// SPDX-License-Identifier: GPL-2.0
/*
 * Endpoint Function Driver to implement Non-Transparent Bridge functionality
 *
 * Copyright (C) 2020 Texas Instruments
 * Author: Kishon Vijay Abraham I <kishon@ti.com>
 */

/*
 * The PCI NTB function driver configures the SoC with multiple PCIe Endpoint
 * (EP) controller instances (see diagram below) in such a way that
 * transactions from one EP controller are routed to the other EP controller.
 * Once PCI NTB function driver configures the SoC with multiple EP instances,
 * HOST1 and HOST2 can communicate with each other using SoC as a bridge.
 *
 *    +-------------+                                   +-------------+
 *    |             |                                   |             |
 *    |    HOST1    |                                   |    HOST2    |
 *    |             |                                   |             |
 *    +------^------+                                   +------^------+
 *           |                                                 |
 *           |                                                 |
 * +---------|-------------------------------------------------|---------+
 * |  +------v------+                                   +------v------+  |
 * |  |             |                                   |             |  |
 * |  |     EP      |                                   |     EP      |  |
 * |  | CONTROLLER1 |                                   | CONTROLLER2 |  |
 * |  |             <----------------------------------->             |  |
 * |  |             |                                   |             |  |
 * |  |             |                                   |             |  |
 * |  |             |  SoC With Multiple EP Instances   |             |  |
 * |  |             |  (Configured using NTB Function)  |             |  |
 * |  +-------------+                                   +-------------+  |
 * +---------------------------------------------------------------------+
 */

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <linux/pci-epc.h>
#include <linux/pci-epf.h>

static struct workqueue_struct *kpcintb_workqueue;

#define COMMAND_CONFIGURE_DOORBELL	1
#define COMMAND_TEARDOWN_DOORBELL	2
#define COMMAND_CONFIGURE_MW		3
#define COMMAND_TEARDOWN_MW		4
#define COMMAND_LINK_UP			5
#define COMMAND_LINK_DOWN		6

#define COMMAND_STATUS_OK		1
#define COMMAND_STATUS_ERROR		2

#define LINK_STATUS_UP			BIT(0)

#define SPAD_COUNT			64
#define DB_COUNT			4
#define NTB_MW_OFFSET			2
#define DB_COUNT_MASK			GENMASK(15, 0)
#define MSIX_ENABLE			BIT(16)
#define MAX_DB_COUNT			32
#define MAX_MW				4

enum epf_ntb_bar {
	BAR_CONFIG,
	BAR_PEER_SPAD,
	BAR_DB_MW1,
	BAR_MW2,
	BAR_MW3,
	BAR_MW4,
};

struct epf_ntb {
	u32 num_mws;
	u32 db_count;
	u32 spad_count;
	struct pci_epf *epf;
	u64 mws_size[MAX_MW];
	struct config_group group;
	struct epf_ntb_epc *epc[2];
};

#define to_epf_ntb(epf_group) container_of((epf_group), struct epf_ntb, group)

struct epf_ntb_epc {
	u8 func_no;
	u8 vfunc_no;
	bool linkup;
	bool is_msix;
	int msix_bar;
	u32 spad_size;
	struct pci_epc *epc;
	struct epf_ntb *epf_ntb;
	void __iomem *mw_addr[6];
	size_t msix_table_offset;
	struct epf_ntb_ctrl *reg;
	struct pci_epf_bar *epf_bar;
	enum pci_barno epf_ntb_bar[6];
	struct delayed_work cmd_handler;
	enum pci_epc_interface_type type;
	const struct pci_epc_features *epc_features;
};

struct epf_ntb_ctrl {
	u32	command;
	u32	argument;
	u16	command_status;
	u16	link_status;
	u32	topology;
	u64	addr;
	u64	size;
	u32	num_mws;
	u32	mw1_offset;
	u32	spad_offset;
	u32	spad_count;
	u32	db_entry_size;
	u32	db_data[MAX_DB_COUNT];
	u32	db_offset[MAX_DB_COUNT];
} __packed;

static struct pci_epf_header epf_ntb_header = {
	.vendorid	= PCI_ANY_ID,
	.deviceid	= PCI_ANY_ID,
	.baseclass_code	= PCI_BASE_CLASS_MEMORY,
	.interrupt_pin	= PCI_INTERRUPT_INTA,
};

/**
 * epf_ntb_link_up() - Raise link_up interrupt to both the hosts
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @link_up: true or false indicating Link is UP or Down
 *
 * Once NTB function in HOST1 and the NTB function in HOST2 invoke
 * ntb_link_enable(), this NTB function driver will trigger a link event to
 * the NTB client in both the hosts.
 */
static int epf_ntb_link_up(struct epf_ntb *ntb, bool link_up)
{
	enum pci_epc_interface_type type;
	enum pci_epc_irq_type irq_type;
	struct epf_ntb_epc *ntb_epc;
	struct epf_ntb_ctrl *ctrl;
	struct pci_epc *epc;
	u8 func_no, vfunc_no;
	bool is_msix;
	int ret;

	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++) {
		ntb_epc = ntb->epc[type];
		epc = ntb_epc->epc;
		func_no = ntb_epc->func_no;
		vfunc_no = ntb_epc->vfunc_no;
		is_msix = ntb_epc->is_msix;
		ctrl = ntb_epc->reg;
		if (link_up)
			ctrl->link_status |= LINK_STATUS_UP;
		else
			ctrl->link_status &= ~LINK_STATUS_UP;
		irq_type = is_msix ? PCI_EPC_IRQ_MSIX : PCI_EPC_IRQ_MSI;
		ret = pci_epc_raise_irq(epc, func_no, vfunc_no, irq_type, 1);
		if (ret) {
			dev_err(&epc->dev,
				"%s intf: Failed to raise Link Up IRQ\n",
				pci_epc_interface_string(type));
			return ret;
		}
	}

	return 0;
}

/**
 * epf_ntb_configure_mw() - Configure the Outbound Address Space for one host
 *   to access the memory window of other host
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 * @mw: Index of the memory window (either 0, 1, 2 or 3)
 *
 * +-----------------+    +---->+----------------+-----------+-----------------+
 * |       BAR0      |    |     |   Doorbell 1   +-----------> MSI|X ADDRESS 1 |
 * +-----------------+    |     +----------------+           +-----------------+
 * |       BAR1      |    |     |   Doorbell 2   +---------+ |                 |
 * +-----------------+----+     +----------------+         | |                 |
 * |       BAR2      |          |   Doorbell 3   +-------+ | +-----------------+
 * +-----------------+----+     +----------------+       | +-> MSI|X ADDRESS 2 |
 * |       BAR3      |    |     |   Doorbell 4   +-----+ |   +-----------------+
 * +-----------------+    |     |----------------+     | |   |                 |
 * |       BAR4      |    |     |                |     | |   +-----------------+
 * +-----------------+    |     |      MW1       +---+ | +-->+ MSI|X ADDRESS 3||
 * |       BAR5      |    |     |                |   | |     +-----------------+
 * +-----------------+    +---->-----------------+   | |     |                 |
 *   EP CONTROLLER 1            |                |   | |     +-----------------+
 *                              |                |   | +---->+ MSI|X ADDRESS 4 |
 *                              +----------------+   |       +-----------------+
 *                      (A)      EP CONTROLLER 2     |       |                 |
 *                                 (OB SPACE)        |       |                 |
 *                                                   +------->      MW1        |
 *                                                           |                 |
 *                                                           |                 |
 *                                                   (B)     +-----------------+
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           +-----------------+
 *                                                           PCI Address Space
 *                                                           (Managed by HOST2)
 *
 * This function performs stage (B) in the above diagram (see MW1) i.e., map OB
 * address space of memory window to PCI address space.
 *
 * This operation requires 3 parameters
 *  1) Address in the outbound address space
 *  2) Address in the PCI Address space
 *  3) Size of the address region to be mapped
 *
 * The address in the outbound address space (for MW1, MW2, MW3 and MW4) is
 * stored in epf_bar corresponding to BAR_DB_MW1 for MW1 and BAR_MW2, BAR_MW3
 * BAR_MW4 for rest of the BARs of epf_ntb_epc that is connected to HOST1. This
 * is populated in epf_ntb_alloc_peer_mem() in this driver.
 *
 * The address and size of the PCI address region that has to be mapped would
 * be provided by HOST2 in ctrl->addr and ctrl->size of epf_ntb_epc that is
 * connected to HOST2.
 *
 * Please note Memory window1 (MW1) and Doorbell registers together will be
 * mapped to a single BAR (BAR2) above for 32-bit BARs. The exact BAR that's
 * used for Memory window (MW) can be obtained from epf_ntb_bar[BAR_DB_MW1],
 * epf_ntb_bar[BAR_MW2], epf_ntb_bar[BAR_MW2], epf_ntb_bar[BAR_MW2].
 */
static int epf_ntb_configure_mw(struct epf_ntb *ntb,
				enum pci_epc_interface_type type, u32 mw)
{
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	struct pci_epf_bar *peer_epf_bar;
	enum pci_barno peer_barno;
	struct epf_ntb_ctrl *ctrl;
	phys_addr_t phys_addr;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	u64 addr, size;
	int ret = 0;

	ntb_epc = ntb->epc[type];
	epc = ntb_epc->epc;

	peer_ntb_epc = ntb->epc[!type];
	peer_barno = peer_ntb_epc->epf_ntb_bar[mw + NTB_MW_OFFSET];
	peer_epf_bar = &peer_ntb_epc->epf_bar[peer_barno];

	phys_addr = peer_epf_bar->phys_addr;
	ctrl = ntb_epc->reg;
	addr = ctrl->addr;
	size = ctrl->size;
	if (mw + NTB_MW_OFFSET == BAR_DB_MW1)
		phys_addr += ctrl->mw1_offset;

	if (size > ntb->mws_size[mw]) {
		dev_err(&epc->dev,
			"%s intf: MW: %d Req Sz:%llxx > Supported Sz:%llx\n",
			pci_epc_interface_string(type), mw, size,
			ntb->mws_size[mw]);
		ret = -EINVAL;
		goto err_invalid_size;
	}

	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	ret = pci_epc_map_addr(epc, func_no, vfunc_no, phys_addr, addr, size);
	if (ret)
		dev_err(&epc->dev,
			"%s intf: Failed to map memory window %d address\n",
			pci_epc_interface_string(type), mw);

err_invalid_size:

	return ret;
}

/**
 * epf_ntb_teardown_mw() - Teardown the configured OB ATU
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 * @mw: Index of the memory window (either 0, 1, 2 or 3)
 *
 * Teardown the configured OB ATU configured in epf_ntb_configure_mw() using
 * pci_epc_unmap_addr()
 */
static void epf_ntb_teardown_mw(struct epf_ntb *ntb,
				enum pci_epc_interface_type type, u32 mw)
{
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	struct pci_epf_bar *peer_epf_bar;
	enum pci_barno peer_barno;
	struct epf_ntb_ctrl *ctrl;
	phys_addr_t phys_addr;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;

	ntb_epc = ntb->epc[type];
	epc = ntb_epc->epc;

	peer_ntb_epc = ntb->epc[!type];
	peer_barno = peer_ntb_epc->epf_ntb_bar[mw + NTB_MW_OFFSET];
	peer_epf_bar = &peer_ntb_epc->epf_bar[peer_barno];

	phys_addr = peer_epf_bar->phys_addr;
	ctrl = ntb_epc->reg;
	if (mw + NTB_MW_OFFSET == BAR_DB_MW1)
		phys_addr += ctrl->mw1_offset;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	pci_epc_unmap_addr(epc, func_no, vfunc_no, phys_addr);
}

/**
 * epf_ntb_configure_msi() - Map OB address space to MSI address
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 * @db_count: Number of doorbell interrupts to map
 *
 *+-----------------+    +----->+----------------+-----------+-----------------+
 *|       BAR0      |    |      |   Doorbell 1   +---+------->   MSI ADDRESS   |
 *+-----------------+    |      +----------------+   |       +-----------------+
 *|       BAR1      |    |      |   Doorbell 2   +---+       |                 |
 *+-----------------+----+      +----------------+   |       |                 |
 *|       BAR2      |           |   Doorbell 3   +---+       |                 |
 *+-----------------+----+      +----------------+   |       |                 |
 *|       BAR3      |    |      |   Doorbell 4   +---+       |                 |
 *+-----------------+    |      |----------------+           |                 |
 *|       BAR4      |    |      |                |           |                 |
 *+-----------------+    |      |      MW1       |           |                 |
 *|       BAR5      |    |      |                |           |                 |
 *+-----------------+    +----->-----------------+           |                 |
 *  EP CONTROLLER 1             |                |           |                 |
 *                              |                |           |                 |
 *                              +----------------+           +-----------------+
 *                     (A)       EP CONTROLLER 2             |                 |
 *                                 (OB SPACE)                |                 |
 *                                                           |      MW1        |
 *                                                           |                 |
 *                                                           |                 |
 *                                                   (B)     +-----------------+
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           +-----------------+
 *                                                           PCI Address Space
 *                                                           (Managed by HOST2)
 *
 *
 * This function performs stage (B) in the above diagram (see Doorbell 1,
 * Doorbell 2, Doorbell 3, Doorbell 4) i.e map OB address space corresponding to
 * doorbell to MSI address in PCI address space.
 *
 * This operation requires 3 parameters
 *  1) Address reserved for doorbell in the outbound address space
 *  2) MSI-X address in the PCIe Address space
 *  3) Number of MSI-X interrupts that has to be configured
 *
 * The address in the outbound address space (for the Doorbell) is stored in
 * epf_bar corresponding to BAR_DB_MW1 of epf_ntb_epc that is connected to
 * HOST1. This is populated in epf_ntb_alloc_peer_mem() in this driver along
 * with address for MW1.
 *
 * pci_epc_map_msi_irq() takes the MSI address from MSI capability register
 * and maps the OB address (obtained in epf_ntb_alloc_peer_mem()) to the MSI
 * address.
 *
 * epf_ntb_configure_msi() also stores the MSI data to raise each interrupt
 * in db_data of the peer's control region. This helps the peer to raise
 * doorbell of the other host by writing db_data to the BAR corresponding to
 * BAR_DB_MW1.
 */
static int epf_ntb_configure_msi(struct epf_ntb *ntb,
				 enum pci_epc_interface_type type, u16 db_count)
{
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	u32 db_entry_size, db_data, db_offset;
	struct pci_epf_bar *peer_epf_bar;
	struct epf_ntb_ctrl *peer_ctrl;
	enum pci_barno peer_barno;
	phys_addr_t phys_addr;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	int ret, i;

	ntb_epc = ntb->epc[type];
	epc = ntb_epc->epc;

	peer_ntb_epc = ntb->epc[!type];
	peer_barno = peer_ntb_epc->epf_ntb_bar[BAR_DB_MW1];
	peer_epf_bar = &peer_ntb_epc->epf_bar[peer_barno];
	peer_ctrl = peer_ntb_epc->reg;
	db_entry_size = peer_ctrl->db_entry_size;

	phys_addr = peer_epf_bar->phys_addr;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	ret = pci_epc_map_msi_irq(epc, func_no, vfunc_no, phys_addr, db_count,
				  db_entry_size, &db_data, &db_offset);
	if (ret) {
		dev_err(&epc->dev, "%s intf: Failed to map MSI IRQ\n",
			pci_epc_interface_string(type));
		return ret;
	}

	for (i = 0; i < db_count; i++) {
		peer_ctrl->db_data[i] = db_data | i;
		peer_ctrl->db_offset[i] = db_offset;
	}

	return 0;
}

/**
 * epf_ntb_configure_msix() - Map OB address space to MSI-X address
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 * @db_count: Number of doorbell interrupts to map
 *
 *+-----------------+    +----->+----------------+-----------+-----------------+
 *|       BAR0      |    |      |   Doorbell 1   +-----------> MSI-X ADDRESS 1 |
 *+-----------------+    |      +----------------+           +-----------------+
 *|       BAR1      |    |      |   Doorbell 2   +---------+ |                 |
 *+-----------------+----+      +----------------+         | |                 |
 *|       BAR2      |           |   Doorbell 3   +-------+ | +-----------------+
 *+-----------------+----+      +----------------+       | +-> MSI-X ADDRESS 2 |
 *|       BAR3      |    |      |   Doorbell 4   +-----+ |   +-----------------+
 *+-----------------+    |      |----------------+     | |   |                 |
 *|       BAR4      |    |      |                |     | |   +-----------------+
 *+-----------------+    |      |      MW1       +     | +-->+ MSI-X ADDRESS 3||
 *|       BAR5      |    |      |                |     |     +-----------------+
 *+-----------------+    +----->-----------------+     |     |                 |
 *  EP CONTROLLER 1             |                |     |     +-----------------+
 *                              |                |     +---->+ MSI-X ADDRESS 4 |
 *                              +----------------+           +-----------------+
 *                     (A)       EP CONTROLLER 2             |                 |
 *                                 (OB SPACE)                |                 |
 *                                                           |      MW1        |
 *                                                           |                 |
 *                                                           |                 |
 *                                                   (B)     +-----------------+
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           +-----------------+
 *                                                           PCI Address Space
 *                                                           (Managed by HOST2)
 *
 * This function performs stage (B) in the above diagram (see Doorbell 1,
 * Doorbell 2, Doorbell 3, Doorbell 4) i.e map OB address space corresponding to
 * doorbell to MSI-X address in PCI address space.
 *
 * This operation requires 3 parameters
 *  1) Address reserved for doorbell in the outbound address space
 *  2) MSI-X address in the PCIe Address space
 *  3) Number of MSI-X interrupts that has to be configured
 *
 * The address in the outbound address space (for the Doorbell) is stored in
 * epf_bar corresponding to BAR_DB_MW1 of epf_ntb_epc that is connected to
 * HOST1. This is populated in epf_ntb_alloc_peer_mem() in this driver along
 * with address for MW1.
 *
 * The MSI-X address is in the MSI-X table of EP CONTROLLER 2 and
 * the count of doorbell is in ctrl->argument of epf_ntb_epc that is connected
 * to HOST2. MSI-X table is stored memory mapped to ntb_epc->msix_bar and the
 * offset is in ntb_epc->msix_table_offset. From this epf_ntb_configure_msix()
 * gets the MSI-X address and data.
 *
 * epf_ntb_configure_msix() also stores the MSI-X data to raise each interrupt
 * in db_data of the peer's control region. This helps the peer to raise
 * doorbell of the other host by writing db_data to the BAR corresponding to
 * BAR_DB_MW1.
 */
static int epf_ntb_configure_msix(struct epf_ntb *ntb,
				  enum pci_epc_interface_type type,
				  u16 db_count)
{
	const struct pci_epc_features *epc_features;
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	struct pci_epf_bar *peer_epf_bar, *epf_bar;
	struct pci_epf_msix_tbl *msix_tbl;
	struct epf_ntb_ctrl *peer_ctrl;
	u32 db_entry_size, msg_data;
	enum pci_barno peer_barno;
	phys_addr_t phys_addr;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	size_t align;
	u64 msg_addr;
	int ret, i;

	ntb_epc = ntb->epc[type];
	epc = ntb_epc->epc;

	epf_bar = &ntb_epc->epf_bar[ntb_epc->msix_bar];
	msix_tbl = epf_bar->addr + ntb_epc->msix_table_offset;

	peer_ntb_epc = ntb->epc[!type];
	peer_barno = peer_ntb_epc->epf_ntb_bar[BAR_DB_MW1];
	peer_epf_bar = &peer_ntb_epc->epf_bar[peer_barno];
	phys_addr = peer_epf_bar->phys_addr;
	peer_ctrl = peer_ntb_epc->reg;
	epc_features = ntb_epc->epc_features;
	align = epc_features->align;

	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;
	db_entry_size = peer_ctrl->db_entry_size;

	for (i = 0; i < db_count; i++) {
		msg_addr = ALIGN_DOWN(msix_tbl[i].msg_addr, align);
		msg_data = msix_tbl[i].msg_data;
		ret = pci_epc_map_addr(epc, func_no, vfunc_no, phys_addr, msg_addr,
				       db_entry_size);
		if (ret) {
			dev_err(&epc->dev,
				"%s intf: Failed to configure MSI-X IRQ\n",
				pci_epc_interface_string(type));
			return ret;
		}
		phys_addr = phys_addr + db_entry_size;
		peer_ctrl->db_data[i] = msg_data;
		peer_ctrl->db_offset[i] = msix_tbl[i].msg_addr & (align - 1);
	}
	ntb_epc->is_msix = true;

	return 0;
}

/**
 * epf_ntb_configure_db() - Configure the Outbound Address Space for one host
 *   to ring the doorbell of other host
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 * @db_count: Count of the number of doorbells that has to be configured
 * @msix: Indicates whether MSI-X or MSI should be used
 *
 * Invokes epf_ntb_configure_msix() or epf_ntb_configure_msi() required for
 * one HOST to ring the doorbell of other HOST.
 */
static int epf_ntb_configure_db(struct epf_ntb *ntb,
				enum pci_epc_interface_type type,
				u16 db_count, bool msix)
{
	struct epf_ntb_epc *ntb_epc;
	struct pci_epc *epc;
	int ret;

	if (db_count > MAX_DB_COUNT)
		return -EINVAL;

	ntb_epc = ntb->epc[type];
	epc = ntb_epc->epc;

	if (msix)
		ret = epf_ntb_configure_msix(ntb, type, db_count);
	else
		ret = epf_ntb_configure_msi(ntb, type, db_count);

	if (ret)
		dev_err(&epc->dev, "%s intf: Failed to configure DB\n",
			pci_epc_interface_string(type));

	return ret;
}

/**
 * epf_ntb_teardown_db() - Unmap address in OB address space to MSI/MSI-X
 *   address
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Invoke pci_epc_unmap_addr() to unmap OB address to MSI/MSI-X address.
 */
static void
epf_ntb_teardown_db(struct epf_ntb *ntb, enum pci_epc_interface_type type)
{
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	struct pci_epf_bar *peer_epf_bar;
	enum pci_barno peer_barno;
	phys_addr_t phys_addr;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;

	ntb_epc = ntb->epc[type];
	epc = ntb_epc->epc;

	peer_ntb_epc = ntb->epc[!type];
	peer_barno = peer_ntb_epc->epf_ntb_bar[BAR_DB_MW1];
	peer_epf_bar = &peer_ntb_epc->epf_bar[peer_barno];
	phys_addr = peer_epf_bar->phys_addr;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	pci_epc_unmap_addr(epc, func_no, vfunc_no, phys_addr);
}

/**
 * epf_ntb_cmd_handler() - Handle commands provided by the NTB Host
 * @work: work_struct for the two epf_ntb_epc (PRIMARY and SECONDARY)
 *
 * Workqueue function that gets invoked for the two epf_ntb_epc
 * periodically (once every 5ms) to see if it has received any commands
 * from NTB host. The host can send commands to configure doorbell or
 * configure memory window or to update link status.
 */
static void epf_ntb_cmd_handler(struct work_struct *work)
{
	enum pci_epc_interface_type type;
	struct epf_ntb_epc *ntb_epc;
	struct epf_ntb_ctrl *ctrl;
	u32 command, argument;
	struct epf_ntb *ntb;
	struct device *dev;
	u16 db_count;
	bool is_msix;
	int ret;

	ntb_epc = container_of(work, struct epf_ntb_epc, cmd_handler.work);
	ctrl = ntb_epc->reg;
	command = ctrl->command;
	if (!command)
		goto reset_handler;
	argument = ctrl->argument;

	ctrl->command = 0;
	ctrl->argument = 0;

	ctrl = ntb_epc->reg;
	type = ntb_epc->type;
	ntb = ntb_epc->epf_ntb;
	dev = &ntb->epf->dev;

	switch (command) {
	case COMMAND_CONFIGURE_DOORBELL:
		db_count = argument & DB_COUNT_MASK;
		is_msix = argument & MSIX_ENABLE;
		ret = epf_ntb_configure_db(ntb, type, db_count, is_msix);
		if (ret < 0)
			ctrl->command_status = COMMAND_STATUS_ERROR;
		else
			ctrl->command_status = COMMAND_STATUS_OK;
		break;
	case COMMAND_TEARDOWN_DOORBELL:
		epf_ntb_teardown_db(ntb, type);
		ctrl->command_status = COMMAND_STATUS_OK;
		break;
	case COMMAND_CONFIGURE_MW:
		ret = epf_ntb_configure_mw(ntb, type, argument);
		if (ret < 0)
			ctrl->command_status = COMMAND_STATUS_ERROR;
		else
			ctrl->command_status = COMMAND_STATUS_OK;
		break;
	case COMMAND_TEARDOWN_MW:
		epf_ntb_teardown_mw(ntb, type, argument);
		ctrl->command_status = COMMAND_STATUS_OK;
		break;
	case COMMAND_LINK_UP:
		ntb_epc->linkup = true;
		if (ntb->epc[PRIMARY_INTERFACE]->linkup &&
		    ntb->epc[SECONDARY_INTERFACE]->linkup) {
			ret = epf_ntb_link_up(ntb, true);
			if (ret < 0)
				ctrl->command_status = COMMAND_STATUS_ERROR;
			else
				ctrl->command_status = COMMAND_STATUS_OK;
			goto reset_handler;
		}
		ctrl->command_status = COMMAND_STATUS_OK;
		break;
	case COMMAND_LINK_DOWN:
		ntb_epc->linkup = false;
		ret = epf_ntb_link_up(ntb, false);
		if (ret < 0)
			ctrl->command_status = COMMAND_STATUS_ERROR;
		else
			ctrl->command_status = COMMAND_STATUS_OK;
		break;
	default:
		dev_err(dev, "%s intf UNKNOWN command: %d\n",
			pci_epc_interface_string(type), command);
		break;
	}

reset_handler:
	queue_delayed_work(kpcintb_workqueue, &ntb_epc->cmd_handler,
			   msecs_to_jiffies(5));
}

/**
 * epf_ntb_peer_spad_bar_clear() - Clear Peer Scratchpad BAR
 * @ntb_epc: EPC associated with one of the HOST which holds peer's outbound
 *	     address.
 *
 *+-----------------+------->+------------------+        +-----------------+
 *|       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
 *+-----------------+----+   +------------------+<-------+-----------------+
 *|       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
 *+-----------------+    +-->+------------------+<-------+-----------------+
 *|       BAR2      |            Local Memory            |       BAR2      |
 *+-----------------+                                    +-----------------+
 *|       BAR3      |                                    |       BAR3      |
 *+-----------------+                                    +-----------------+
 *|       BAR4      |                                    |       BAR4      |
 *+-----------------+                                    +-----------------+
 *|       BAR5      |                                    |       BAR5      |
 *+-----------------+                                    +-----------------+
 *  EP CONTROLLER 1                                        EP CONTROLLER 2
 *
 * Clear BAR1 of EP CONTROLLER 2 which contains the HOST2's peer scratchpad
 * region. While BAR1 is the default peer scratchpad BAR, an NTB could have
 * other BARs for peer scratchpad (because of 64-bit BARs or reserved BARs).
 * This function can get the exact BAR used for peer scratchpad from
 * epf_ntb_bar[BAR_PEER_SPAD].
 *
 * Since HOST2's peer scratchpad is also HOST1's self scratchpad, this function
 * gets the address of peer scratchpad from
 * peer_ntb_epc->epf_ntb_bar[BAR_CONFIG].
 */
static void epf_ntb_peer_spad_bar_clear(struct epf_ntb_epc *ntb_epc)
{
	struct pci_epf_bar *epf_bar;
	enum pci_barno barno;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;

	epc = ntb_epc->epc;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;
	barno = ntb_epc->epf_ntb_bar[BAR_PEER_SPAD];
	epf_bar = &ntb_epc->epf_bar[barno];
	pci_epc_clear_bar(epc, func_no, vfunc_no, epf_bar);
}

/**
 * epf_ntb_peer_spad_bar_set() - Set peer scratchpad BAR
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 *+-----------------+------->+------------------+        +-----------------+
 *|       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
 *+-----------------+----+   +------------------+<-------+-----------------+
 *|       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
 *+-----------------+    +-->+------------------+<-------+-----------------+
 *|       BAR2      |            Local Memory            |       BAR2      |
 *+-----------------+                                    +-----------------+
 *|       BAR3      |                                    |       BAR3      |
 *+-----------------+                                    +-----------------+
 *|       BAR4      |                                    |       BAR4      |
 *+-----------------+                                    +-----------------+
 *|       BAR5      |                                    |       BAR5      |
 *+-----------------+                                    +-----------------+
 *  EP CONTROLLER 1                                        EP CONTROLLER 2
 *
 * Set BAR1 of EP CONTROLLER 2 which contains the HOST2's peer scratchpad
 * region. While BAR1 is the default peer scratchpad BAR, an NTB could have
 * other BARs for peer scratchpad (because of 64-bit BARs or reserved BARs).
 * This function can get the exact BAR used for peer scratchpad from
 * epf_ntb_bar[BAR_PEER_SPAD].
 *
 * Since HOST2's peer scratchpad is also HOST1's self scratchpad, this function
 * gets the address of peer scratchpad from
 * peer_ntb_epc->epf_ntb_bar[BAR_CONFIG].
 */
static int epf_ntb_peer_spad_bar_set(struct epf_ntb *ntb,
				     enum pci_epc_interface_type type)
{
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	struct pci_epf_bar *peer_epf_bar, *epf_bar;
	enum pci_barno peer_barno, barno;
	u32 peer_spad_offset;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	struct device *dev;
	int ret;

	dev = &ntb->epf->dev;

	peer_ntb_epc = ntb->epc[!type];
	peer_barno = peer_ntb_epc->epf_ntb_bar[BAR_CONFIG];
	peer_epf_bar = &peer_ntb_epc->epf_bar[peer_barno];

	ntb_epc = ntb->epc[type];
	barno = ntb_epc->epf_ntb_bar[BAR_PEER_SPAD];
	epf_bar = &ntb_epc->epf_bar[barno];
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;
	epc = ntb_epc->epc;

	peer_spad_offset = peer_ntb_epc->reg->spad_offset;
	epf_bar->phys_addr = peer_epf_bar->phys_addr + peer_spad_offset;
	epf_bar->size = peer_ntb_epc->spad_size;
	epf_bar->barno = barno;
	epf_bar->flags = PCI_BASE_ADDRESS_MEM_TYPE_32;

	ret = pci_epc_set_bar(epc, func_no, vfunc_no, epf_bar);
	if (ret) {
		dev_err(dev, "%s intf: peer SPAD BAR set failed\n",
			pci_epc_interface_string(type));
		return ret;
	}

	return 0;
}

/**
 * epf_ntb_config_sspad_bar_clear() - Clear Config + Self scratchpad BAR
 * @ntb_epc: EPC associated with one of the HOST which holds peer's outbound
 *	     address.
 *
 * +-----------------+------->+------------------+        +-----------------+
 * |       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
 * +-----------------+----+   +------------------+<-------+-----------------+
 * |       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
 * +-----------------+    +-->+------------------+<-------+-----------------+
 * |       BAR2      |            Local Memory            |       BAR2      |
 * +-----------------+                                    +-----------------+
 * |       BAR3      |                                    |       BAR3      |
 * +-----------------+                                    +-----------------+
 * |       BAR4      |                                    |       BAR4      |
 * +-----------------+                                    +-----------------+
 * |       BAR5      |                                    |       BAR5      |
 * +-----------------+                                    +-----------------+
 *   EP CONTROLLER 1                                        EP CONTROLLER 2
 *
 * Clear BAR0 of EP CONTROLLER 1 which contains the HOST1's config and
 * self scratchpad region (removes inbound ATU configuration). While BAR0 is
 * the default self scratchpad BAR, an NTB could have other BARs for self
 * scratchpad (because of reserved BARs). This function can get the exact BAR
 * used for self scratchpad from epf_ntb_bar[BAR_CONFIG].
 *
 * Please note the self scratchpad region and config region is combined to
 * a single region and mapped using the same BAR. Also note HOST2's peer
 * scratchpad is HOST1's self scratchpad.
 */
static void epf_ntb_config_sspad_bar_clear(struct epf_ntb_epc *ntb_epc)
{
	struct pci_epf_bar *epf_bar;
	enum pci_barno barno;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;

	epc = ntb_epc->epc;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;
	barno = ntb_epc->epf_ntb_bar[BAR_CONFIG];
	epf_bar = &ntb_epc->epf_bar[barno];
	pci_epc_clear_bar(epc, func_no, vfunc_no, epf_bar);
}

/**
 * epf_ntb_config_sspad_bar_set() - Set Config + Self scratchpad BAR
 * @ntb_epc: EPC associated with one of the HOST which holds peer's outbound
 *	     address.
 *
 * +-----------------+------->+------------------+        +-----------------+
 * |       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
 * +-----------------+----+   +------------------+<-------+-----------------+
 * |       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
 * +-----------------+    +-->+------------------+<-------+-----------------+
 * |       BAR2      |            Local Memory            |       BAR2      |
 * +-----------------+                                    +-----------------+
 * |       BAR3      |                                    |       BAR3      |
 * +-----------------+                                    +-----------------+
 * |       BAR4      |                                    |       BAR4      |
 * +-----------------+                                    +-----------------+
 * |       BAR5      |                                    |       BAR5      |
 * +-----------------+                                    +-----------------+
 *   EP CONTROLLER 1                                        EP CONTROLLER 2
 *
 * Map BAR0 of EP CONTROLLER 1 which contains the HOST1's config and
 * self scratchpad region. While BAR0 is the default self scratchpad BAR, an
 * NTB could have other BARs for self scratchpad (because of reserved BARs).
 * This function can get the exact BAR used for self scratchpad from
 * epf_ntb_bar[BAR_CONFIG].
 *
 * Please note the self scratchpad region and config region is combined to
 * a single region and mapped using the same BAR. Also note HOST2's peer
 * scratchpad is HOST1's self scratchpad.
 */
static int epf_ntb_config_sspad_bar_set(struct epf_ntb_epc *ntb_epc)
{
	struct pci_epf_bar *epf_bar;
	enum pci_barno barno;
	u8 func_no, vfunc_no;
	struct epf_ntb *ntb;
	struct pci_epc *epc;
	struct device *dev;
	int ret;

	ntb = ntb_epc->epf_ntb;
	dev = &ntb->epf->dev;

	epc = ntb_epc->epc;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;
	barno = ntb_epc->epf_ntb_bar[BAR_CONFIG];
	epf_bar = &ntb_epc->epf_bar[barno];

	ret = pci_epc_set_bar(epc, func_no, vfunc_no, epf_bar);
	if (ret) {
		dev_err(dev, "%s inft: Config/Status/SPAD BAR set failed\n",
			pci_epc_interface_string(ntb_epc->type));
		return ret;
	}

	return 0;
}

/**
 * epf_ntb_config_spad_bar_free() - Free the physical memory associated with
 *   config + scratchpad region
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * +-----------------+------->+------------------+        +-----------------+
 * |       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
 * +-----------------+----+   +------------------+<-------+-----------------+
 * |       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
 * +-----------------+    +-->+------------------+<-------+-----------------+
 * |       BAR2      |            Local Memory            |       BAR2      |
 * +-----------------+                                    +-----------------+
 * |       BAR3      |                                    |       BAR3      |
 * +-----------------+                                    +-----------------+
 * |       BAR4      |                                    |       BAR4      |
 * +-----------------+                                    +-----------------+
 * |       BAR5      |                                    |       BAR5      |
 * +-----------------+                                    +-----------------+
 *   EP CONTROLLER 1                                        EP CONTROLLER 2
 *
 * Free the Local Memory mentioned in the above diagram. After invoking this
 * function, any of config + self scratchpad region of HOST1 or peer scratchpad
 * region of HOST2 should not be accessed.
 */
static void epf_ntb_config_spad_bar_free(struct epf_ntb *ntb)
{
	enum pci_epc_interface_type type;
	struct epf_ntb_epc *ntb_epc;
	enum pci_barno barno;
	struct pci_epf *epf;

	epf = ntb->epf;
	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++) {
		ntb_epc = ntb->epc[type];
		barno = ntb_epc->epf_ntb_bar[BAR_CONFIG];
		if (ntb_epc->reg)
			pci_epf_free_space(epf, ntb_epc->reg, barno, type);
	}
}

/**
 * epf_ntb_config_spad_bar_alloc() - Allocate memory for config + scratchpad
 *   region
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * +-----------------+------->+------------------+        +-----------------+
 * |       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
 * +-----------------+----+   +------------------+<-------+-----------------+
 * |       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
 * +-----------------+    +-->+------------------+<-------+-----------------+
 * |       BAR2      |            Local Memory            |       BAR2      |
 * +-----------------+                                    +-----------------+
 * |       BAR3      |                                    |       BAR3      |
 * +-----------------+                                    +-----------------+
 * |       BAR4      |                                    |       BAR4      |
 * +-----------------+                                    +-----------------+
 * |       BAR5      |                                    |       BAR5      |
 * +-----------------+                                    +-----------------+
 *   EP CONTROLLER 1                                        EP CONTROLLER 2
 *
 * Allocate the Local Memory mentioned in the above diagram. The size of
 * CONFIG REGION is sizeof(struct epf_ntb_ctrl) and size of SCRATCHPAD REGION
 * is obtained from "spad-count" configfs entry.
 *
 * The size of both config region and scratchpad region has to be aligned,
 * since the scratchpad region will also be mapped as PEER SCRATCHPAD of
 * other host using a separate BAR.
 */
static int epf_ntb_config_spad_bar_alloc(struct epf_ntb *ntb,
					 enum pci_epc_interface_type type)
{
	const struct pci_epc_features *peer_epc_features, *epc_features;
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	size_t msix_table_size, pba_size, align;
	enum pci_barno peer_barno, barno;
	struct epf_ntb_ctrl *ctrl;
	u32 spad_size, ctrl_size;
	u64 size, peer_size;
	struct pci_epf *epf;
	struct device *dev;
	bool msix_capable;
	u32 spad_count;
	void *base;

	epf = ntb->epf;
	dev = &epf->dev;
	ntb_epc = ntb->epc[type];

	epc_features = ntb_epc->epc_features;
	barno = ntb_epc->epf_ntb_bar[BAR_CONFIG];
	size = epc_features->bar_fixed_size[barno];
	align = epc_features->align;

	peer_ntb_epc = ntb->epc[!type];
	peer_epc_features = peer_ntb_epc->epc_features;
	peer_barno = ntb_epc->epf_ntb_bar[BAR_PEER_SPAD];
	peer_size = peer_epc_features->bar_fixed_size[peer_barno];

	/* Check if epc_features is populated incorrectly */
	if ((!IS_ALIGNED(size, align)))
		return -EINVAL;

	spad_count = ntb->spad_count;

	ctrl_size = sizeof(struct epf_ntb_ctrl);
	spad_size = spad_count * 4;

	msix_capable = epc_features->msix_capable;
	if (msix_capable) {
		msix_table_size = PCI_MSIX_ENTRY_SIZE * ntb->db_count;
		ctrl_size = ALIGN(ctrl_size, 8);
		ntb_epc->msix_table_offset = ctrl_size;
		ntb_epc->msix_bar = barno;
		/* Align to QWORD or 8 Bytes */
		pba_size = ALIGN(DIV_ROUND_UP(ntb->db_count, 8), 8);
		ctrl_size = ctrl_size + msix_table_size + pba_size;
	}

	if (!align) {
		ctrl_size = roundup_pow_of_two(ctrl_size);
		spad_size = roundup_pow_of_two(spad_size);
	} else {
		ctrl_size = ALIGN(ctrl_size, align);
		spad_size = ALIGN(spad_size, align);
	}

	if (peer_size) {
		if (peer_size < spad_size)
			spad_count = peer_size / 4;
		spad_size = peer_size;
	}

	/*
	 * In order to make sure SPAD offset is aligned to its size,
	 * expand control region size to the size of SPAD if SPAD size
	 * is greater than control region size.
	 */
	if (spad_size > ctrl_size)
		ctrl_size = spad_size;

	if (!size)
		size = ctrl_size + spad_size;
	else if (size < ctrl_size + spad_size)
		return -EINVAL;

	base = pci_epf_alloc_space(epf, size, barno, align, type);
	if (!base) {
		dev_err(dev, "%s intf: Config/Status/SPAD alloc region fail\n",
			pci_epc_interface_string(type));
		return -ENOMEM;
	}

	ntb_epc->reg = base;

	ctrl = ntb_epc->reg;
	ctrl->spad_offset = ctrl_size;
	ctrl->spad_count = spad_count;
	ctrl->num_mws = ntb->num_mws;
	ctrl->db_entry_size = align ? align : 4;
	ntb_epc->spad_size = spad_size;

	return 0;
}

/**
 * epf_ntb_config_spad_bar_alloc_interface() - Allocate memory for config +
 *   scratchpad region for each of PRIMARY and SECONDARY interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * Wrapper for epf_ntb_config_spad_bar_alloc() which allocates memory for
 * config + scratchpad region for a specific interface
 */
static int epf_ntb_config_spad_bar_alloc_interface(struct epf_ntb *ntb)
{
	enum pci_epc_interface_type type;
	struct device *dev;
	int ret;

	dev = &ntb->epf->dev;

	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++) {
		ret = epf_ntb_config_spad_bar_alloc(ntb, type);
		if (ret) {
			dev_err(dev, "%s intf: Config/SPAD BAR alloc failed\n",
				pci_epc_interface_string(type));
			return ret;
		}
	}

	return 0;
}

/**
 * epf_ntb_free_peer_mem() - Free memory allocated in peers outbound address
 *   space
 * @ntb_epc: EPC associated with one of the HOST which holds peers outbound
 *   address regions
 *
 * +-----------------+    +---->+----------------+-----------+-----------------+
 * |       BAR0      |    |     |   Doorbell 1   +-----------> MSI|X ADDRESS 1 |
 * +-----------------+    |     +----------------+           +-----------------+
 * |       BAR1      |    |     |   Doorbell 2   +---------+ |                 |
 * +-----------------+----+     +----------------+         | |                 |
 * |       BAR2      |          |   Doorbell 3   +-------+ | +-----------------+
 * +-----------------+----+     +----------------+       | +-> MSI|X ADDRESS 2 |
 * |       BAR3      |    |     |   Doorbell 4   +-----+ |   +-----------------+
 * +-----------------+    |     |----------------+     | |   |                 |
 * |       BAR4      |    |     |                |     | |   +-----------------+
 * +-----------------+    |     |      MW1       +---+ | +-->+ MSI|X ADDRESS 3||
 * |       BAR5      |    |     |                |   | |     +-----------------+
 * +-----------------+    +---->-----------------+   | |     |                 |
 *   EP CONTROLLER 1            |                |   | |     +-----------------+
 *                              |                |   | +---->+ MSI|X ADDRESS 4 |
 *                              +----------------+   |       +-----------------+
 *                      (A)      EP CONTROLLER 2     |       |                 |
 *                                 (OB SPACE)        |       |                 |
 *                                                   +------->      MW1        |
 *                                                           |                 |
 *                                                           |                 |
 *                                                   (B)     +-----------------+
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           +-----------------+
 *                                                           PCI Address Space
 *                                                           (Managed by HOST2)
 *
 * Free memory allocated in EP CONTROLLER 2 (OB SPACE) in the above diagram.
 * It'll free Doorbell 1, Doorbell 2, Doorbell 3, Doorbell 4, MW1 (and MW2, MW3,
 * MW4).
 */
static void epf_ntb_free_peer_mem(struct epf_ntb_epc *ntb_epc)
{
	struct pci_epf_bar *epf_bar;
	void __iomem *mw_addr;
	phys_addr_t phys_addr;
	enum epf_ntb_bar bar;
	enum pci_barno barno;
	struct pci_epc *epc;
	size_t size;

	epc = ntb_epc->epc;

	for (bar = BAR_DB_MW1; bar < BAR_MW4; bar++) {
		barno = ntb_epc->epf_ntb_bar[bar];
		mw_addr = ntb_epc->mw_addr[barno];
		epf_bar = &ntb_epc->epf_bar[barno];
		phys_addr = epf_bar->phys_addr;
		size = epf_bar->size;
		if (mw_addr) {
			pci_epc_mem_free_addr(epc, phys_addr, mw_addr, size);
			ntb_epc->mw_addr[barno] = NULL;
		}
	}
}

/**
 * epf_ntb_db_mw_bar_clear() - Clear doorbell and memory BAR
 * @ntb_epc: EPC associated with one of the HOST which holds peer's outbound
 *   address
 *
 * +-----------------+    +---->+----------------+-----------+-----------------+
 * |       BAR0      |    |     |   Doorbell 1   +-----------> MSI|X ADDRESS 1 |
 * +-----------------+    |     +----------------+           +-----------------+
 * |       BAR1      |    |     |   Doorbell 2   +---------+ |                 |
 * +-----------------+----+     +----------------+         | |                 |
 * |       BAR2      |          |   Doorbell 3   +-------+ | +-----------------+
 * +-----------------+----+     +----------------+       | +-> MSI|X ADDRESS 2 |
 * |       BAR3      |    |     |   Doorbell 4   +-----+ |   +-----------------+
 * +-----------------+    |     |----------------+     | |   |                 |
 * |       BAR4      |    |     |                |     | |   +-----------------+
 * +-----------------+    |     |      MW1       +---+ | +-->+ MSI|X ADDRESS 3||
 * |       BAR5      |    |     |                |   | |     +-----------------+
 * +-----------------+    +---->-----------------+   | |     |                 |
 *   EP CONTROLLER 1            |                |   | |     +-----------------+
 *                              |                |   | +---->+ MSI|X ADDRESS 4 |
 *                              +----------------+   |       +-----------------+
 *                      (A)      EP CONTROLLER 2     |       |                 |
 *                                 (OB SPACE)        |       |                 |
 *                                                   +------->      MW1        |
 *                                                           |                 |
 *                                                           |                 |
 *                                                   (B)     +-----------------+
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           +-----------------+
 *                                                           PCI Address Space
 *                                                           (Managed by HOST2)
 *
 * Clear doorbell and memory BARs (remove inbound ATU configuration). In the above
 * diagram it clears BAR2 TO BAR5 of EP CONTROLLER 1 (Doorbell BAR, MW1 BAR, MW2
 * BAR, MW3 BAR and MW4 BAR).
 */
static void epf_ntb_db_mw_bar_clear(struct epf_ntb_epc *ntb_epc)
{
	struct pci_epf_bar *epf_bar;
	enum epf_ntb_bar bar;
	enum pci_barno barno;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;

	epc = ntb_epc->epc;

	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	for (bar = BAR_DB_MW1; bar < BAR_MW4; bar++) {
		barno = ntb_epc->epf_ntb_bar[bar];
		epf_bar = &ntb_epc->epf_bar[barno];
		pci_epc_clear_bar(epc, func_no, vfunc_no, epf_bar);
	}
}

/**
 * epf_ntb_db_mw_bar_cleanup() - Clear doorbell/memory BAR and free memory
 *   allocated in peers outbound address space
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Wrapper for epf_ntb_db_mw_bar_clear() to clear HOST1's BAR and
 * epf_ntb_free_peer_mem() which frees up HOST2 outbound memory.
 */
static void epf_ntb_db_mw_bar_cleanup(struct epf_ntb *ntb,
				      enum pci_epc_interface_type type)
{
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;

	ntb_epc = ntb->epc[type];
	peer_ntb_epc = ntb->epc[!type];

	epf_ntb_db_mw_bar_clear(ntb_epc);
	epf_ntb_free_peer_mem(peer_ntb_epc);
}

/**
 * epf_ntb_configure_interrupt() - Configure MSI/MSI-X capaiblity
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Configure MSI/MSI-X capability for each interface with number of
 * interrupts equal to "db_count" configfs entry.
 */
static int epf_ntb_configure_interrupt(struct epf_ntb *ntb,
				       enum pci_epc_interface_type type)
{
	const struct pci_epc_features *epc_features;
	bool msix_capable, msi_capable;
	struct epf_ntb_epc *ntb_epc;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	struct device *dev;
	u32 db_count;
	int ret;

	ntb_epc = ntb->epc[type];
	dev = &ntb->epf->dev;

	epc_features = ntb_epc->epc_features;
	msix_capable = epc_features->msix_capable;
	msi_capable = epc_features->msi_capable;

	if (!(msix_capable || msi_capable)) {
		dev_err(dev, "MSI or MSI-X is required for doorbell\n");
		return -EINVAL;
	}

	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	db_count = ntb->db_count;
	if (db_count > MAX_DB_COUNT) {
		dev_err(dev, "DB count cannot be more than %d\n", MAX_DB_COUNT);
		return -EINVAL;
	}

	ntb->db_count = db_count;
	epc = ntb_epc->epc;

	if (msi_capable) {
		ret = pci_epc_set_msi(epc, func_no, vfunc_no, db_count);
		if (ret) {
			dev_err(dev, "%s intf: MSI configuration failed\n",
				pci_epc_interface_string(type));
			return ret;
		}
	}

	if (msix_capable) {
		ret = pci_epc_set_msix(epc, func_no, vfunc_no, db_count,
				       ntb_epc->msix_bar,
				       ntb_epc->msix_table_offset);
		if (ret) {
			dev_err(dev, "MSI configuration failed\n");
			return ret;
		}
	}

	return 0;
}

/**
 * epf_ntb_alloc_peer_mem() - Allocate memory in peer's outbound address space
 * @dev: The PCI device.
 * @ntb_epc: EPC associated with one of the HOST whose BAR holds peer's outbound
 *   address
 * @bar: BAR of @ntb_epc in for which memory has to be allocated (could be
 *   BAR_DB_MW1, BAR_MW2, BAR_MW3, BAR_MW4)
 * @peer_ntb_epc: EPC associated with HOST whose outbound address space is
 *   used by @ntb_epc
 * @size: Size of the address region that has to be allocated in peers OB SPACE
 *
 *
 * +-----------------+    +---->+----------------+-----------+-----------------+
 * |       BAR0      |    |     |   Doorbell 1   +-----------> MSI|X ADDRESS 1 |
 * +-----------------+    |     +----------------+           +-----------------+
 * |       BAR1      |    |     |   Doorbell 2   +---------+ |                 |
 * +-----------------+----+     +----------------+         | |                 |
 * |       BAR2      |          |   Doorbell 3   +-------+ | +-----------------+
 * +-----------------+----+     +----------------+       | +-> MSI|X ADDRESS 2 |
 * |       BAR3      |    |     |   Doorbell 4   +-----+ |   +-----------------+
 * +-----------------+    |     |----------------+     | |   |                 |
 * |       BAR4      |    |     |                |     | |   +-----------------+
 * +-----------------+    |     |      MW1       +---+ | +-->+ MSI|X ADDRESS 3||
 * |       BAR5      |    |     |                |   | |     +-----------------+
 * +-----------------+    +---->-----------------+   | |     |                 |
 *   EP CONTROLLER 1            |                |   | |     +-----------------+
 *                              |                |   | +---->+ MSI|X ADDRESS 4 |
 *                              +----------------+   |       +-----------------+
 *                      (A)      EP CONTROLLER 2     |       |                 |
 *                                 (OB SPACE)        |       |                 |
 *                                                   +------->      MW1        |
 *                                                           |                 |
 *                                                           |                 |
 *                                                   (B)     +-----------------+
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           |                 |
 *                                                           +-----------------+
 *                                                           PCI Address Space
 *                                                           (Managed by HOST2)
 *
 * Allocate memory in OB space of EP CONTROLLER 2 in the above diagram. Allocate
 * for Doorbell 1, Doorbell 2, Doorbell 3, Doorbell 4, MW1 (and MW2, MW3, MW4).
 */
static int epf_ntb_alloc_peer_mem(struct device *dev,
				  struct epf_ntb_epc *ntb_epc,
				  enum epf_ntb_bar bar,
				  struct epf_ntb_epc *peer_ntb_epc,
				  size_t size)
{
	const struct pci_epc_features *epc_features;
	struct pci_epf_bar *epf_bar;
	struct pci_epc *peer_epc;
	phys_addr_t phys_addr;
	void __iomem *mw_addr;
	enum pci_barno barno;
	size_t align;

	epc_features = ntb_epc->epc_features;
	align = epc_features->align;

	if (size < 128)
		size = 128;

	if (align)
		size = ALIGN(size, align);
	else
		size = roundup_pow_of_two(size);

	peer_epc = peer_ntb_epc->epc;
	mw_addr = pci_epc_mem_alloc_addr(peer_epc, &phys_addr, size);
	if (!mw_addr) {
		dev_err(dev, "%s intf: Failed to allocate OB address\n",
			pci_epc_interface_string(peer_ntb_epc->type));
		return -ENOMEM;
	}

	barno = ntb_epc->epf_ntb_bar[bar];
	epf_bar = &ntb_epc->epf_bar[barno];
	ntb_epc->mw_addr[barno] = mw_addr;

	epf_bar->phys_addr = phys_addr;
	epf_bar->size = size;
	epf_bar->barno = barno;
	epf_bar->flags = PCI_BASE_ADDRESS_MEM_TYPE_32;

	return 0;
}

/**
 * epf_ntb_db_mw_bar_init() - Configure Doorbell and Memory window BARs
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Wrapper for epf_ntb_alloc_peer_mem() and pci_epc_set_bar() that allocates
 * memory in OB address space of HOST2 and configures BAR of HOST1
 */
static int epf_ntb_db_mw_bar_init(struct epf_ntb *ntb,
				  enum pci_epc_interface_type type)
{
	const struct pci_epc_features *epc_features;
	struct epf_ntb_epc *peer_ntb_epc, *ntb_epc;
	struct pci_epf_bar *epf_bar;
	struct epf_ntb_ctrl *ctrl;
	u32 num_mws, db_count;
	enum epf_ntb_bar bar;
	enum pci_barno barno;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	struct device *dev;
	size_t align;
	int ret, i;
	u64 size;

	ntb_epc = ntb->epc[type];
	peer_ntb_epc = ntb->epc[!type];

	dev = &ntb->epf->dev;
	epc_features = ntb_epc->epc_features;
	align = epc_features->align;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;
	epc = ntb_epc->epc;
	num_mws = ntb->num_mws;
	db_count = ntb->db_count;

	for (bar = BAR_DB_MW1, i = 0; i < num_mws; bar++, i++) {
		if (bar == BAR_DB_MW1) {
			align = align ? align : 4;
			size = db_count * align;
			size = ALIGN(size, ntb->mws_size[i]);
			ctrl = ntb_epc->reg;
			ctrl->mw1_offset = size;
			size += ntb->mws_size[i];
		} else {
			size = ntb->mws_size[i];
		}

		ret = epf_ntb_alloc_peer_mem(dev, ntb_epc, bar,
					     peer_ntb_epc, size);
		if (ret) {
			dev_err(dev, "%s intf: DoorBell mem alloc failed\n",
				pci_epc_interface_string(type));
			goto err_alloc_peer_mem;
		}

		barno = ntb_epc->epf_ntb_bar[bar];
		epf_bar = &ntb_epc->epf_bar[barno];

		ret = pci_epc_set_bar(epc, func_no, vfunc_no, epf_bar);
		if (ret) {
			dev_err(dev, "%s intf: DoorBell BAR set failed\n",
				pci_epc_interface_string(type));
			goto err_alloc_peer_mem;
		}
	}

	return 0;

err_alloc_peer_mem:
	epf_ntb_db_mw_bar_cleanup(ntb, type);

	return ret;
}

/**
 * epf_ntb_epc_destroy_interface() - Cleanup NTB EPC interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Unbind NTB function device from EPC and relinquish reference to pci_epc
 * for each of the interface.
 */
static void epf_ntb_epc_destroy_interface(struct epf_ntb *ntb,
					  enum pci_epc_interface_type type)
{
	struct epf_ntb_epc *ntb_epc;
	struct pci_epc *epc;
	struct pci_epf *epf;

	if (type < 0)
		return;

	epf = ntb->epf;
	ntb_epc = ntb->epc[type];
	if (!ntb_epc)
		return;
	epc = ntb_epc->epc;
	pci_epc_remove_epf(epc, epf, type);
	pci_epc_put(epc);
}

/**
 * epf_ntb_epc_destroy() - Cleanup NTB EPC interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * Wrapper for epf_ntb_epc_destroy_interface() to cleanup all the NTB interfaces
 */
static void epf_ntb_epc_destroy(struct epf_ntb *ntb)
{
	enum pci_epc_interface_type type;

	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++)
		epf_ntb_epc_destroy_interface(ntb, type);
}

/**
 * epf_ntb_epc_create_interface() - Create and initialize NTB EPC interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @epc: struct pci_epc to which a particular NTB interface should be associated
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Allocate memory for NTB EPC interface and initialize it.
 */
static int epf_ntb_epc_create_interface(struct epf_ntb *ntb,
					struct pci_epc *epc,
					enum pci_epc_interface_type type)
{
	const struct pci_epc_features *epc_features;
	struct pci_epf_bar *epf_bar;
	struct epf_ntb_epc *ntb_epc;
	u8 func_no, vfunc_no;
	struct pci_epf *epf;
	struct device *dev;

	dev = &ntb->epf->dev;

	ntb_epc = devm_kzalloc(dev, sizeof(*ntb_epc), GFP_KERNEL);
	if (!ntb_epc)
		return -ENOMEM;

	epf = ntb->epf;
	vfunc_no = epf->vfunc_no;
	if (type == PRIMARY_INTERFACE) {
		func_no = epf->func_no;
		epf_bar = epf->bar;
	} else {
		func_no = epf->sec_epc_func_no;
		epf_bar = epf->sec_epc_bar;
	}

	ntb_epc->linkup = false;
	ntb_epc->epc = epc;
	ntb_epc->func_no = func_no;
	ntb_epc->vfunc_no = vfunc_no;
	ntb_epc->type = type;
	ntb_epc->epf_bar = epf_bar;
	ntb_epc->epf_ntb = ntb;

	epc_features = pci_epc_get_features(epc, func_no, vfunc_no);
	if (!epc_features)
		return -EINVAL;
	ntb_epc->epc_features = epc_features;

	ntb->epc[type] = ntb_epc;

	return 0;
}

/**
 * epf_ntb_epc_create() - Create and initialize NTB EPC interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * Get a reference to EPC device and bind NTB function device to that EPC
 * for each of the interface. It is also a wrapper to
 * epf_ntb_epc_create_interface() to allocate memory for NTB EPC interface
 * and initialize it
 */
static int epf_ntb_epc_create(struct epf_ntb *ntb)
{
	struct pci_epf *epf;
	struct device *dev;
	int ret;

	epf = ntb->epf;
	dev = &epf->dev;

	ret = epf_ntb_epc_create_interface(ntb, epf->epc, PRIMARY_INTERFACE);
	if (ret) {
		dev_err(dev, "PRIMARY intf: Fail to create NTB EPC\n");
		return ret;
	}

	ret = epf_ntb_epc_create_interface(ntb, epf->sec_epc,
					   SECONDARY_INTERFACE);
	if (ret) {
		dev_err(dev, "SECONDARY intf: Fail to create NTB EPC\n");
		goto err_epc_create;
	}

	return 0;

err_epc_create:
	epf_ntb_epc_destroy_interface(ntb, PRIMARY_INTERFACE);

	return ret;
}

/**
 * epf_ntb_init_epc_bar_interface() - Identify BARs to be used for each of
 *   the NTB constructs (scratchpad region, doorbell, memorywindow)
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Identify the free BARs to be used for each of BAR_CONFIG, BAR_PEER_SPAD,
 * BAR_DB_MW1, BAR_MW2, BAR_MW3 and BAR_MW4.
 */
static int epf_ntb_init_epc_bar_interface(struct epf_ntb *ntb,
					  enum pci_epc_interface_type type)
{
	const struct pci_epc_features *epc_features;
	struct epf_ntb_epc *ntb_epc;
	enum pci_barno barno;
	enum epf_ntb_bar bar;
	struct device *dev;
	u32 num_mws;
	int i;

	barno = BAR_0;
	ntb_epc = ntb->epc[type];
	num_mws = ntb->num_mws;
	dev = &ntb->epf->dev;
	epc_features = ntb_epc->epc_features;

	/* These are required BARs which are mandatory for NTB functionality */
	for (bar = BAR_CONFIG; bar <= BAR_DB_MW1; bar++, barno++) {
		barno = pci_epc_get_next_free_bar(epc_features, barno);
		if (barno < 0) {
			dev_err(dev, "%s intf: Fail to get NTB function BAR\n",
				pci_epc_interface_string(type));
			return barno;
		}
		ntb_epc->epf_ntb_bar[bar] = barno;
	}

	/* These are optional BARs which don't impact NTB functionality */
	for (bar = BAR_MW2, i = 1; i < num_mws; bar++, barno++, i++) {
		barno = pci_epc_get_next_free_bar(epc_features, barno);
		if (barno < 0) {
			ntb->num_mws = i;
			dev_dbg(dev, "BAR not available for > MW%d\n", i + 1);
		}
		ntb_epc->epf_ntb_bar[bar] = barno;
	}

	return 0;
}

/**
 * epf_ntb_init_epc_bar() - Identify BARs to be used for each of the NTB
 * constructs (scratchpad region, doorbell, memorywindow)
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * Wrapper to epf_ntb_init_epc_bar_interface() to identify the free BARs
 * to be used for each of BAR_CONFIG, BAR_PEER_SPAD, BAR_DB_MW1, BAR_MW2,
 * BAR_MW3 and BAR_MW4 for all the interfaces.
 */
static int epf_ntb_init_epc_bar(struct epf_ntb *ntb)
{
	enum pci_epc_interface_type type;
	struct device *dev;
	int ret;

	dev = &ntb->epf->dev;
	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++) {
		ret = epf_ntb_init_epc_bar_interface(ntb, type);
		if (ret) {
			dev_err(dev, "Fail to init EPC bar for %s interface\n",
				pci_epc_interface_string(type));
			return ret;
		}
	}

	return 0;
}

/**
 * epf_ntb_epc_init_interface() - Initialize NTB interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Wrapper to initialize a particular EPC interface and start the workqueue
 * to check for commands from host. This function will write to the
 * EP controller HW for configuring it.
 */
static int epf_ntb_epc_init_interface(struct epf_ntb *ntb,
				      enum pci_epc_interface_type type)
{
	struct epf_ntb_epc *ntb_epc;
	u8 func_no, vfunc_no;
	struct pci_epc *epc;
	struct pci_epf *epf;
	struct device *dev;
	int ret;

	ntb_epc = ntb->epc[type];
	epf = ntb->epf;
	dev = &epf->dev;
	epc = ntb_epc->epc;
	func_no = ntb_epc->func_no;
	vfunc_no = ntb_epc->vfunc_no;

	ret = epf_ntb_config_sspad_bar_set(ntb->epc[type]);
	if (ret) {
		dev_err(dev, "%s intf: Config/self SPAD BAR init failed\n",
			pci_epc_interface_string(type));
		return ret;
	}

	ret = epf_ntb_peer_spad_bar_set(ntb, type);
	if (ret) {
		dev_err(dev, "%s intf: Peer SPAD BAR init failed\n",
			pci_epc_interface_string(type));
		goto err_peer_spad_bar_init;
	}

	ret = epf_ntb_configure_interrupt(ntb, type);
	if (ret) {
		dev_err(dev, "%s intf: Interrupt configuration failed\n",
			pci_epc_interface_string(type));
		goto err_peer_spad_bar_init;
	}

	ret = epf_ntb_db_mw_bar_init(ntb, type);
	if (ret) {
		dev_err(dev, "%s intf: DB/MW BAR init failed\n",
			pci_epc_interface_string(type));
		goto err_db_mw_bar_init;
	}

	if (vfunc_no <= 1) {
		ret = pci_epc_write_header(epc, func_no, vfunc_no, epf->header);
		if (ret) {
			dev_err(dev, "%s intf: Configuration header write failed\n",
				pci_epc_interface_string(type));
			goto err_write_header;
		}
	}

	INIT_DELAYED_WORK(&ntb->epc[type]->cmd_handler, epf_ntb_cmd_handler);
	queue_work(kpcintb_workqueue, &ntb->epc[type]->cmd_handler.work);

	return 0;

err_write_header:
	epf_ntb_db_mw_bar_cleanup(ntb, type);

err_db_mw_bar_init:
	epf_ntb_peer_spad_bar_clear(ntb->epc[type]);

err_peer_spad_bar_init:
	epf_ntb_config_sspad_bar_clear(ntb->epc[type]);

	return ret;
}

/**
 * epf_ntb_epc_cleanup_interface() - Cleanup NTB interface
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 * @type: PRIMARY interface or SECONDARY interface
 *
 * Wrapper to cleanup a particular NTB interface.
 */
static void epf_ntb_epc_cleanup_interface(struct epf_ntb *ntb,
					  enum pci_epc_interface_type type)
{
	struct epf_ntb_epc *ntb_epc;

	if (type < 0)
		return;

	ntb_epc = ntb->epc[type];
	cancel_delayed_work(&ntb_epc->cmd_handler);
	epf_ntb_db_mw_bar_cleanup(ntb, type);
	epf_ntb_peer_spad_bar_clear(ntb_epc);
	epf_ntb_config_sspad_bar_clear(ntb_epc);
}

/**
 * epf_ntb_epc_cleanup() - Cleanup all NTB interfaces
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * Wrapper to cleanup all NTB interfaces.
 */
static void epf_ntb_epc_cleanup(struct epf_ntb *ntb)
{
	enum pci_epc_interface_type type;

	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++)
		epf_ntb_epc_cleanup_interface(ntb, type);
}

/**
 * epf_ntb_epc_init() - Initialize all NTB interfaces
 * @ntb: NTB device that facilitates communication between HOST1 and HOST2
 *
 * Wrapper to initialize all NTB interface and start the workqueue
 * to check for commands from host.
 */
static int epf_ntb_epc_init(struct epf_ntb *ntb)
{
	enum pci_epc_interface_type type;
	struct device *dev;
	int ret;

	dev = &ntb->epf->dev;

	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++) {
		ret = epf_ntb_epc_init_interface(ntb, type);
		if (ret) {
			dev_err(dev, "%s intf: Failed to initialize\n",
				pci_epc_interface_string(type));
			goto err_init_type;
		}
	}

	return 0;

err_init_type:
	epf_ntb_epc_cleanup_interface(ntb, type - 1);

	return ret;
}

/**
 * epf_ntb_bind() - Initialize endpoint controller to provide NTB functionality
 * @epf: NTB endpoint function device
 *
 * Initialize both the endpoint controllers associated with NTB function device.
 * Invoked when a primary interface or secondary interface is bound to EPC
 * device. This function will succeed only when EPC is bound to both the
 * interfaces.
 */
static int epf_ntb_bind(struct pci_epf *epf)
{
	struct epf_ntb *ntb = epf_get_drvdata(epf);
	struct device *dev = &epf->dev;
	int ret;

	if (!epf->epc) {
		dev_dbg(dev, "PRIMARY EPC interface not yet bound\n");
		return 0;
	}

	if (!epf->sec_epc) {
		dev_dbg(dev, "SECONDARY EPC interface not yet bound\n");
		return 0;
	}

	ret = epf_ntb_epc_create(ntb);
	if (ret) {
		dev_err(dev, "Failed to create NTB EPC\n");
		return ret;
	}

	ret = epf_ntb_init_epc_bar(ntb);
	if (ret) {
		dev_err(dev, "Failed to create NTB EPC\n");
		goto err_bar_init;
	}

	ret = epf_ntb_config_spad_bar_alloc_interface(ntb);
	if (ret) {
		dev_err(dev, "Failed to allocate BAR memory\n");
		goto err_bar_alloc;
	}

	ret = epf_ntb_epc_init(ntb);
	if (ret) {
		dev_err(dev, "Failed to initialize EPC\n");
		goto err_bar_alloc;
	}

	epf_set_drvdata(epf, ntb);

	return 0;

err_bar_alloc:
	epf_ntb_config_spad_bar_free(ntb);

err_bar_init:
	epf_ntb_epc_destroy(ntb);

	return ret;
}

/**
 * epf_ntb_unbind() - Cleanup the initialization from epf_ntb_bind()
 * @epf: NTB endpoint function device
 *
 * Cleanup the initialization from epf_ntb_bind()
 */
static void epf_ntb_unbind(struct pci_epf *epf)
{
	struct epf_ntb *ntb = epf_get_drvdata(epf);

	epf_ntb_epc_cleanup(ntb);
	epf_ntb_config_spad_bar_free(ntb);
	epf_ntb_epc_destroy(ntb);
}

#define EPF_NTB_R(_name)						\
static ssize_t epf_ntb_##_name##_show(struct config_item *item,		\
				      char *page)			\
{									\
	struct config_group *group = to_config_group(item);		\
	struct epf_ntb *ntb = to_epf_ntb(group);			\
									\
	return sysfs_emit(page, "%d\n", ntb->_name);			\
}

#define EPF_NTB_W(_name)						\
static ssize_t epf_ntb_##_name##_store(struct config_item *item,	\
				       const char *page, size_t len)	\
{									\
	struct config_group *group = to_config_group(item);		\
	struct epf_ntb *ntb = to_epf_ntb(group);			\
	u32 val;							\
									\
	if (kstrtou32(page, 0, &val) < 0)				\
		return -EINVAL;						\
									\
	ntb->_name = val;						\
									\
	return len;							\
}

#define EPF_NTB_MW_R(_name)						\
static ssize_t epf_ntb_##_name##_show(struct config_item *item,		\
				      char *page)			\
{									\
	struct config_group *group = to_config_group(item);		\
	struct epf_ntb *ntb = to_epf_ntb(group);			\
	int win_no;							\
									\
	sscanf(#_name, "mw%d", &win_no);				\
									\
	return sysfs_emit(page, "%lld\n", ntb->mws_size[win_no - 1]);	\
}

#define EPF_NTB_MW_W(_name)						\
static ssize_t epf_ntb_##_name##_store(struct config_item *item,	\
				       const char *page, size_t len)	\
{									\
	struct config_group *group = to_config_group(item);		\
	struct epf_ntb *ntb = to_epf_ntb(group);			\
	struct device *dev = &ntb->epf->dev;				\
	int win_no;							\
	u64 val;							\
									\
	if (kstrtou64(page, 0, &val) < 0)				\
		return -EINVAL;						\
									\
	if (sscanf(#_name, "mw%d", &win_no) != 1)			\
		return -EINVAL;						\
									\
	if (ntb->num_mws < win_no) {					\
		dev_err(dev, "Invalid num_nws: %d value\n", ntb->num_mws); \
		return -EINVAL;						\
	}								\
									\
	ntb->mws_size[win_no - 1] = val;				\
									\
	return len;							\
}

static ssize_t epf_ntb_num_mws_store(struct config_item *item,
				     const char *page, size_t len)
{
	struct config_group *group = to_config_group(item);
	struct epf_ntb *ntb = to_epf_ntb(group);
	u32 val;

	if (kstrtou32(page, 0, &val) < 0)
		return -EINVAL;

	if (val > MAX_MW)
		return -EINVAL;

	ntb->num_mws = val;

	return len;
}

EPF_NTB_R(spad_count)
EPF_NTB_W(spad_count)
EPF_NTB_R(db_count)
EPF_NTB_W(db_count)
EPF_NTB_R(num_mws)
EPF_NTB_MW_R(mw1)
EPF_NTB_MW_W(mw1)
EPF_NTB_MW_R(mw2)
EPF_NTB_MW_W(mw2)
EPF_NTB_MW_R(mw3)
EPF_NTB_MW_W(mw3)
EPF_NTB_MW_R(mw4)
EPF_NTB_MW_W(mw4)

CONFIGFS_ATTR(epf_ntb_, spad_count);
CONFIGFS_ATTR(epf_ntb_, db_count);
CONFIGFS_ATTR(epf_ntb_, num_mws);
CONFIGFS_ATTR(epf_ntb_, mw1);
CONFIGFS_ATTR(epf_ntb_, mw2);
CONFIGFS_ATTR(epf_ntb_, mw3);
CONFIGFS_ATTR(epf_ntb_, mw4);

static struct configfs_attribute *epf_ntb_attrs[] = {
	&epf_ntb_attr_spad_count,
	&epf_ntb_attr_db_count,
	&epf_ntb_attr_num_mws,
	&epf_ntb_attr_mw1,
	&epf_ntb_attr_mw2,
	&epf_ntb_attr_mw3,
	&epf_ntb_attr_mw4,
	NULL,
};

static const struct config_item_type ntb_group_type = {
	.ct_attrs	= epf_ntb_attrs,
	.ct_owner	= THIS_MODULE,
};

/**
 * epf_ntb_add_cfs() - Add configfs directory specific to NTB
 * @epf: NTB endpoint function device
 * @group: A pointer to the config_group structure referencing a group of
 *	   config_items of a specific type that belong to a specific sub-system.
 *
 * Add configfs directory specific to NTB. This directory will hold
 * NTB specific properties like db_count, spad_count, num_mws etc.,
 */
static struct config_group *epf_ntb_add_cfs(struct pci_epf *epf,
					    struct config_group *group)
{
	struct epf_ntb *ntb = epf_get_drvdata(epf);
	struct config_group *ntb_group = &ntb->group;
	struct device *dev = &epf->dev;

	config_group_init_type_name(ntb_group, dev_name(dev), &ntb_group_type);

	return ntb_group;
}

/**
 * epf_ntb_probe() - Probe NTB function driver
 * @epf: NTB endpoint function device
 *
 * Probe NTB function driver when endpoint function bus detects a NTB
 * endpoint function.
 */
static int epf_ntb_probe(struct pci_epf *epf)
{
	struct epf_ntb *ntb;
	struct device *dev;

	dev = &epf->dev;

	ntb = devm_kzalloc(dev, sizeof(*ntb), GFP_KERNEL);
	if (!ntb)
		return -ENOMEM;

	epf->header = &epf_ntb_header;
	ntb->epf = epf;
	epf_set_drvdata(epf, ntb);

	return 0;
}

static struct pci_epf_ops epf_ntb_ops = {
	.bind	= epf_ntb_bind,
	.unbind	= epf_ntb_unbind,
	.add_cfs = epf_ntb_add_cfs,
};

static const struct pci_epf_device_id epf_ntb_ids[] = {
	{
		.name = "pci_epf_ntb",
	},
	{},
};

static struct pci_epf_driver epf_ntb_driver = {
	.driver.name	= "pci_epf_ntb",
	.probe		= epf_ntb_probe,
	.id_table	= epf_ntb_ids,
	.ops		= &epf_ntb_ops,
	.owner		= THIS_MODULE,
};

static int __init epf_ntb_init(void)
{
	int ret;

	kpcintb_workqueue = alloc_workqueue("kpcintb", WQ_MEM_RECLAIM |
					    WQ_HIGHPRI, 0);
	ret = pci_epf_register_driver(&epf_ntb_driver);
	if (ret) {
		destroy_workqueue(kpcintb_workqueue);
		pr_err("Failed to register pci epf ntb driver --> %d\n", ret);
		return ret;
	}

	return 0;
}
module_init(epf_ntb_init);

static void __exit epf_ntb_exit(void)
{
	pci_epf_unregister_driver(&epf_ntb_driver);
	destroy_workqueue(kpcintb_workqueue);
}
module_exit(epf_ntb_exit);

MODULE_DESCRIPTION("PCI EPF NTB DRIVER");
MODULE_AUTHOR("Kishon Vijay Abraham I <kishon@ti.com>");
MODULE_LICENSE("GPL v2");