text: // SPDX-License-Identifier: GPL-2.0
  /*
   * event.c - exporting ACPI events via procfs
   *
   *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   *
   */
  
  #define pr_fmt(fmt) "ACPI: " fmt
  
  #include <linux/spinlock.h>
  #include <linux/export.h>
  #include <linux/proc_fs.h>
  #include <linux/init.h>
  #include <linux/poll.h>
  #include <linux/gfp.h>
  #include <linux/acpi.h>
  #include <net/netlink.h>
  #include <net/genetlink.h>
  
  #include "internal.h"
  
  /* ACPI notifier chain */
  static BLOCKING_NOTIFIER_HEAD(acpi_chain_head);
  
  int acpi_notifier_call_chain(struct acpi_device *dev, u32 type, u32 data)
  {
  	struct acpi_bus_event event;
  
  	strcpy(event.device_class, dev->pnp.device_class);
  	strcpy(event.bus_id, dev->pnp.bus_id);
  	event.type = type;
  	event.data = data;
  	return (blocking_notifier_call_chain(&acpi_chain_head, 0, (void *)&event)
  			== NOTIFY_BAD) ? -EINVAL : 0;
  }
  EXPORT_SYMBOL(acpi_notifier_call_chain);
  
  int register_acpi_notifier(struct notifier_block *nb)
  {
  	return blocking_notifier_chain_register(&acpi_chain_head, nb);
  }
  EXPORT_SYMBOL(register_acpi_notifier);
  
  int unregister_acpi_notifier(struct notifier_block *nb)
  {
  	return blocking_notifier_chain_unregister(&acpi_chain_head, nb);
  }
  EXPORT_SYMBOL(unregister_acpi_notifier);
  
  #ifdef CONFIG_NET
  static unsigned int acpi_event_seqnum;
  struct acpi_genl_event {
  	acpi_device_class device_class;
  	char bus_id[15];
  	u32 type;
  	u32 data;
  };
  
  /* attributes of acpi_genl_family */
  enum {
  	ACPI_GENL_ATTR_UNSPEC,
  	ACPI_GENL_ATTR_EVENT,	/* ACPI event info needed by user space */
  	__ACPI_GENL_ATTR_MAX,
  };
  #define ACPI_GENL_ATTR_MAX (__ACPI_GENL_ATTR_MAX - 1)
  
  /* commands supported by the acpi_genl_family */
  enum {
  	ACPI_GENL_CMD_UNSPEC,
  	ACPI_GENL_CMD_EVENT,	/* kernel->user notifications for ACPI events */
  	__ACPI_GENL_CMD_MAX,
  };
  #define ACPI_GENL_CMD_MAX (__ACPI_GENL_CMD_MAX - 1)
  
  #define ACPI_GENL_FAMILY_NAME		"acpi_event"
  #define ACPI_GENL_VERSION		0x01
  #define ACPI_GENL_MCAST_GROUP_NAME 	"acpi_mc_group"
  
  static const struct genl_multicast_group acpi_event_mcgrps[] = {
  	{ .name = ACPI_GENL_MCAST_GROUP_NAME, },
  };
  
  static struct genl_family acpi_event_genl_family __ro_after_init = {
  	.module = THIS_MODULE,
  	.name = ACPI_GENL_FAMILY_NAME,
  	.version = ACPI_GENL_VERSION,
  	.maxattr = ACPI_GENL_ATTR_MAX,
  	.mcgrps = acpi_event_mcgrps,
  	.n_mcgrps = ARRAY_SIZE(acpi_event_mcgrps),
  };
  
  int acpi_bus_generate_netlink_event(const char *device_class,
  				      const char *bus_id,
  				      u8 type, int data)
  {
  	struct sk_buff *skb;
  	struct nlattr *attr;
  	struct acpi_genl_event *event;
  	void *msg_header;
  	int size;
  
  	/* allocate memory */
  	size = nla_total_size(sizeof(struct acpi_genl_event)) +
  	    nla_total_size(0);
  
  	skb = genlmsg_new(size, GFP_ATOMIC);
  	if (!skb)
  		return -ENOMEM;
  
  	/* add the genetlink message header */
  	msg_header = genlmsg_put(skb, 0, acpi_event_seqnum++,
  				 &acpi_event_genl_family, 0,
  				 ACPI_GENL_CMD_EVENT);
  	if (!msg_header) {
  		nlmsg_free(skb);
  		return -ENOMEM;
  	}
  
  	/* fill the data */
  	attr =
  	    nla_reserve(skb, ACPI_GENL_ATTR_EVENT,
  			sizeof(struct acpi_genl_event));
  	if (!attr) {
  		nlmsg_free(skb);
  		return -EINVAL;
  	}
  
  	event = nla_data(attr);
  	memset(event, 0, sizeof(struct acpi_genl_event));
  
  	strscpy(event->device_class, device_class, sizeof(event->device_class));
  	strscpy(event->bus_id, bus_id, sizeof(event->bus_id));
  	event->type = type;
  	event->data = data;
  
  	/* send multicast genetlink message */
  	genlmsg_end(skb, msg_header);
  
  	genlmsg_multicast(&acpi_event_genl_family, skb, 0, 0, GFP_ATOMIC);
  	return 0;
  }
  
  EXPORT_SYMBOL(acpi_bus_generate_netlink_event);
  
  static int __init acpi_event_genetlink_init(void)
  {
  	return genl_register_family(&acpi_event_genl_family);
  }
  
  #else
  int acpi_bus_generate_netlink_event(const char *device_class,
  				      const char *bus_id,
  				      u8 type, int data)
  {
  	return 0;
  }
  
  EXPORT_SYMBOL(acpi_bus_generate_netlink_event);
  
  static int acpi_event_genetlink_init(void)
  {
  	return -ENODEV;
  }
  #endif
  
  static int __init acpi_event_init(void)
  {
  	int error;
  
  	if (acpi_disabled)
  		return 0;
  
  	/* create genetlink for acpi event */
  	error = acpi_event_genetlink_init();
  	if (error)
  		pr_warn("Failed to create genetlink family for ACPI event\n");
  
  	return 0;
  }
  
  fs_initcall(acpi_event_init);
  