// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * 	cn_test.c
   * 

   * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>

   * All rights reserved.

   */

  #define pr_fmt(fmt) "cn_test: " fmt

  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/skbuff.h>

  #include <linux/slab.h>

  #include <linux/timer.h>

  #include <linux/connector.h>

  static struct cb_id cn_test_id = { CN_NETLINK_USERS + 3, 0x456 };

  static char cn_test_name[] = "cn_test";
  static struct sock *nls;
  static struct timer_list cn_test_timer;

  static void cn_test_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)

  {

  	pr_info("%s: %lu: idx=%x, val=%x, seq=%u, ack=%u, len=%d: %s.
  ",
  	        __func__, jiffies, msg->id.idx, msg->id.val,
  	        msg->seq, msg->ack, msg->len,
  	        msg->len ? (char *)msg->data : "");

  }

  /*
   * Do not remove this function even if no one is using it as
   * this is an example of how to get notifications about new
   * connector user registration
   */
  #if 0

  static int cn_test_want_notify(void)
  {
  	struct cn_ctl_msg *ctl;
  	struct cn_notify_req *req;
  	struct cn_msg *msg = NULL;
  	int size, size0;
  	struct sk_buff *skb;
  	struct nlmsghdr *nlh;
  	u32 group = 1;
  
  	size0 = sizeof(*msg) + sizeof(*ctl) + 3 * sizeof(*req);
  
  	size = NLMSG_SPACE(size0);
  
  	skb = alloc_skb(size, GFP_ATOMIC);
  	if (!skb) {

  		pr_err("failed to allocate new skb with size=%u
  ", size);

  		return -ENOMEM;
  	}

  	nlh = nlmsg_put(skb, 0, 0x123, NLMSG_DONE, size - sizeof(*nlh), 0);
  	if (!nlh) {
  		kfree_skb(skb);
  		return -EMSGSIZE;
  	}

  	msg = nlmsg_data(nlh);

  
  	memset(msg, 0, size0);
  
  	msg->id.idx = -1;
  	msg->id.val = -1;
  	msg->seq = 0x123;
  	msg->ack = 0x345;
  	msg->len = size0 - sizeof(*msg);
  
  	ctl = (struct cn_ctl_msg *)(msg + 1);
  
  	ctl->idx_notify_num = 1;
  	ctl->val_notify_num = 2;
  	ctl->group = group;
  	ctl->len = msg->len - sizeof(*ctl);
  
  	req = (struct cn_notify_req *)(ctl + 1);
  
  	/*
  	 * Idx.
  	 */
  	req->first = cn_test_id.idx;
  	req->range = 10;
  
  	/*
  	 * Val 0.
  	 */
  	req++;
  	req->first = cn_test_id.val;
  	req->range = 10;
  
  	/*
  	 * Val 1.
  	 */
  	req++;
  	req->first = cn_test_id.val + 20;
  	req->range = 10;

  	NETLINK_CB(skb).dst_group = ctl->group;

  	//netlink_broadcast(nls, skb, 0, ctl->group, GFP_ATOMIC);
  	netlink_unicast(nls, skb, 0, 0);

  	pr_info("request was sent: group=0x%x
  ", ctl->group);

  
  	return 0;

  }

  #endif

  
  static u32 cn_test_timer_counter;

  static void cn_test_timer_func(struct timer_list *unused)

  {
  	struct cn_msg *m;
  	char data[32];

  	pr_debug("%s: timer fired
  ", __func__);

  	m = kzalloc(sizeof(*m) + sizeof(data), GFP_ATOMIC);

  	if (m) {

  
  		memcpy(&m->id, &cn_test_id, sizeof(m->id));
  		m->seq = cn_test_timer_counter;
  		m->len = sizeof(data);
  
  		m->len =
  		    scnprintf(data, sizeof(data), "counter = %u",
  			      cn_test_timer_counter) + 1;
  
  		memcpy(m + 1, data, m->len);

  		cn_netlink_send(m, 0, 0, GFP_ATOMIC);

  		kfree(m);
  	}
  
  	cn_test_timer_counter++;

  	mod_timer(&cn_test_timer, jiffies + msecs_to_jiffies(1000));

  }
  
  static int cn_test_init(void)
  {
  	int err;
  
  	err = cn_add_callback(&cn_test_id, cn_test_name, cn_test_callback);
  	if (err)
  		goto err_out;
  	cn_test_id.val++;
  	err = cn_add_callback(&cn_test_id, cn_test_name, cn_test_callback);
  	if (err) {
  		cn_del_callback(&cn_test_id);
  		goto err_out;
  	}

  	timer_setup(&cn_test_timer, cn_test_timer_func, 0);

  	mod_timer(&cn_test_timer, jiffies + msecs_to_jiffies(1000));
  
  	pr_info("initialized with id={%u.%u}
  ",
  		cn_test_id.idx, cn_test_id.val);

  
  	return 0;
  
        err_out:
  	if (nls && nls->sk_socket)
  		sock_release(nls->sk_socket);
  
  	return err;
  }
  
  static void cn_test_fini(void)
  {
  	del_timer_sync(&cn_test_timer);
  	cn_del_callback(&cn_test_id);
  	cn_test_id.val--;
  	cn_del_callback(&cn_test_id);
  	if (nls && nls->sk_socket)
  		sock_release(nls->sk_socket);
  }
  
  module_init(cn_test_init);
  module_exit(cn_test_fini);
  
  MODULE_LICENSE("GPL");

  MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");

  MODULE_DESCRIPTION("Connector's test module");