Add an ioctl callback for uio devices.

Signed-off-by: Neil Armstrong <narmstrong@neotion.com>
---

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 2d2440c..38044fb 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -385,6 +385,18 @@ static unsigned int uio_poll(struct file *filep,
poll_table *wait)
     return 0;
 }
 
+static int uio_ioctl(struct inode *inode, struct file *filep,
+            unsigned int cmd, unsigned long arg)
+{
+    struct uio_listener *listener = filep->private_data;
+    struct uio_device *idev = listener->dev;
+
+    if (idev->info->ioctl)
+        return idev->info->ioctl(idev->info, cmd, arg);
+
+    return -ENOSYS;
+}
+
 static ssize_t uio_read(struct file *filep, char __user *buf,
             size_t count, loff_t *ppos)
 {
@@ -590,6 +602,7 @@ static const struct file_operations uio_fops = {
     .mmap        = uio_mmap,
     .poll        = uio_poll,
     .fasync        = uio_fasync,
+    .ioctl        = uio_ioctl,
 };
 
 static int uio_major_init(void)
diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h
index cdf338d..e44e89b 100644
--- a/include/linux/uio_driver.h
+++ b/include/linux/uio_driver.h
@@ -68,6 +68,8 @@ struct uio_info {
     int (*open)(struct uio_info *info, struct inode *inode);
     int (*release)(struct uio_info *info, struct inode *inode);
     int (*irqcontrol)(struct uio_info *info, s32 irq_on);
+    int (*ioctl)(struct uio_info *info, unsigned int cmd,
+            unsigned long arg);
 };
 
 extern int __must_check