/*
 * drivers/pci/pcie/aer/aerdrv.c
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * This file implements the AER root port service driver. The driver will
 * register an irq handler. When root port triggers an AER interrupt, the irq
 * handler will collect root port status and schedule a work.
 *
 * Copyright (C) 2006 Intel Corp.
 *      Tom Long Nguyen (tom.l.nguyen@intel.com)
 *      Zhang Yanmin (yanmin.zhang@intel.com)
 *
 */

#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/pcieport_if.h>
#include <linux/slab.h>

#include "aerdrv.h"
#include "../../pci.h"

/*
 * Version Information
 */
#define DRIVER_VERSION "v1.0"
#define DRIVER_AUTHOR "tom.l.nguyen@intel.com"
#define DRIVER_DESC "Root Port Advanced Error Reporting Driver"

static int aer_probe(struct pcie_device *dev);
static void aer_remove(struct pcie_device *dev);
static pci_ers_result_t aer_error_detected(struct pci_dev *dev,
        enum pci_channel_state error);
static void aer_error_resume(struct pci_dev *dev);
static pci_ers_result_t aer_root_reset(struct pci_dev *dev);

static const struct pci_error_handlers aer_error_handlers = {
        .error_detected = aer_error_detected,
        .resume         = aer_error_resume,
};

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,

        .err_handler    = &aer_error_handlers,

        .reset_link     = aer_root_reset,
};

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();
}

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->port;
        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->port;
        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_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);

/**
 * 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;
        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->device;

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

        rpc->isr = 1;

        aer_enable_rootport(rpc);

        return status;
}

/**
 * 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);
        dev_printk(KERN_DEBUG, &dev->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_detected - update severity status
 * @dev: pointer to Root Port's pci_dev data structure
 * @error: error severity being notified by port bus
 *
 * Invoked by Port Bus driver during error recovery.
 */
static pci_ers_result_t aer_error_detected(struct pci_dev *dev,
                        enum pci_channel_state error)
{
        /* Root Port has no impact. Always recovers. */
        return PCI_ERS_RESULT_CAN_RECOVER;
}

/**
 * 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);
        if (dev->error_state == pci_channel_io_normal)
                status &= ~mask; /* Clear corresponding nonfatal bits */
        else
                status &= mask; /* Clear corresponding fatal bits */
        pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);
}

/**
 * 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);