// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2022, STMicroelectronics
 * Copyright (c) 2016, Linaro Ltd.
 * Copyright (c) 2012, Michal Simek <monstr@monstr.eu>
 * Copyright (c) 2012, PetaLogix
 * Copyright (c) 2011, Texas Instruments, Inc.
 * Copyright (c) 2011, Google, Inc.
 *
 * Based on rpmsg performance statistics driver by Michal Simek, which in turn
 * was based on TI & Google OMX rpmsg driver.
 */

#define pr_fmt(fmt)             KBUILD_MODNAME ": " fmt

#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rpmsg.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <uapi/linux/rpmsg.h>

#include "rpmsg_char.h"
#include "rpmsg_internal.h"

#define RPMSG_DEV_MAX   (MINORMASK + 1)

static dev_t rpmsg_major;

static DEFINE_IDA(rpmsg_ctrl_ida);
static DEFINE_IDA(rpmsg_minor_ida);

#define dev_to_ctrldev(dev) container_of(dev, struct rpmsg_ctrldev, dev)
#define cdev_to_ctrldev(i_cdev) container_of(i_cdev, struct rpmsg_ctrldev, cdev)

/**
 * struct rpmsg_ctrldev - control device for instantiating endpoint devices
 * @rpdev:      underlaying rpmsg device
 * @cdev:       cdev for the ctrl device
 * @dev:        device for the ctrl device
 * @ctrl_lock:  serialize the ioctrls.
 */
struct rpmsg_ctrldev {
        struct rpmsg_device *rpdev;
        struct cdev cdev;
        struct device dev;
        struct mutex ctrl_lock;
};

static int rpmsg_ctrldev_open(struct inode *inode, struct file *filp)
{
        struct rpmsg_ctrldev *ctrldev = cdev_to_ctrldev(inode->i_cdev);

        get_device(&ctrldev->dev);
        filp->private_data = ctrldev;

        return 0;
}

static int rpmsg_ctrldev_release(struct inode *inode, struct file *filp)
{
        struct rpmsg_ctrldev *ctrldev = cdev_to_ctrldev(inode->i_cdev);

        put_device(&ctrldev->dev);

        return 0;
}

static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
                                unsigned long arg)
{
        struct rpmsg_ctrldev *ctrldev = fp->private_data;
        void __user *argp = (void __user *)arg;
        struct rpmsg_endpoint_info eptinfo;
        struct rpmsg_channel_info chinfo;
        struct rpmsg_device *rpdev;
        int ret = 0;

        if (copy_from_user(&eptinfo, argp, sizeof(eptinfo)))
                return -EFAULT;

        memcpy(chinfo.name, eptinfo.name, RPMSG_NAME_SIZE);
        chinfo.name[RPMSG_NAME_SIZE - 1] = '\0';
        chinfo.src = eptinfo.src;
        chinfo.dst = eptinfo.dst;

        mutex_lock(&ctrldev->ctrl_lock);
        switch (cmd) {
        case RPMSG_CREATE_EPT_IOCTL:
                ret = rpmsg_chrdev_eptdev_create(ctrldev->rpdev, &ctrldev->dev, chinfo);
                break;

        case RPMSG_CREATE_DEV_IOCTL:
                rpdev = rpmsg_create_channel(ctrldev->rpdev, &chinfo);
                if (!rpdev) {
                        dev_err(&ctrldev->dev, "failed to create %s channel\n", chinfo.name);
                        ret = -ENXIO;
                }
                break;

        case RPMSG_RELEASE_DEV_IOCTL:
                ret = rpmsg_release_channel(ctrldev->rpdev, &chinfo);
                if (ret)
                        dev_err(&ctrldev->dev, "failed to release %s channel (%d)\n",
                                chinfo.name, ret);
                break;

        default:
                ret = -EINVAL;
        }
        mutex_unlock(&ctrldev->ctrl_lock);

        return ret;
};

static const struct file_operations rpmsg_ctrldev_fops = {
        .owner = THIS_MODULE,
        .open = rpmsg_ctrldev_open,
        .release = rpmsg_ctrldev_release,
        .unlocked_ioctl = rpmsg_ctrldev_ioctl,
        .compat_ioctl = compat_ptr_ioctl,
};

static void rpmsg_ctrldev_release_device(struct device *dev)
{
        struct rpmsg_ctrldev *ctrldev = dev_to_ctrldev(dev);

        ida_free(&rpmsg_ctrl_ida, dev->id);
        ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
        kfree(ctrldev);
}

static int rpmsg_ctrldev_probe(struct rpmsg_device *rpdev)
{
        struct rpmsg_ctrldev *ctrldev;
        struct device *dev;
        int ret;

        ctrldev = kzalloc_obj(*ctrldev);
        if (!ctrldev)
                return -ENOMEM;

        ctrldev->rpdev = rpdev;

        dev = &ctrldev->dev;
        device_initialize(dev);
        dev->parent = &rpdev->dev;
        dev->class = &rpmsg_class;

        mutex_init(&ctrldev->ctrl_lock);
        cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);
        ctrldev->cdev.owner = THIS_MODULE;

        ret = ida_alloc_max(&rpmsg_minor_ida, RPMSG_DEV_MAX - 1, GFP_KERNEL);
        if (ret < 0)
                goto free_ctrldev;
        dev->devt = MKDEV(MAJOR(rpmsg_major), ret);

        ret = ida_alloc(&rpmsg_ctrl_ida, GFP_KERNEL);
        if (ret < 0)
                goto free_minor_ida;
        dev->id = ret;
        dev_set_name(&ctrldev->dev, "rpmsg_ctrl%d", ret);

        ret = cdev_device_add(&ctrldev->cdev, &ctrldev->dev);
        if (ret)
                goto free_ctrl_ida;

        /* We can now rely on the release function for cleanup */
        dev->release = rpmsg_ctrldev_release_device;

        dev_set_drvdata(&rpdev->dev, ctrldev);

        return ret;

free_ctrl_ida:
        ida_free(&rpmsg_ctrl_ida, dev->id);
free_minor_ida:
        ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
free_ctrldev:
        put_device(dev);
        kfree(ctrldev);

        return ret;
}

static void rpmsg_ctrldev_remove(struct rpmsg_device *rpdev)
{
        struct rpmsg_ctrldev *ctrldev = dev_get_drvdata(&rpdev->dev);
        int ret;

        mutex_lock(&ctrldev->ctrl_lock);
        /* Destroy all endpoints */
        ret = device_for_each_child(&ctrldev->dev, NULL, rpmsg_chrdev_eptdev_destroy);
        if (ret)
                dev_warn(&rpdev->dev, "failed to nuke endpoints: %d\n", ret);
        mutex_unlock(&ctrldev->ctrl_lock);

        cdev_device_del(&ctrldev->cdev, &ctrldev->dev);
        put_device(&ctrldev->dev);
}

static struct rpmsg_driver rpmsg_ctrldev_driver = {
        .probe = rpmsg_ctrldev_probe,
        .remove = rpmsg_ctrldev_remove,
        .drv = {
                .name = "rpmsg_ctrl",
        },
};

static int rpmsg_ctrldev_init(void)
{
        int ret;

        ret = alloc_chrdev_region(&rpmsg_major, 0, RPMSG_DEV_MAX, "rpmsg_ctrl");
        if (ret < 0) {
                pr_err("failed to allocate char dev region\n");
                return ret;
        }

        ret = register_rpmsg_driver(&rpmsg_ctrldev_driver);
        if (ret < 0) {
                pr_err("failed to register rpmsg driver\n");
                unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
        }

        return ret;
}
postcore_initcall(rpmsg_ctrldev_init);

static void rpmsg_ctrldev_exit(void)
{
        unregister_rpmsg_driver(&rpmsg_ctrldev_driver);
        unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
}
module_exit(rpmsg_ctrldev_exit);

MODULE_DESCRIPTION("rpmsg control interface");
MODULE_ALIAS("rpmsg:" KBUILD_MODNAME);
MODULE_LICENSE("GPL v2");