// SPDX-License-Identifier: GPL-2.0
/*
 * FPGA Bridge Framework Driver
 *
 *  Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
 *  Copyright (C) 2017 Intel Corporation
 */
#include <linux/fpga/fpga-bridge.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

/* For enabling manual bridge set(enable/disable) function */
#ifdef CONFIG_DEBUG_KERNEL
#undef DEBUG
#define DEBUG
#endif

static DEFINE_IDA(fpga_bridge_ida);
static struct class *fpga_bridge_class;

/* Lock for adding/removing bridges to linked lists*/
static spinlock_t bridge_list_lock;

/**
 * fpga_bridge_enable - Enable transactions on the bridge
 *
 * @bridge: FPGA bridge
 *
 * Return: 0 for success, error code otherwise.
 */
int fpga_bridge_enable(struct fpga_bridge *bridge)
{
        dev_dbg(&bridge->dev, "enable\n");

        if (bridge->br_ops && bridge->br_ops->enable_set)
                return bridge->br_ops->enable_set(bridge, 1);

        return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_enable);

/**
 * fpga_bridge_disable - Disable transactions on the bridge
 *
 * @bridge: FPGA bridge
 *
 * Return: 0 for success, error code otherwise.
 */
int fpga_bridge_disable(struct fpga_bridge *bridge)
{
        dev_dbg(&bridge->dev, "disable\n");

        if (bridge->br_ops && bridge->br_ops->enable_set)
                return bridge->br_ops->enable_set(bridge, 0);

        return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_disable);

static struct fpga_bridge *__fpga_bridge_get(struct device *dev,
                                             struct fpga_image_info *info)
{
        struct fpga_bridge *bridge;
        int ret = -ENODEV;

        bridge = to_fpga_bridge(dev);

        bridge->info = info;

        if (!mutex_trylock(&bridge->mutex)) {
                ret = -EBUSY;
                goto err_dev;
        }

        if (!try_module_get(dev->parent->driver->owner))
                goto err_ll_mod;

        dev_dbg(&bridge->dev, "get\n");

        return bridge;

err_ll_mod:
        mutex_unlock(&bridge->mutex);
err_dev:
        put_device(dev);
        return ERR_PTR(ret);
}

/**
 * of_fpga_bridge_get - get an exclusive reference to a fpga bridge
 *
 * @np: node pointer of a FPGA bridge
 * @info: fpga image specific information
 *
 * Return fpga_bridge struct if successful.
 * Return -EBUSY if someone already has a reference to the bridge.
 * Return -ENODEV if @np is not a FPGA Bridge.
 */
struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
                                       struct fpga_image_info *info)
{
        struct device *dev;

        dev = class_find_device_by_of_node(fpga_bridge_class, np);
        if (!dev)
                return ERR_PTR(-ENODEV);

        return __fpga_bridge_get(dev, info);
}
EXPORT_SYMBOL_GPL(of_fpga_bridge_get);

static int fpga_bridge_dev_match(struct device *dev, const void *data)
{
        return dev->parent == data;
}

/**
 * fpga_bridge_get - get an exclusive reference to a fpga bridge
 * @dev:        parent device that fpga bridge was registered with
 * @info:       fpga manager info
 *
 * Given a device, get an exclusive reference to a fpga bridge.
 *
 * Return: fpga bridge struct or IS_ERR() condition containing error code.
 */
struct fpga_bridge *fpga_bridge_get(struct device *dev,
                                    struct fpga_image_info *info)
{
        struct device *bridge_dev;

        bridge_dev = class_find_device(fpga_bridge_class, NULL, dev,
                                       fpga_bridge_dev_match);
        if (!bridge_dev)
                return ERR_PTR(-ENODEV);

        return __fpga_bridge_get(bridge_dev, info);
}
EXPORT_SYMBOL_GPL(fpga_bridge_get);

/**
 * fpga_bridge_put - release a reference to a bridge
 *
 * @bridge: FPGA bridge
 */
void fpga_bridge_put(struct fpga_bridge *bridge)
{
        dev_dbg(&bridge->dev, "put\n");

        bridge->info = NULL;
        module_put(bridge->dev.parent->driver->owner);
        mutex_unlock(&bridge->mutex);
        put_device(&bridge->dev);
}
EXPORT_SYMBOL_GPL(fpga_bridge_put);

/**
 * fpga_bridges_enable - enable bridges in a list
 * @bridge_list: list of FPGA bridges
 *
 * Enable each bridge in the list.  If list is empty, do nothing.
 *
 * Return 0 for success or empty bridge list; return error code otherwise.
 */
int fpga_bridges_enable(struct list_head *bridge_list)
{
        struct fpga_bridge *bridge;
        int ret;

        list_for_each_entry(bridge, bridge_list, node) {
                ret = fpga_bridge_enable(bridge);
                if (ret)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridges_enable);

/**
 * fpga_bridges_disable - disable bridges in a list
 *
 * @bridge_list: list of FPGA bridges
 *
 * Disable each bridge in the list.  If list is empty, do nothing.
 *
 * Return 0 for success or empty bridge list; return error code otherwise.
 */
int fpga_bridges_disable(struct list_head *bridge_list)
{
        struct fpga_bridge *bridge;
        int ret;

        list_for_each_entry(bridge, bridge_list, node) {
                ret = fpga_bridge_disable(bridge);
                if (ret)
                        return ret;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridges_disable);

/**
 * fpga_bridges_put - put bridges
 *
 * @bridge_list: list of FPGA bridges
 *
 * For each bridge in the list, put the bridge and remove it from the list.
 * If list is empty, do nothing.
 */
void fpga_bridges_put(struct list_head *bridge_list)
{
        struct fpga_bridge *bridge, *next;
        unsigned long flags;

        list_for_each_entry_safe(bridge, next, bridge_list, node) {
                fpga_bridge_put(bridge);

                spin_lock_irqsave(&bridge_list_lock, flags);
                list_del(&bridge->node);
                spin_unlock_irqrestore(&bridge_list_lock, flags);
        }
}
EXPORT_SYMBOL_GPL(fpga_bridges_put);

/**
 * of_fpga_bridge_get_to_list - get a bridge, add it to a list
 *
 * @np: node pointer of a FPGA bridge
 * @info: fpga image specific information
 * @bridge_list: list of FPGA bridges
 *
 * Get an exclusive reference to the bridge and and it to the list.
 *
 * Return 0 for success, error code from of_fpga_bridge_get() othewise.
 */
int of_fpga_bridge_get_to_list(struct device_node *np,
                               struct fpga_image_info *info,
                               struct list_head *bridge_list)
{
        struct fpga_bridge *bridge;
        unsigned long flags;

        bridge = of_fpga_bridge_get(np, info);
        if (IS_ERR(bridge))
                return PTR_ERR(bridge);

        spin_lock_irqsave(&bridge_list_lock, flags);
        list_add(&bridge->node, bridge_list);
        spin_unlock_irqrestore(&bridge_list_lock, flags);

        return 0;
}
EXPORT_SYMBOL_GPL(of_fpga_bridge_get_to_list);

/**
 * fpga_bridge_get_to_list - given device, get a bridge, add it to a list
 *
 * @dev: FPGA bridge device
 * @info: fpga image specific information
 * @bridge_list: list of FPGA bridges
 *
 * Get an exclusive reference to the bridge and and it to the list.
 *
 * Return 0 for success, error code from fpga_bridge_get() othewise.
 */
int fpga_bridge_get_to_list(struct device *dev,
                            struct fpga_image_info *info,
                            struct list_head *bridge_list)
{
        struct fpga_bridge *bridge;
        unsigned long flags;

        bridge = fpga_bridge_get(dev, info);
        if (IS_ERR(bridge))
                return PTR_ERR(bridge);

        spin_lock_irqsave(&bridge_list_lock, flags);
        list_add(&bridge->node, bridge_list);
        spin_unlock_irqrestore(&bridge_list_lock, flags);

        return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_get_to_list);

static ssize_t name_show(struct device *dev,
                         struct device_attribute *attr, char *buf)
{
        struct fpga_bridge *bridge = to_fpga_bridge(dev);

        return sprintf(buf, "%s\n", bridge->name);
}

static ssize_t state_show(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        struct fpga_bridge *bridge = to_fpga_bridge(dev);
        int enable = 1;

        if (bridge->br_ops && bridge->br_ops->enable_show)
                enable = bridge->br_ops->enable_show(bridge);

        return sprintf(buf, "%s\n", enable ? "enabled" : "disabled");
}

static DEVICE_ATTR_RO(name);
static DEVICE_ATTR_RO(state);

#ifdef DEBUG
static ssize_t set_store(struct device *dev,
                         struct device_attribute *attr,
                         const char *buf, size_t count)
{
        struct fpga_bridge *bridge = to_fpga_bridge(dev);
        long enable;
        int ret;

        ret = kstrtol(buf, 16, &enable);
        if (ret)
                return ret;

        if (bridge->br_ops && bridge->br_ops->enable_set)
                enable = bridge->br_ops->enable_set(bridge, !!enable);

        return count;
}
static DEVICE_ATTR_WO(set);
#endif

static struct attribute *fpga_bridge_attrs[] = {
        &dev_attr_name.attr,
        &dev_attr_state.attr,
#ifdef DEBUG
        &dev_attr_set.attr,
#endif
        NULL,
};
ATTRIBUTE_GROUPS(fpga_bridge);

/**
 * fpga_bridge_create - create and initialize a struct fpga_bridge
 * @dev:        FPGA bridge device from pdev
 * @name:       FPGA bridge name
 * @br_ops:     pointer to structure of fpga bridge ops
 * @priv:       FPGA bridge private data
 *
 * The caller of this function is responsible for freeing the bridge with
 * fpga_bridge_free().  Using devm_fpga_bridge_create() instead is recommended.
 *
 * Return: struct fpga_bridge or NULL
 */
struct fpga_bridge *fpga_bridge_create(struct device *dev, const char *name,
                                       const struct fpga_bridge_ops *br_ops,
                                       void *priv)
{
        struct fpga_bridge *bridge;
        int id, ret;

        if (!name || !strlen(name)) {
                dev_err(dev, "Attempt to register with no name!\n");
                return NULL;
        }

        bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
        if (!bridge)
                return NULL;

        id = ida_simple_get(&fpga_bridge_ida, 0, 0, GFP_KERNEL);
        if (id < 0)
                goto error_kfree;

        mutex_init(&bridge->mutex);
        INIT_LIST_HEAD(&bridge->node);

        bridge->name = name;
        bridge->br_ops = br_ops;
        bridge->priv = priv;

        device_initialize(&bridge->dev);
        bridge->dev.groups = br_ops->groups;
        bridge->dev.class = fpga_bridge_class;
        bridge->dev.parent = dev;
        bridge->dev.of_node = dev->of_node;
        bridge->dev.id = id;

        ret = dev_set_name(&bridge->dev, "br%d", id);
        if (ret)
                goto error_device;

        return bridge;

error_device:
        ida_simple_remove(&fpga_bridge_ida, id);
error_kfree:
        kfree(bridge);

        return NULL;
}
EXPORT_SYMBOL_GPL(fpga_bridge_create);

/**
 * fpga_bridge_free - free a fpga bridge created by fpga_bridge_create()
 * @bridge:     FPGA bridge struct
 */
void fpga_bridge_free(struct fpga_bridge *bridge)
{
        ida_simple_remove(&fpga_bridge_ida, bridge->dev.id);
        kfree(bridge);
}
EXPORT_SYMBOL_GPL(fpga_bridge_free);

static void devm_fpga_bridge_release(struct device *dev, void *res)
{
        struct fpga_bridge *bridge = *(struct fpga_bridge **)res;

        fpga_bridge_free(bridge);
}

/**
 * devm_fpga_bridge_create - create and init a managed struct fpga_bridge
 * @dev:        FPGA bridge device from pdev
 * @name:       FPGA bridge name
 * @br_ops:     pointer to structure of fpga bridge ops
 * @priv:       FPGA bridge private data
 *
 * This function is intended for use in a FPGA bridge driver's probe function.
 * After the bridge driver creates the struct with devm_fpga_bridge_create(), it
 * should register the bridge with fpga_bridge_register().  The bridge driver's
 * remove function should call fpga_bridge_unregister().  The bridge struct
 * allocated with this function will be freed automatically on driver detach.
 * This includes the case of a probe function returning error before calling
 * fpga_bridge_register(), the struct will still get cleaned up.
 *
 *  Return: struct fpga_bridge or NULL
 */
struct fpga_bridge
*devm_fpga_bridge_create(struct device *dev, const char *name,
                         const struct fpga_bridge_ops *br_ops, void *priv)
{
        struct fpga_bridge **ptr, *bridge;

        ptr = devres_alloc(devm_fpga_bridge_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return NULL;

        bridge = fpga_bridge_create(dev, name, br_ops, priv);
        if (!bridge) {
                devres_free(ptr);
        } else {
                *ptr = bridge;
                devres_add(dev, ptr);
        }

        return bridge;
}
EXPORT_SYMBOL_GPL(devm_fpga_bridge_create);

/**
 * fpga_bridge_register - register a FPGA bridge
 *
 * @bridge: FPGA bridge struct
 *
 * Return: 0 for success, error code otherwise.
 */
int fpga_bridge_register(struct fpga_bridge *bridge)
{
        struct device *dev = &bridge->dev;
        int ret;

        ret = device_add(dev);
        if (ret)
                return ret;

        of_platform_populate(dev->of_node, NULL, NULL, dev);

        dev_info(dev->parent, "fpga bridge [%s] registered\n", bridge->name);

        return 0;
}
EXPORT_SYMBOL_GPL(fpga_bridge_register);

/**
 * fpga_bridge_unregister - unregister a FPGA bridge
 *
 * @bridge: FPGA bridge struct
 *
 * This function is intended for use in a FPGA bridge driver's remove function.
 */
void fpga_bridge_unregister(struct fpga_bridge *bridge)
{
        /*
         * If the low level driver provides a method for putting bridge into
         * a desired state upon unregister, do it.
         */
        if (bridge->br_ops && bridge->br_ops->fpga_bridge_remove)
                bridge->br_ops->fpga_bridge_remove(bridge);

        device_unregister(&bridge->dev);
}
EXPORT_SYMBOL_GPL(fpga_bridge_unregister);

static void fpga_bridge_dev_release(struct device *dev)
{
}

static int __init fpga_bridge_dev_init(void)
{
        spin_lock_init(&bridge_list_lock);

        fpga_bridge_class = class_create(THIS_MODULE, "fpga_bridge");
        if (IS_ERR(fpga_bridge_class))
                return PTR_ERR(fpga_bridge_class);

        fpga_bridge_class->dev_groups = fpga_bridge_groups;
        fpga_bridge_class->dev_release = fpga_bridge_dev_release;

        return 0;
}

static void __exit fpga_bridge_dev_exit(void)
{
        class_destroy(fpga_bridge_class);
        ida_destroy(&fpga_bridge_ida);
}

MODULE_DESCRIPTION("FPGA Bridge Driver");
MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
MODULE_LICENSE("GPL v2");

subsys_initcall(fpga_bridge_dev_init);
module_exit(fpga_bridge_dev_exit);