[PATCH 2/3] Initial skeleton of VFIO support for Device Tree based devices

[a.motakis@virtualopensystems.com (Antonios Motakis)]

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.motakis@virtualopensystems.com>
---
 drivers/vfio/Kconfig      |  10 +++
 drivers/vfio/Makefile     |   1 +
 drivers/vfio/vfio_dt.c    | 187 ++++++++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h |   1 +
 4 files changed, 199 insertions(+)
 create mode 100644 drivers/vfio/vfio_dt.c

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 1f84eda..a77a2e4 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -13,4 +13,14 @@ menuconfig VFIO
 
 	  If you don't know what to do here, say N.
 
+config VFIO_DT
+	tristate "VFIO support for Device Tree devices"
+	depends on VFIO && EVENTFD
+	help
+	  Support for the VFIO Device Tree driver.  This is required to make
+	  use of platform devices present on Device Tree nodes using the VFIO
+	  framework.
+
+	  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..d599a67 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_DT) += vfio_dt.o
diff --git a/drivers/vfio/vfio_dt.c b/drivers/vfio/vfio_dt.c
new file mode 100644
index 0000000..ad4d31d
--- /dev/null
+++ b/drivers/vfio/vfio_dt.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2013 - Virtual Open Systems
+ * Author: Antonios Motakis <a.motakis@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.motakis@virtualopensystems.com>"
+#define DRIVER_DESC     "VFIO Device Tree devices - User Level meta-driver"
+
+struct vfio_dt_device {
+	struct platform_device	*pdev;
+};
+
+static void vfio_dt_release(void *device_data)
+{
+	module_put(THIS_MODULE);
+}
+
+static int vfio_dt_open(void *device_data)
+{
+	if (!try_module_get(THIS_MODULE))
+		return -ENODEV;
+
+	return 0;
+}
+
+static long vfio_dt_ioctl(void *device_data,
+			   unsigned int cmd, unsigned long arg)
+{
+	struct vfio_dt_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_DT;
+		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_dt_read(void *device_data, char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	return 0;
+}
+
+static ssize_t vfio_dt_write(void *device_data, const char __user *buf,
+			      size_t count, loff_t *ppos)
+{
+	return 0;
+}
+
+static int vfio_dt_mmap(void *device_data, struct vm_area_struct *vma)
+{
+	return -EINVAL;
+}
+
+static const struct vfio_device_ops vfio_dt_ops = {
+	.name		= "vfio-dts",
+	.open		= vfio_dt_open,
+	.release	= vfio_dt_release,
+	.ioctl		= vfio_dt_ioctl,
+	.read		= vfio_dt_read,
+	.write		= vfio_dt_write,
+	.mmap		= vfio_dt_mmap,
+};
+
+static int vfio_dt_probe(struct platform_device *pdev)
+{
+	struct vfio_dt_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_dt_ops, vdev);
+	if (ret) {
+		iommu_group_put(group);
+		kfree(vdev);
+	}
+
+	return ret;
+}
+
+static int vfio_dt_remove(struct platform_device *pdev)
+{
+	struct vfio_dt_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_dt_match[] = {
+	/* In the future, we can 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-dt",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, vfio_dt_match);
+
+static struct platform_driver vfio_dt_driver = {
+	.probe		= vfio_dt_probe,
+	.remove		= vfio_dt_remove,
+	.driver	= {
+		.name	= "vfio-dt",
+		.owner	= THIS_MODULE,
+		.of_match_table = vfio_dt_match,
+	},
+};
+
+module_platform_driver(vfio_dt_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..1e4bef2 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_DT	(1 << 2)	/* vfio-dt device */
 	__u32	num_regions;	/* Max region index + 1 */
 	__u32	num_irqs;	/* Max IRQ index + 1 */
 };
-- 
1.8.1.2