/*
 * 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/pm_runtime.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/pcieport_if.h>
#include <linux/aer.h>

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

bool pciehp_msi_disabled;

static int __init pciehp_setup(char *str)
{
        if (!strncmp(str, "nomsi", 5))
                pciehp_msi_disabled = true;

        return 1;
}
__setup("pcie_hp=", pciehp_setup);

/**
 * 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 already 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_vec_count(dev);
        if (nr_entries < 0)
                return nr_entries;
        BUG_ON(!nr_entries);
        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_exact(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."
                 */
                pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
                entry = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
                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_exact(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;
}

/**
 * init_service_irqs - initialize irqs for PCI Express port services
 * @dev: PCI Express port to handle
 * @irqs: Array of irqs to populate
 * @mask: Bitmask of port capabilities returned by get_port_device_capability()
 *
 * Return value: Interrupt mode associated with the port
 */
static int init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
{
        int i, irq = -1;

        /*
         * If MSI cannot be used for PCIe PME or hotplug, we have to use
         * INTx or other interrupts, e.g. system shared interrupt.
         */
        if (((mask & PCIE_PORT_SERVICE_PME) && pcie_pme_no_msi()) ||
            ((mask & PCIE_PORT_SERVICE_HP) && pciehp_no_msi())) {
                if (dev->irq)
                        irq = dev->irq;
                goto no_msi;
        }

        /* Try to use MSI-X if supported */
        if (!pcie_port_enable_msix(dev, irqs, mask))
                return 0;

        /*
         * We're not going to use MSI-X, so try MSI and fall back to INTx.
         * If neither MSI/MSI-X nor INTx available, try other interrupt.  On
         * some platforms, root port doesn't support MSI/MSI-X/INTx in RC mode.
         */
        if (!pci_enable_msi(dev) || dev->irq)
                irq = dev->irq;

 no_msi:
        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
                irqs[i] = irq;
        irqs[PCIE_PORT_SERVICE_VC_SHIFT] = -1;

        if (irq < 0)
                return -ENODEV;
        return 0;
}

static void cleanup_service_irqs(struct pci_dev *dev)
{
        if (dev->msix_enabled)
                pci_disable_msix(dev);
        else if (dev->msi_enabled)
                pci_disable_msi(dev);
}

/**
 * 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;
        int cap_mask = 0;

        if (pcie_ports_disabled)
                return 0;

        cap_mask = PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP
                        | PCIE_PORT_SERVICE_VC | PCIE_PORT_SERVICE_DPC;
        if (pci_aer_available())
                cap_mask |= PCIE_PORT_SERVICE_AER;

        if (pcie_ports_auto)
                pcie_port_platform_notify(dev, &cap_mask);

        /* Hot-Plug Capable */
        if ((cap_mask & PCIE_PORT_SERVICE_HP) && dev->is_hotplug_bridge) {
                services |= PCIE_PORT_SERVICE_HP;
                /*
                 * Disable hot-plug interrupts in case they have been enabled
                 * by the BIOS and the hot-plug service driver is not loaded.
                 */
                pcie_capability_clear_word(dev, PCI_EXP_SLTCTL,
                          PCI_EXP_SLTCTL_CCIE | PCI_EXP_SLTCTL_HPIE);
        }
        /* AER capable */
        if ((cap_mask & PCIE_PORT_SERVICE_AER)
            && pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR)) {
                services |= PCIE_PORT_SERVICE_AER;
                /*
                 * Disable AER on this port in case it's been enabled by the
                 * BIOS (the AER service driver will enable it when necessary).
                 */
                pci_disable_pcie_error_reporting(dev);
        }
        /* VC support */
        if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VC))
                services |= PCIE_PORT_SERVICE_VC;
        /* Root ports are capable of generating PME too */
        if ((cap_mask & PCIE_PORT_SERVICE_PME)
            && pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
                services |= PCIE_PORT_SERVICE_PME;
                /*
                 * Disable PME interrupt on this port in case it's been enabled
                 * by the BIOS (the PME service driver will enable it when
                 * necessary).
                 */
                pcie_pme_interrupt_enable(dev, false);
        }
        if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC))
                services |= PCIE_PORT_SERVICE_DPC;

        return services;
}

/**
 * pcie_device_init - allocate and initialize PCI Express port service device
 * @pdev: PCI Express port to associate the service device with
 * @service: Type of service to associate with the service device
 * @irq: Interrupt vector to associate with the service device
 */
static int pcie_device_init(struct pci_dev *pdev, int service, int irq)
{
        int retval;
        struct pcie_device *pcie;
        struct device *device;

        pcie = kzalloc(sizeof(*pcie), GFP_KERNEL);
        if (!pcie)
                return -ENOMEM;
        pcie->port = pdev;
        pcie->irq = irq;
        pcie->service = service;

        /* Initialize generic device interface */
        device = &pcie->device;
        device->bus = &pcie_port_bus_type;
        device->release = release_pcie_device;  /* callback to free pcie dev */
        dev_set_name(device, "%s:pcie%03x",
                     pci_name(pdev),
                     get_descriptor_id(pci_pcie_type(pdev), service));
        device->parent = &pdev->dev;
        device_enable_async_suspend(device);

        retval = device_register(device);
        if (retval) {
                put_device(device);
                return retval;
        }

        pm_runtime_no_callbacks(device);

        return 0;
}

/**
 * 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)
{
        int status, capabilities, i, nr_service;
        int irqs[PCIE_PORT_DEVICE_MAXSERVICES];

        /* Enable PCI Express port device */
        status = pci_enable_device(dev);
        if (status)
                return status;

        /* Get and check PCI Express port services */
        capabilities = get_port_device_capability(dev);
        if (!capabilities)
                return 0;

        pci_set_master(dev);
        /*
         * Initialize service irqs. Don't use service devices that
         * require interrupts if there is no way to generate them.
         * However, some drivers may have a polling mode (e.g. pciehp_poll_mode)
         * that can be used in the absence of irqs.  Allow them to determine
         * if that is to be used.
         */
        status = init_service_irqs(dev, irqs, capabilities);
        if (status) {
                capabilities &= PCIE_PORT_SERVICE_VC | PCIE_PORT_SERVICE_HP;
                if (!capabilities)
                        goto error_disable;
        }

        /* Allocate child services if any */
        status = -ENODEV;
        nr_service = 0;
        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++) {
                int service = 1 << i;
                if (!(capabilities & service))
                        continue;
                if (!pcie_device_init(dev, service, irqs[i]))
                        nr_service++;
        }
        if (!nr_service)
                goto error_cleanup_irqs;

        return 0;

error_cleanup_irqs:
        cleanup_service_irqs(dev);
error_disable:
        pci_disable_device(dev);
        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_resume - 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)
                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)
{
        device_for_each_child(&dev->dev, NULL, remove_iter);
        cleanup_service_irqs(dev);
        pci_disable_device(dev);
}

/**
 * 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)
                return status;

        dev_printk(KERN_DEBUG, dev, "service driver %s loaded\n", driver->name);
        get_device(dev);
        return 0;
}

/**
 * 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)
{
        if (pcie_ports_disabled)
                return -ENODEV;

        new->driver.name = 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);
}
EXPORT_SYMBOL(pcie_port_service_register);

/**
 * 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_unregister);