/*
 * File:        portdrv_core.c
 * Purpose:     PCI Express Port Bus Driver's Core Functions
 *
 * Copyright (C) 2004 Intel
 * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com)
 */

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/pm.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/pcieport_if.h>

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

/**
 * release_pcie_device - free PCI Express port service device structure
 * @dev: Port service device to release
 *
 * Invoked automatically when device is being removed in response to
 * device_unregister(dev).  Release all resources being claimed.
 */
static void release_pcie_device(struct device *dev)
{
        kfree(to_pcie_device(dev));                     
}

/**
 * pcie_port_msix_add_entry - add entry to given array of MSI-X entries
 * @entries: Array of MSI-X entries
 * @new_entry: Index of the entry to add to the array
 * @nr_entries: Number of entries aleady in the array
 *
 * Return value: Position of the added entry in the array
 */
static int pcie_port_msix_add_entry(
        struct msix_entry *entries, int new_entry, int nr_entries)
{
        int j;

        for (j = 0; j < nr_entries; j++)
                if (entries[j].entry == new_entry)
                        return j;

        entries[j].entry = new_entry;
        return j;
}

/**
 * pcie_port_enable_msix - try to set up MSI-X as interrupt mode for given port
 * @dev: PCI Express port to handle
 * @vectors: Array of interrupt vectors to populate
 * @mask: Bitmask of port capabilities returned by get_port_device_capability()
 *
 * Return value: 0 on success, error code on failure
 */
static int pcie_port_enable_msix(struct pci_dev *dev, int *vectors, int mask)
{
        struct msix_entry *msix_entries;
        int idx[PCIE_PORT_DEVICE_MAXSERVICES];
        int nr_entries, status, pos, i, nvec;
        u16 reg16;
        u32 reg32;

        nr_entries = pci_msix_table_size(dev);
        if (!nr_entries)
                return -EINVAL;
        if (nr_entries > PCIE_PORT_MAX_MSIX_ENTRIES)
                nr_entries = PCIE_PORT_MAX_MSIX_ENTRIES;

        msix_entries = kzalloc(sizeof(*msix_entries) * nr_entries, GFP_KERNEL);
        if (!msix_entries)
                return -ENOMEM;

        /*
         * Allocate as many entries as the port wants, so that we can check
         * which of them will be useful.  Moreover, if nr_entries is correctly
         * equal to the number of entries this port actually uses, we'll happily
         * go through without any tricks.
         */
        for (i = 0; i < nr_entries; i++)
                msix_entries[i].entry = i;

        status = pci_enable_msix(dev, msix_entries, nr_entries);
        if (status)
                goto Exit;

        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
                idx[i] = -1;
        status = -EIO;
        nvec = 0;

        if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
                int entry;

                /*
                 * The code below follows the PCI Express Base Specification 2.0
                 * stating in Section 6.1.6 that "PME and Hot-Plug Event
                 * interrupts (when both are implemented) always share the same
                 * MSI or MSI-X vector, as indicated by the Interrupt Message
                 * Number field in the PCI Express Capabilities register", where
                 * according to Section 7.8.2 of the specification "For MSI-X,
                 * the value in this field indicates which MSI-X Table entry is
                 * used to generate the interrupt message."
                 */
                pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
                pci_read_config_word(dev, pos + PCIE_CAPABILITIES_REG, &reg16);
                entry = (reg16 >> 9) & PCIE_PORT_MSI_VECTOR_MASK;
                if (entry >= nr_entries)
                        goto Error;

                i = pcie_port_msix_add_entry(msix_entries, entry, nvec);
                if (i == nvec)
                        nvec++;

                idx[PCIE_PORT_SERVICE_PME_SHIFT] = i;
                idx[PCIE_PORT_SERVICE_HP_SHIFT] = i;
        }

        if (mask & PCIE_PORT_SERVICE_AER) {
                int entry;

                /*
                 * The code below follows Section 7.10.10 of the PCI Express
                 * Base Specification 2.0 stating that bits 31-27 of the Root
                 * Error Status Register contain a value indicating which of the
                 * MSI/MSI-X vectors assigned to the port is going to be used
                 * for AER, where "For MSI-X, the value in this register
                 * indicates which MSI-X Table entry is used to generate the
                 * interrupt message."
                 */
                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR);
                pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &reg32);
                entry = reg32 >> 27;
                if (entry >= nr_entries)
                        goto Error;

                i = pcie_port_msix_add_entry(msix_entries, entry, nvec);
                if (i == nvec)
                        nvec++;

                idx[PCIE_PORT_SERVICE_AER_SHIFT] = i;
        }

        /*
         * If nvec is equal to the allocated number of entries, we can just use
         * what we have.  Otherwise, the port has some extra entries not for the
         * services we know and we need to work around that.
         */
        if (nvec == nr_entries) {
                status = 0;
        } else {
                /* Drop the temporary MSI-X setup */
                pci_disable_msix(dev);

                /* Now allocate the MSI-X vectors for real */
                status = pci_enable_msix(dev, msix_entries, nvec);
                if (status)
                        goto Exit;
        }

        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
                vectors[i] = idx[i] >= 0 ? msix_entries[idx[i]].vector : -1;

 Exit:
        kfree(msix_entries);
        return status;

 Error:
        pci_disable_msix(dev);
        goto Exit;
}

/**
 * assign_interrupt_mode - choose interrupt mode for PCI Express port services
 *                         (INTx, MSI-X, MSI) and set up vectors
 * @dev: PCI Express port to handle
 * @vectors: Array of interrupt vectors to populate
 * @mask: Bitmask of port capabilities returned by get_port_device_capability()
 *
 * Return value: Interrupt mode associated with the port
 */
static int assign_interrupt_mode(struct pci_dev *dev, int *vectors, int mask)
{
        int irq, interrupt_mode = PCIE_PORT_NO_IRQ;
        int i;

        /* Try to use MSI-X if supported */
        if (!pcie_port_enable_msix(dev, vectors, mask))
                return PCIE_PORT_MSIX_MODE;

        /* We're not going to use MSI-X, so try MSI and fall back to INTx */
        if (!pci_enable_msi(dev))
                interrupt_mode = PCIE_PORT_MSI_MODE;

        if (interrupt_mode == PCIE_PORT_NO_IRQ && dev->pin)
                interrupt_mode = PCIE_PORT_INTx_MODE;

        irq = interrupt_mode != PCIE_PORT_NO_IRQ ? dev->irq : -1;
        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
                vectors[i] = irq;

        vectors[PCIE_PORT_SERVICE_VC_SHIFT] = -1;

        return interrupt_mode;
}

/**
 * get_port_device_capability - discover capabilities of a PCI Express port
 * @dev: PCI Express port to examine
 *
 * The capabilities are read from the port's PCI Express configuration registers
 * as described in PCI Express Base Specification 1.0a sections 7.8.2, 7.8.9 and
 * 7.9 - 7.11.
 *
 * Return value: Bitmask of discovered port capabilities
 */
static int get_port_device_capability(struct pci_dev *dev)
{
        int services = 0, pos;
        u16 reg16;
        u32 reg32;

        pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
        pci_read_config_word(dev, pos + PCIE_CAPABILITIES_REG, &reg16);
        /* Hot-Plug Capable */
        if (reg16 & PORT_TO_SLOT_MASK) {
                pci_read_config_dword(dev, 
                        pos + PCIE_SLOT_CAPABILITIES_REG, &reg32);
                if (reg32 & SLOT_HP_CAPABLE_MASK)
                        services |= PCIE_PORT_SERVICE_HP;
        }
        /* AER capable */
        if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR))
                services |= PCIE_PORT_SERVICE_AER;
        /* VC support */
        if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VC))
                services |= PCIE_PORT_SERVICE_VC;

        return services;
}

/**
 * pcie_device_init - initialize PCI Express port service device
 * @dev: Port service device to initialize
 * @parent: PCI Express port to associate the service device with
 * @port_type: Type of the port
 * @service_type: Type of service to associate with the service device
 * @irq: Interrupt vector to associate with the service device
 */
static void pcie_device_init(struct pci_dev *parent, struct pcie_device *dev, 
        int service_type, int irq)
{
        struct pcie_port_data *port_data = pci_get_drvdata(parent);
        struct device *device;
        int port_type = port_data->port_type;

        dev->port = parent;
        dev->irq = irq;
        dev->service = service_type;

        /* Initialize generic device interface */
        device = &dev->device;
        memset(device, 0, sizeof(struct device));
        device->bus = &pcie_port_bus_type;
        device->driver = NULL;
        dev_set_drvdata(device, NULL);
        device->release = release_pcie_device;  /* callback to free pcie dev */
        dev_set_name(device, "%s:pcie%02x",
                 pci_name(parent), get_descriptor_id(port_type, service_type));
        device->parent = &parent->dev;
}

/**
 * alloc_pcie_device - allocate PCI Express port service device structure
 * @parent: PCI Express port to associate the service device with
 * @port_type: Type of the port
 * @service_type: Type of service to associate with the service device
 * @irq: Interrupt vector to associate with the service device
 */
static struct pcie_device* alloc_pcie_device(struct pci_dev *parent,
        int service_type, int irq)
{
        struct pcie_device *device;

        device = kzalloc(sizeof(struct pcie_device), GFP_KERNEL);
        if (!device)
                return NULL;

        pcie_device_init(parent, device, service_type, irq);
        return device;
}

/**
 * pcie_port_device_probe - check if device is a PCI Express port
 * @dev: Device to check
 */
int pcie_port_device_probe(struct pci_dev *dev)
{
        int pos, type;
        u16 reg;

        if (!(pos = pci_find_capability(dev, PCI_CAP_ID_EXP)))
                return -ENODEV;

        pci_read_config_word(dev, pos + PCIE_CAPABILITIES_REG, &reg);
        type = (reg >> 4) & PORT_TYPE_MASK;
        if (    type == PCIE_RC_PORT || type == PCIE_SW_UPSTREAM_PORT ||
                type == PCIE_SW_DOWNSTREAM_PORT )
                return 0;

        return -ENODEV;
}

/**
 * pcie_port_device_register - register PCI Express port
 * @dev: PCI Express port to register
 *
 * Allocate the port extension structure and register services associated with
 * the port.
 */
int pcie_port_device_register(struct pci_dev *dev)
{
        struct pcie_port_data *port_data;
        int status, capabilities, irq_mode, i, nr_serv;
        int vectors[PCIE_PORT_DEVICE_MAXSERVICES];
        u16 reg16;

        port_data = kzalloc(sizeof(*port_data), GFP_KERNEL);
        if (!port_data)
                return -ENOMEM;
        pci_set_drvdata(dev, port_data);

        /* Get port type */
        pci_read_config_word(dev,
                pci_find_capability(dev, PCI_CAP_ID_EXP) +
                PCIE_CAPABILITIES_REG, &reg16);
        port_data->port_type = (reg16 >> 4) & PORT_TYPE_MASK;

        capabilities = get_port_device_capability(dev);
        /* Root ports are capable of generating PME too */
        if (port_data->port_type == PCIE_RC_PORT)
                capabilities |= PCIE_PORT_SERVICE_PME;

        irq_mode = assign_interrupt_mode(dev, vectors, capabilities);
        if (irq_mode == PCIE_PORT_NO_IRQ) {
                /*
                 * Don't use service devices that require interrupts if there is
                 * no way to generate them.
                 */
                if (!(capabilities & PCIE_PORT_SERVICE_VC)) {
                        status = -ENODEV;
                        goto Error;
                }
                capabilities = PCIE_PORT_SERVICE_VC;
        }
        port_data->port_irq_mode = irq_mode;

        status = pci_enable_device(dev);
        if (status)
                goto Error;
        pci_set_master(dev);

        /* Allocate child services if any */
        for (i = 0, nr_serv = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++) {
                struct pcie_device *child;
                int service = 1 << i;

                if (!(capabilities & service))
                        continue;

                child = alloc_pcie_device(dev, service, vectors[i]);
                if (!child)
                        continue;

                status = device_register(&child->device);
                if (status) {
                        kfree(child);
                        continue;
                }

                get_device(&child->device);
                nr_serv++;
        }
        if (!nr_serv) {
                pci_disable_device(dev);
                status = -ENODEV;
                goto Error;
        }

        return 0;

 Error:
        kfree(port_data);
        return status;
}

#ifdef CONFIG_PM
static int suspend_iter(struct device *dev, void *data)
{
        struct pcie_port_service_driver *service_driver;

        if ((dev->bus == &pcie_port_bus_type) &&
            (dev->driver)) {
                service_driver = to_service_driver(dev->driver);
                if (service_driver->suspend)
                        service_driver->suspend(to_pcie_device(dev));
        }
        return 0;
}

/**
 * pcie_port_device_suspend - suspend port services associated with a PCIe port
 * @dev: PCI Express port to handle
 */
int pcie_port_device_suspend(struct device *dev)
{
        return device_for_each_child(dev, NULL, suspend_iter);
}

static int resume_iter(struct device *dev, void *data)
{
        struct pcie_port_service_driver *service_driver;

        if ((dev->bus == &pcie_port_bus_type) &&
            (dev->driver)) {
                service_driver = to_service_driver(dev->driver);
                if (service_driver->resume)
                        service_driver->resume(to_pcie_device(dev));
        }
        return 0;
}

/**
 * pcie_port_device_suspend - resume port services associated with a PCIe port
 * @dev: PCI Express port to handle
 */
int pcie_port_device_resume(struct device *dev)
{
        return device_for_each_child(dev, NULL, resume_iter);
}
#endif /* PM */

static int remove_iter(struct device *dev, void *data)
{
        if (dev->bus == &pcie_port_bus_type) {
                put_device(dev);
                device_unregister(dev);
        }
        return 0;
}

/**
 * pcie_port_device_remove - unregister PCI Express port service devices
 * @dev: PCI Express port the service devices to unregister are associated with
 *
 * Remove PCI Express port service devices associated with given port and
 * disable MSI-X or MSI for the port.
 */
void pcie_port_device_remove(struct pci_dev *dev)
{
        struct pcie_port_data *port_data = pci_get_drvdata(dev);

        device_for_each_child(&dev->dev, NULL, remove_iter);
        pci_disable_device(dev);

        switch (port_data->port_irq_mode) {
        case PCIE_PORT_MSIX_MODE:
                pci_disable_msix(dev);
                break;
        case PCIE_PORT_MSI_MODE:
                pci_disable_msi(dev);
                break;
        }

        kfree(port_data);
}

/**
 * pcie_port_probe_service - probe driver for given PCI Express port service
 * @dev: PCI Express port service device to probe against
 *
 * If PCI Express port service driver is registered with
 * pcie_port_service_register(), this function will be called by the driver core
 * whenever match is found between the driver and a port service device.
 */
static int pcie_port_probe_service(struct device *dev)
{
        struct pcie_device *pciedev;
        struct pcie_port_service_driver *driver;
        int status;

        if (!dev || !dev->driver)
                return -ENODEV;

        driver = to_service_driver(dev->driver);
        if (!driver || !driver->probe)
                return -ENODEV;

        pciedev = to_pcie_device(dev);
        status = driver->probe(pciedev);
        if (!status) {
                dev_printk(KERN_DEBUG, dev, "service driver %s loaded\n",
                        driver->name);
                get_device(dev);
        }
        return status;
}

/**
 * pcie_port_remove_service - detach driver from given PCI Express port service
 * @dev: PCI Express port service device to handle
 *
 * If PCI Express port service driver is registered with
 * pcie_port_service_register(), this function will be called by the driver core
 * when device_unregister() is called for the port service device associated
 * with the driver.
 */
static int pcie_port_remove_service(struct device *dev)
{
        struct pcie_device *pciedev;
        struct pcie_port_service_driver *driver;

        if (!dev || !dev->driver)
                return 0;

        pciedev = to_pcie_device(dev);
        driver = to_service_driver(dev->driver);
        if (driver && driver->remove) {
                dev_printk(KERN_DEBUG, dev, "unloading service driver %s\n",
                        driver->name);
                driver->remove(pciedev);
                put_device(dev);
        }
        return 0;
}

/**
 * pcie_port_shutdown_service - shut down given PCI Express port service
 * @dev: PCI Express port service device to handle
 *
 * If PCI Express port service driver is registered with
 * pcie_port_service_register(), this function will be called by the driver core
 * when device_shutdown() is called for the port service device associated
 * with the driver.
 */
static void pcie_port_shutdown_service(struct device *dev) {}

/**
 * pcie_port_service_register - register PCI Express port service driver
 * @new: PCI Express port service driver to register
 */
int pcie_port_service_register(struct pcie_port_service_driver *new)
{
        new->driver.name = (char *)new->name;
        new->driver.bus = &pcie_port_bus_type;
        new->driver.probe = pcie_port_probe_service;
        new->driver.remove = pcie_port_remove_service;
        new->driver.shutdown = pcie_port_shutdown_service;

        return driver_register(&new->driver);
}

/**
 * pcie_port_service_unregister - unregister PCI Express port service driver
 * @drv: PCI Express port service driver to unregister
 */
void pcie_port_service_unregister(struct pcie_port_service_driver *drv)
{
        driver_unregister(&drv->driver);
}

EXPORT_SYMBOL(pcie_port_service_register);
EXPORT_SYMBOL(pcie_port_service_unregister);