// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Endpoint *Function* (EPF) library
 *
 * Copyright (C) 2017 Texas Instruments
 * Author: Kishon Vijay Abraham I <kishon@ti.com>
 */

#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/module.h>

#include <linux/pci-epc.h>
#include <linux/pci-epf.h>
#include <linux/pci-ep-cfs.h>

static DEFINE_MUTEX(pci_epf_mutex);

static struct bus_type pci_epf_bus_type;
static const struct device_type pci_epf_type;

/**
 * pci_epf_type_add_cfs() - Help function drivers to expose function specific
 *                          attributes in configfs
 * @epf: the EPF device that has to be configured using configfs
 * @group: the parent configfs group (corresponding to entries in
 *         pci_epf_device_id)
 *
 * Invoke to expose function specific attributes in configfs. If the function
 * driver does not have anything to expose (attributes configured by user),
 * return NULL.
 */
struct config_group *pci_epf_type_add_cfs(struct pci_epf *epf,
                                          struct config_group *group)
{
        struct config_group *epf_type_group;

        if (!epf->driver) {
                dev_err(&epf->dev, "epf device not bound to driver\n");
                return NULL;
        }

        if (!epf->driver->ops->add_cfs)
                return NULL;

        mutex_lock(&epf->lock);
        epf_type_group = epf->driver->ops->add_cfs(epf, group);
        mutex_unlock(&epf->lock);

        return epf_type_group;
}
EXPORT_SYMBOL_GPL(pci_epf_type_add_cfs);

/**
 * pci_epf_unbind() - Notify the function driver that the binding between the
 *                    EPF device and EPC device has been lost
 * @epf: the EPF device which has lost the binding with the EPC device
 *
 * Invoke to notify the function driver that the binding between the EPF device
 * and EPC device has been lost.
 */
void pci_epf_unbind(struct pci_epf *epf)
{
        struct pci_epf *epf_vf;

        if (!epf->driver) {
                dev_WARN(&epf->dev, "epf device not bound to driver\n");
                return;
        }

        mutex_lock(&epf->lock);
        list_for_each_entry(epf_vf, &epf->pci_vepf, list) {
                if (epf_vf->is_bound)
                        epf_vf->driver->ops->unbind(epf_vf);
        }
        if (epf->is_bound)
                epf->driver->ops->unbind(epf);
        mutex_unlock(&epf->lock);
        module_put(epf->driver->owner);
}
EXPORT_SYMBOL_GPL(pci_epf_unbind);

/**
 * pci_epf_bind() - Notify the function driver that the EPF device has been
 *                  bound to a EPC device
 * @epf: the EPF device which has been bound to the EPC device
 *
 * Invoke to notify the function driver that it has been bound to a EPC device
 */
int pci_epf_bind(struct pci_epf *epf)
{
        struct device *dev = &epf->dev;
        struct pci_epf *epf_vf;
        u8 func_no, vfunc_no;
        struct pci_epc *epc;
        int ret;

        if (!epf->driver) {
                dev_WARN(dev, "epf device not bound to driver\n");
                return -EINVAL;
        }

        if (!try_module_get(epf->driver->owner))
                return -EAGAIN;

        mutex_lock(&epf->lock);
        list_for_each_entry(epf_vf, &epf->pci_vepf, list) {
                vfunc_no = epf_vf->vfunc_no;

                if (vfunc_no < 1) {
                        dev_err(dev, "Invalid virtual function number\n");
                        ret = -EINVAL;
                        goto ret;
                }

                epc = epf->epc;
                func_no = epf->func_no;
                if (!IS_ERR_OR_NULL(epc)) {
                        if (!epc->max_vfs) {
                                dev_err(dev, "No support for virt function\n");
                                ret = -EINVAL;
                                goto ret;
                        }

                        if (vfunc_no > epc->max_vfs[func_no]) {
                                dev_err(dev, "PF%d: Exceeds max vfunc number\n",
                                        func_no);
                                ret = -EINVAL;
                                goto ret;
                        }
                }

                epc = epf->sec_epc;
                func_no = epf->sec_epc_func_no;
                if (!IS_ERR_OR_NULL(epc)) {
                        if (!epc->max_vfs) {
                                dev_err(dev, "No support for virt function\n");
                                ret = -EINVAL;
                                goto ret;
                        }

                        if (vfunc_no > epc->max_vfs[func_no]) {
                                dev_err(dev, "PF%d: Exceeds max vfunc number\n",
                                        func_no);
                                ret = -EINVAL;
                                goto ret;
                        }
                }

                epf_vf->func_no = epf->func_no;
                epf_vf->sec_epc_func_no = epf->sec_epc_func_no;
                epf_vf->epc = epf->epc;
                epf_vf->sec_epc = epf->sec_epc;
                ret = epf_vf->driver->ops->bind(epf_vf);
                if (ret)
                        goto ret;
                epf_vf->is_bound = true;
        }

        ret = epf->driver->ops->bind(epf);
        if (ret)
                goto ret;
        epf->is_bound = true;

        mutex_unlock(&epf->lock);
        return 0;

ret:
        mutex_unlock(&epf->lock);
        pci_epf_unbind(epf);

        return ret;
}
EXPORT_SYMBOL_GPL(pci_epf_bind);

/**
 * pci_epf_add_vepf() - associate virtual EP function to physical EP function
 * @epf_pf: the physical EP function to which the virtual EP function should be
 *   associated
 * @epf_vf: the virtual EP function to be added
 *
 * A physical endpoint function can be associated with multiple virtual
 * endpoint functions. Invoke pci_epf_add_epf() to add a virtual PCI endpoint
 * function to a physical PCI endpoint function.
 */
int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
{
        u32 vfunc_no;

        if (IS_ERR_OR_NULL(epf_pf) || IS_ERR_OR_NULL(epf_vf))
                return -EINVAL;

        if (epf_pf->epc || epf_vf->epc || epf_vf->epf_pf)
                return -EBUSY;

        if (epf_pf->sec_epc || epf_vf->sec_epc)
                return -EBUSY;

        mutex_lock(&epf_pf->lock);
        vfunc_no = find_first_zero_bit(&epf_pf->vfunction_num_map,
                                       BITS_PER_LONG);
        if (vfunc_no >= BITS_PER_LONG) {
                mutex_unlock(&epf_pf->lock);
                return -EINVAL;
        }

        set_bit(vfunc_no, &epf_pf->vfunction_num_map);
        epf_vf->vfunc_no = vfunc_no;

        epf_vf->epf_pf = epf_pf;
        epf_vf->is_vf = true;

        list_add_tail(&epf_vf->list, &epf_pf->pci_vepf);
        mutex_unlock(&epf_pf->lock);

        return 0;
}
EXPORT_SYMBOL_GPL(pci_epf_add_vepf);

/**
 * pci_epf_remove_vepf() - remove virtual EP function from physical EP function
 * @epf_pf: the physical EP function from which the virtual EP function should
 *   be removed
 * @epf_vf: the virtual EP function to be removed
 *
 * Invoke to remove a virtual endpoint function from the physcial endpoint
 * function.
 */
void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf)
{
        if (IS_ERR_OR_NULL(epf_pf) || IS_ERR_OR_NULL(epf_vf))
                return;

        mutex_lock(&epf_pf->lock);
        clear_bit(epf_vf->vfunc_no, &epf_pf->vfunction_num_map);
        list_del(&epf_vf->list);
        mutex_unlock(&epf_pf->lock);
}
EXPORT_SYMBOL_GPL(pci_epf_remove_vepf);

/**
 * pci_epf_free_space() - free the allocated PCI EPF register space
 * @epf: the EPF device from whom to free the memory
 * @addr: the virtual address of the PCI EPF register space
 * @bar: the BAR number corresponding to the register space
 * @type: Identifies if the allocated space is for primary EPC or secondary EPC
 *
 * Invoke to free the allocated PCI EPF register space.
 */
void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
                        enum pci_epc_interface_type type)
{
        struct device *dev;
        struct pci_epf_bar *epf_bar;
        struct pci_epc *epc;

        if (!addr)
                return;

        if (type == PRIMARY_INTERFACE) {
                epc = epf->epc;
                epf_bar = epf->bar;
        } else {
                epc = epf->sec_epc;
                epf_bar = epf->sec_epc_bar;
        }

        dev = epc->dev.parent;
        dma_free_coherent(dev, epf_bar[bar].size, addr,
                          epf_bar[bar].phys_addr);

        epf_bar[bar].phys_addr = 0;
        epf_bar[bar].addr = NULL;
        epf_bar[bar].size = 0;
        epf_bar[bar].barno = 0;
        epf_bar[bar].flags = 0;
}
EXPORT_SYMBOL_GPL(pci_epf_free_space);

/**
 * pci_epf_alloc_space() - allocate memory for the PCI EPF register space
 * @epf: the EPF device to whom allocate the memory
 * @size: the size of the memory that has to be allocated
 * @bar: the BAR number corresponding to the allocated register space
 * @align: alignment size for the allocation region
 * @type: Identifies if the allocation is for primary EPC or secondary EPC
 *
 * Invoke to allocate memory for the PCI EPF register space.
 */
void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
                          size_t align, enum pci_epc_interface_type type)
{
        struct pci_epf_bar *epf_bar;
        dma_addr_t phys_addr;
        struct pci_epc *epc;
        struct device *dev;
        void *space;

        if (size < 128)
                size = 128;

        if (align)
                size = ALIGN(size, align);
        else
                size = roundup_pow_of_two(size);

        if (type == PRIMARY_INTERFACE) {
                epc = epf->epc;
                epf_bar = epf->bar;
        } else {
                epc = epf->sec_epc;
                epf_bar = epf->sec_epc_bar;
        }

        dev = epc->dev.parent;
        space = dma_alloc_coherent(dev, size, &phys_addr, GFP_KERNEL);
        if (!space) {
                dev_err(dev, "failed to allocate mem space\n");
                return NULL;
        }

        epf_bar[bar].phys_addr = phys_addr;
        epf_bar[bar].addr = space;
        epf_bar[bar].size = size;
        epf_bar[bar].barno = bar;
        epf_bar[bar].flags |= upper_32_bits(size) ?
                                PCI_BASE_ADDRESS_MEM_TYPE_64 :
                                PCI_BASE_ADDRESS_MEM_TYPE_32;

        return space;
}
EXPORT_SYMBOL_GPL(pci_epf_alloc_space);

static void pci_epf_remove_cfs(struct pci_epf_driver *driver)
{
        struct config_group *group, *tmp;

        if (!IS_ENABLED(CONFIG_PCI_ENDPOINT_CONFIGFS))
                return;

        mutex_lock(&pci_epf_mutex);
        list_for_each_entry_safe(group, tmp, &driver->epf_group, group_entry)
                pci_ep_cfs_remove_epf_group(group);
        list_del(&driver->epf_group);
        mutex_unlock(&pci_epf_mutex);
}

/**
 * pci_epf_unregister_driver() - unregister the PCI EPF driver
 * @driver: the PCI EPF driver that has to be unregistered
 *
 * Invoke to unregister the PCI EPF driver.
 */
void pci_epf_unregister_driver(struct pci_epf_driver *driver)
{
        pci_epf_remove_cfs(driver);
        driver_unregister(&driver->driver);
}
EXPORT_SYMBOL_GPL(pci_epf_unregister_driver);

static int pci_epf_add_cfs(struct pci_epf_driver *driver)
{
        struct config_group *group;
        const struct pci_epf_device_id *id;

        if (!IS_ENABLED(CONFIG_PCI_ENDPOINT_CONFIGFS))
                return 0;

        INIT_LIST_HEAD(&driver->epf_group);

        id = driver->id_table;
        while (id->name[0]) {
                group = pci_ep_cfs_add_epf_group(id->name);
                if (IS_ERR(group)) {
                        pci_epf_remove_cfs(driver);
                        return PTR_ERR(group);
                }

                mutex_lock(&pci_epf_mutex);
                list_add_tail(&group->group_entry, &driver->epf_group);
                mutex_unlock(&pci_epf_mutex);
                id++;
        }

        return 0;
}

/**
 * __pci_epf_register_driver() - register a new PCI EPF driver
 * @driver: structure representing PCI EPF driver
 * @owner: the owner of the module that registers the PCI EPF driver
 *
 * Invoke to register a new PCI EPF driver.
 */
int __pci_epf_register_driver(struct pci_epf_driver *driver,
                              struct module *owner)
{
        int ret;

        if (!driver->ops)
                return -EINVAL;

        if (!driver->ops->bind || !driver->ops->unbind)
                return -EINVAL;

        driver->driver.bus = &pci_epf_bus_type;
        driver->driver.owner = owner;

        ret = driver_register(&driver->driver);
        if (ret)
                return ret;

        pci_epf_add_cfs(driver);

        return 0;
}
EXPORT_SYMBOL_GPL(__pci_epf_register_driver);

/**
 * pci_epf_destroy() - destroy the created PCI EPF device
 * @epf: the PCI EPF device that has to be destroyed.
 *
 * Invoke to destroy the PCI EPF device created by invoking pci_epf_create().
 */
void pci_epf_destroy(struct pci_epf *epf)
{
        device_unregister(&epf->dev);
}
EXPORT_SYMBOL_GPL(pci_epf_destroy);

/**
 * pci_epf_create() - create a new PCI EPF device
 * @name: the name of the PCI EPF device. This name will be used to bind the
 *        the EPF device to a EPF driver
 *
 * Invoke to create a new PCI EPF device by providing the name of the function
 * device.
 */
struct pci_epf *pci_epf_create(const char *name)
{
        int ret;
        struct pci_epf *epf;
        struct device *dev;
        int len;

        epf = kzalloc(sizeof(*epf), GFP_KERNEL);
        if (!epf)
                return ERR_PTR(-ENOMEM);

        len = strchrnul(name, '.') - name;
        epf->name = kstrndup(name, len, GFP_KERNEL);
        if (!epf->name) {
                kfree(epf);
                return ERR_PTR(-ENOMEM);
        }

        /* VFs are numbered starting with 1. So set BIT(0) by default */
        epf->vfunction_num_map = 1;
        INIT_LIST_HEAD(&epf->pci_vepf);

        dev = &epf->dev;
        device_initialize(dev);
        dev->bus = &pci_epf_bus_type;
        dev->type = &pci_epf_type;
        mutex_init(&epf->lock);

        ret = dev_set_name(dev, "%s", name);
        if (ret) {
                put_device(dev);
                return ERR_PTR(ret);
        }

        ret = device_add(dev);
        if (ret) {
                put_device(dev);
                return ERR_PTR(ret);
        }

        return epf;
}
EXPORT_SYMBOL_GPL(pci_epf_create);

static void pci_epf_dev_release(struct device *dev)
{
        struct pci_epf *epf = to_pci_epf(dev);

        kfree(epf->name);
        kfree(epf);
}

static const struct device_type pci_epf_type = {
        .release        = pci_epf_dev_release,
};

static int
pci_epf_match_id(const struct pci_epf_device_id *id, const struct pci_epf *epf)
{
        while (id->name[0]) {
                if (strcmp(epf->name, id->name) == 0)
                        return true;
                id++;
        }

        return false;
}

static int pci_epf_device_match(struct device *dev, struct device_driver *drv)
{
        struct pci_epf *epf = to_pci_epf(dev);
        struct pci_epf_driver *driver = to_pci_epf_driver(drv);

        if (driver->id_table)
                return pci_epf_match_id(driver->id_table, epf);

        return !strcmp(epf->name, drv->name);
}

static int pci_epf_device_probe(struct device *dev)
{
        struct pci_epf *epf = to_pci_epf(dev);
        struct pci_epf_driver *driver = to_pci_epf_driver(dev->driver);

        if (!driver->probe)
                return -ENODEV;

        epf->driver = driver;

        return driver->probe(epf);
}

static void pci_epf_device_remove(struct device *dev)
{
        struct pci_epf *epf = to_pci_epf(dev);
        struct pci_epf_driver *driver = to_pci_epf_driver(dev->driver);

        if (driver->remove)
                driver->remove(epf);
        epf->driver = NULL;
}

static struct bus_type pci_epf_bus_type = {
        .name           = "pci-epf",
        .match          = pci_epf_device_match,
        .probe          = pci_epf_device_probe,
        .remove         = pci_epf_device_remove,
};

static int __init pci_epf_init(void)
{
        int ret;

        ret = bus_register(&pci_epf_bus_type);
        if (ret) {
                pr_err("failed to register pci epf bus --> %d\n", ret);
                return ret;
        }

        return 0;
}
module_init(pci_epf_init);

static void __exit pci_epf_exit(void)
{
        bus_unregister(&pci_epf_bus_type);
}
module_exit(pci_epf_exit);

MODULE_DESCRIPTION("PCI EPF Library");
MODULE_AUTHOR("Kishon Vijay Abraham I <kishon@ti.com>");
MODULE_LICENSE("GPL v2");