linux/drivers/pci/pcie/aer.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Implement the AER root port service driver. The driver registers an IRQ
 * handler. When a root port triggers an AER interrupt, the IRQ handler
 * collects root port status and schedules work.
 *
 * Copyright (C) 2006 Intel Corp.
 *	Tom Long Nguyen (tom.l.nguyen@intel.com)
 *	Zhang Yanmin (yanmin.zhang@intel.com)
 *
 * (C) Copyright 2009 Hewlett-Packard Development Company, L.P.
 *    Andrew Patterson <andrew.patterson@hp.com>
 */

#include <linux/cper.h>
#include <linux/pci.h>
#include <linux/pci-acpi.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/pm.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/kfifo.h>
#include <linux/slab.h>
#include <acpi/apei.h>
#include <ras/ras_event.h>

#include "../pci.h"
#include "portdrv.h"

#define AER_ERROR_SOURCES_MAX		100
#define AER_MAX_MULTI_ERR_DEVICES	5	/* Not likely to have more */

struct aer_err_info {
	struct pci_dev *dev[AER_MAX_MULTI_ERR_DEVICES];
	int error_dev_num;

	unsigned int id:16;

	unsigned int severity:2;	/* 0:NONFATAL | 1:FATAL | 2:COR */
	unsigned int __pad1:5;
	unsigned int multi_error_valid:1;

	unsigned int first_error:5;
	unsigned int __pad2:2;
	unsigned int tlp_header_valid:1;

	unsigned int status;		/* COR/UNCOR Error Status */
	unsigned int mask;		/* COR/UNCOR Error Mask */
	struct aer_header_log_regs tlp;	/* TLP Header */
};

struct aer_err_source {
	unsigned int status;
	unsigned int id;
};

struct aer_rpc {
	struct pci_dev *rpd;		/* Root Port device */
	struct work_struct dpc_handler;
	struct aer_err_source e_sources[AER_ERROR_SOURCES_MAX];
	struct aer_err_info e_info;
	unsigned short prod_idx;	/* Error Producer Index */
	unsigned short cons_idx;	/* Error Consumer Index */
	int isr;
	spinlock_t e_lock;		/*
					 * Lock access to Error Status/ID Regs
					 * and error producer/consumer index
					 */
	struct mutex rpc_mutex;		/*
					 * only one thread could do
					 * recovery on the same
					 * root port hierarchy
					 */
};

#define AER_LOG_TLP_MASKS		(PCI_ERR_UNC_POISON_TLP|	\
					PCI_ERR_UNC_ECRC|		\
					PCI_ERR_UNC_UNSUP|		\
					PCI_ERR_UNC_COMP_ABORT|		\
					PCI_ERR_UNC_UNX_COMP|		\
					PCI_ERR_UNC_MALF_TLP)

#define SYSTEM_ERROR_INTR_ON_MESG_MASK	(PCI_EXP_RTCTL_SECEE|	\
					PCI_EXP_RTCTL_SENFEE|	\
					PCI_EXP_RTCTL_SEFEE)
#define ROOT_PORT_INTR_ON_MESG_MASK	(PCI_ERR_ROOT_CMD_COR_EN|	\
					PCI_ERR_ROOT_CMD_NONFATAL_EN|	\
					PCI_ERR_ROOT_CMD_FATAL_EN)
#define ERR_COR_ID(d)			(d & 0xffff)
#define ERR_UNCOR_ID(d)			(d >> 16)

static int pcie_aer_disable;

void pci_no_aer(void)
{
	pcie_aer_disable = 1;
}

bool pci_aer_available(void)
{
	return !pcie_aer_disable && pci_msi_enabled();
}

#ifdef CONFIG_PCIE_ECRC

#define ECRC_POLICY_DEFAULT 0		/* ECRC set by BIOS */
#define ECRC_POLICY_OFF     1		/* ECRC off for performance */
#define ECRC_POLICY_ON      2		/* ECRC on for data integrity */

static int ecrc_policy = ECRC_POLICY_DEFAULT;

static const char *ecrc_policy_str[] = {
	[ECRC_POLICY_DEFAULT] = "bios",
	[ECRC_POLICY_OFF] = "off",
	[ECRC_POLICY_ON] = "on"
};

/**
 * enable_ercr_checking - enable PCIe ECRC checking for a device
 * @dev: the PCI device
 *
 * Returns 0 on success, or negative on failure.
 */
static int enable_ecrc_checking(struct pci_dev *dev)
{
	int pos;
	u32 reg32;

	if (!pci_is_pcie(dev))
		return -ENODEV;

	pos = dev->aer_cap;
	if (!pos)
		return -ENODEV;

	pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
	if (reg32 & PCI_ERR_CAP_ECRC_GENC)
		reg32 |= PCI_ERR_CAP_ECRC_GENE;
	if (reg32 & PCI_ERR_CAP_ECRC_CHKC)
		reg32 |= PCI_ERR_CAP_ECRC_CHKE;
	pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);

	return 0;
}

/**
 * disable_ercr_checking - disables PCIe ECRC checking for a device
 * @dev: the PCI device
 *
 * Returns 0 on success, or negative on failure.
 */
static int disable_ecrc_checking(struct pci_dev *dev)
{
	int pos;
	u32 reg32;

	if (!pci_is_pcie(dev))
		return -ENODEV;

	pos = dev->aer_cap;
	if (!pos)
		return -ENODEV;

	pci_read_config_dword(dev, pos + PCI_ERR_CAP, &reg32);
	reg32 &= ~(PCI_ERR_CAP_ECRC_GENE | PCI_ERR_CAP_ECRC_CHKE);
	pci_write_config_dword(dev, pos + PCI_ERR_CAP, reg32);

	return 0;
}

/**
 * pcie_set_ecrc_checking - set/unset PCIe ECRC checking for a device based on global policy
 * @dev: the PCI device
 */
void pcie_set_ecrc_checking(struct pci_dev *dev)
{
	switch (ecrc_policy) {
	case ECRC_POLICY_DEFAULT:
		return;
	case ECRC_POLICY_OFF:
		disable_ecrc_checking(dev);
		break;
	case ECRC_POLICY_ON:
		enable_ecrc_checking(dev);
		break;
	default:
		return;
	}
}

/**
 * pcie_ecrc_get_policy - parse kernel command-line ecrc option
 */
void pcie_ecrc_get_policy(char *str)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(ecrc_policy_str); i++)
		if (!strncmp(str, ecrc_policy_str[i],
			     strlen(ecrc_policy_str[i])))
			break;
	if (i >= ARRAY_SIZE(ecrc_policy_str))
		return;

	ecrc_policy = i;
}
#endif	/* CONFIG_PCIE_ECRC */

#ifdef CONFIG_ACPI_APEI
static inline int hest_match_pci(struct acpi_hest_aer_common *p,
				 struct pci_dev *pci)
{
	return   ACPI_HEST_SEGMENT(p->bus) == pci_domain_nr(pci->bus) &&
		 ACPI_HEST_BUS(p->bus)     == pci->bus->number &&
		 p->device                 == PCI_SLOT(pci->devfn) &&
		 p->function               == PCI_FUNC(pci->devfn);
}

static inline bool hest_match_type(struct acpi_hest_header *hest_hdr,
				struct pci_dev *dev)
{
	u16 hest_type = hest_hdr->type;
	u8 pcie_type = pci_pcie_type(dev);

	if ((hest_type == ACPI_HEST_TYPE_AER_ROOT_PORT &&
		pcie_type == PCI_EXP_TYPE_ROOT_PORT) ||
	    (hest_type == ACPI_HEST_TYPE_AER_ENDPOINT &&
		pcie_type == PCI_EXP_TYPE_ENDPOINT) ||
	    (hest_type == ACPI_HEST_TYPE_AER_BRIDGE &&
		(dev->class >> 16) == PCI_BASE_CLASS_BRIDGE))
		return true;
	return false;
}

struct aer_hest_parse_info {
	struct pci_dev *pci_dev;
	int firmware_first;
};

static int hest_source_is_pcie_aer(struct acpi_hest_header *hest_hdr)
{
	if (hest_hdr->type == ACPI_HEST_TYPE_AER_ROOT_PORT ||
	    hest_hdr->type == ACPI_HEST_TYPE_AER_ENDPOINT ||
	    hest_hdr->type == ACPI_HEST_TYPE_AER_BRIDGE)
		return 1;
	return 0;
}

static int aer_hest_parse(struct acpi_hest_header *hest_hdr, void *data)
{
	struct aer_hest_parse_info *info = data;
	struct acpi_hest_aer_common *p;
	int ff;

	if (!hest_source_is_pcie_aer(hest_hdr))
		return 0;

	p = (struct acpi_hest_aer_common *)(hest_hdr + 1);
	ff = !!(p->flags & ACPI_HEST_FIRMWARE_FIRST);

	/*
	 * If no specific device is supplied, determine whether
	 * FIRMWARE_FIRST is set for *any* PCIe device.
	 */
	if (!info->pci_dev) {
		info->firmware_first |= ff;
		return 0;
	}

	/* Otherwise, check the specific device */
	if (p->flags & ACPI_HEST_GLOBAL) {
		if (hest_match_type(hest_hdr, info->pci_dev))
			info->firmware_first = ff;
	} else
		if (hest_match_pci(p, info->pci_dev))
			info->firmware_first = ff;

	return 0;
}

static void aer_set_firmware_first(struct pci_dev *pci_dev)
{
	int rc;
	struct aer_hest_parse_info info = {
		.pci_dev	= pci_dev,
		.firmware_first	= 0,
	};

	rc = apei_hest_parse(aer_hest_parse, &info);

	if (rc)
		pci_dev->__aer_firmware_first = 0;
	else
		pci_dev->__aer_firmware_first = info.firmware_first;
	pci_dev->__aer_firmware_first_valid = 1;
}

int pcie_aer_get_firmware_first(struct pci_dev *dev)
{
	if (!pci_is_pcie(dev))
		return 0;

	if (!dev->__aer_firmware_first_valid)
		aer_set_firmware_first(dev);
	return dev->__aer_firmware_first;
}
#define	PCI_EXP_AER_FLAGS	(PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE | \
				 PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE)

static bool aer_firmware_first;

/**
 * aer_acpi_firmware_first - Check if APEI should control AER.
 */
bool aer_acpi_firmware_first(void)
{
	static bool parsed = false;
	struct aer_hest_parse_info info = {
		.pci_dev	= NULL,	/* Check all PCIe devices */
		.firmware_first	= 0,
	};

	if (!parsed) {
		apei_hest_parse(aer_hest_parse, &info);
		aer_firmware_first = info.firmware_first;
		parsed = true;
	}
	return aer_firmware_first;
}
#endif

#define	PCI_EXP_AER_FLAGS	(PCI_EXP_DEVCTL_CERE | PCI_EXP_DEVCTL_NFERE | \
				 PCI_EXP_DEVCTL_FERE | PCI_EXP_DEVCTL_URRE)

int pci_enable_pcie_error_reporting(struct pci_dev *dev)
{
	if (pcie_aer_get_firmware_first(dev))
		return -EIO;

	if (!dev->aer_cap)
		return -EIO;

	return pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_AER_FLAGS);
}
EXPORT_SYMBOL_GPL(pci_enable_pcie_error_reporting);

int pci_disable_pcie_error_reporting(struct pci_dev *dev)
{
	if (pcie_aer_get_firmware_first(dev))
		return -EIO;

	return pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
					  PCI_EXP_AER_FLAGS);
}
EXPORT_SYMBOL_GPL(pci_disable_pcie_error_reporting);

int pci_cleanup_aer_uncorrect_error_status(struct pci_dev *dev)
{
	int pos;
	u32 status;

	pos = dev->aer_cap;
	if (!pos)
		return -EIO;

	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, &status);
	if (status)
		pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);

	return 0;
}
EXPORT_SYMBOL_GPL(pci_cleanup_aer_uncorrect_error_status);

int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
{
	int pos;
	u32 status;
	int port_type;

	if (!pci_is_pcie(dev))
		return -ENODEV;

	pos = dev->aer_cap;
	if (!pos)
		return -EIO;

	port_type = pci_pcie_type(dev);
	if (port_type == PCI_EXP_TYPE_ROOT_PORT) {
		pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &status);
		pci_write_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, status);
	}

	pci_read_config_dword(dev, pos + PCI_ERR_COR_STATUS, &status);
	pci_write_config_dword(dev, pos + PCI_ERR_COR_STATUS, status);

	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, &status);
	pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);

	return 0;
}

int pci_aer_init(struct pci_dev *dev)
{
	dev->aer_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
	return pci_cleanup_aer_error_status_regs(dev);
}

#define AER_AGENT_RECEIVER		0
#define AER_AGENT_REQUESTER		1
#define AER_AGENT_COMPLETER		2
#define AER_AGENT_TRANSMITTER		3

#define AER_AGENT_REQUESTER_MASK(t)	((t == AER_CORRECTABLE) ?	\
	0 : (PCI_ERR_UNC_COMP_TIME|PCI_ERR_UNC_UNSUP))
#define AER_AGENT_COMPLETER_MASK(t)	((t == AER_CORRECTABLE) ?	\
	0 : PCI_ERR_UNC_COMP_ABORT)
#define AER_AGENT_TRANSMITTER_MASK(t)	((t == AER_CORRECTABLE) ?	\
	(PCI_ERR_COR_REP_ROLL|PCI_ERR_COR_REP_TIMER) : 0)

#define AER_GET_AGENT(t, e)						\
	((e & AER_AGENT_COMPLETER_MASK(t)) ? AER_AGENT_COMPLETER :	\
	(e & AER_AGENT_REQUESTER_MASK(t)) ? AER_AGENT_REQUESTER :	\
	(e & AER_AGENT_TRANSMITTER_MASK(t)) ? AER_AGENT_TRANSMITTER :	\
	AER_AGENT_RECEIVER)

#define AER_PHYSICAL_LAYER_ERROR	0
#define AER_DATA_LINK_LAYER_ERROR	1
#define AER_TRANSACTION_LAYER_ERROR	2

#define AER_PHYSICAL_LAYER_ERROR_MASK(t) ((t == AER_CORRECTABLE) ?	\
	PCI_ERR_COR_RCVR : 0)
#define AER_DATA_LINK_LAYER_ERROR_MASK(t) ((t == AER_CORRECTABLE) ?	\
	(PCI_ERR_COR_BAD_TLP|						\
	PCI_ERR_COR_BAD_DLLP|						\
	PCI_ERR_COR_REP_ROLL|						\
	PCI_ERR_COR_REP_TIMER) : PCI_ERR_UNC_DLP)

#define AER_GET_LAYER_ERROR(t, e)					\
	((e & AER_PHYSICAL_LAYER_ERROR_MASK(t)) ? AER_PHYSICAL_LAYER_ERROR : \
	(e & AER_DATA_LINK_LAYER_ERROR_MASK(t)) ? AER_DATA_LINK_LAYER_ERROR : \
	AER_TRANSACTION_LAYER_ERROR)

/*
 * AER error strings
 */
static const char *aer_error_severity_string[] = {
	"Uncorrected (Non-Fatal)",
	"Uncorrected (Fatal)",
	"Corrected"
};

static const char *aer_error_layer[] = {
	"Physical Layer",
	"Data Link Layer",
	"Transaction Layer"
};

static const char *aer_correctable_error_string[] = {
	"Receiver Error",		/* Bit Position 0	*/
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	"Bad TLP",			/* Bit Position 6	*/
	"Bad DLLP",			/* Bit Position 7	*/
	"RELAY_NUM Rollover",		/* Bit Position 8	*/
	NULL,
	NULL,
	NULL,
	"Replay Timer Timeout",		/* Bit Position 12	*/
	"Advisory Non-Fatal",		/* Bit Position 13	*/
	"Corrected Internal Error",	/* Bit Position 14	*/
	"Header Log Overflow",		/* Bit Position 15	*/
};

static const char *aer_uncorrectable_error_string[] = {
	"Undefined",			/* Bit Position 0	*/
	NULL,
	NULL,
	NULL,
	"Data Link Protocol",		/* Bit Position 4	*/
	"Surprise Down Error",		/* Bit Position 5	*/
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	"Poisoned TLP",			/* Bit Position 12	*/
	"Flow Control Protocol",	/* Bit Position 13	*/
	"Completion Timeout",		/* Bit Position 14	*/
	"Completer Abort",		/* Bit Position 15	*/
	"Unexpected Completion",	/* Bit Position 16	*/
	"Receiver Overflow",		/* Bit Position 17	*/
	"Malformed TLP",		/* Bit Position 18	*/
	"ECRC",				/* Bit Position 19	*/
	"Unsupported Request",		/* Bit Position 20	*/
	"ACS Violation",		/* Bit Position 21	*/
	"Uncorrectable Internal Error",	/* Bit Position 22	*/
	"MC Blocked TLP",		/* Bit Position 23	*/
	"AtomicOp Egress Blocked",	/* Bit Position 24	*/
	"TLP Prefix Blocked Error",	/* Bit Position 25	*/
};

static const char *aer_agent_string[] = {
	"Receiver ID",
	"Requester ID",
	"Completer ID",
	"Transmitter ID"
};

static void __print_tlp_header(struct pci_dev *dev,
			       struct aer_header_log_regs *t)
{
	pci_err(dev, "  TLP Header: %08x %08x %08x %08x\n",
		t->dw0, t->dw1, t->dw2, t->dw3);
}

static void __aer_print_error(struct pci_dev *dev,
			      struct aer_err_info *info)
{
	int i, status;
	const char *errmsg = NULL;
	status = (info->status & ~info->mask);

	for (i = 0; i < 32; i++) {
		if (!(status & (1 << i)))
			continue;

		if (info->severity == AER_CORRECTABLE)
			errmsg = i < ARRAY_SIZE(aer_correctable_error_string) ?
				aer_correctable_error_string[i] : NULL;
		else
			errmsg = i < ARRAY_SIZE(aer_uncorrectable_error_string) ?
				aer_uncorrectable_error_string[i] : NULL;

		if (errmsg)
			pci_err(dev, "   [%2d] %-22s%s\n", i, errmsg,
				info->first_error == i ? " (First)" : "");
		else
			pci_err(dev, "   [%2d] Unknown Error Bit%s\n",
				i, info->first_error == i ? " (First)" : "");
	}
}

static void aer_print_error(struct pci_dev *dev, struct aer_err_info *info)
{
	int layer, agent;
	int id = ((dev->bus->number << 8) | dev->devfn);

	if (!info->status) {
		pci_err(dev, "PCIe Bus Error: severity=%s, type=Inaccessible, (Unregistered Agent ID)\n",
			aer_error_severity_string[info->severity]);
		goto out;
	}

	layer = AER_GET_LAYER_ERROR(info->severity, info->status);
	agent = AER_GET_AGENT(info->severity, info->status);

	pci_err(dev, "PCIe Bus Error: severity=%s, type=%s, (%s)\n",
		aer_error_severity_string[info->severity],
		aer_error_layer[layer], aer_agent_string[agent]);

	pci_err(dev, "  device [%04x:%04x] error status/mask=%08x/%08x\n",
		dev->vendor, dev->device,
		info->status, info->mask);

	__aer_print_error(dev, info);

	if (info->tlp_header_valid)
		__print_tlp_header(dev, &info->tlp);

out:
	if (info->id && info->error_dev_num > 1 && info->id == id)
		pci_err(dev, "  Error of this Agent is reported first\n");

	trace_aer_event(dev_name(&dev->dev), (info->status & ~info->mask),
			info->severity, info->tlp_header_valid, &info->tlp);
}

static void aer_print_port_info(struct pci_dev *dev, struct aer_err_info *info)
{
	u8 bus = info->id >> 8;
	u8 devfn = info->id & 0xff;

	pci_info(dev, "AER: %s%s error received: %04x:%02x:%02x.%d\n",
		info->multi_error_valid ? "Multiple " : "",
		aer_error_severity_string[info->severity],
		pci_domain_nr(dev->bus), bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
}

#ifdef CONFIG_ACPI_APEI_PCIEAER
int cper_severity_to_aer(int cper_severity)
{
	switch (cper_severity) {
	case CPER_SEV_RECOVERABLE:
		return AER_NONFATAL;
	case CPER_SEV_FATAL:
		return AER_FATAL;
	default:
		return AER_CORRECTABLE;
	}
}
EXPORT_SYMBOL_GPL(cper_severity_to_aer);

void cper_print_aer(struct pci_dev *dev, int aer_severity,
		    struct aer_capability_regs *aer)
{
	int layer, agent, tlp_header_valid = 0;
	u32 status, mask;
	struct aer_err_info info;

	if (aer_severity == AER_CORRECTABLE) {
		status = aer->cor_status;
		mask = aer->cor_mask;
	} else {
		status = aer->uncor_status;
		mask = aer->uncor_mask;
		tlp_header_valid = status & AER_LOG_TLP_MASKS;
	}

	layer = AER_GET_LAYER_ERROR(aer_severity, status);
	agent = AER_GET_AGENT(aer_severity, status);

	memset(&info, 0, sizeof(info));
	info.severity = aer_severity;
	info.status = status;
	info.mask = mask;
	info.first_error = PCI_ERR_CAP_FEP(aer->cap_control);

	pci_err(dev, "aer_status: 0x%08x, aer_mask: 0x%08x\n", status, mask);
	__aer_print_error(dev, &info);
	pci_err(dev, "aer_layer=%s, aer_agent=%s\n",
		aer_error_layer[layer], aer_agent_string[agent]);

	if (aer_severity != AER_CORRECTABLE)
		pci_err(dev, "aer_uncor_severity: 0x%08x\n",
			aer->uncor_severity);

	if (tlp_header_valid)
		__print_tlp_header(dev, &aer->header_log);

	trace_aer_event(dev_name(&dev->dev), (status & ~mask),
			aer_severity, tlp_header_valid, &aer->header_log);
}
#endif

/**
 * add_error_device - list device to be handled
 * @e_info: pointer to error info
 * @dev: pointer to pci_dev to be added
 */
static int add_error_device(struct aer_err_info *e_info, struct pci_dev *dev)
{
	if (e_info->error_dev_num < AER_MAX_MULTI_ERR_DEVICES) {
		e_info->dev[e_info->error_dev_num] = dev;
		e_info->error_dev_num++;
		return 0;
	}
	return -ENOSPC;
}

/**
 * is_error_source - check whether the device is source of reported error
 * @dev: pointer to pci_dev to be checked
 * @e_info: pointer to reported error info
 */
static bool is_error_source(struct pci_dev *dev, struct aer_err_info *e_info)
{
	int pos;
	u32 status, mask;
	u16 reg16;

	/*
	 * When bus id is equal to 0, it might be a bad id
	 * reported by root port.
	 */
	if ((PCI_BUS_NUM(e_info->id) != 0) &&
	    !(dev->bus->bus_flags & PCI_BUS_FLAGS_NO_AERSID)) {
		/* Device ID match? */
		if (e_info->id == ((dev->bus->number << 8) | dev->devfn))
			return true;

		/* Continue id comparing if there is no multiple error */
		if (!e_info->multi_error_valid)
			return false;
	}

	/*
	 * When either
	 *      1) bus id is equal to 0. Some ports might lose the bus
	 *              id of error source id;
	 *      2) bus flag PCI_BUS_FLAGS_NO_AERSID is set
	 *      3) There are multiple errors and prior ID comparing fails;
	 * We check AER status registers to find possible reporter.
	 */
	if (atomic_read(&dev->enable_cnt) == 0)
		return false;

	/* Check if AER is enabled */
	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &reg16);
	if (!(reg16 & PCI_EXP_AER_FLAGS))
		return false;

	pos = dev->aer_cap;
	if (!pos)
		return false;

	/* Check if error is recorded */
	if (e_info->severity == AER_CORRECTABLE) {
		pci_read_config_dword(dev, pos + PCI_ERR_COR_STATUS, &status);
		pci_read_config_dword(dev, pos + PCI_ERR_COR_MASK, &mask);
	} else {
		pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, &status);
		pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_MASK, &mask);
	}
	if (status & ~mask)
		return true;

	return false;
}

static int find_device_iter(struct pci_dev *dev, void *data)
{
	struct aer_err_info *e_info = (struct aer_err_info *)data;

	if (is_error_source(dev, e_info)) {
		/* List this device */
		if (add_error_device(e_info, dev)) {
			/* We cannot handle more... Stop iteration */
			/* TODO: Should print error message here? */
			return 1;
		}

		/* If there is only a single error, stop iteration */
		if (!e_info->multi_error_valid)
			return 1;
	}
	return 0;
}

/**
 * find_source_device - search through device hierarchy for source device
 * @parent: pointer to Root Port pci_dev data structure
 * @e_info: including detailed error information such like id
 *
 * Return true if found.
 *
 * Invoked by DPC when error is detected at the Root Port.
 * Caller of this function must set id, severity, and multi_error_valid of
 * struct aer_err_info pointed by @e_info properly.  This function must fill
 * e_info->error_dev_num and e_info->dev[], based on the given information.
 */
static bool find_source_device(struct pci_dev *parent,
		struct aer_err_info *e_info)
{
	struct pci_dev *dev = parent;
	int result;

	/* Must reset in this function */
	e_info->error_dev_num = 0;

	/* Is Root Port an agent that sends error message? */
	result = find_device_iter(dev, e_info);
	if (result)
		return true;

	pci_walk_bus(parent->subordinate, find_device_iter, e_info);

	if (!e_info->error_dev_num) {
		pci_printk(KERN_DEBUG, parent, "can't find device of ID%04x\n",
			   e_info->id);
		return false;
	}
	return true;
}

/**
 * handle_error_source - handle logging error into an event log
 * @dev: pointer to pci_dev data structure of error source device
 * @info: comprehensive error information
 *
 * Invoked when an error being detected by Root Port.
 */
static void handle_error_source(struct pci_dev *dev, struct aer_err_info *info)
{
	int pos;

	if (info->severity == AER_CORRECTABLE) {
		/*
		 * Correctable error does not need software intervention.
		 * No need to go through error recovery process.
		 */
		pos = dev->aer_cap;
		if (pos)
			pci_write_config_dword(dev, pos + PCI_ERR_COR_STATUS,
					info->status);
	} else if (info->severity == AER_NONFATAL)
		pcie_do_nonfatal_recovery(dev);
	else if (info->severity == AER_FATAL)
		pcie_do_fatal_recovery(dev, PCIE_PORT_SERVICE_AER);
}

#ifdef CONFIG_ACPI_APEI_PCIEAER

#define AER_RECOVER_RING_ORDER		4
#define AER_RECOVER_RING_SIZE		(1 << AER_RECOVER_RING_ORDER)

struct aer_recover_entry {
	u8	bus;
	u8	devfn;
	u16	domain;
	int	severity;
	struct aer_capability_regs *regs;
};

static DEFINE_KFIFO(aer_recover_ring, struct aer_recover_entry,
		    AER_RECOVER_RING_SIZE);

static void aer_recover_work_func(struct work_struct *work)
{
	struct aer_recover_entry entry;
	struct pci_dev *pdev;

	while (kfifo_get(&aer_recover_ring, &entry)) {
		pdev = pci_get_domain_bus_and_slot(entry.domain, entry.bus,
						   entry.devfn);
		if (!pdev) {
			pr_err("AER recover: Can not find pci_dev for %04x:%02x:%02x:%x\n",
			       entry.domain, entry.bus,
			       PCI_SLOT(entry.devfn), PCI_FUNC(entry.devfn));
			continue;
		}
		cper_print_aer(pdev, entry.severity, entry.regs);
		if (entry.severity == AER_NONFATAL)
			pcie_do_nonfatal_recovery(pdev);
		else if (entry.severity == AER_FATAL)
			pcie_do_fatal_recovery(pdev, PCIE_PORT_SERVICE_AER);
		pci_dev_put(pdev);
	}
}

/*
 * Mutual exclusion for writers of aer_recover_ring, reader side don't
 * need lock, because there is only one reader and lock is not needed
 * between reader and writer.
 */
static DEFINE_SPINLOCK(aer_recover_ring_lock);
static DECLARE_WORK(aer_recover_work, aer_recover_work_func);

void aer_recover_queue(int domain, unsigned int bus, unsigned int devfn,
		       int severity, struct aer_capability_regs *aer_regs)
{
	unsigned long flags;
	struct aer_recover_entry entry = {
		.bus		= bus,
		.devfn		= devfn,
		.domain		= domain,
		.severity	= severity,
		.regs		= aer_regs,
	};

	spin_lock_irqsave(&aer_recover_ring_lock, flags);
	if (kfifo_put(&aer_recover_ring, entry))
		schedule_work(&aer_recover_work);
	else
		pr_err("AER recover: Buffer overflow when recovering AER for %04x:%02x:%02x:%x\n",
		       domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
	spin_unlock_irqrestore(&aer_recover_ring_lock, flags);
}
EXPORT_SYMBOL_GPL(aer_recover_queue);
#endif

/**
 * get_device_error_info - read error status from dev and store it to info
 * @dev: pointer to the device expected to have a error record
 * @info: pointer to structure to store the error record
 *
 * Return 1 on success, 0 on error.
 *
 * Note that @info is reused among all error devices. Clear fields properly.
 */
static int get_device_error_info(struct pci_dev *dev, struct aer_err_info *info)
{
	int pos, temp;

	/* Must reset in this function */
	info->status = 0;
	info->tlp_header_valid = 0;

	pos = dev->aer_cap;

	/* The device might not support AER */
	if (!pos)
		return 0;

	if (info->severity == AER_CORRECTABLE) {
		pci_read_config_dword(dev, pos + PCI_ERR_COR_STATUS,
			&info->status);
		pci_read_config_dword(dev, pos + PCI_ERR_COR_MASK,
			&info->mask);
		if (!(info->status & ~info->mask))
			return 0;
	} else if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
		info->severity == AER_NONFATAL) {

		/* Link is still healthy for IO reads */
		pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS,
			&info->status);
		pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_MASK,
			&info->mask);
		if (!(info->status & ~info->mask))
			return 0;

		/* Get First Error Pointer */
		pci_read_config_dword(dev, pos + PCI_ERR_CAP, &temp);
		info->first_error = PCI_ERR_CAP_FEP(temp);

		if (info->status & AER_LOG_TLP_MASKS) {
			info->tlp_header_valid = 1;
			pci_read_config_dword(dev,
				pos + PCI_ERR_HEADER_LOG, &info->tlp.dw0);
			pci_read_config_dword(dev,
				pos + PCI_ERR_HEADER_LOG + 4, &info->tlp.dw1);
			pci_read_config_dword(dev,
				pos + PCI_ERR_HEADER_LOG + 8, &info->tlp.dw2);
			pci_read_config_dword(dev,
				pos + PCI_ERR_HEADER_LOG + 12, &info->tlp.dw3);
		}
	}

	return 1;
}

static inline void aer_process_err_devices(struct aer_err_info *e_info)
{
	int i;

	/* Report all before handle them, not to lost records by reset etc. */
	for (i = 0; i < e_info->error_dev_num && e_info->dev[i]; i++) {
		if (get_device_error_info(e_info->dev[i], e_info))
			aer_print_error(e_info->dev[i], e_info);
	}
	for (i = 0; i < e_info->error_dev_num && e_info->dev[i]; i++) {
		if (get_device_error_info(e_info->dev[i], e_info))
			handle_error_source(e_info->dev[i], e_info);
	}
}

/**
 * aer_isr_one_error - consume an error detected by root port
 * @rpc: pointer to the root port which holds an error
 * @e_src: pointer to an error source
 */
static void aer_isr_one_error(struct aer_rpc *rpc,
		struct aer_err_source *e_src)
{
	struct pci_dev *pdev = rpc->rpd;
	struct aer_err_info *e_info = &rpc->e_info;

	/*
	 * There is a possibility that both correctable error and
	 * uncorrectable error being logged. Report correctable error first.
	 */
	if (e_src->status & PCI_ERR_ROOT_COR_RCV) {
		e_info->id = ERR_COR_ID(e_src->id);
		e_info->severity = AER_CORRECTABLE;

		if (e_src->status & PCI_ERR_ROOT_MULTI_COR_RCV)
			e_info->multi_error_valid = 1;
		else
			e_info->multi_error_valid = 0;
		aer_print_port_info(pdev, e_info);

		if (find_source_device(pdev, e_info))
			aer_process_err_devices(e_info);
	}

	if (e_src->status & PCI_ERR_ROOT_UNCOR_RCV) {
		e_info->id = ERR_UNCOR_ID(e_src->id);

		if (e_src->status & PCI_ERR_ROOT_FATAL_RCV)
			e_info->severity = AER_FATAL;
		else
			e_info->severity = AER_NONFATAL;

		if (e_src->status & PCI_ERR_ROOT_MULTI_UNCOR_RCV)
			e_info->multi_error_valid = 1;
		else
			e_info->multi_error_valid = 0;

		aer_print_port_info(pdev, e_info);

		if (find_source_device(pdev, e_info))
			aer_process_err_devices(e_info);
	}
}

/**
 * get_e_source - retrieve an error source
 * @rpc: pointer to the root port which holds an error
 * @e_src: pointer to store retrieved error source
 *
 * Return 1 if an error source is retrieved, otherwise 0.
 *
 * Invoked by DPC handler to consume an error.
 */
static int get_e_source(struct aer_rpc *rpc, struct aer_err_source *e_src)
{
	unsigned long flags;

	/* Lock access to Root error producer/consumer index */
	spin_lock_irqsave(&rpc->e_lock, flags);
	if (rpc->prod_idx == rpc->cons_idx) {
		spin_unlock_irqrestore(&rpc->e_lock, flags);
		return 0;
	}

	*e_src = rpc->e_sources[rpc->cons_idx];
	rpc->cons_idx++;
	if (rpc->cons_idx == AER_ERROR_SOURCES_MAX)
		rpc->cons_idx = 0;
	spin_unlock_irqrestore(&rpc->e_lock, flags);

	return 1;
}

/**
 * aer_isr - consume errors detected by root port
 * @work: definition of this work item
 *
 * Invoked, as DPC, when root port records new detected error
 */
static void aer_isr(struct work_struct *work)
{
	struct aer_rpc *rpc = container_of(work, struct aer_rpc, dpc_handler);
	struct aer_err_source uninitialized_var(e_src);

	mutex_lock(&rpc->rpc_mutex);
	while (get_e_source(rpc, &e_src))
		aer_isr_one_error(rpc, &e_src);
	mutex_unlock(&rpc->rpc_mutex);
}

/**
 * aer_irq - Root Port's ISR
 * @irq: IRQ assigned to Root Port
 * @context: pointer to Root Port data structure
 *
 * Invoked when Root Port detects AER messages.
 */
irqreturn_t aer_irq(int irq, void *context)
{
	unsigned int status, id;
	struct pcie_device *pdev = (struct pcie_device *)context;
	struct aer_rpc *rpc = get_service_data(pdev);
	int next_prod_idx;
	unsigned long flags;
	int pos;

	pos = pdev->port->aer_cap;
	/*
	 * Must lock access to Root Error Status Reg, Root Error ID Reg,
	 * and Root error producer/consumer index
	 */
	spin_lock_irqsave(&rpc->e_lock, flags);

	/* Read error status */
	pci_read_config_dword(pdev->port, pos + PCI_ERR_ROOT_STATUS, &status);
	if (!(status & (PCI_ERR_ROOT_UNCOR_RCV|PCI_ERR_ROOT_COR_RCV))) {
		spin_unlock_irqrestore(&rpc->e_lock, flags);
		return IRQ_NONE;
	}

	/* Read error source and clear error status */
	pci_read_config_dword(pdev->port, pos + PCI_ERR_ROOT_ERR_SRC, &id);
	pci_write_config_dword(pdev->port, pos + PCI_ERR_ROOT_STATUS, status);

	/* Store error source for later DPC handler */
	next_prod_idx = rpc->prod_idx + 1;
	if (next_prod_idx == AER_ERROR_SOURCES_MAX)
		next_prod_idx = 0;
	if (next_prod_idx == rpc->cons_idx) {
		/*
		 * Error Storm Condition - possibly the same error occurred.
		 * Drop the error.
		 */
		spin_unlock_irqrestore(&rpc->e_lock, flags);
		return IRQ_HANDLED;
	}
	rpc->e_sources[rpc->prod_idx].status =  status;
	rpc->e_sources[rpc->prod_idx].id = id;
	rpc->prod_idx = next_prod_idx;
	spin_unlock_irqrestore(&rpc->e_lock, flags);

	/*  Invoke DPC handler */
	schedule_work(&rpc->dpc_handler);

	return IRQ_HANDLED;
}
EXPORT_SYMBOL_GPL(aer_irq);

static int set_device_error_reporting(struct pci_dev *dev, void *data)
{
	bool enable = *((bool *)data);
	int type = pci_pcie_type(dev);

	if ((type == PCI_EXP_TYPE_ROOT_PORT) ||
	    (type == PCI_EXP_TYPE_UPSTREAM) ||
	    (type == PCI_EXP_TYPE_DOWNSTREAM)) {
		if (enable)
			pci_enable_pcie_error_reporting(dev);
		else
			pci_disable_pcie_error_reporting(dev);
	}

	if (enable)
		pcie_set_ecrc_checking(dev);

	return 0;
}

/**
 * set_downstream_devices_error_reporting - enable/disable the error reporting  bits on the root port and its downstream ports.
 * @dev: pointer to root port's pci_dev data structure
 * @enable: true = enable error reporting, false = disable error reporting.
 */
static void set_downstream_devices_error_reporting(struct pci_dev *dev,
						   bool enable)
{
	set_device_error_reporting(dev, &enable);

	if (!dev->subordinate)
		return;
	pci_walk_bus(dev->subordinate, set_device_error_reporting, &enable);
}

/**
 * aer_enable_rootport - enable Root Port's interrupts when receiving messages
 * @rpc: pointer to a Root Port data structure
 *
 * Invoked when PCIe bus loads AER service driver.
 */
static void aer_enable_rootport(struct aer_rpc *rpc)
{
	struct pci_dev *pdev = rpc->rpd;
	int aer_pos;
	u16 reg16;
	u32 reg32;

	/* Clear PCIe Capability's Device Status */
	pcie_capability_read_word(pdev, PCI_EXP_DEVSTA, &reg16);
	pcie_capability_write_word(pdev, PCI_EXP_DEVSTA, reg16);

	/* Disable system error generation in response to error messages */
	pcie_capability_clear_word(pdev, PCI_EXP_RTCTL,
				   SYSTEM_ERROR_INTR_ON_MESG_MASK);

	aer_pos = pdev->aer_cap;
	/* Clear error status */
	pci_read_config_dword(pdev, aer_pos + PCI_ERR_ROOT_STATUS, &reg32);
	pci_write_config_dword(pdev, aer_pos + PCI_ERR_ROOT_STATUS, reg32);
	pci_read_config_dword(pdev, aer_pos + PCI_ERR_COR_STATUS, &reg32);
	pci_write_config_dword(pdev, aer_pos + PCI_ERR_COR_STATUS, reg32);
	pci_read_config_dword(pdev, aer_pos + PCI_ERR_UNCOR_STATUS, &reg32);
	pci_write_config_dword(pdev, aer_pos + PCI_ERR_UNCOR_STATUS, reg32);

	/*
	 * Enable error reporting for the root port device and downstream port
	 * devices.
	 */
	set_downstream_devices_error_reporting(pdev, true);

	/* Enable Root Port's interrupt in response to error messages */
	pci_read_config_dword(pdev, aer_pos + PCI_ERR_ROOT_COMMAND, &reg32);
	reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
	pci_write_config_dword(pdev, aer_pos + PCI_ERR_ROOT_COMMAND, reg32);
}

/**
 * aer_disable_rootport - disable Root Port's interrupts when receiving messages
 * @rpc: pointer to a Root Port data structure
 *
 * Invoked when PCIe bus unloads AER service driver.
 */
static void aer_disable_rootport(struct aer_rpc *rpc)
{
	struct pci_dev *pdev = rpc->rpd;
	u32 reg32;
	int pos;

	/*
	 * Disable error reporting for the root port device and downstream port
	 * devices.
	 */
	set_downstream_devices_error_reporting(pdev, false);

	pos = pdev->aer_cap;
	/* Disable Root's interrupt in response to error messages */
	pci_read_config_dword(pdev, pos + PCI_ERR_ROOT_COMMAND, &reg32);
	reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
	pci_write_config_dword(pdev, pos + PCI_ERR_ROOT_COMMAND, reg32);

	/* Clear Root's error status reg */
	pci_read_config_dword(pdev, pos + PCI_ERR_ROOT_STATUS, &reg32);
	pci_write_config_dword(pdev, pos + PCI_ERR_ROOT_STATUS, reg32);
}

/**
 * aer_alloc_rpc - allocate Root Port data structure
 * @dev: pointer to the pcie_dev data structure
 *
 * Invoked when Root Port's AER service is loaded.
 */
static struct aer_rpc *aer_alloc_rpc(struct pcie_device *dev)
{
	struct aer_rpc *rpc;

	rpc = kzalloc(sizeof(struct aer_rpc), GFP_KERNEL);
	if (!rpc)
		return NULL;

	/* Initialize Root lock access, e_lock, to Root Error Status Reg */
	spin_lock_init(&rpc->e_lock);

	rpc->rpd = dev->port;
	INIT_WORK(&rpc->dpc_handler, aer_isr);
	mutex_init(&rpc->rpc_mutex);

	/* Use PCIe bus function to store rpc into PCIe device */
	set_service_data(dev, rpc);

	return rpc;
}

/**
 * aer_remove - clean up resources
 * @dev: pointer to the pcie_dev data structure
 *
 * Invoked when PCI Express bus unloads or AER probe fails.
 */
static void aer_remove(struct pcie_device *dev)
{
	struct aer_rpc *rpc = get_service_data(dev);

	if (rpc) {
		/* If register interrupt service, it must be free. */
		if (rpc->isr)
			free_irq(dev->irq, dev);

		flush_work(&rpc->dpc_handler);
		aer_disable_rootport(rpc);
		kfree(rpc);
		set_service_data(dev, NULL);
	}
}

/**
 * aer_probe - initialize resources
 * @dev: pointer to the pcie_dev data structure
 *
 * Invoked when PCI Express bus loads AER service driver.
 */
static int aer_probe(struct pcie_device *dev)
{
	int status;
	struct aer_rpc *rpc;
	struct device *device = &dev->port->dev;

	/* Alloc rpc data structure */
	rpc = aer_alloc_rpc(dev);
	if (!rpc) {
		dev_printk(KERN_DEBUG, device, "alloc AER rpc failed\n");
		aer_remove(dev);
		return -ENOMEM;
	}

	/* Request IRQ ISR */
	status = request_irq(dev->irq, aer_irq, IRQF_SHARED, "aerdrv", dev);
	if (status) {
		dev_printk(KERN_DEBUG, device, "request AER IRQ %d failed\n",
			   dev->irq);
		aer_remove(dev);
		return status;
	}

	rpc->isr = 1;

	aer_enable_rootport(rpc);
	dev_info(device, "AER enabled with IRQ %d\n", dev->irq);
	return 0;
}

/**
 * aer_root_reset - reset link on Root Port
 * @dev: pointer to Root Port's pci_dev data structure
 *
 * Invoked by Port Bus driver when performing link reset at Root Port.
 */
static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
{
	u32 reg32;
	int pos;

	pos = dev->aer_cap;

	/* Disable Root's interrupt in response to error messages */
	pci_read_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, &reg32);
	reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
	pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, reg32);

	pci_reset_bridge_secondary_bus(dev);
	pci_printk(KERN_DEBUG, dev, "Root Port link has been reset\n");

	/* Clear Root Error Status */
	pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &reg32);
	pci_write_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, reg32);

	/* Enable Root Port's interrupt in response to error messages */
	pci_read_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, &reg32);
	reg32 |= ROOT_PORT_INTR_ON_MESG_MASK;
	pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, reg32);

	return PCI_ERS_RESULT_RECOVERED;
}

/**
 * aer_error_resume - clean up corresponding error status bits
 * @dev: pointer to Root Port's pci_dev data structure
 *
 * Invoked by Port Bus driver during nonfatal recovery.
 */
static void aer_error_resume(struct pci_dev *dev)
{
	int pos;
	u32 status, mask;
	u16 reg16;

	/* Clean up Root device status */
	pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &reg16);
	pcie_capability_write_word(dev, PCI_EXP_DEVSTA, reg16);

	/* Clean AER Root Error Status */
	pos = dev->aer_cap;
	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, &status);
	pci_read_config_dword(dev, pos + PCI_ERR_UNCOR_SEVER, &mask);
	status &= ~mask; /* Clear corresponding nonfatal bits */
	pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);
}

static struct pcie_port_service_driver aerdriver = {
	.name		= "aer",
	.port_type	= PCI_EXP_TYPE_ROOT_PORT,
	.service	= PCIE_PORT_SERVICE_AER,

	.probe		= aer_probe,
	.remove		= aer_remove,
	.error_resume	= aer_error_resume,
	.reset_link	= aer_root_reset,
};

/**
 * aer_service_init - register AER root service driver
 *
 * Invoked when AER root service driver is loaded.
 */
static int __init aer_service_init(void)
{
	if (!pci_aer_available() || aer_acpi_firmware_first())
		return -ENXIO;
	return pcie_port_service_register(&aerdriver);
}
device_initcall(aer_service_init);