    module_put(idev->owner);
    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)
        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)
        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 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 (!idev->info->irq)
        return -EIO;

    if (count != sizeof(s32))
        return -EINVAL;

    if (!idev->info->irqcontrol)
        return -ENOSYS;

    if (copy_from_user(&irq_on, buf, count))
        return -EFAULT;

    retval = idev->info->irqcontrol(idev->info, irq_on);

    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 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 int uio_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
    struct uio_device *idev = vma->vm_private_data;
    struct page *page;
    unsigned long offset;

    int mi = uio_find_mem_index(vma);
    if (mi < 0)
        return VM_FAULT_SIGBUS;

    /*
     * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
     * to use mem[N].
     */
    offset = (vmf->pgoff - mi) << PAGE_SHIFT;

    if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
        page = virt_to_page(idev->info->mem[mi].addr + offset);
    else
        page = vmalloc_to_page((void *)(unsigned long)idev->info->mem[mi].addr + offset);
    get_page(page);
    vmf->page = page;
    return 0;
}

static const struct vm_operations_struct uio_vm_ops = {
    .open = uio_vma_open,
    .close = uio_vma_close,
    .fault = uio_vma_fault,
};

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_page_prot = pgprot_noncached(vma->vm_page_prot);

    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_DONTEXPAND | VM_DONTDUMP;
    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].addr & ~PAGE_MASK)
            + idev->info->mem[mi].size + PAGE_SIZE -1) >> PAGE_SHIFT;
    if (requested_pages > actual_pages)
        return -EINVAL;

    if (idev->info->mmap) {
        ret = idev->info->mmap(idev->info, vma);
        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 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;
    }
    return 0;

err_class_register:
    uio_major_cleanup();
exit:
    return ret;
}

static void release_uio_class(void)
{
    class_unregister(&uio_class);
    uio_major_cleanup();
}

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;

    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, parent,
                  MKDEV(uio_major, idev->minor), idev,
                  "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;
    }

    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)) {
        ret = request_irq(info->irq, uio_interrupt,
                  info->irq_flags, 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, MKDEV(uio_major, idev->minor));
err_device_create:
    uio_free_minor(idev);
err_get_minor:
    kfree(idev);
err_kzalloc:
    return ret;
}
EXPORT_SYMBOL_GPL(__uio_register_device);

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 && (info->irq != UIO_IRQ_CUSTOM))
        free_irq(info->irq, idev);

    uio_dev_del_attributes(idev);

    device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
    kfree(idev);

    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();
}

module_init(uio_init)
module_exit(uio_exit)
MODULE_LICENSE("GPL v2");