linux/drivers/pci/vc.c

// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Virtual Channel support
 *
 * Copyright (C) 2013 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <[email protected]>
 */

#include <linux/bitfield.h>
#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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

static struct { … } vc_caps[] = …;

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }