/* Intel PRO/1000 Linux driver
 * Copyright (c) 2017, Linaro Limited
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 */

#include <linux/netdevice.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/mm.h>
#include <linux/vfio.h>
#include <linux/mdev.h>

#include "e1000.h"
#include "vfio-net.h"

static struct net_device *netmdev_get_netdev(struct mdev_device *mdev);

/* Common vfio-net code: move to core */
#if 1
struct iovamap {
	u64 iova;
	void *vaddr;
	struct device *dev;
	u32 size; /* maximum of 32MB */
	enum dma_data_direction direction; /*  DMA_FROM_DEVICE... */
};

typedef struct netmdev {
	union {
		char page0[4096];
		struct {
			struct net_device *netdev;
			/* FIXME USE A LINKED LIST */
			int mappings_count;
			struct iovamap mappings[128]; /* 3.5KB */
		};
	};
	union {
		/* shadow features & statistics page */
		char page1[4096];
		struct {
			netdev_features_t	features;
			netdev_features_t	hw_features;
			netdev_features_t	wanted_features;
			netdev_features_t	vlan_features;
			netdev_features_t	hw_enc_features;
			netdev_features_t	mpls_features;
			netdev_features_t	gso_partial_features;
			struct net_device_stats	stats;
			atomic_long_t		rx_dropped;
			atomic_long_t		tx_dropped;
			atomic_long_t		rx_nohandler;
		};
	};
} netmdev;

#define VFIO_NET_OFFSET_SHIFT   40

#define VFIO_NET_OFFSET_TO_INDEX(off)	(off >> VFIO_NET_OFFSET_SHIFT)
#define VFIO_NET_INDEX_TO_OFFSET(index)	((u64)(index) << VFIO_NET_OFFSET_SHIFT)
#define VFIO_NET_OFFSET_MASK		(((u64)(1) << VFIO_NET_OFFSET_SHIFT) - 1)
#endif

/**
 * e1000e_vfio_net_open - decouple from network stack
 * @mdev: mediated device to open
 *
 * Decouple network device from the stack and make it available to userspace
 * packet reception and transmission.
 */
static int e1000e_vfio_net_open(struct mdev_device *mdev)
{
	struct net_device *netdev = netmdev_get_netdev(mdev);
	struct e1000_adapter *adapter = netdev_priv(netdev);

	dev_hold(adapter->netdev);

	set_bit(__E1000_VFIO_NET, &adapter->state);
	if (netif_running(adapter->netdev))
		e1000e_reinit_locked(adapter);
	else
		e1000e_reset(adapter);

	return 0;
}

/**
 * e1000e_vfio_net_release - cleanup attach to network stack
 * @mdev: mediated device to release
 *
 * Cleanup all mediated device resources and restore network stack
 * connection.
 */
static void e1000e_vfio_net_release(struct mdev_device *mdev)
{
	struct net_device *netdev = netmdev_get_netdev(mdev);
	struct e1000_adapter *adapter = netdev_priv(netdev);

	clear_bit(__E1000_VFIO_NET, &adapter->state);
	if (netif_running(adapter->netdev))
		e1000e_reinit_locked(adapter);
	else
		e1000e_reset(adapter);

	dev_put(adapter->netdev);
}

/**
 * e1000e_vfio_net_device_info_get - query vfio device information
 * @adapter: board private structure
 * @info: vfio device description
 *
 * Retrieves information about the device. Fills in provided
 * struct vfio_device_info.
 */
static void e1000e_vfio_net_device_info_get(struct e1000_adapter *adapter,
		struct vfio_device_info *info)
{
	info->flags = VFIO_DEVICE_FLAGS_PCI | VFIO_DEVICE_FLAGS_RESET;
	info->num_regions = VFIO_PCI_NUM_REGIONS + 3;
	info->num_irqs = 1;
}

/**
 * e1000e_vfio_net_region_info_get - query vfio region information
 * @adapter: board private structure
 * @info: vfio region description
 *
 * Retrieves information about the region. The region to query is specified in
 * @info->index. Fills in provided struct vfio_region_info.
 */
static int e1000e_vfio_net_region_info_get(struct e1000_adapter *adapter,
		struct vfio_region_info *info)
{
	int ret = 0;

	switch (info->index) {
	case VFIO_PCI_BAR0_REGION_INDEX:
		/* PCI resource 0 */
		info->offset = VFIO_NET_INDEX_TO_OFFSET(info->index);
		info->size = pci_resource_len(adapter->pdev, info->index);
		info->flags = VFIO_REGION_INFO_FLAG_MMAP;
		break;

	case VFIO_PCI_NUM_REGIONS + 1:
		/* RX descriptor rings */
		info->offset = VFIO_NET_INDEX_TO_OFFSET(info->index);
		info->size = adapter->rx_ring[0].size;
		info->flags = VFIO_REGION_INFO_FLAG_MMAP;
		break;

	case VFIO_PCI_NUM_REGIONS + 2:
		/* TX descriptor ring */
		info->offset = VFIO_NET_INDEX_TO_OFFSET(info->index);
		info->size = adapter->tx_ring[0].size;
		info->flags = VFIO_REGION_INFO_FLAG_MMAP;
		break;

	default:
		ret = -EINVAL;
		break;
	}

	return ret;
}

/**
 * e1000e_vfio_net_irq_info_get - query vfio irq information
 * @adapter: board private structure
 * @info: vfio irq description
 *
 * Retrieves information about the irq. Fills in provided
 * struct vfio_irq_info.
 */
static void e1000e_vfio_net_irq_info_get(struct e1000_adapter *adapter,
		struct vfio_irq_info *info)
{
	info->count = 1;
	info->flags = VFIO_IRQ_INFO_EVENTFD |
		VFIO_IRQ_INFO_MASKABLE |
		VFIO_IRQ_INFO_AUTOMASKED;
}

/**
 * e1000e_vfio_net_ioctl - vfio-net ioctl
 * @mdev:
 * @cmd:
 * @arg:
 *
 * Implement device and region queries, DMA memory mapping and device reset
 **/
static long e1000e_vfio_net_ioctl(struct mdev_device *mdev, unsigned int cmd,
		unsigned long arg)
{
	struct net_device *netdev = netmdev_get_netdev(mdev);
	struct e1000_adapter *adapter = netdev_priv(netdev);
	struct vfio_device_info device_info;
	struct vfio_region_info region_info;
	struct vfio_irq_info irq_info;
	unsigned long minsz;
	int ret;

	switch (cmd) {
	case VFIO_DEVICE_GET_INFO:
		minsz = offsetofend(struct vfio_device_info, num_irqs);
		if (copy_from_user(&device_info, (void __user *)arg, minsz))
			return -EFAULT;

		if (device_info.argsz < minsz)
			return -EINVAL;

		e1000e_vfio_net_device_info_get(adapter, &device_info);

		if (copy_to_user((void __user *)arg, &device_info, minsz))
			return -EFAULT;

		return 0;

	case VFIO_DEVICE_GET_REGION_INFO:
		minsz = offsetofend(struct vfio_region_info, offset);

		if (copy_from_user(&region_info, (void __user *)arg, minsz))
			return -EFAULT;

		if (region_info.argsz < minsz)
			return -EINVAL;

		ret = e1000e_vfio_net_region_info_get(adapter, &region_info);

		if (ret < 0)
			return ret;

		if (copy_to_user((void __user *)arg, &region_info, minsz))
			return -EFAULT;

		return 0;

	case VFIO_DEVICE_GET_IRQ_INFO:
		minsz = offsetofend(struct vfio_irq_info, count);

		if (copy_from_user(&irq_info, (void __user *)arg, minsz))
			return -EFAULT;

		if (irq_info.argsz < minsz || irq_info.index != 0)
			return -EINVAL;

		e1000e_vfio_net_irq_info_get(adapter, &irq_info);

		return copy_to_user((void __user *)arg, &irq_info, minsz) ?
			-EFAULT : 0;

	case VFIO_IOMMU_MAP_DMA:
/* Common vfio-net code: move to core */
#if 1
	{
		struct netmdev *netmdev = mdev_get_drvdata(mdev);
		struct vfio_iommu_type1_dma_map map;
		struct vm_area_struct *vma;
		void *data;
		struct device *parent_dev;
		int node;
		dma_addr_t mapping;
		int ret = -EINVAL;

		/* allocate DMA area and map it where the userland asks
		 * userland need to mmap an area WITHOUT allocating pages:
		 * mmap(vaddr,size, PROT_READ | PROT_WRITE, MAP_SHARED |
		 * MAP_ANONYMOUS | MAP_NORESERVE | MAP_FIXED, -1, 0
		 * MAP_NORESERVE ensures only VA space is booked, no pages are
		 * mapped * the mapping must be the entire area, not partial on
		 * the vma
		 */

		if (netmdev->mappings_count >= 128)
			return -EFAULT;

		minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);

		if (copy_from_user(&map, (void __user *)arg, minsz)) {
			ret = -EFAULT;
			goto out;
		}

		if (map.argsz < minsz)
			goto out;

		printk(KERN_INFO"VFIO_IOMMU_MAP_DMA: find_vma(%llx)\n", map.vaddr);
		/*
		 * locates the containing vma for the required map.vaddr
		 * the vma must point to the entire zone allocated by mmap in
		 * userland
		 */
		vma = find_vma(current->mm, map.vaddr);
		if (!vma)
			return -EFAULT;
		if (map.vaddr >= vma->vm_end)
			return -EFAULT;

		printk(KERN_INFO"VFIO_IOMMU_MAP_DMA: found vma(%llx) -> start=%lx end=%lx pg_off=%lx\n",
		       map.vaddr, vma->vm_start, vma->vm_end, vma->vm_pgoff);
		/* the iova will be returned as part of the ioctl to the userland */
		//parent_dev = &tp->pci_dev->dev;
		parent_dev = mdev_parent_dev(mdev);

		node = netdev->dev.parent ? dev_to_node(netdev->dev.parent) : -1;
		data = kmalloc_node(map.size, GFP_KERNEL, node);
		if (!data)
			/* return ret? */
			return -ENOMEM;

		printk(KERN_INFO"VFIO_IOMMU_MAP_DMA: about to dma_map_single(%p, %p, %lld, DMA_FROM_DEVICE)\n",
		       parent_dev, data, map.size);
		mapping = dma_map_single(parent_dev, data, map.size,
					 DMA_FROM_DEVICE);
		if (unlikely(dma_mapping_error(parent_dev, mapping))) {
			if (net_ratelimit())
				printk(KERN_ERR"Failed to dma_map_single buffer for userland!\n");
			kfree(data);
			goto out;
		}
		map.iova = mapping;
		ret = io_remap_pfn_range(vma, map.vaddr,
					 virt_to_phys(data) >> PAGE_SHIFT,
					 map.size, vma->vm_page_prot);
		printk(KERN_INFO"VFIO_IOMMU_MAP_DMA: io_remap_pfn_range %llx -> physmem <- @%llx, %lld:%d\n",
		       map.vaddr, map.iova, map.size, ret);
		if (ret != 0) {
			dma_unmap_single(parent_dev, mapping, map.size,
					 DMA_FROM_DEVICE);
			kfree(data);
			printk(KERN_ERR"VFIO_IOMMU_MAP_DMA: io_remap_pfn_range failed\n");
				return -EFAULT;
		}

		printk(KERN_INFO"VFIO_IOMMU_MAP_DMA: recording the mapping %d\n",
		       netmdev->mappings_count);
		netmdev->mappings[netmdev->mappings_count].dev = parent_dev;
		netmdev->mappings[netmdev->mappings_count].vaddr = data;
		netmdev->mappings[netmdev->mappings_count].iova = mapping;
		netmdev->mappings[netmdev->mappings_count].size = map.size;
		netmdev->mappings_count++;

		printk(KERN_INFO"VFIO_IOMMU_MAP_DMA: preparing response back to user\n");
		if (copy_to_user((void __user *)arg, &map, minsz))
			return -EFAULT;

		ret = 0;
out:
		return ret;
	}
#endif
		return -EOPNOTSUPP;

	case VFIO_DEVICE_RESET:
		if (netif_running(adapter->netdev))
			e1000e_reinit_locked(adapter);
		else
			e1000e_reset(adapter);

		return 0;

        default:
                return -EOPNOTSUPP;
	}
}

static int e1000e_vfio_net_mmap(struct mdev_device *mdev,
		struct vm_area_struct *vma)
{
	struct net_device *netdev = netmdev_get_netdev(mdev);
	struct e1000_adapter *adapter = netdev_priv(netdev);
	u64 phys_len, req_len, pgoff, req_start;
	unsigned long phys_pfn;
	unsigned int index;

	if (vma->vm_end < vma->vm_start)
		return -EINVAL;
	if ((vma->vm_flags & VM_SHARED) == 0)
		return -EINVAL;

	index = vma->vm_pgoff >> (VFIO_NET_OFFSET_SHIFT - PAGE_SHIFT);

	switch (index) {
	case VFIO_PCI_BAR0_REGION_INDEX:
		/* PCI resource 0 */
		phys_pfn = pci_resource_start(adapter->pdev, index) >> PAGE_SHIFT;
		phys_len = pci_resource_len(adapter->pdev, index);
		break;

	case VFIO_PCI_NUM_REGIONS + 1:
		/* RX descriptor rings */
		phys_pfn = (u64)virt_to_phys(adapter->rx_ring[0].desc) >> PAGE_SHIFT;
		phys_len = adapter->rx_ring[0].size;
		break;

	case VFIO_PCI_NUM_REGIONS + 2:
		/* TX descriptor rings */
		phys_pfn = (u64)virt_to_phys(adapter->tx_ring[0].desc) >> PAGE_SHIFT;
		phys_len = adapter->tx_ring[0].size;
		break;

	default:
		return -EINVAL;
	}

	req_len = vma->vm_end - vma->vm_start;
	pgoff = vma->vm_pgoff &
		((1U << (VFIO_NET_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
	req_start = pgoff << PAGE_SHIFT;

	if (req_start + req_len > phys_len)
		return -EINVAL;

	vma->vm_private_data = NULL;
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_pgoff = phys_pfn + pgoff;

	return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
			       req_len, vma->vm_page_prot);
}

/* Common vfio-net code: move to core */
#if 1
/*
SYSFS structure for the controlling device
*/

static ssize_t available_instances_show(struct kobject *kobj, struct device *dev,
					char *buf)
{
	return scnprintf(buf, PAGE_SIZE, "%d\n", 1);
}
static MDEV_TYPE_ATTR_RO(available_instances);

static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
			       char *buf)
{
	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
}
static MDEV_TYPE_ATTR_RO(device_api);

static struct attribute *sysfs_vfnetdev_attributes[] = {
	&mdev_type_attr_available_instances.attr,
	&mdev_type_attr_device_api.attr,
	NULL,
};

static struct attribute_group sysfs_vfnetdev_type = {
	.name = "vfnetdev",
	.attrs = sysfs_vfnetdev_attributes,
};

/* Only 1 supported for now */
static struct attribute_group *sysfs_type_list[] = {
	&sysfs_vfnetdev_type,
	NULL
};

/*
 * libraries
 */
static struct net_device *netmdev_get_netdev(struct mdev_device *mdev)
{
	struct netmdev *netmdev;

	netmdev = mdev_get_drvdata(mdev);
	if (!netmdev)
		return NULL;

	return netmdev->netdev;
}
/*
 * SYSFS structure for created mdevices
 */
static ssize_t netdev_show(struct device *dev, struct device_attribute *attr,
	char *buf)
{
	struct mdev_device *mdev;
	struct net_device *netdev;

	mdev = mdev_from_dev(dev);
	if (!mdev)
		return scnprintf(buf, PAGE_SIZE, "mdev not found\n");

	netdev = netmdev_get_netdev(mdev);
	if (!netdev)
		return scnprintf(buf, PAGE_SIZE, "ndev-mdev not found\n");

	return scnprintf(buf, PAGE_SIZE, "%.16s\n", netdev->name);
}

static ssize_t netdev_store(struct device *dev, struct device_attribute *attr,
			    const char *buf, size_t count)
{
	struct mdev_device *mdev;
	struct net_device *port;
	struct netmdev *netmdev;
	char name[IFNAMSIZ+1];

	if (count < 2)
		return -EINVAL;

	mdev = mdev_from_dev(dev);
	if (!mdev)
		return -ENODEV;

	netmdev = mdev_get_drvdata(mdev);
	if (netmdev)
		return -ENODEV;

	netmdev = kzalloc(sizeof(*netmdev), GFP_KERNEL);
	if (!netmdev)
		return -ENOMEM;
	mdev_set_drvdata(mdev, netmdev);

	if (count > IFNAMSIZ)
		return -ENODEV;

	memset(name, 0, sizeof(name));
	scnprintf(name, IFNAMSIZ + 1, "%.*s", (int)count - 1, buf);
	port = dev_get_by_name(&init_net, name);
	if (!port)
		return -ENODEV;

	/* FIXME find a way to check if this is the parent device */
	//if (&port->dev != mdev_parent_dev(mdev)) return -1;

	netmdev->netdev = port;

	return count;
}

static DEVICE_ATTR_RW(netdev);
static struct attribute *sysfs_mdev_vfnetdev_attributes[] = {
	&dev_attr_netdev.attr,
	NULL,
};

static struct attribute_group sysfs_mdev_vfnetdev_group = {
	.name = "vfnetdev",
	.attrs = sysfs_mdev_vfnetdev_attributes,
};

static const struct attribute_group *sysfs_mdev_groups[] = {
	&sysfs_mdev_vfnetdev_group,
	NULL,
};

static int e1000_vfio_net_create(struct kobject *kobj, struct mdev_device *mdev)
{
	return 0;
}

static int e1000_vfio_net_remove(struct mdev_device *mdev)
{
	struct netmdev *netmdev = mdev_get_drvdata(mdev);
	struct net_device *port;

	printk(KERN_INFO "%s %d\n", __func__, __LINE__);
	port = netmdev_get_netdev(mdev);
	dev_put(port);
	kfree(netmdev);
	mdev_set_drvdata(mdev, NULL);

	return 0;
}
#endif

const struct mdev_parent_ops e1000_vfio_net_ops = {
	.supported_type_groups = sysfs_type_list,
	.mdev_attr_groups = sysfs_mdev_groups,
	.create = e1000_vfio_net_create,
	.remove = e1000_vfio_net_remove,

	.open = e1000e_vfio_net_open,
	.release = e1000e_vfio_net_release,

	.read = NULL,
	.write = NULL,
	.mmap = e1000e_vfio_net_mmap,
	.ioctl = e1000e_vfio_net_ioctl,
};