// SPDX-License-Identifier: GPL-2.0-only
/*
 * MEN Chameleon Bus.
 *
 * Copyright (C) 2013 MEN Mikroelektronik GmbH (www.men.de)
 * Author: Johannes Thumshirn <johannes.thumshirn@men.de>
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/idr.h>
#include <linux/mcb.h>

static DEFINE_IDA(mcb_ida);

static const struct mcb_device_id *mcb_match_id(const struct mcb_device_id *ids,
                                                struct mcb_device *dev)
{
        if (ids) {
                while (ids->device) {
                        if (ids->device == dev->id)
                                return ids;
                        ids++;
                }
        }

        return NULL;
}

static int mcb_match(struct device *dev, struct device_driver *drv)
{
        struct mcb_driver *mdrv = to_mcb_driver(drv);
        struct mcb_device *mdev = to_mcb_device(dev);
        const struct mcb_device_id *found_id;

        found_id = mcb_match_id(mdrv->id_table, mdev);
        if (found_id)
                return 1;

        return 0;
}

static int mcb_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct mcb_device *mdev = to_mcb_device(dev);
        int ret;

        ret = add_uevent_var(env, "MODALIAS=mcb:16z%03d", mdev->id);
        if (ret)
                return -ENOMEM;

        return 0;
}

static int mcb_probe(struct device *dev)
{
        struct mcb_driver *mdrv = to_mcb_driver(dev->driver);
        struct mcb_device *mdev = to_mcb_device(dev);
        const struct mcb_device_id *found_id;
        struct module *carrier_mod;
        int ret;

        found_id = mcb_match_id(mdrv->id_table, mdev);
        if (!found_id)
                return -ENODEV;

        carrier_mod = mdev->dev.parent->driver->owner;
        if (!try_module_get(carrier_mod))
                return -EINVAL;

        get_device(dev);
        ret = mdrv->probe(mdev, found_id);
        if (ret)
                module_put(carrier_mod);

        return ret;
}

static void mcb_remove(struct device *dev)
{
        struct mcb_driver *mdrv = to_mcb_driver(dev->driver);
        struct mcb_device *mdev = to_mcb_device(dev);
        struct module *carrier_mod;

        mdrv->remove(mdev);

        carrier_mod = mdev->dev.parent->driver->owner;
        module_put(carrier_mod);

        put_device(&mdev->dev);
}

static void mcb_shutdown(struct device *dev)
{
        struct mcb_driver *mdrv = to_mcb_driver(dev->driver);
        struct mcb_device *mdev = to_mcb_device(dev);

        if (mdrv && mdrv->shutdown)
                mdrv->shutdown(mdev);
}

static ssize_t revision_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct mcb_bus *bus = to_mcb_bus(dev);

        return scnprintf(buf, PAGE_SIZE, "%d\n", bus->revision);
}
static DEVICE_ATTR_RO(revision);

static ssize_t model_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct mcb_bus *bus = to_mcb_bus(dev);

        return scnprintf(buf, PAGE_SIZE, "%c\n", bus->model);
}
static DEVICE_ATTR_RO(model);

static ssize_t minor_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct mcb_bus *bus = to_mcb_bus(dev);

        return scnprintf(buf, PAGE_SIZE, "%d\n", bus->minor);
}
static DEVICE_ATTR_RO(minor);

static ssize_t name_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct mcb_bus *bus = to_mcb_bus(dev);

        return scnprintf(buf, PAGE_SIZE, "%s\n", bus->name);
}
static DEVICE_ATTR_RO(name);

static struct attribute *mcb_bus_attrs[] = {
        &dev_attr_revision.attr,
        &dev_attr_model.attr,
        &dev_attr_minor.attr,
        &dev_attr_name.attr,
        NULL,
};

static const struct attribute_group mcb_carrier_group = {
        .attrs = mcb_bus_attrs,
};

static const struct attribute_group *mcb_carrier_groups[] = {
        &mcb_carrier_group,
        NULL,
};


static struct bus_type mcb_bus_type = {
        .name = "mcb",
        .match = mcb_match,
        .uevent = mcb_uevent,
        .probe = mcb_probe,
        .remove = mcb_remove,
        .shutdown = mcb_shutdown,
};

static struct device_type mcb_carrier_device_type = {
        .name = "mcb-carrier",
        .groups = mcb_carrier_groups,
};

/**
 * __mcb_register_driver() - Register a @mcb_driver at the system
 * @drv: The @mcb_driver
 * @owner: The @mcb_driver's module
 * @mod_name: The name of the @mcb_driver's module
 *
 * Register a @mcb_driver at the system. Perform some sanity checks, if
 * the .probe and .remove methods are provided by the driver.
 */
int __mcb_register_driver(struct mcb_driver *drv, struct module *owner,
                        const char *mod_name)
{
        if (!drv->probe || !drv->remove)
                return -EINVAL;

        drv->driver.owner = owner;
        drv->driver.bus = &mcb_bus_type;
        drv->driver.mod_name = mod_name;

        return driver_register(&drv->driver);
}
EXPORT_SYMBOL_NS_GPL(__mcb_register_driver, MCB);

/**
 * mcb_unregister_driver() - Unregister a @mcb_driver from the system
 * @drv: The @mcb_driver
 *
 * Unregister a @mcb_driver from the system.
 */
void mcb_unregister_driver(struct mcb_driver *drv)
{
        driver_unregister(&drv->driver);
}
EXPORT_SYMBOL_NS_GPL(mcb_unregister_driver, MCB);

static void mcb_release_dev(struct device *dev)
{
        struct mcb_device *mdev = to_mcb_device(dev);

        mcb_bus_put(mdev->bus);
        kfree(mdev);
}

/**
 * mcb_device_register() - Register a mcb_device
 * @bus: The @mcb_bus of the device
 * @dev: The @mcb_device
 *
 * Register a specific @mcb_device at a @mcb_bus and the system itself.
 */
int mcb_device_register(struct mcb_bus *bus, struct mcb_device *dev)
{
        int ret;
        int device_id;

        device_initialize(&dev->dev);
        mcb_bus_get(bus);
        dev->dev.bus = &mcb_bus_type;
        dev->dev.parent = bus->dev.parent;
        dev->dev.release = mcb_release_dev;
        dev->dma_dev = bus->carrier;

        device_id = dev->id;
        dev_set_name(&dev->dev, "mcb%d-16z%03d-%d:%d:%d",
                bus->bus_nr, device_id, dev->inst, dev->group, dev->var);

        ret = device_add(&dev->dev);
        if (ret < 0) {
                pr_err("Failed registering device 16z%03d on bus mcb%d (%d)\n",
                        device_id, bus->bus_nr, ret);
                goto out;
        }

        return 0;

out:

        return ret;
}
EXPORT_SYMBOL_NS_GPL(mcb_device_register, MCB);

static void mcb_free_bus(struct device *dev)
{
        struct mcb_bus *bus = to_mcb_bus(dev);

        put_device(bus->carrier);
        ida_simple_remove(&mcb_ida, bus->bus_nr);
        kfree(bus);
}

/**
 * mcb_alloc_bus() - Allocate a new @mcb_bus
 *
 * Allocate a new @mcb_bus.
 */
struct mcb_bus *mcb_alloc_bus(struct device *carrier)
{
        struct mcb_bus *bus;
        int bus_nr;
        int rc;

        bus = kzalloc(sizeof(struct mcb_bus), GFP_KERNEL);
        if (!bus)
                return ERR_PTR(-ENOMEM);

        bus_nr = ida_simple_get(&mcb_ida, 0, 0, GFP_KERNEL);
        if (bus_nr < 0) {
                kfree(bus);
                return ERR_PTR(bus_nr);
        }

        bus->bus_nr = bus_nr;
        bus->carrier = get_device(carrier);

        device_initialize(&bus->dev);
        bus->dev.parent = carrier;
        bus->dev.bus = &mcb_bus_type;
        bus->dev.type = &mcb_carrier_device_type;
        bus->dev.release = &mcb_free_bus;

        dev_set_name(&bus->dev, "mcb:%d", bus_nr);
        rc = device_add(&bus->dev);
        if (rc)
                goto err_put;

        return bus;

err_put:
        put_device(&bus->dev);
        return ERR_PTR(rc);
}
EXPORT_SYMBOL_NS_GPL(mcb_alloc_bus, MCB);

static int __mcb_devices_unregister(struct device *dev, void *data)
{
        device_unregister(dev);
        return 0;
}

static void mcb_devices_unregister(struct mcb_bus *bus)
{
        bus_for_each_dev(&mcb_bus_type, NULL, NULL, __mcb_devices_unregister);
}
/**
 * mcb_release_bus() - Free a @mcb_bus
 * @bus: The @mcb_bus to release
 *
 * Release an allocated @mcb_bus from the system.
 */
void mcb_release_bus(struct mcb_bus *bus)
{
        mcb_devices_unregister(bus);
}
EXPORT_SYMBOL_NS_GPL(mcb_release_bus, MCB);

/**
 * mcb_bus_put() - Increment refcnt
 * @bus: The @mcb_bus
 *
 * Get a @mcb_bus' ref
 */
struct mcb_bus *mcb_bus_get(struct mcb_bus *bus)
{
        if (bus)
                get_device(&bus->dev);

        return bus;
}
EXPORT_SYMBOL_NS_GPL(mcb_bus_get, MCB);

/**
 * mcb_bus_put() - Decrement refcnt
 * @bus: The @mcb_bus
 *
 * Release a @mcb_bus' ref
 */
void mcb_bus_put(struct mcb_bus *bus)
{
        if (bus)
                put_device(&bus->dev);
}
EXPORT_SYMBOL_NS_GPL(mcb_bus_put, MCB);

/**
 * mcb_alloc_dev() - Allocate a device
 * @bus: The @mcb_bus the device is part of
 *
 * Allocate a @mcb_device and add bus.
 */
struct mcb_device *mcb_alloc_dev(struct mcb_bus *bus)
{
        struct mcb_device *dev;

        dev = kzalloc(sizeof(struct mcb_device), GFP_KERNEL);
        if (!dev)
                return NULL;

        dev->bus = bus;

        return dev;
}
EXPORT_SYMBOL_NS_GPL(mcb_alloc_dev, MCB);

/**
 * mcb_free_dev() - Free @mcb_device
 * @dev: The device to free
 *
 * Free a @mcb_device
 */
void mcb_free_dev(struct mcb_device *dev)
{
        kfree(dev);
}
EXPORT_SYMBOL_NS_GPL(mcb_free_dev, MCB);

static int __mcb_bus_add_devices(struct device *dev, void *data)
{
        struct mcb_device *mdev = to_mcb_device(dev);
        int retval;

        if (mdev->is_added)
                return 0;

        retval = device_attach(dev);
        if (retval < 0)
                dev_err(dev, "Error adding device (%d)\n", retval);

        mdev->is_added = true;

        return 0;
}

/**
 * mcb_bus_add_devices() - Add devices in the bus' internal device list
 * @bus: The @mcb_bus we add the devices
 *
 * Add devices in the bus' internal device list to the system.
 */
void mcb_bus_add_devices(const struct mcb_bus *bus)
{
        bus_for_each_dev(&mcb_bus_type, NULL, NULL, __mcb_bus_add_devices);
}
EXPORT_SYMBOL_NS_GPL(mcb_bus_add_devices, MCB);

/**
 * mcb_get_resource() - get a resource for a mcb device
 * @dev: the mcb device
 * @type: the type of resource
 */
struct resource *mcb_get_resource(struct mcb_device *dev, unsigned int type)
{
        if (type == IORESOURCE_MEM)
                return &dev->mem;
        else if (type == IORESOURCE_IRQ)
                return &dev->irq;
        else
                return NULL;
}
EXPORT_SYMBOL_NS_GPL(mcb_get_resource, MCB);

/**
 * mcb_request_mem() - Request memory
 * @dev: The @mcb_device the memory is for
 * @name: The name for the memory reference.
 *
 * Request memory for a @mcb_device. If @name is NULL the driver name will
 * be used.
 */
struct resource *mcb_request_mem(struct mcb_device *dev, const char *name)
{
        struct resource *mem;
        u32 size;

        if (!name)
                name = dev->dev.driver->name;

        size = resource_size(&dev->mem);

        mem = request_mem_region(dev->mem.start, size, name);
        if (!mem)
                return ERR_PTR(-EBUSY);

        return mem;
}
EXPORT_SYMBOL_NS_GPL(mcb_request_mem, MCB);

/**
 * mcb_release_mem() - Release memory requested by device
 * @dev: The @mcb_device that requested the memory
 *
 * Release memory that was prior requested via @mcb_request_mem().
 */
void mcb_release_mem(struct resource *mem)
{
        u32 size;

        size = resource_size(mem);
        release_mem_region(mem->start, size);
}
EXPORT_SYMBOL_NS_GPL(mcb_release_mem, MCB);

static int __mcb_get_irq(struct mcb_device *dev)
{
        struct resource *irq;

        irq = mcb_get_resource(dev, IORESOURCE_IRQ);

        return irq->start;
}

/**
 * mcb_get_irq() - Get device's IRQ number
 * @dev: The @mcb_device the IRQ is for
 *
 * Get the IRQ number of a given @mcb_device.
 */
int mcb_get_irq(struct mcb_device *dev)
{
        struct mcb_bus *bus = dev->bus;

        if (bus->get_irq)
                return bus->get_irq(dev);

        return __mcb_get_irq(dev);
}
EXPORT_SYMBOL_NS_GPL(mcb_get_irq, MCB);

static int mcb_init(void)
{
        return bus_register(&mcb_bus_type);
}

static void mcb_exit(void)
{
        ida_destroy(&mcb_ida);
        bus_unregister(&mcb_bus_type);
}

/* mcb must be initialized after PCI but before the chameleon drivers.
 * That means we must use some initcall between subsys_initcall and
 * device_initcall.
 */
fs_initcall(mcb_init);
module_exit(mcb_exit);

MODULE_DESCRIPTION("MEN Chameleon Bus Driver");
MODULE_AUTHOR("Johannes Thumshirn <johannes.thumshirn@men.de>");
MODULE_LICENSE("GPL v2");