// SPDX-License-Identifier: GPL-2.0-only
/*
 * adummy.c: a dummy ATM driver
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/byteorder.h>
#include <linux/uaccess.h>

#include <linux/atmdev.h>
#include <linux/atm.h>
#include <linux/sonet.h>

/* version definition */

#define DRV_VERSION "1.0"

#define DEV_LABEL "adummy"

#define ADUMMY_DEV(dev) ((struct adummy_dev *) (dev)->dev_data)

struct adummy_dev {
        struct atm_dev *atm_dev;

        struct list_head entry;
};

/* globals */

static LIST_HEAD(adummy_devs);

static ssize_t __set_signal(struct device *dev,
                struct device_attribute *attr,
                const char *buf, size_t len)
{
        struct atm_dev *atm_dev = container_of(dev, struct atm_dev, class_dev);
        int signal;

        if (sscanf(buf, "%d", &signal) == 1) {

                if (signal < ATM_PHY_SIG_LOST || signal > ATM_PHY_SIG_FOUND)
                        signal = ATM_PHY_SIG_UNKNOWN;

                atm_dev_signal_change(atm_dev, signal);
                return 1;
        }
        return -EINVAL;
}

static ssize_t __show_signal(struct device *dev,
        struct device_attribute *attr, char *buf)
{
        struct atm_dev *atm_dev = container_of(dev, struct atm_dev, class_dev);
        return sprintf(buf, "%d\n", atm_dev->signal);
}
static DEVICE_ATTR(signal, 0644, __show_signal, __set_signal);

static struct attribute *adummy_attrs[] = {
        &dev_attr_signal.attr,
        NULL
};

static const struct attribute_group adummy_group_attrs = {
        .name = NULL, /* We want them in dev's root folder */
        .attrs = adummy_attrs
};

static int __init
adummy_start(struct atm_dev *dev)
{
        dev->ci_range.vpi_bits = 4;
        dev->ci_range.vci_bits = 12;

        return 0;
}

static int
adummy_open(struct atm_vcc *vcc)
{
        short vpi = vcc->vpi;
        int vci = vcc->vci;

        if (vci == ATM_VCI_UNSPEC || vpi == ATM_VPI_UNSPEC)
                return 0;

        set_bit(ATM_VF_ADDR, &vcc->flags);
        set_bit(ATM_VF_READY, &vcc->flags);

        return 0;
}

static void
adummy_close(struct atm_vcc *vcc)
{
        clear_bit(ATM_VF_READY, &vcc->flags);
        clear_bit(ATM_VF_ADDR, &vcc->flags);
}

static int
adummy_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
        if (vcc->pop)
                vcc->pop(vcc, skb);
        else
                dev_kfree_skb_any(skb);
        atomic_inc(&vcc->stats->tx);

        return 0;
}

static int
adummy_proc_read(struct atm_dev *dev, loff_t *pos, char *page)
{
        int left = *pos;

        if (!left--)
                return sprintf(page, "version %s\n", DRV_VERSION);

        return 0;
}

static const struct atmdev_ops adummy_ops =
{
        .open =         adummy_open,
        .close =        adummy_close,   
        .send =         adummy_send,
        .proc_read =    adummy_proc_read,
        .owner =        THIS_MODULE
};

static int __init adummy_init(void)
{
        struct atm_dev *atm_dev;
        struct adummy_dev *adummy_dev;
        int err = 0;

        printk(KERN_ERR "adummy: version %s\n", DRV_VERSION);

        adummy_dev = kzalloc_obj(struct adummy_dev);
        if (!adummy_dev) {
                printk(KERN_ERR DEV_LABEL ": kzalloc() failed\n");
                err = -ENOMEM;
                goto out;
        }
        atm_dev = atm_dev_register(DEV_LABEL, NULL, &adummy_ops, -1, NULL);
        if (!atm_dev) {
                printk(KERN_ERR DEV_LABEL ": atm_dev_register() failed\n");
                err = -ENODEV;
                goto out_kfree;
        }

        adummy_dev->atm_dev = atm_dev;
        atm_dev->dev_data = adummy_dev;

        if (sysfs_create_group(&atm_dev->class_dev.kobj, &adummy_group_attrs))
                dev_err(&atm_dev->class_dev, "Could not register attrs for adummy\n");

        if (adummy_start(atm_dev)) {
                printk(KERN_ERR DEV_LABEL ": adummy_start() failed\n");
                err = -ENODEV;
                goto out_unregister;
        }

        list_add(&adummy_dev->entry, &adummy_devs);
out:
        return err;

out_unregister:
        atm_dev_deregister(atm_dev);
out_kfree:
        kfree(adummy_dev);
        goto out;
}

static void __exit adummy_cleanup(void)
{
        struct adummy_dev *adummy_dev, *next;

        list_for_each_entry_safe(adummy_dev, next, &adummy_devs, entry) {
                atm_dev_deregister(adummy_dev->atm_dev);
                kfree(adummy_dev);
        }
}

module_init(adummy_init);
module_exit(adummy_cleanup);

MODULE_AUTHOR("chas williams <chas@cmf.nrl.navy.mil>");
MODULE_DESCRIPTION("dummy ATM driver");
MODULE_LICENSE("GPL");