/*
 * 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/module.h>
#include <linux/pci.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 "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"
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

static int __devinit 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 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      = PCIE_RC_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;   /* has priority over 'forceload' */
}

/**
 * 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 = pci_find_ext_capability(pdev->port, PCI_EXT_CAP_ID_ERR);
        /*
         * 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 & ROOT_ERR_STATUS_MASKS)) {
                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_COR_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,
         * Root Error ID Reg, and Root error producer/consumer index.
         */
        spin_lock_init(&rpc->e_lock);

        rpc->rpd = dev;
        INIT_WORK(&rpc->dpc_handler, aer_isr);
        rpc->prod_idx = rpc->cons_idx = 0;
        mutex_init(&rpc->rpc_mutex);
        init_waitqueue_head(&rpc->wait_release);

        /* 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);

                wait_event(rpc->wait_release, rpc->prod_idx == rpc->cons_idx);

                aer_delete_rootport(rpc);
                set_service_data(dev, NULL);
        }
}

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

        /* Init */
        status = aer_init(dev);
        if (status)
                return status;

        /* 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)
{
        u16 p2p_ctrl;
        u32 status;
        int pos;

        pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);

        /* Disable Root's interrupt in response to error messages */
        pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, 0);

        /* Assert Secondary Bus Reset */
        pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &p2p_ctrl);
        p2p_ctrl |= PCI_CB_BRIDGE_CTL_CB_RESET;
        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, p2p_ctrl);

        /* De-assert Secondary Bus Reset */
        p2p_ctrl &= ~PCI_CB_BRIDGE_CTL_CB_RESET;
        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, p2p_ctrl);

        /*
         * System software must wait for at least 100ms from the end
         * of a reset of one or more device before it is permitted
         * to issue Configuration Requests to those devices.
         */
        msleep(200);
        dev_printk(KERN_DEBUG, &dev->dev, "Root Port link has been reset\n");

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

        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 */
        pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
        pci_read_config_word(dev, pos + PCI_EXP_DEVSTA, &reg16);
        pci_write_config_word(dev, pos + PCI_EXP_DEVSTA, reg16);

        /* Clean AER Root Error Status */
        pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
        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 (pcie_aer_disable)
                return -ENXIO;
        if (!pci_msi_enabled())
                return -ENXIO;
        return pcie_port_service_register(&aerdriver);
}

/**
 * aer_service_exit - unregister AER root service driver
 *
 * Invoked when AER root service driver is unloaded.
 **/
static void __exit aer_service_exit(void)
{
        pcie_port_service_unregister(&aerdriver);
}

module_init(aer_service_init);
module_exit(aer_service_exit);