/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2014 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 * Intel MIC Bus driver.
 *
 * This implementation is very similar to the the virtio bus driver
 * implementation @ drivers/virtio/virtio.c
 */
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/mic_bus.h>

/* Unique numbering for mbus devices. */
static DEFINE_IDA(mbus_index_ida);

static ssize_t device_show(struct device *d,
                           struct device_attribute *attr, char *buf)
{
        struct mbus_device *dev = dev_to_mbus(d);
        return sprintf(buf, "0x%04x\n", dev->id.device);
}
static DEVICE_ATTR_RO(device);

static ssize_t vendor_show(struct device *d,
                           struct device_attribute *attr, char *buf)
{
        struct mbus_device *dev = dev_to_mbus(d);
        return sprintf(buf, "0x%04x\n", dev->id.vendor);
}
static DEVICE_ATTR_RO(vendor);

static ssize_t modalias_show(struct device *d,
                             struct device_attribute *attr, char *buf)
{
        struct mbus_device *dev = dev_to_mbus(d);
        return sprintf(buf, "mbus:d%08Xv%08X\n",
                       dev->id.device, dev->id.vendor);
}
static DEVICE_ATTR_RO(modalias);

static struct attribute *mbus_dev_attrs[] = {
        &dev_attr_device.attr,
        &dev_attr_vendor.attr,
        &dev_attr_modalias.attr,
        NULL,
};
ATTRIBUTE_GROUPS(mbus_dev);

static inline int mbus_id_match(const struct mbus_device *dev,
                                const struct mbus_device_id *id)
{
        if (id->device != dev->id.device && id->device != MBUS_DEV_ANY_ID)
                return 0;

        return id->vendor == MBUS_DEV_ANY_ID || id->vendor == dev->id.vendor;
}

/*
 * This looks through all the IDs a driver claims to support.  If any of them
 * match, we return 1 and the kernel will call mbus_dev_probe().
 */
static int mbus_dev_match(struct device *dv, struct device_driver *dr)
{
        unsigned int i;
        struct mbus_device *dev = dev_to_mbus(dv);
        const struct mbus_device_id *ids;

        ids = drv_to_mbus(dr)->id_table;
        for (i = 0; ids[i].device; i++)
                if (mbus_id_match(dev, &ids[i]))
                        return 1;
        return 0;
}

static int mbus_uevent(struct device *dv, struct kobj_uevent_env *env)
{
        struct mbus_device *dev = dev_to_mbus(dv);

        return add_uevent_var(env, "MODALIAS=mbus:d%08Xv%08X",
                              dev->id.device, dev->id.vendor);
}

static int mbus_dev_probe(struct device *d)
{
        int err;
        struct mbus_device *dev = dev_to_mbus(d);
        struct mbus_driver *drv = drv_to_mbus(dev->dev.driver);

        err = drv->probe(dev);
        if (!err)
                if (drv->scan)
                        drv->scan(dev);
        return err;
}

static int mbus_dev_remove(struct device *d)
{
        struct mbus_device *dev = dev_to_mbus(d);
        struct mbus_driver *drv = drv_to_mbus(dev->dev.driver);

        drv->remove(dev);
        return 0;
}

static struct bus_type mic_bus = {
        .name  = "mic_bus",
        .match = mbus_dev_match,
        .dev_groups = mbus_dev_groups,
        .uevent = mbus_uevent,
        .probe = mbus_dev_probe,
        .remove = mbus_dev_remove,
};

int mbus_register_driver(struct mbus_driver *driver)
{
        driver->driver.bus = &mic_bus;
        return driver_register(&driver->driver);
}
EXPORT_SYMBOL_GPL(mbus_register_driver);

void mbus_unregister_driver(struct mbus_driver *driver)
{
        driver_unregister(&driver->driver);
}
EXPORT_SYMBOL_GPL(mbus_unregister_driver);

static void mbus_release_dev(struct device *d)
{
        struct mbus_device *mbdev = dev_to_mbus(d);
        kfree(mbdev);
}

struct mbus_device *
mbus_register_device(struct device *pdev, int id, struct dma_map_ops *dma_ops,
                     struct mbus_hw_ops *hw_ops, void __iomem *mmio_va)
{
        int ret;
        struct mbus_device *mbdev;

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

        mbdev->mmio_va = mmio_va;
        mbdev->dev.parent = pdev;
        mbdev->id.device = id;
        mbdev->id.vendor = MBUS_DEV_ANY_ID;
        mbdev->dev.archdata.dma_ops = dma_ops;
        mbdev->dev.dma_mask = &mbdev->dev.coherent_dma_mask;
        dma_set_mask(&mbdev->dev, DMA_BIT_MASK(64));
        mbdev->dev.release = mbus_release_dev;
        mbdev->hw_ops = hw_ops;
        mbdev->dev.bus = &mic_bus;

        /* Assign a unique device index and hence name. */
        ret = ida_simple_get(&mbus_index_ida, 0, 0, GFP_KERNEL);
        if (ret < 0)
                goto free_mbdev;

        mbdev->index = ret;
        dev_set_name(&mbdev->dev, "mbus-dev%u", mbdev->index);
        /*
         * device_register() causes the bus infrastructure to look for a
         * matching driver.
         */
        ret = device_register(&mbdev->dev);
        if (ret)
                goto ida_remove;
        return mbdev;
ida_remove:
        ida_simple_remove(&mbus_index_ida, mbdev->index);
free_mbdev:
        kfree(mbdev);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(mbus_register_device);

void mbus_unregister_device(struct mbus_device *mbdev)
{
        int index = mbdev->index; /* save for after device release */

        device_unregister(&mbdev->dev);
        ida_simple_remove(&mbus_index_ida, index);
}
EXPORT_SYMBOL_GPL(mbus_unregister_device);

static int __init mbus_init(void)
{
        return bus_register(&mic_bus);
}

static void __exit mbus_exit(void)
{
        bus_unregister(&mic_bus);
        ida_destroy(&mbus_index_ida);
}

core_initcall(mbus_init);
module_exit(mbus_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Intel(R) MIC Bus driver");
MODULE_LICENSE("GPL v2");