linux/drivers/platform/x86/p2sb.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Primary to Sideband (P2SB) bridge access support
 *
 * Copyright (c) 2017, 2021-2022 Intel Corporation.
 *
 * Authors: Andy Shevchenko <[email protected]>
 *	    Jonathan Yong <[email protected]>
 */

#include <linux/bits.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <linux/platform_data/x86/p2sb.h>

#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>

#define P2SBC …
#define P2SBC_HIDE …

#define P2SB_DEVFN_DEFAULT …
#define P2SB_DEVFN_GOLDMONT …
#define SPI_DEVFN_GOLDMONT …

static const struct x86_cpu_id p2sb_cpu_ids[] = …;

/*
 * Cache BAR0 of P2SB device functions 0 to 7.
 * TODO: The constant 8 is the number of functions that PCI specification
 *       defines. Same definitions exist tree-wide. Unify this definition and
 *       the other definitions then move to include/uapi/linux/pci.h.
 */
#define NR_P2SB_RES_CACHE …

struct p2sb_res_cache { … };

static struct p2sb_res_cache p2sb_resources[NR_P2SB_RES_CACHE];

static void p2sb_get_devfn(unsigned int *devfn)
{ … }

static bool p2sb_valid_resource(const struct resource *res)
{ … }

/* Copy resource from the first BAR of the device in question */
static void p2sb_read_bar0(struct pci_dev *pdev, struct resource *mem)
{ … }

static void p2sb_scan_and_cache_devfn(struct pci_bus *bus, unsigned int devfn)
{ … }

static int p2sb_scan_and_cache(struct pci_bus *bus, unsigned int devfn)
{ … }

static struct pci_bus *p2sb_get_bus(struct pci_bus *bus)
{ … }

static int p2sb_cache_resources(void)
{ … }

/**
 * p2sb_bar - Get Primary to Sideband (P2SB) bridge device BAR
 * @bus: PCI bus to communicate with
 * @devfn: PCI slot and function to communicate with
 * @mem: memory resource to be filled in
 *
 * If @bus is NULL, the bus 0 in domain 0 will be used.
 * If @devfn is 0, it will be replaced by devfn of the P2SB device.
 *
 * Caller must provide a valid pointer to @mem.
 *
 * Return:
 * 0 on success or appropriate errno value on error.
 */
int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
{ … }
EXPORT_SYMBOL_GPL(…);

static int __init p2sb_fs_init(void)
{ … }

/*
 * pci_rescan_remove_lock() can not be locked in sysfs PCI bus rescan path
 * because of deadlock. To avoid the deadlock, access P2SB devices with the lock
 * at an early step in kernel initialization and cache required resources.
 *
 * We want to run as early as possible. If the P2SB was assigned a bad BAR,
 * we'll need to wait on pcibios_assign_resources() to fix it. So, our list of
 * initcall dependencies looks something like this:
 *
 * ...
 * subsys_initcall (pci_subsys_init)
 * fs_initcall     (pcibios_assign_resources)
 */
fs_initcall_sync(p2sb_fs_init);