// SPDX-License-Identifier: GPL-2.0
/*
 * 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/aer.h>

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

struct portdrv_service_data {
        struct pcie_port_service_driver *drv;
        struct device *dev;
        u32 service;
};

/**
 * 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));
}

/*
 * Fill in *pme, *aer, *dpc with the relevant Interrupt Message Numbers if
 * services are enabled in "mask".  Return the number of MSI/MSI-X vectors
 * required to accommodate the largest Message Number.
 */
static int pcie_message_numbers(struct pci_dev *dev, int mask,
                                u32 *pme, u32 *aer, u32 *dpc)
{
        u32 nvec = 0, pos;
        u16 reg16;

        /*
         * The Interrupt Message Number indicates which vector is used, i.e.,
         * the MSI-X table entry or the MSI offset between the base Message
         * Data and the generated interrupt message.  See PCIe r3.1, sec
         * 7.8.2, 7.10.10, 7.31.2.
         */

        if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
                    PCIE_PORT_SERVICE_BWNOTIF)) {
                pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
                *pme = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
                nvec = *pme + 1;
        }

#ifdef CONFIG_PCIEAER
        if (mask & PCIE_PORT_SERVICE_AER) {
                u32 reg32;

                pos = dev->aer_cap;
                if (pos) {
                        pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS,
                                              &reg32);
                        *aer = (reg32 & PCI_ERR_ROOT_AER_IRQ) >> 27;
                        nvec = max(nvec, *aer + 1);
                }
        }
#endif

        if (mask & PCIE_PORT_SERVICE_DPC) {
                pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC);
                if (pos) {
                        pci_read_config_word(dev, pos + PCI_EXP_DPC_CAP,
                                             &reg16);
                        *dpc = reg16 & PCI_EXP_DPC_IRQ;
                        nvec = max(nvec, *dpc + 1);
                }
        }

        return nvec;
}

/**
 * pcie_port_enable_irq_vec - try to set up MSI-X or MSI as interrupt mode
 * for given port
 * @dev: PCI Express port to handle
 * @irqs: 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_irq_vec(struct pci_dev *dev, int *irqs, int mask)
{
        int nr_entries, nvec, pcie_irq;
        u32 pme = 0, aer = 0, dpc = 0;

        /* Allocate the maximum possible number of MSI/MSI-X vectors */
        nr_entries = pci_alloc_irq_vectors(dev, 1, PCIE_PORT_MAX_MSI_ENTRIES,
                        PCI_IRQ_MSIX | PCI_IRQ_MSI);
        if (nr_entries < 0)
                return nr_entries;

        /* See how many and which Interrupt Message Numbers we actually use */
        nvec = pcie_message_numbers(dev, mask, &pme, &aer, &dpc);
        if (nvec > nr_entries) {
                pci_free_irq_vectors(dev);
                return -EIO;
        }

        /*
         * If we allocated more than we need, free them and reallocate fewer.
         *
         * Reallocating may change the specific vectors we get, so
         * pci_irq_vector() must be done *after* the reallocation.
         *
         * If we're using MSI, hardware is *allowed* to change the Interrupt
         * Message Numbers when we free and reallocate the vectors, but we
         * assume it won't because we allocate enough vectors for the
         * biggest Message Number we found.
         */
        if (nvec != nr_entries) {
                pci_free_irq_vectors(dev);

                nr_entries = pci_alloc_irq_vectors(dev, nvec, nvec,
                                PCI_IRQ_MSIX | PCI_IRQ_MSI);
                if (nr_entries < 0)
                        return nr_entries;
        }

        /* PME, hotplug and bandwidth notification share an MSI/MSI-X vector */
        if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
                    PCIE_PORT_SERVICE_BWNOTIF)) {
                pcie_irq = pci_irq_vector(dev, pme);
                irqs[PCIE_PORT_SERVICE_PME_SHIFT] = pcie_irq;
                irqs[PCIE_PORT_SERVICE_HP_SHIFT] = pcie_irq;
                irqs[PCIE_PORT_SERVICE_BWNOTIF_SHIFT] = pcie_irq;
        }

        if (mask & PCIE_PORT_SERVICE_AER)
                irqs[PCIE_PORT_SERVICE_AER_SHIFT] = pci_irq_vector(dev, aer);

        if (mask & PCIE_PORT_SERVICE_DPC)
                irqs[PCIE_PORT_SERVICE_DPC_SHIFT] = pci_irq_vector(dev, dpc);

        return 0;
}

/**
 * pcie_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 pcie_init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
{
        int ret, i;

        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
                irqs[i] = -1;

        /*
         * If we support PME but can't use MSI/MSI-X for it, we have to
         * fall back to INTx or other interrupts, e.g., a system shared
         * interrupt.
         */
        if ((mask & PCIE_PORT_SERVICE_PME) && pcie_pme_no_msi())
                goto legacy_irq;

        /* Try to use MSI-X or MSI if supported */
        if (pcie_port_enable_irq_vec(dev, irqs, mask) == 0)
                return 0;

legacy_irq:
        /* fall back to legacy IRQ */
        ret = pci_alloc_irq_vectors(dev, 1, 1, PCI_IRQ_LEGACY);
        if (ret < 0)
                return -ENODEV;

        for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
                irqs[i] = pci_irq_vector(dev, 0);

        return 0;
}

/**
 * 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)
{
        struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
        int services = 0;

        if (dev->is_hotplug_bridge &&
            (pcie_ports_native || host->native_pcie_hotplug)) {
                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);
        }

#ifdef CONFIG_PCIEAER
        if (dev->aer_cap && pci_aer_available() &&
            (pcie_ports_native || host->native_aer)) {
                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);
        }
#endif

        /*
         * Root ports are capable of generating PME too.  Root Complex
         * Event Collectors can also generate PMEs, but we don't handle
         * those yet.
         */
        if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT &&
            (pcie_ports_native || host->native_pme)) {
                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);
        }

        /*
         * With dpc-native, allow Linux to use DPC even if it doesn't have
         * permission to use AER.
         */
        if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
            pci_aer_available() &&
            (pcie_ports_dpc_native || (services & PCIE_PORT_SERVICE_AER)))
                services |= PCIE_PORT_SERVICE_DPC;

        if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM ||
            pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
                services |= PCIE_PORT_SERVICE_BWNOTIF;

        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 = pcie_init_service_irqs(dev, irqs, capabilities);
        if (status) {
                capabilities &= 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:
        pci_free_irq_vectors(dev);
error_disable:
        pci_disable_device(dev);
        return status;
}

#ifdef CONFIG_PM
typedef int (*pcie_pm_callback_t)(struct pcie_device *);

static int pm_iter(struct device *dev, void *data)
{
        struct pcie_port_service_driver *service_driver;
        size_t offset = *(size_t *)data;
        pcie_pm_callback_t cb;

        if ((dev->bus == &pcie_port_bus_type) && dev->driver) {
                service_driver = to_service_driver(dev->driver);
                cb = *(pcie_pm_callback_t *)((void *)service_driver + offset);
                if (cb)
                        return cb(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)
{
        size_t off = offsetof(struct pcie_port_service_driver, suspend);
        return device_for_each_child(dev, &off, pm_iter);
}

int pcie_port_device_resume_noirq(struct device *dev)
{
        size_t off = offsetof(struct pcie_port_service_driver, resume_noirq);
        return device_for_each_child(dev, &off, pm_iter);
}

/**
 * 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)
{
        size_t off = offsetof(struct pcie_port_service_driver, resume);
        return device_for_each_child(dev, &off, pm_iter);
}

/**
 * pcie_port_device_runtime_suspend - runtime suspend port services
 * @dev: PCI Express port to handle
 */
int pcie_port_device_runtime_suspend(struct device *dev)
{
        size_t off = offsetof(struct pcie_port_service_driver, runtime_suspend);
        return device_for_each_child(dev, &off, pm_iter);
}

/**
 * pcie_port_device_runtime_resume - runtime resume port services
 * @dev: PCI Express port to handle
 */
int pcie_port_device_runtime_resume(struct device *dev)
{
        size_t off = offsetof(struct pcie_port_service_driver, runtime_resume);
        return device_for_each_child(dev, &off, pm_iter);
}
#endif /* PM */

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

static int find_service_iter(struct device *device, void *data)
{
        struct pcie_port_service_driver *service_driver;
        struct portdrv_service_data *pdrvs;
        u32 service;

        pdrvs = (struct portdrv_service_data *) data;
        service = pdrvs->service;

        if (device->bus == &pcie_port_bus_type && device->driver) {
                service_driver = to_service_driver(device->driver);
                if (service_driver->service == service) {
                        pdrvs->drv = service_driver;
                        pdrvs->dev = device;
                        return 1;
                }
        }

        return 0;
}

/**
 * pcie_port_find_device - find the struct device
 * @dev: PCI Express port the service is associated with
 * @service: For the service to find
 *
 * Find the struct device associated with given service on a pci_dev
 */
struct device *pcie_port_find_device(struct pci_dev *dev,
                                      u32 service)
{
        struct device *device;
        struct portdrv_service_data pdrvs;

        pdrvs.dev = NULL;
        pdrvs.service = service;
        device_for_each_child(&dev->dev, &pdrvs, find_service_iter);

        device = pdrvs.dev;
        return device;
}
EXPORT_SYMBOL_GPL(pcie_port_find_device);

/**
 * 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);
        pci_free_irq_vectors(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;

        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) {
                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);