Platform devices in the Linux kernel are usually managed by the DT
interface. This patch forms the base to support these kind of devices
with VFIO.

Signed-off-by: Antonios Motakis <a.mota...@virtualopensystems.com>
---
 drivers/vfio/Kconfig         |  11 +++
 drivers/vfio/Makefile        |   1 +
 drivers/vfio/vfio_platform.c | 187 +++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h    |   1 +
 4 files changed, 200 insertions(+)
 create mode 100644 drivers/vfio/vfio_platform.c

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 1f84eda..35254b7 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -13,4 +13,15 @@ menuconfig VFIO
 
          If you don't know what to do here, say N.
 
+config VFIO_PLATFORM
+       tristate "VFIO support for device tree based platform devices"
+       depends on VFIO && EVENTFD && OF
+       help
+         Support for platform devices with VFIO. This is required to make
+         use of platform devices present on device tree nodes using the VFIO
+         framework. Devices that are not described in the device tree cannot
+         be used by this driver.
+
+         If you don't know what to do here, say N.
+
 source "drivers/vfio/pci/Kconfig"
diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
index 2398d4a..575c8dd 100644
--- a/drivers/vfio/Makefile
+++ b/drivers/vfio/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_VFIO) += vfio.o
 obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
 obj-$(CONFIG_VFIO_PCI) += pci/
+obj-$(CONFIG_VFIO_PLATFORM) += vfio_platform.o
diff --git a/drivers/vfio/vfio_platform.c b/drivers/vfio/vfio_platform.c
new file mode 100644
index 0000000..b9686b0
--- /dev/null
+++ b/drivers/vfio/vfio_platform.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2013 - Virtual Open Systems
+ * Author: Antonios Motakis <a.mota...@virtualopensystems.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <linux/device.h>
+#include <linux/eventfd.h>
+#include <linux/interrupt.h>
+#include <linux/iommu.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/vfio.h>
+
+#define DRIVER_VERSION  "0.1"
+#define DRIVER_AUTHOR   "Antonios Motakis <a.mota...@virtualopensystems.com>"
+#define DRIVER_DESC     "VFIO Device Tree devices - User Level meta-driver"
+
+struct vfio_platform_device {
+       struct platform_device  *pdev;
+};
+
+static void vfio_platform_release(void *device_data)
+{
+       module_put(THIS_MODULE);
+}
+
+static int vfio_platform_open(void *device_data)
+{
+       if (!try_module_get(THIS_MODULE))
+               return -ENODEV;
+
+       return 0;
+}
+
+static long vfio_platform_ioctl(void *device_data,
+                          unsigned int cmd, unsigned long arg)
+{
+       struct vfio_platform_device *vdev = device_data;
+       unsigned long minsz;
+
+       if (cmd == VFIO_DEVICE_GET_INFO) {
+               struct vfio_device_info info;
+
+               minsz = offsetofend(struct vfio_device_info, num_irqs);
+
+               if (copy_from_user(&info, (void __user *)arg, minsz))
+                       return -EFAULT;
+
+               if (info.argsz < minsz)
+                       return -EINVAL;
+
+               info.flags = VFIO_DEVICE_FLAGS_PLATFORM;
+               info.num_regions = 0;
+               info.num_irqs = 0;
+
+               return copy_to_user((void __user *)arg, &info, minsz);
+
+       } else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
+               return -EINVAL;
+
+       else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
+               return -EINVAL;
+
+       else if (cmd == VFIO_DEVICE_SET_IRQS)
+               return -EINVAL;
+
+       else if (cmd == VFIO_DEVICE_RESET)
+               return -EINVAL;
+
+       return -ENOTTY;
+}
+
+static ssize_t vfio_platform_read(void *device_data, char __user *buf,
+                            size_t count, loff_t *ppos)
+{
+       return 0;
+}
+
+static ssize_t vfio_platform_write(void *device_data, const char __user *buf,
+                             size_t count, loff_t *ppos)
+{
+       return 0;
+}
+
+static int vfio_platform_mmap(void *device_data, struct vm_area_struct *vma)
+{
+       return -EINVAL;
+}
+
+static const struct vfio_device_ops vfio_platform_ops = {
+       .name           = "vfio-platform",
+       .open           = vfio_platform_open,
+       .release        = vfio_platform_release,
+       .ioctl          = vfio_platform_ioctl,
+       .read           = vfio_platform_read,
+       .write          = vfio_platform_write,
+       .mmap           = vfio_platform_mmap,
+};
+
+static int vfio_platform_probe(struct platform_device *pdev)
+{
+       struct vfio_platform_device *vdev;
+       struct iommu_group *group;
+       int ret;
+
+       group = iommu_group_get(&pdev->dev);
+       if (!group) {
+               pr_err("VFIO: No IOMMU group for device %s\n", pdev->name);
+               return -EINVAL;
+       }
+
+       vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
+       if (!vdev) {
+               iommu_group_put(group);
+               return -ENOMEM;
+       }
+
+       vdev->pdev = pdev;
+
+       ret = vfio_add_group_dev(&pdev->dev, &vfio_platform_ops, vdev);
+       if (ret) {
+               iommu_group_put(group);
+               kfree(vdev);
+       }
+
+       return ret;
+}
+
+static int vfio_platform_remove(struct platform_device *pdev)
+{
+       struct vfio_platform_device *vdev;
+
+       vdev = vfio_del_group_dev(&pdev->dev);
+       if (!vdev)
+               return -EINVAL;
+
+       iommu_group_put(pdev->dev.iommu_group);
+       kfree(vdev);
+
+       return 0;
+}
+
+static const struct of_device_id vfio_platform_match[] = {
+       /* Before this series can be applied, we shall implement a better
+        * mechanism to bind the module to any device. For now add the
+        * compatible property to the dtb of the devices we want to use. */
+       {
+               .compatible = "vfio",
+       },
+       {},
+};
+MODULE_DEVICE_TABLE(of, vfio_platform_match);
+
+static struct platform_driver vfio_platform_driver = {
+       .probe          = vfio_platform_probe,
+       .remove         = vfio_platform_remove,
+       .driver = {
+               .name   = "vfio-platform",
+               .owner  = THIS_MODULE,
+               .of_match_table = vfio_platform_match,
+       },
+};
+
+module_platform_driver(vfio_platform_driver);
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 284ff24..8d7434d 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -147,6 +147,7 @@ struct vfio_device_info {
        __u32   flags;
 #define VFIO_DEVICE_FLAGS_RESET        (1 << 0)        /* Device supports 
reset */
 #define VFIO_DEVICE_FLAGS_PCI  (1 << 1)        /* vfio-pci device */
+#define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2)    /* vfio-platform device */
        __u32   num_regions;    /* Max region index + 1 */
        __u32   num_irqs;       /* Max IRQ index + 1 */
 };
-- 
1.8.1.2

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