/*
 * 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 kobject          *map_dir;
};

static int uio_major;
static DEFINE_IDR(uio_idr);
static const struct file_operations uio_fops;

/* UIO class infrastructure */
static struct uio_class {
        struct kref kref;
        struct class *class;
} *uio_class;

/*
 * 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_addr_show(struct uio_mem *mem, char *buf)
{
        return sprintf(buf, "0x%lx\n", mem->addr);
}

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

struct uio_sysfs_entry {
        struct attribute attr;
        ssize_t (*show)(struct uio_mem *, char *);
        ssize_t (*store)(struct uio_mem *, const char *, size_t);
};

static struct uio_sysfs_entry addr_attribute =
        __ATTR(addr, S_IRUGO, map_addr_show, NULL);
static struct uio_sysfs_entry size_attribute =
        __ATTR(size, S_IRUGO, map_size_show, NULL);

static struct attribute *attrs[] = {
        &addr_attribute.attr,
        &size_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 uio_sysfs_entry *entry;

        entry = container_of(attr, struct uio_sysfs_entry, attr);

        if (!entry->show)
                return -EIO;

        return entry->show(mem, buf);
}

static struct sysfs_ops uio_sysfs_ops = {
        .show = map_type_show,
};

static struct kobj_type map_attr_type = {
        .release        = map_release,
        .sysfs_ops      = &uio_sysfs_ops,
        .default_attrs  = 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;
        struct uio_map *map;

        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;
                        idev->map_dir = kobject_create_and_add("maps",
                                                        &idev->dev->kobj);
                        if (!idev->map_dir)
                                goto err;
                }
                map = kzalloc(sizeof(*map), GFP_KERNEL);
                if (!map)
                        goto err;
                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;
                ret = kobject_uevent(&map->kobj, KOBJ_ADD);
                if (ret)
                        goto err;
        }

        return 0;

err:
        for (mi--; mi>=0; mi--) {
                mem = &idev->info->mem[mi];
                map = mem->map;
                kobject_put(&map->kobj);
        }
        kobject_put(idev->map_dir);
        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_put(&mem->map->kobj);
        }
        kobject_put(idev->map_dir);
        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;

        if (!try_module_get(idev->owner))
                return -ENODEV;

        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);

        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);

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

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

        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);
        vmf->page = page;
        return 0;
}

static 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_flags |= VM_IO | VM_RESERVED;

        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_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) {
                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,
        .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_drvdata(uio_class->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 (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");