drivers/pci/vc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * PCI Virtual Channel support
  *
  * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
  *     Author: Alex Williamson <alex.williamson@redhat.com>
  */

 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/types.h>

 #include "pci.h"

 /**
  * pci_vc_save_restore_dwords - Save or restore a series of dwords
  * @dev: device
  * @pos: starting config space position
  * @buf: buffer to save to or restore from
  * @dwords: number of dwords to save/restore
  * @save: whether to save or restore
  */
 static void pci_vc_save_restore_dwords(struct pci_dev *dev, int pos,
 				       u32 *buf, int dwords, bool save)
 {
 	int i;

 	for (i = 0; i < dwords; i++, buf++) {
 		if (save)
 			pci_read_config_dword(dev, pos + (i * 4), buf);
 		else
 			pci_write_config_dword(dev, pos + (i * 4), *buf);
 	}
 }

 /**
  * pci_vc_load_arb_table - load and wait for VC arbitration table
  * @dev: device
  * @pos: starting position of VC capability (VC/VC9/MFVC)
  *
  * Set Load VC Arbitration Table bit requesting hardware to apply the VC
  * Arbitration Table (previously loaded).  When the VC Arbitration Table
  * Status clears, hardware has latched the table into VC arbitration logic.
  */
 static void pci_vc_load_arb_table(struct pci_dev *dev, int pos)
 {
 	u16 ctrl;

 	pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL, &ctrl);
 	pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
 			      ctrl | PCI_VC_PORT_CTRL_LOAD_TABLE);
 	if (pci_wait_for_pending(dev, pos + PCI_VC_PORT_STATUS,
 				 PCI_VC_PORT_STATUS_TABLE))
 		return;

 	pci_err(dev, "VC arbitration table failed to load\n");
 }

 /**
  * pci_vc_load_port_arb_table - Load and wait for VC port arbitration table
  * @dev: device
  * @pos: starting position of VC capability (VC/VC9/MFVC)
  * @res: VC resource number, ie. VCn (0-7)
  *
  * Set Load Port Arbitration Table bit requesting hardware to apply the Port
  * Arbitration Table (previously loaded).  When the Port Arbitration Table
  * Status clears, hardware has latched the table into port arbitration logic.
  */
 static void pci_vc_load_port_arb_table(struct pci_dev *dev, int pos, int res)
 {
 	int ctrl_pos, status_pos;
 	u32 ctrl;

 	ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
 	status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);

 	pci_read_config_dword(dev, ctrl_pos, &ctrl);
 	pci_write_config_dword(dev, ctrl_pos,
 			       ctrl | PCI_VC_RES_CTRL_LOAD_TABLE);

 	if (pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_TABLE))
 		return;

 	pci_err(dev, "VC%d port arbitration table failed to load\n", res);
 }

 /**
  * pci_vc_enable - Enable virtual channel
  * @dev: device
  * @pos: starting position of VC capability (VC/VC9/MFVC)
  * @res: VC res number, ie. VCn (0-7)
  *
  * A VC is enabled by setting the enable bit in matching resource control
  * registers on both sides of a link.  We therefore need to find the opposite
  * end of the link.  To keep this simple we enable from the downstream device.
  * RC devices do not have an upstream device, nor does it seem that VC9 do
  * (spec is unclear).  Once we find the upstream device, match the VC ID to
  * get the correct resource, disable and enable on both ends.
  */
 static void pci_vc_enable(struct pci_dev *dev, int pos, int res)
 {
 	int ctrl_pos, status_pos, id, pos2, evcc, i, ctrl_pos2, status_pos2;
 	u32 ctrl, header, cap1, ctrl2;
 	struct pci_dev *link = NULL;

 	/* Enable VCs from the downstream device */
 	if (!pci_is_pcie(dev) || !pcie_downstream_port(dev))
 		return;

 	ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
 	status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);

 	pci_read_config_dword(dev, ctrl_pos, &ctrl);
 	id = ctrl & PCI_VC_RES_CTRL_ID;

 	pci_read_config_dword(dev, pos, &header);

 	/* If there is no opposite end of the link, skip to enable */
 	if (PCI_EXT_CAP_ID(header) == PCI_EXT_CAP_ID_VC9 ||
 	    pci_is_root_bus(dev->bus))
 		goto enable;

 	pos2 = pci_find_ext_capability(dev->bus->self, PCI_EXT_CAP_ID_VC);
 	if (!pos2)
 		goto enable;

 	pci_read_config_dword(dev->bus->self, pos2 + PCI_VC_PORT_CAP1, &cap1);
 	evcc = cap1 & PCI_VC_CAP1_EVCC;

 	/* VC0 is hardwired enabled, so we can start with 1 */
 	for (i = 1; i < evcc + 1; i++) {
 		ctrl_pos2 = pos2 + PCI_VC_RES_CTRL +
 				(i * PCI_CAP_VC_PER_VC_SIZEOF);
 		status_pos2 = pos2 + PCI_VC_RES_STATUS +
 				(i * PCI_CAP_VC_PER_VC_SIZEOF);
 		pci_read_config_dword(dev->bus->self, ctrl_pos2, &ctrl2);
 		if ((ctrl2 & PCI_VC_RES_CTRL_ID) == id) {
 			link = dev->bus->self;
 			break;
 		}
 	}

 	if (!link)
 		goto enable;

 	/* Disable if enabled */
 	if (ctrl2 & PCI_VC_RES_CTRL_ENABLE) {
 		ctrl2 &= ~PCI_VC_RES_CTRL_ENABLE;
 		pci_write_config_dword(link, ctrl_pos2, ctrl2);
 	}

 	/* Enable on both ends */
 	ctrl2 |= PCI_VC_RES_CTRL_ENABLE;
 	pci_write_config_dword(link, ctrl_pos2, ctrl2);
 enable:
 	ctrl |= PCI_VC_RES_CTRL_ENABLE;
 	pci_write_config_dword(dev, ctrl_pos, ctrl);

 	if (!pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_NEGO))
 		pci_err(dev, "VC%d negotiation stuck pending\n", id);

 	if (link && !pci_wait_for_pending(link, status_pos2,
 					  PCI_VC_RES_STATUS_NEGO))
 		pci_err(link, "VC%d negotiation stuck pending\n", id);
 }

 /**
  * pci_vc_do_save_buffer - Size, save, or restore VC state
  * @dev: device
  * @pos: starting position of VC capability (VC/VC9/MFVC)
  * @save_state: buffer for save/restore
  * @save: if provided a buffer, this indicates what to do with it
  *
  * Walking Virtual Channel config space to size, save, or restore it
  * is complicated, so we do it all from one function to reduce code and
  * guarantee ordering matches in the buffer.  When called with NULL
  * @save_state, return the size of the necessary save buffer.  When called
  * with a non-NULL @save_state, @save determines whether we save to the
  * buffer or restore from it.
  */
 static int pci_vc_do_save_buffer(struct pci_dev *dev, int pos,
 				 struct pci_cap_saved_state *save_state,
 				 bool save)
 {
 	u32 cap1;
 	char evcc, lpevcc, parb_size;
 	int i, len = 0;
 	u8 *buf = save_state ? (u8 *)save_state->cap.data : NULL;

 	/* Sanity check buffer size for save/restore */
 	if (buf && save_state->cap.size !=
 	    pci_vc_do_save_buffer(dev, pos, NULL, save)) {
 		pci_err(dev, "VC save buffer size does not match @0x%x\n", pos);
 		return -ENOMEM;
 	}

 	pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP1, &cap1);
 	/* Extended VC Count (not counting VC0) */
 	evcc = cap1 & PCI_VC_CAP1_EVCC;
 	/* Low Priority Extended VC Count (not counting VC0) */
 	lpevcc = (cap1 & PCI_VC_CAP1_LPEVCC) >> 4;
 	/* Port Arbitration Table Entry Size (bits) */
 	parb_size = 1 << ((cap1 & PCI_VC_CAP1_ARB_SIZE) >> 10);

 	/*
 	 * Port VC Control Register contains VC Arbitration Select, which
 	 * cannot be modified when more than one LPVC is in operation.  We
 	 * therefore save/restore it first, as only VC0 should be enabled
 	 * after device reset.
 	 */
 	if (buf) {
 		if (save)
 			pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL,
 					     (u16 *)buf);
 		else
 			pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
 					      *(u16 *)buf);
 		buf += 4;
 	}
 	len += 4;

 	/*
 	 * If we have any Low Priority VCs and a VC Arbitration Table Offset
 	 * in Port VC Capability Register 2 then save/restore it next.
 	 */
 	if (lpevcc) {
 		u32 cap2;
 		int vcarb_offset;

 		pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP2, &cap2);
 		vcarb_offset = ((cap2 & PCI_VC_CAP2_ARB_OFF) >> 24) * 16;

 		if (vcarb_offset) {
 			int size, vcarb_phases = 0;

 			if (cap2 & PCI_VC_CAP2_128_PHASE)
 				vcarb_phases = 128;
 			else if (cap2 & PCI_VC_CAP2_64_PHASE)
 				vcarb_phases = 64;
 			else if (cap2 & PCI_VC_CAP2_32_PHASE)
 				vcarb_phases = 32;

 			/* Fixed 4 bits per phase per lpevcc (plus VC0) */
 			size = ((lpevcc + 1) * vcarb_phases * 4) / 8;

 			if (size && buf) {
 				pci_vc_save_restore_dwords(dev,
 							   pos + vcarb_offset,
 							   (u32 *)buf,
 							   size / 4, save);
 				/*
 				 * On restore, we need to signal hardware to
 				 * re-load the VC Arbitration Table.
 				 */
 				if (!save)
 					pci_vc_load_arb_table(dev, pos);

 				buf += size;
 			}
 			len += size;
 		}
 	}

 	/*
 	 * In addition to each VC Resource Control Register, we may have a
 	 * Port Arbitration Table attached to each VC.  The Port Arbitration
 	 * Table Offset in each VC Resource Capability Register tells us if
 	 * it exists.  The entry size is global from the Port VC Capability
 	 * Register1 above.  The number of phases is determined per VC.
 	 */
 	for (i = 0; i < evcc + 1; i++) {
 		u32 cap;
 		int parb_offset;

 		pci_read_config_dword(dev, pos + PCI_VC_RES_CAP +
 				      (i * PCI_CAP_VC_PER_VC_SIZEOF), &cap);
 		parb_offset = ((cap & PCI_VC_RES_CAP_ARB_OFF) >> 24) * 16;
 		if (parb_offset) {
 			int size, parb_phases = 0;

 			if (cap & PCI_VC_RES_CAP_256_PHASE)
 				parb_phases = 256;
 			else if (cap & (PCI_VC_RES_CAP_128_PHASE |
 					PCI_VC_RES_CAP_128_PHASE_TB))
 				parb_phases = 128;
 			else if (cap & PCI_VC_RES_CAP_64_PHASE)
 				parb_phases = 64;
 			else if (cap & PCI_VC_RES_CAP_32_PHASE)
 				parb_phases = 32;

 			size = (parb_size * parb_phases) / 8;

 			if (size && buf) {
 				pci_vc_save_restore_dwords(dev,
 							   pos + parb_offset,
 							   (u32 *)buf,
 							   size / 4, save);
 				buf += size;
 			}
 			len += size;
 		}

 		/* VC Resource Control Register */
 		if (buf) {
 			int ctrl_pos = pos + PCI_VC_RES_CTRL +
 						(i * PCI_CAP_VC_PER_VC_SIZEOF);
 			if (save)
 				pci_read_config_dword(dev, ctrl_pos,
 						      (u32 *)buf);
 			else {
 				u32 tmp, ctrl = *(u32 *)buf;
 				/*
 				 * For an FLR case, the VC config may remain.
 				 * Preserve enable bit, restore the rest.
 				 */
 				pci_read_config_dword(dev, ctrl_pos, &tmp);
 				tmp &= PCI_VC_RES_CTRL_ENABLE;
 				tmp |= ctrl & ~PCI_VC_RES_CTRL_ENABLE;
 				pci_write_config_dword(dev, ctrl_pos, tmp);
 				/* Load port arbitration table if used */
 				if (ctrl & PCI_VC_RES_CTRL_ARB_SELECT)
 					pci_vc_load_port_arb_table(dev, pos, i);
 				/* Re-enable if needed */
 				if ((ctrl ^ tmp) & PCI_VC_RES_CTRL_ENABLE)
 					pci_vc_enable(dev, pos, i);
 			}
 			buf += 4;
 		}
 		len += 4;
 	}

 	return buf ? 0 : len;
 }

 static struct {
 	u16 id;
 	const char *name;
 } vc_caps[] = { { PCI_EXT_CAP_ID_MFVC, "MFVC" },
 		{ PCI_EXT_CAP_ID_VC, "VC" },
 		{ PCI_EXT_CAP_ID_VC9, "VC9" } };

 /**
  * pci_save_vc_state - Save VC state to pre-allocate save buffer
  * @dev: device
  *
  * For each type of VC capability, VC/VC9/MFVC, find the capability and
  * save it to the pre-allocated save buffer.
  */
 int pci_save_vc_state(struct pci_dev *dev)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
 		int pos, ret;
 		struct pci_cap_saved_state *save_state;

 		pos = pci_find_ext_capability(dev, vc_caps[i].id);
 		if (!pos)
 			continue;

 		save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
 		if (!save_state) {
 			pci_err(dev, "%s buffer not found in %s\n",
 				vc_caps[i].name, __func__);
 			return -ENOMEM;
 		}

 		ret = pci_vc_do_save_buffer(dev, pos, save_state, true);
 		if (ret) {
 			pci_err(dev, "%s save unsuccessful %s\n",
 				vc_caps[i].name, __func__);
 			return ret;
 		}
 	}

 	return 0;
 }

 /**
  * pci_restore_vc_state - Restore VC state from save buffer
  * @dev: device
  *
  * For each type of VC capability, VC/VC9/MFVC, find the capability and
  * restore it from the previously saved buffer.
  */
 void pci_restore_vc_state(struct pci_dev *dev)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
 		int pos;
 		struct pci_cap_saved_state *save_state;

 		pos = pci_find_ext_capability(dev, vc_caps[i].id);
 		save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
 		if (!save_state || !pos)
 			continue;

 		pci_vc_do_save_buffer(dev, pos, save_state, false);
 	}
 }

 /**
  * pci_allocate_vc_save_buffers - Allocate save buffers for VC caps
  * @dev: device
  *
  * For each type of VC capability, VC/VC9/MFVC, find the capability, size
  * it, and allocate a buffer for save/restore.
  */
 void pci_allocate_vc_save_buffers(struct pci_dev *dev)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
 		int len, pos = pci_find_ext_capability(dev, vc_caps[i].id);

 		if (!pos)
 			continue;

 		len = pci_vc_do_save_buffer(dev, pos, NULL, false);
 		if (pci_add_ext_cap_save_buffer(dev, vc_caps[i].id, len))
 			pci_err(dev, "unable to preallocate %s save buffer\n",
 				vc_caps[i].name);
 	}
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* PCI Virtual Channel support
	*
	* Copyright (C) 2013 Red Hat, Inc. All rights reserved.
	* Author: Alex Williamson <alex.williamson@redhat.com>
	*/

	#include <linux/device.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/pci.h>
	#include <linux/pci_regs.h>
	#include <linux/types.h>

	#include "pci.h"

	/**
	* pci_vc_save_restore_dwords - Save or restore a series of dwords
	* @dev: device
	* @pos: starting config space position
	* @buf: buffer to save to or restore from
	* @dwords: number of dwords to save/restore
	* @save: whether to save or restore
	*/
	static void pci_vc_save_restore_dwords(struct pci_dev *dev, int pos,
	u32 *buf, int dwords, bool save)
	{
	int i;

	for (i = 0; i < dwords; i++, buf++) {
	if (save)
	pci_read_config_dword(dev, pos + (i * 4), buf);
	else
	pci_write_config_dword(dev, pos + (i * 4), *buf);
	}
	}

	/**
	* pci_vc_load_arb_table - load and wait for VC arbitration table
	* @dev: device
	* @pos: starting position of VC capability (VC/VC9/MFVC)
	*
	* Set Load VC Arbitration Table bit requesting hardware to apply the VC
	* Arbitration Table (previously loaded). When the VC Arbitration Table
	* Status clears, hardware has latched the table into VC arbitration logic.
	*/
	static void pci_vc_load_arb_table(struct pci_dev *dev, int pos)
	{
	u16 ctrl;

	pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL, &ctrl);
	pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
	ctrl \| PCI_VC_PORT_CTRL_LOAD_TABLE);
	if (pci_wait_for_pending(dev, pos + PCI_VC_PORT_STATUS,
	PCI_VC_PORT_STATUS_TABLE))
	return;

	pci_err(dev, "VC arbitration table failed to load\n");
	}

	/**
	* pci_vc_load_port_arb_table - Load and wait for VC port arbitration table
	* @dev: device
	* @pos: starting position of VC capability (VC/VC9/MFVC)
	* @res: VC resource number, ie. VCn (0-7)
	*
	* Set Load Port Arbitration Table bit requesting hardware to apply the Port
	* Arbitration Table (previously loaded). When the Port Arbitration Table
	* Status clears, hardware has latched the table into port arbitration logic.
	*/
	static void pci_vc_load_port_arb_table(struct pci_dev *dev, int pos, int res)
	{
	int ctrl_pos, status_pos;
	u32 ctrl;

	ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
	status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);

	pci_read_config_dword(dev, ctrl_pos, &ctrl);
	pci_write_config_dword(dev, ctrl_pos,
	ctrl \| PCI_VC_RES_CTRL_LOAD_TABLE);

	if (pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_TABLE))
	return;

	pci_err(dev, "VC%d port arbitration table failed to load\n", res);
	}

	/**
	* pci_vc_enable - Enable virtual channel
	* @dev: device
	* @pos: starting position of VC capability (VC/VC9/MFVC)
	* @res: VC res number, ie. VCn (0-7)
	*
	* A VC is enabled by setting the enable bit in matching resource control
	* registers on both sides of a link. We therefore need to find the opposite
	* end of the link. To keep this simple we enable from the downstream device.
	* RC devices do not have an upstream device, nor does it seem that VC9 do
	* (spec is unclear). Once we find the upstream device, match the VC ID to
	* get the correct resource, disable and enable on both ends.
	*/
	static void pci_vc_enable(struct pci_dev *dev, int pos, int res)
	{
	int ctrl_pos, status_pos, id, pos2, evcc, i, ctrl_pos2, status_pos2;
	u32 ctrl, header, cap1, ctrl2;
	struct pci_dev *link = NULL;

	/* Enable VCs from the downstream device */
	if (!pci_is_pcie(dev) \|\| !pcie_downstream_port(dev))
	return;

	ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);
	status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF);

	pci_read_config_dword(dev, ctrl_pos, &ctrl);
	id = ctrl & PCI_VC_RES_CTRL_ID;

	pci_read_config_dword(dev, pos, &header);

	/* If there is no opposite end of the link, skip to enable */
	if (PCI_EXT_CAP_ID(header) == PCI_EXT_CAP_ID_VC9 \|\|
	pci_is_root_bus(dev->bus))
	goto enable;

	pos2 = pci_find_ext_capability(dev->bus->self, PCI_EXT_CAP_ID_VC);
	if (!pos2)
	goto enable;

	pci_read_config_dword(dev->bus->self, pos2 + PCI_VC_PORT_CAP1, &cap1);
	evcc = cap1 & PCI_VC_CAP1_EVCC;

	/* VC0 is hardwired enabled, so we can start with 1 */
	for (i = 1; i < evcc + 1; i++) {
	ctrl_pos2 = pos2 + PCI_VC_RES_CTRL +
	(i * PCI_CAP_VC_PER_VC_SIZEOF);
	status_pos2 = pos2 + PCI_VC_RES_STATUS +
	(i * PCI_CAP_VC_PER_VC_SIZEOF);
	pci_read_config_dword(dev->bus->self, ctrl_pos2, &ctrl2);
	if ((ctrl2 & PCI_VC_RES_CTRL_ID) == id) {
	link = dev->bus->self;
	break;
	}
	}

	if (!link)
	goto enable;

	/* Disable if enabled */
	if (ctrl2 & PCI_VC_RES_CTRL_ENABLE) {
	ctrl2 &= ~PCI_VC_RES_CTRL_ENABLE;
	pci_write_config_dword(link, ctrl_pos2, ctrl2);
	}

	/* Enable on both ends */
	ctrl2 \|= PCI_VC_RES_CTRL_ENABLE;
	pci_write_config_dword(link, ctrl_pos2, ctrl2);
	enable:
	ctrl \|= PCI_VC_RES_CTRL_ENABLE;
	pci_write_config_dword(dev, ctrl_pos, ctrl);

	if (!pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_NEGO))
	pci_err(dev, "VC%d negotiation stuck pending\n", id);

	if (link && !pci_wait_for_pending(link, status_pos2,
	PCI_VC_RES_STATUS_NEGO))
	pci_err(link, "VC%d negotiation stuck pending\n", id);
	}

	/**
	* pci_vc_do_save_buffer - Size, save, or restore VC state
	* @dev: device
	* @pos: starting position of VC capability (VC/VC9/MFVC)
	* @save_state: buffer for save/restore
	* @save: if provided a buffer, this indicates what to do with it
	*
	* Walking Virtual Channel config space to size, save, or restore it
	* is complicated, so we do it all from one function to reduce code and
	* guarantee ordering matches in the buffer. When called with NULL
	* @save_state, return the size of the necessary save buffer. When called
	* with a non-NULL @save_state, @save determines whether we save to the
	* buffer or restore from it.
	*/
	static int pci_vc_do_save_buffer(struct pci_dev *dev, int pos,
	struct pci_cap_saved_state *save_state,
	bool save)
	{
	u32 cap1;
	char evcc, lpevcc, parb_size;
	int i, len = 0;
	u8 buf = save_state ? (u8 )save_state->cap.data : NULL;

	/* Sanity check buffer size for save/restore */
	if (buf && save_state->cap.size !=
	pci_vc_do_save_buffer(dev, pos, NULL, save)) {
	pci_err(dev, "VC save buffer size does not match @0x%x\n", pos);
	return -ENOMEM;
	}

	pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP1, &cap1);
	/* Extended VC Count (not counting VC0) */
	evcc = cap1 & PCI_VC_CAP1_EVCC;
	/* Low Priority Extended VC Count (not counting VC0) */
	lpevcc = (cap1 & PCI_VC_CAP1_LPEVCC) >> 4;
	/* Port Arbitration Table Entry Size (bits) */
	parb_size = 1 << ((cap1 & PCI_VC_CAP1_ARB_SIZE) >> 10);

	/*
	* Port VC Control Register contains VC Arbitration Select, which
	* cannot be modified when more than one LPVC is in operation. We
	* therefore save/restore it first, as only VC0 should be enabled
	* after device reset.
	*/
	if (buf) {
	if (save)
	pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL,
	(u16 *)buf);
	else
	pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL,
	(u16 )buf);
	buf += 4;
	}
	len += 4;

	/*
	* If we have any Low Priority VCs and a VC Arbitration Table Offset
	* in Port VC Capability Register 2 then save/restore it next.
	*/
	if (lpevcc) {
	u32 cap2;
	int vcarb_offset;

	pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP2, &cap2);
	vcarb_offset = ((cap2 & PCI_VC_CAP2_ARB_OFF) >> 24) * 16;

	if (vcarb_offset) {
	int size, vcarb_phases = 0;

	if (cap2 & PCI_VC_CAP2_128_PHASE)
	vcarb_phases = 128;
	else if (cap2 & PCI_VC_CAP2_64_PHASE)
	vcarb_phases = 64;
	else if (cap2 & PCI_VC_CAP2_32_PHASE)
	vcarb_phases = 32;

	/* Fixed 4 bits per phase per lpevcc (plus VC0) */
	size = ((lpevcc + 1) * vcarb_phases * 4) / 8;

	if (size && buf) {
	pci_vc_save_restore_dwords(dev,
	pos + vcarb_offset,
	(u32 *)buf,
	size / 4, save);
	/*
	* On restore, we need to signal hardware to
	* re-load the VC Arbitration Table.
	*/
	if (!save)
	pci_vc_load_arb_table(dev, pos);

	buf += size;
	}
	len += size;
	}
	}

	/*
	* In addition to each VC Resource Control Register, we may have a
	* Port Arbitration Table attached to each VC. The Port Arbitration
	* Table Offset in each VC Resource Capability Register tells us if
	* it exists. The entry size is global from the Port VC Capability
	* Register1 above. The number of phases is determined per VC.
	*/
	for (i = 0; i < evcc + 1; i++) {
	u32 cap;
	int parb_offset;

	pci_read_config_dword(dev, pos + PCI_VC_RES_CAP +
	(i * PCI_CAP_VC_PER_VC_SIZEOF), &cap);
	parb_offset = ((cap & PCI_VC_RES_CAP_ARB_OFF) >> 24) * 16;
	if (parb_offset) {
	int size, parb_phases = 0;

	if (cap & PCI_VC_RES_CAP_256_PHASE)
	parb_phases = 256;
	else if (cap & (PCI_VC_RES_CAP_128_PHASE \|
	PCI_VC_RES_CAP_128_PHASE_TB))
	parb_phases = 128;
	else if (cap & PCI_VC_RES_CAP_64_PHASE)
	parb_phases = 64;
	else if (cap & PCI_VC_RES_CAP_32_PHASE)
	parb_phases = 32;

	size = (parb_size * parb_phases) / 8;

	if (size && buf) {
	pci_vc_save_restore_dwords(dev,
	pos + parb_offset,
	(u32 *)buf,
	size / 4, save);
	buf += size;
	}
	len += size;
	}

	/* VC Resource Control Register */
	if (buf) {
	int ctrl_pos = pos + PCI_VC_RES_CTRL +
	(i * PCI_CAP_VC_PER_VC_SIZEOF);
	if (save)
	pci_read_config_dword(dev, ctrl_pos,
	(u32 *)buf);
	else {
	u32 tmp, ctrl = (u32 )buf;
	/*
	* For an FLR case, the VC config may remain.
	* Preserve enable bit, restore the rest.
	*/
	pci_read_config_dword(dev, ctrl_pos, &tmp);
	tmp &= PCI_VC_RES_CTRL_ENABLE;
	tmp \|= ctrl & ~PCI_VC_RES_CTRL_ENABLE;
	pci_write_config_dword(dev, ctrl_pos, tmp);
	/* Load port arbitration table if used */
	if (ctrl & PCI_VC_RES_CTRL_ARB_SELECT)
	pci_vc_load_port_arb_table(dev, pos, i);
	/* Re-enable if needed */
	if ((ctrl ^ tmp) & PCI_VC_RES_CTRL_ENABLE)
	pci_vc_enable(dev, pos, i);
	}
	buf += 4;
	}
	len += 4;
	}

	return buf ? 0 : len;
	}

	static struct {
	u16 id;
	const char *name;
	} vc_caps[] = { { PCI_EXT_CAP_ID_MFVC, "MFVC" },
	{ PCI_EXT_CAP_ID_VC, "VC" },
	{ PCI_EXT_CAP_ID_VC9, "VC9" } };

	/**
	* pci_save_vc_state - Save VC state to pre-allocate save buffer
	* @dev: device
	*
	* For each type of VC capability, VC/VC9/MFVC, find the capability and
	* save it to the pre-allocated save buffer.
	*/
	int pci_save_vc_state(struct pci_dev *dev)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
	int pos, ret;
	struct pci_cap_saved_state *save_state;

	pos = pci_find_ext_capability(dev, vc_caps[i].id);
	if (!pos)
	continue;

	save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
	if (!save_state) {
	pci_err(dev, "%s buffer not found in %s\n",
	vc_caps[i].name, __func__);
	return -ENOMEM;
	}

	ret = pci_vc_do_save_buffer(dev, pos, save_state, true);
	if (ret) {
	pci_err(dev, "%s save unsuccessful %s\n",
	vc_caps[i].name, __func__);
	return ret;
	}
	}

	return 0;
	}

	/**
	* pci_restore_vc_state - Restore VC state from save buffer
	* @dev: device
	*
	* For each type of VC capability, VC/VC9/MFVC, find the capability and
	* restore it from the previously saved buffer.
	*/
	void pci_restore_vc_state(struct pci_dev *dev)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
	int pos;
	struct pci_cap_saved_state *save_state;

	pos = pci_find_ext_capability(dev, vc_caps[i].id);
	save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
	if (!save_state \|\| !pos)
	continue;

	pci_vc_do_save_buffer(dev, pos, save_state, false);
	}
	}

	/**
	* pci_allocate_vc_save_buffers - Allocate save buffers for VC caps
	* @dev: device
	*
	* For each type of VC capability, VC/VC9/MFVC, find the capability, size
	* it, and allocate a buffer for save/restore.
	*/
	void pci_allocate_vc_save_buffers(struct pci_dev *dev)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
	int len, pos = pci_find_ext_capability(dev, vc_caps[i].id);

	if (!pos)
	continue;

	len = pci_vc_do_save_buffer(dev, pos, NULL, false);
	if (pci_add_ext_cap_save_buffer(dev, vc_caps[i].id, len))
	pci_err(dev, "unable to preallocate %s save buffer\n",
	vc_caps[i].name);
	}
	}