/*
 *
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Hank Janssen  <hjanssen@microsoft.com>
 *
 */

#define KERNEL_2_6_27

#include <linux/init.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/device.h>
#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
#include <asm/io.h>
#else
#include <linux/io.h>
#endif
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <net/arp.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/pkt_sched.h>

#include "include/logging.h"
#include "include/vmbus.h"

#include "include/NetVscApi.h"

MODULE_LICENSE("GPL");

//
// Static decl
//
static int netvsc_probe(struct device *device);
static int netvsc_remove(struct device *device);
static int netvsc_open(struct net_device *net);
static void netvsc_xmit_completion(void *context);
static int netvsc_start_xmit (struct sk_buff *skb, struct net_device *net);
static int netvsc_recv_callback(DEVICE_OBJECT *device_obj, NETVSC_PACKET* Packet);
static int netvsc_close(struct net_device *net);
static struct net_device_stats *netvsc_get_stats(struct net_device *net);
static void netvsc_linkstatus_callback(DEVICE_OBJECT *device_obj, unsigned int status);

//
// Data types
//
struct net_device_context {
	struct device_context	*device_ctx; // point back to our device context
	struct net_device_stats stats;
};

struct netvsc_driver_context {
	// !! These must be the first 2 fields !!
	struct driver_context	drv_ctx;
	NETVSC_DRIVER_OBJECT	drv_obj;
};

//
// Globals
//

static int netvsc_ringbuffer_size = NETVSC_DEVICE_RING_BUFFER_SIZE;

// The one and only one
static struct netvsc_driver_context g_netvsc_drv;

//
// Routines
//

/*++

Name:	netvsc_drv_init()

Desc:	NetVsc driver initialization

--*/
int netvsc_drv_init(PFN_DRIVERINITIALIZE pfn_drv_init)
{
	int ret=0;
	NETVSC_DRIVER_OBJECT *net_drv_obj=&g_netvsc_drv.drv_obj;
	struct driver_context *drv_ctx=&g_netvsc_drv.drv_ctx;

	DPRINT_ENTER(NETVSC_DRV);

	vmbus_get_interface(&net_drv_obj->Base.VmbusChannelInterface);

	net_drv_obj->RingBufferSize = netvsc_ringbuffer_size;
	net_drv_obj->OnReceiveCallback = netvsc_recv_callback;
	net_drv_obj->OnLinkStatusChanged = netvsc_linkstatus_callback;

	// Callback to client driver to complete the initialization
	pfn_drv_init(&net_drv_obj->Base);

	drv_ctx->driver.name = net_drv_obj->Base.name;
	memcpy(&drv_ctx->class_id, &net_drv_obj->Base.deviceType, sizeof(GUID));

#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
	drv_ctx->driver.probe = netvsc_probe;
	drv_ctx->driver.remove = netvsc_remove;
#else
	drv_ctx->probe = netvsc_probe;
	drv_ctx->remove = netvsc_remove;
#endif

	// The driver belongs to vmbus
	vmbus_child_driver_register(drv_ctx);

	DPRINT_EXIT(NETVSC_DRV);

	return ret;
}

/*++

Name:	netvsc_get_stats()

Desc:	Get the network stats

--*/
static struct net_device_stats *netvsc_get_stats(struct net_device *net)
{
	struct net_device_context *net_device_ctx = netdev_priv(net);

	return &net_device_ctx->stats;
}

/*++

Name:	netvsc_set_multicast_list()

Desc:	Set the multicast list

Remark:	No-op here
--*/
static void netvsc_set_multicast_list(UNUSED_VAR(struct net_device *net))
{
}


static const struct net_device_ops device_ops = {
	.ndo_open = netvsc_open,
	.ndo_stop = netvsc_close,
	.ndo_start_xmit	= netvsc_start_xmit,
	.ndo_get_stats = netvsc_get_stats,
	.ndo_set_multicast_list = netvsc_set_multicast_list,
};

/*++

Name:	netvsc_probe()

Desc:	Add the specified new device to this driver

--*/
static int netvsc_probe(struct device *device)
{
	int ret=0;

	struct driver_context *driver_ctx = driver_to_driver_context(device->driver);
	struct netvsc_driver_context *net_drv_ctx = (struct netvsc_driver_context*)driver_ctx;
	NETVSC_DRIVER_OBJECT *net_drv_obj = &net_drv_ctx->drv_obj;

	struct device_context *device_ctx = device_to_device_context(device);
	DEVICE_OBJECT *device_obj = &device_ctx->device_obj;

	struct net_device *net = NULL;
	struct net_device_context *net_device_ctx;
	NETVSC_DEVICE_INFO device_info;

	DPRINT_ENTER(NETVSC_DRV);

	if (!net_drv_obj->Base.OnDeviceAdd)
	{
		return -1;
	}

	net = alloc_netdev(sizeof(struct net_device_context), "seth%d", ether_setup);
	//net = alloc_etherdev(sizeof(struct net_device_context));
	if (!net)
	{
		return -1;
	}

	// Set initial state
	netif_carrier_off(net);
	netif_stop_queue(net);

	net_device_ctx = netdev_priv(net);
	net_device_ctx->device_ctx = device_ctx;
	dev_set_drvdata(device, net);

	// Notify the netvsc driver of the new device
	ret = net_drv_obj->Base.OnDeviceAdd(device_obj, (void*)&device_info);
	if (ret != 0)
	{
		free_netdev(net);
		dev_set_drvdata(device, NULL);

		DPRINT_ERR(NETVSC_DRV, "unable to add netvsc device (ret %d)", ret);
		return ret;
	}

	// If carrier is still off ie we did not get a link status callback, update it if necessary
	// FIXME: We should use a atomic or test/set instead to avoid getting out of sync with the device's link status
	if (!netif_carrier_ok(net))
	{
		if (!device_info.LinkState)
		{
			netif_carrier_on(net);
		}
	}

	memcpy(net->dev_addr, device_info.MacAddr, ETH_ALEN);

	net->netdev_ops = &device_ops;

#if !defined(KERNEL_2_6_27)
	SET_MODULE_OWNER(net);
#endif
	SET_NETDEV_DEV(net, device);

	ret = register_netdev(net);
	if (ret != 0)
	{
		// Remove the device and release the resource
		net_drv_obj->Base.OnDeviceRemove(device_obj);
		free_netdev(net);
	}

	DPRINT_EXIT(NETVSC_DRV);

	return ret;
}

static int netvsc_remove(struct device *device)
{
	int ret=0;
	struct driver_context *driver_ctx = driver_to_driver_context(device->driver);
	struct netvsc_driver_context *net_drv_ctx = (struct netvsc_driver_context*)driver_ctx;
	NETVSC_DRIVER_OBJECT *net_drv_obj = &net_drv_ctx->drv_obj;

	struct device_context *device_ctx = device_to_device_context(device);
	struct net_device *net = dev_get_drvdata(&device_ctx->device);
	DEVICE_OBJECT *device_obj = &device_ctx->device_obj;

	DPRINT_ENTER(NETVSC_DRV);

	if (net == NULL)
	{
		DPRINT_INFO(NETVSC, "no net device to remove");
		DPRINT_EXIT(NETVSC_DRV);
		return 0;
	}

	if (!net_drv_obj->Base.OnDeviceRemove)
	{
		DPRINT_EXIT(NETVSC_DRV);
		return -1;
	}

	// Stop outbound asap
	netif_stop_queue(net);
	//netif_carrier_off(net);

	unregister_netdev(net);

	// Call to the vsc driver to let it know that the device is being removed
	ret = net_drv_obj->Base.OnDeviceRemove(device_obj);
	if (ret != 0)
	{
		// TODO:
		DPRINT_ERR(NETVSC, "unable to remove vsc device (ret %d)", ret);
	}

	free_netdev(net);

	DPRINT_EXIT(NETVSC_DRV);

	return ret;
}

/*++

Name:	netvsc_open()

Desc:	Open the specified interface device

--*/
static int netvsc_open(struct net_device *net)
{
	int ret=0;
	struct net_device_context *net_device_ctx = netdev_priv(net);
	struct driver_context *driver_ctx = driver_to_driver_context(net_device_ctx->device_ctx->device.driver);
	struct netvsc_driver_context *net_drv_ctx = (struct netvsc_driver_context*)driver_ctx;
	NETVSC_DRIVER_OBJECT *net_drv_obj = &net_drv_ctx->drv_obj;

	DEVICE_OBJECT *device_obj = &net_device_ctx->device_ctx->device_obj;

	DPRINT_ENTER(NETVSC_DRV);

	if (netif_carrier_ok(net))
	{
		memset(&net_device_ctx->stats, 0 , sizeof(struct net_device_stats));

		// Open up the device
		ret = net_drv_obj->OnOpen(device_obj);
		if (ret != 0)
		{
			DPRINT_ERR(NETVSC_DRV, "unable to open device (ret %d).", ret);
			return ret;
		}

		netif_start_queue(net);
	}
	else
	{
		DPRINT_ERR(NETVSC_DRV, "unable to open device...link is down.");
	}

	DPRINT_EXIT(NETVSC_DRV);
	return ret;
}

/*++

Name:	netvsc_close()

Desc:	Close the specified interface device

--*/
static int netvsc_close(struct net_device *net)
{
	int ret=0;
	struct net_device_context *net_device_ctx = netdev_priv(net);
	struct driver_context *driver_ctx = driver_to_driver_context(net_device_ctx->device_ctx->device.driver);
	struct netvsc_driver_context *net_drv_ctx = (struct netvsc_driver_context*)driver_ctx;
	NETVSC_DRIVER_OBJECT *net_drv_obj = &net_drv_ctx->drv_obj;

	DEVICE_OBJECT *device_obj = &net_device_ctx->device_ctx->device_obj;

	DPRINT_ENTER(NETVSC_DRV);

	netif_stop_queue(net);

	ret = net_drv_obj->OnClose(device_obj);
	if (ret != 0)
	{
		DPRINT_ERR(NETVSC_DRV, "unable to close device (ret %d).", ret);
	}

	DPRINT_EXIT(NETVSC_DRV);

	return ret;
}


/*++

Name:	netvsc_xmit_completion()

Desc:	Send completion processing

--*/
static void netvsc_xmit_completion(void *context)
{
	NETVSC_PACKET *packet = (NETVSC_PACKET *)context;
	struct sk_buff *skb = (struct sk_buff *)(ULONG_PTR)packet->Completion.Send.SendCompletionTid;
	struct net_device* net;

	DPRINT_ENTER(NETVSC_DRV);

	kfree(packet);

	if (skb)
	{
		net = skb->dev;

		dev_kfree_skb_any(skb);

		if (netif_queue_stopped(net))
		{
			DPRINT_INFO(NETVSC_DRV, "net device (%p) waking up...", net);

			netif_wake_queue(net);
		}
	}

	DPRINT_EXIT(NETVSC_DRV);
}

/*++

Name:	netvsc_start_xmit()

Desc:	Start a send

--*/
static int netvsc_start_xmit (struct sk_buff *skb, struct net_device *net)
{
	int ret=0;
	struct net_device_context *net_device_ctx = netdev_priv(net);
	struct driver_context *driver_ctx = driver_to_driver_context(net_device_ctx->device_ctx->device.driver);
	struct netvsc_driver_context *net_drv_ctx = (struct netvsc_driver_context*)driver_ctx;
	NETVSC_DRIVER_OBJECT *net_drv_obj = &net_drv_ctx->drv_obj;

	int i=0;
	NETVSC_PACKET* packet;
	int num_frags;
	int retries=0;

	DPRINT_ENTER(NETVSC_DRV);

	// Support only 1 chain of frags
	ASSERT(skb_shinfo(skb)->frag_list == NULL);
	ASSERT(skb->dev == net);

	DPRINT_DBG(NETVSC_DRV, "xmit packet - len %d data_len %d", skb->len, skb->data_len);

	// Add 1 for skb->data and any additional ones requested
	num_frags = skb_shinfo(skb)->nr_frags + 1 + net_drv_obj->AdditionalRequestPageBufferCount;

	// Allocate a netvsc packet based on # of frags.
	packet = kzalloc(sizeof(NETVSC_PACKET) + (num_frags * sizeof(PAGE_BUFFER)) + net_drv_obj->RequestExtSize, GFP_ATOMIC);
	if (!packet)
	{
		DPRINT_ERR(NETVSC_DRV, "unable to allocate NETVSC_PACKET");
		return -1;
	}

	packet->Extension = (void*)(unsigned long)packet + sizeof(NETVSC_PACKET) + (num_frags * sizeof(PAGE_BUFFER)) ;

	// Setup the rndis header
	packet->PageBufferCount = num_frags;

	// TODO: Flush all write buffers/ memory fence ???
	//wmb();

	// Initialize it from the skb
	ASSERT(skb->data);
	packet->TotalDataBufferLength	= skb->len;

	// Start filling in the page buffers starting at AdditionalRequestPageBufferCount offset
	packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Pfn		= virt_to_phys(skb->data) >> PAGE_SHIFT;
	packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Offset	= (unsigned long)skb->data & (PAGE_SIZE -1);
	packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Length	= skb->len - skb->data_len;

	ASSERT((skb->len - skb->data_len) <= PAGE_SIZE);

	for (i=net_drv_obj->AdditionalRequestPageBufferCount+1; i<num_frags; i++)
	{
		packet->PageBuffers[i].Pfn		= page_to_pfn(skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].page);
		packet->PageBuffers[i].Offset	= skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].page_offset;
		packet->PageBuffers[i].Length	= skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].size;
	}

	// Set the completion routine
	packet->Completion.Send.OnSendCompletion = netvsc_xmit_completion;
	packet->Completion.Send.SendCompletionContext = packet;
	packet->Completion.Send.SendCompletionTid = (ULONG_PTR)skb;

retry_send:
	ret = net_drv_obj->OnSend(&net_device_ctx->device_ctx->device_obj, packet);

	if (ret == 0)
	{
#ifdef KERNEL_2_6_5
#define NETDEV_TX_OK	0
#define NETDEV_TX_BUSY	0
#endif
		ret = NETDEV_TX_OK;
		net_device_ctx->stats.tx_bytes += skb->len;
		net_device_ctx->stats.tx_packets++;
	}
	else
	{
		retries++;
		if (retries < 4)
		{
			DPRINT_ERR(NETVSC_DRV, "unable to send...retrying %d...", retries);
			udelay(100);
			goto retry_send;
		}

		// no more room or we are shutting down
		DPRINT_ERR(NETVSC_DRV, "unable to send (%d)...marking net device (%p) busy", ret, net);
		DPRINT_INFO(NETVSC_DRV, "net device (%p) stopping", net);

		ret = NETDEV_TX_BUSY;
		net_device_ctx->stats.tx_dropped++;

		netif_stop_queue(net);

		// Null it since the caller will free it instead of the completion routine
		packet->Completion.Send.SendCompletionTid = 0;

		// Release the resources since we will not get any send completion
		netvsc_xmit_completion((void*)packet);
	}

	DPRINT_DBG(NETVSC_DRV, "# of xmits %lu total size %lu", net_device_ctx->stats.tx_packets, net_device_ctx->stats.tx_bytes);

	DPRINT_EXIT(NETVSC_DRV);
	return ret;
}


/*++

Name:	netvsc_linkstatus_callback()

Desc:	Link up/down notification

--*/
static void netvsc_linkstatus_callback(DEVICE_OBJECT *device_obj, unsigned int status)
{
	struct device_context* device_ctx = to_device_context(device_obj);
	struct net_device* net = dev_get_drvdata(&device_ctx->device);

	DPRINT_ENTER(NETVSC_DRV);

	if (!net)
	{
		DPRINT_ERR(NETVSC_DRV, "got link status but net device not initialized yet");
		return;
	}

	if (status == 1)
	{
		netif_carrier_on(net);
		netif_wake_queue(net);
	}
	else
	{
		netif_carrier_off(net);
		netif_stop_queue(net);
	}
	DPRINT_EXIT(NETVSC_DRV);
}


/*++

Name:	netvsc_recv_callback()

Desc:	Callback when we receive a packet from the "wire" on the specify device

--*/
static int netvsc_recv_callback(DEVICE_OBJECT *device_obj, NETVSC_PACKET* packet)
{
	int ret=0;
	struct device_context *device_ctx = to_device_context(device_obj);
	struct net_device *net = dev_get_drvdata(&device_ctx->device);
	struct net_device_context *net_device_ctx;

	struct sk_buff *skb;
	void *data;
	int i=0;
	unsigned long flags;

	DPRINT_ENTER(NETVSC_DRV);

	if (!net)
	{
		DPRINT_ERR(NETVSC_DRV, "got receive callback but net device not initialized yet");
		return 0;
	}

	net_device_ctx = netdev_priv(net);

	// Allocate a skb - TODO preallocate this
	//skb = alloc_skb(packet->TotalDataBufferLength, GFP_ATOMIC);
	skb = dev_alloc_skb(packet->TotalDataBufferLength + 2); // Pad 2-bytes to align IP header to 16 bytes
	ASSERT(skb);
	skb_reserve(skb, 2);
	skb->dev = net;

	// for kmap_atomic
	local_irq_save(flags);

	// Copy to skb. This copy is needed here since the memory pointed by NETVSC_PACKET
	// cannot be deallocated
	for (i=0; i<packet->PageBufferCount; i++)
	{
	    data = kmap_atomic(pfn_to_page(packet->PageBuffers[i].Pfn), KM_IRQ1);
	    data = (void*)(unsigned long)data + packet->PageBuffers[i].Offset;

	    memcpy(skb_put(skb, packet->PageBuffers[i].Length), data, packet->PageBuffers[i].Length);

	    kunmap_atomic((void*)((unsigned long)data - packet->PageBuffers[i].Offset), KM_IRQ1);
	}

	local_irq_restore(flags);

	skb->protocol = eth_type_trans(skb, net);

	skb->ip_summed = CHECKSUM_NONE;

	// Pass the skb back up. Network stack will deallocate the skb when it is done
	ret = netif_rx(skb);

	switch (ret)
	{
	case NET_RX_DROP:
		net_device_ctx->stats.rx_dropped++;
		break;
	default:
		net_device_ctx->stats.rx_packets++;
		net_device_ctx->stats.rx_bytes += skb->len;
		break;

	}
	DPRINT_DBG(NETVSC_DRV, "# of recvs %lu total size %lu", net_device_ctx->stats.rx_packets, net_device_ctx->stats.rx_bytes);

	DPRINT_EXIT(NETVSC_DRV);

	return 0;
}

static int netvsc_drv_exit_cb(struct device *dev, void *data)
{
	struct device **curr = (struct device **)data;
	*curr = dev;
	return 1; // stop iterating
}

/*++

Name:	netvsc_drv_exit()

Desc:

--*/
void netvsc_drv_exit(void)
{
	NETVSC_DRIVER_OBJECT *netvsc_drv_obj=&g_netvsc_drv.drv_obj;
	struct driver_context *drv_ctx=&g_netvsc_drv.drv_ctx;

	struct device *current_dev=NULL;
#if defined(KERNEL_2_6_5) || defined(KERNEL_2_6_9)
#define driver_for_each_device(drv, start, data, fn) \
	struct list_head *ptr, *n; \
	list_for_each_safe(ptr, n, &((drv)->devices)) {\
		struct device *curr_dev;\
		curr_dev = list_entry(ptr, struct device, driver_list);\
		fn(curr_dev, data);\
	}
#endif

	DPRINT_ENTER(NETVSC_DRV);

	while (1)
	{
		current_dev = NULL;

		// Get the device
		driver_for_each_device(&drv_ctx->driver, NULL, (void*)&current_dev, netvsc_drv_exit_cb);

		if (current_dev == NULL)
			break;

		// Initiate removal from the top-down
		DPRINT_INFO(NETVSC_DRV, "unregistering device (%p)...", current_dev);

		device_unregister(current_dev);
	}

	if (netvsc_drv_obj->Base.OnCleanup)
		netvsc_drv_obj->Base.OnCleanup(&netvsc_drv_obj->Base);

	vmbus_child_driver_unregister(drv_ctx);

	DPRINT_EXIT(NETVSC_DRV);

	return;
}

static int __init netvsc_init(void)
{
	int ret;

	DPRINT_ENTER(NETVSC_DRV);
	DPRINT_INFO(NETVSC_DRV, "Netvsc initializing....");

	ret = netvsc_drv_init(NetVscInitialize);

	DPRINT_EXIT(NETVSC_DRV);

	return ret;
}

static void __exit netvsc_exit(void)
{
	DPRINT_ENTER(NETVSC_DRV);

	netvsc_drv_exit();

	DPRINT_EXIT(NETVSC_DRV);
}

module_param(netvsc_ringbuffer_size, int, S_IRUGO);

module_init(netvsc_init);
module_exit(netvsc_exit);