staging: vme: mmap() support for vme_user

We also make sure that user won't be able to reconfigure the window while it is
mmap'ed.

Signed-off-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
Cc: Martyn Welch <martyn.welch@ge.com>
Cc: Igor Alekseev <igor.alekseev@itep.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 112 insertions, 0 deletions

diff --git a/drivers/staging/vme/devices/vme_user.c b/drivers/staging/vme/devices/vme_user.c
index 87318386034b..19ba749bb122 100644
--- a/drivers/staging/vme/devices/vme_user.c
+++ b/drivers/staging/vme/devices/vme_user.c
@@ -17,6 +17,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/atomic.h>
 #include <linux/cdev.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -99,6 +100,7 @@ struct image_desc {
         struct device *device;  /* Sysfs device */
         struct vme_resource *resource;  /* VME resource */
         int users;              /* Number of current users */
+        int mmap_count;         /* Number of current mmap's */
 };
 static struct image_desc image[VME_DEVS];
 
@@ -134,6 +136,10 @@ static ssize_t vme_user_write(struct file *, const char __user *, size_t,
         loff_t *);
 static loff_t vme_user_llseek(struct file *, loff_t, int);
 static long vme_user_unlocked_ioctl(struct file *, unsigned int, unsigned long);
+static int vme_user_mmap(struct file *file, struct vm_area_struct *vma);
+
+static void vme_user_vm_open(struct vm_area_struct *vma);
+static void vme_user_vm_close(struct vm_area_struct *vma);
 
 static int vme_user_match(struct vme_dev *);
 static int vme_user_probe(struct vme_dev *);
@@ -147,6 +153,17 @@ static const struct file_operations vme_user_fops = {
         .llseek = vme_user_llseek,
         .unlocked_ioctl = vme_user_unlocked_ioctl,
         .compat_ioctl = vme_user_unlocked_ioctl,
+        .mmap = vme_user_mmap,
+};
+
+struct vme_user_vma_priv {
+        unsigned int minor;
+        atomic_t refcnt;
+};
+
+static const struct vm_operations_struct vme_user_vm_ops = {
+        .open = vme_user_vm_open,
+        .close = vme_user_vm_close,
 };
 
 
@@ -488,6 +505,11 @@ static int vme_user_ioctl(struct inode *inode, struct file *file,
 
                 case VME_SET_MASTER:
 
+                        if (image[minor].mmap_count != 0) {
+                                pr_warn("Can't adjust mapped window\n");
+                                return -EPERM;
+                        }
+
                         copied = copy_from_user(&master, argp, sizeof(master));
                         if (copied != 0) {
                                 pr_warn("Partial copy from userspace\n");
@@ -564,6 +586,69 @@ vme_user_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         return ret;
 }
 
+static void vme_user_vm_open(struct vm_area_struct *vma)
+{
+        struct vme_user_vma_priv *vma_priv = vma->vm_private_data;
+
+        atomic_inc(&vma_priv->refcnt);
+}
+
+static void vme_user_vm_close(struct vm_area_struct *vma)
+{
+        struct vme_user_vma_priv *vma_priv = vma->vm_private_data;
+        unsigned int minor = vma_priv->minor;
+
+        if (!atomic_dec_and_test(&vma_priv->refcnt))
+                return;
+
+        mutex_lock(&image[minor].mutex);
+        image[minor].mmap_count--;
+        mutex_unlock(&image[minor].mutex);
+
+        kfree(vma_priv);
+}
+
+static int vme_user_master_mmap(unsigned int minor, struct vm_area_struct *vma)
+{
+        int err;
+        struct vme_user_vma_priv *vma_priv;
+
+        mutex_lock(&image[minor].mutex);
+
+        err = vme_master_mmap(image[minor].resource, vma);
+        if (err) {
+                mutex_unlock(&image[minor].mutex);
+                return err;
+        }
+
+        vma_priv = kmalloc(sizeof(struct vme_user_vma_priv), GFP_KERNEL);
+        if (vma_priv == NULL) {
+                mutex_unlock(&image[minor].mutex);
+                return -ENOMEM;
+        }
+
+        vma_priv->minor = minor;
+        atomic_set(&vma_priv->refcnt, 1);
+        vma->vm_ops = &vme_user_vm_ops;
+        vma->vm_private_data = vma_priv;
+
+        image[minor].mmap_count++;
+
+        mutex_unlock(&image[minor].mutex);
+
+        return 0;
+}
+
+static int vme_user_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        unsigned int minor = MINOR(file_inode(file)->i_rdev);
+
+        if (type[minor] == MASTER_MINOR)
+                return vme_user_master_mmap(minor, vma);
+
+        return -ENODEV;
+}
+
 
 /*
  * Unallocate a previously allocated buffer
diff --git a/drivers/vme/vme.c b/drivers/vme/vme.c
index d95fb848dd03..6bab2c4ed77c 100644
--- a/drivers/vme/vme.c
+++ b/drivers/vme/vme.c
@@ -609,6 +609,32 @@ unsigned int vme_master_rmw(struct vme_resource *resource, unsigned int mask,
 }
 EXPORT_SYMBOL(vme_master_rmw);
 
+int vme_master_mmap(struct vme_resource *resource, struct vm_area_struct *vma)
+{
+        struct vme_master_resource *image;
+        phys_addr_t phys_addr;
+        unsigned long vma_size;
+
+        if (resource->type != VME_MASTER) {
+                pr_err("Not a master resource\n");
+                return -EINVAL;
+        }
+
+        image = list_entry(resource->entry, struct vme_master_resource, list);
+        phys_addr = image->bus_resource.start + (vma->vm_pgoff << PAGE_SHIFT);
+        vma_size = vma->vm_end - vma->vm_start;
+
+        if (phys_addr + vma_size > image->bus_resource.end + 1) {
+                pr_err("Map size cannot exceed the window size\n");
+                return -EFAULT;
+        }
+
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+        return vm_iomap_memory(vma, phys_addr, vma->vm_end - vma->vm_start);
+}
+EXPORT_SYMBOL(vme_master_mmap);
+
 void vme_master_free(struct vme_resource *resource)
 {
         struct vme_master_resource *master_image;
diff --git a/include/linux/vme.h b/include/linux/vme.h
index 8cd6f19ca518..79242e9c06b8 100644
--- a/include/linux/vme.h
+++ b/include/linux/vme.h
@@ -137,6 +137,7 @@ ssize_t vme_master_read(struct vme_resource *, void *, size_t, loff_t);
 ssize_t vme_master_write(struct vme_resource *, void *, size_t, loff_t);
 unsigned int vme_master_rmw(struct vme_resource *, unsigned int, unsigned int,
         unsigned int, loff_t);
+int vme_master_mmap(struct vme_resource *resource, struct vm_area_struct *vma);
 void vme_master_free(struct vme_resource *);
 
 struct vme_resource *vme_dma_request(struct vme_dev *, u32);