// SPDX-License-Identifier: GPL-2.0+
/*
 * PCI Hot Plug Controller Skeleton Driver - 0.3
 *
 * Copyright (C) 2001,2003 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2001,2003 IBM Corp.
 *
 * All rights reserved.
 *
 * This driver is to be used as a skeleton driver to show how to interface
 * with the pci hotplug core easily.
 *
 * Send feedback to <greg@kroah.com>
 *
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/init.h>

#define SLOT_NAME_SIZE	10
struct slot {
	u8 number;
	struct hotplug_slot *hotplug_slot;
	struct list_head slot_list;
	char name[SLOT_NAME_SIZE];
};

static LIST_HEAD(slot_list);

#define MY_NAME	"pcihp_skeleton"

#define dbg(format, arg...)					\
	do {							\
		if (debug)					\
			printk(KERN_DEBUG "%s: " format "\n",	\
				MY_NAME, ## arg);		\
	} while (0)
#define err(format, arg...) printk(KERN_ERR "%s: " format "\n", MY_NAME, ## arg)
#define info(format, arg...) printk(KERN_INFO "%s: " format "\n", MY_NAME, ## arg)
#define warn(format, arg...) printk(KERN_WARNING "%s: " format "\n", MY_NAME, ## arg)

/* local variables */
static bool debug;
static int num_slots;

#define DRIVER_VERSION	"0.3"
#define DRIVER_AUTHOR	"Greg Kroah-Hartman <greg@kroah.com>"
#define DRIVER_DESC	"Hot Plug PCI Controller Skeleton Driver"

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
module_param(debug, bool, 0644);
MODULE_PARM_DESC(debug, "Debugging mode enabled or not");

static int enable_slot(struct hotplug_slot *slot);
static int disable_slot(struct hotplug_slot *slot);
static int set_attention_status(struct hotplug_slot *slot, u8 value);
static int hardware_test(struct hotplug_slot *slot, u32 value);
static int get_power_status(struct hotplug_slot *slot, u8 *value);
static int get_attention_status(struct hotplug_slot *slot, u8 *value);
static int get_latch_status(struct hotplug_slot *slot, u8 *value);
static int get_adapter_status(struct hotplug_slot *slot, u8 *value);

static struct hotplug_slot_ops skel_hotplug_slot_ops = {
	.enable_slot =		enable_slot,
	.disable_slot =		disable_slot,
	.set_attention_status =	set_attention_status,
	.hardware_test =	hardware_test,
	.get_power_status =	get_power_status,
	.get_attention_status =	get_attention_status,
	.get_latch_status =	get_latch_status,
	.get_adapter_status =	get_adapter_status,
};

static int enable_slot(struct hotplug_slot *hotplug_slot)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	/*
	 * Fill in code here to enable the specified slot
	 */

	return retval;
}

static int disable_slot(struct hotplug_slot *hotplug_slot)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	/*
	 * Fill in code here to disable the specified slot
	 */

	return retval;
}

static int set_attention_status(struct hotplug_slot *hotplug_slot, u8 status)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	switch (status) {
	case 0:
		/*
		 * Fill in code here to turn light off
		 */
		break;

	case 1:
	default:
		/*
		 * Fill in code here to turn light on
		 */
		break;
	}

	return retval;
}

static int hardware_test(struct hotplug_slot *hotplug_slot, u32 value)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	switch (value) {
	case 0:
		/* Specify a test here */
		break;
	case 1:
		/* Specify another test here */
		break;
	}

	return retval;
}

static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	/*
	 * Fill in logic to get the current power status of the specific
	 * slot and store it in the *value location.
	 */

	return retval;
}

static int get_attention_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	/*
	 * Fill in logic to get the current attention status of the specific
	 * slot and store it in the *value location.
	 */

	return retval;
}

static int get_latch_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	/*
	 * Fill in logic to get the current latch status of the specific
	 * slot and store it in the *value location.
	 */

	return retval;
}

static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
	struct slot *slot = hotplug_slot->private;
	int retval = 0;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);

	/*
	 * Fill in logic to get the current adapter status of the specific
	 * slot and store it in the *value location.
	 */

	return retval;
}

static void release_slot(struct hotplug_slot *hotplug_slot)
{
	struct slot *slot = hotplug_slot->private;

	dbg("%s - physical_slot = %s\n", __func__, hotplug_slot->name);
	kfree(slot->hotplug_slot->info);
	kfree(slot->hotplug_slot);
	kfree(slot);
}

static void make_slot_name(struct slot *slot)
{
	/*
	 * Stupid way to make a filename out of the slot name.
	 * replace this if your hardware provides a better way to name slots.
	 */
	snprintf(slot->hotplug_slot->name, SLOT_NAME_SIZE, "%d", slot->number);
}

/**
 * init_slots - initialize 'struct slot' structures for each slot
 *
 */
static int __init init_slots(void)
{
	struct slot *slot;
	struct hotplug_slot *hotplug_slot;
	struct hotplug_slot_info *info;
	int retval;
	int i;

	/*
	 * Create a structure for each slot, and register that slot
	 * with the pci_hotplug subsystem.
	 */
	for (i = 0; i < num_slots; ++i) {
		slot = kzalloc(sizeof(*slot), GFP_KERNEL);
		if (!slot) {
			retval = -ENOMEM;
			goto error;
		}

		hotplug_slot = kzalloc(sizeof(*hotplug_slot), GFP_KERNEL);
		if (!hotplug_slot) {
			retval = -ENOMEM;
			goto error_slot;
		}
		slot->hotplug_slot = hotplug_slot;

		info = kzalloc(sizeof(*info), GFP_KERNEL);
		if (!info) {
			retval = -ENOMEM;
			goto error_hpslot;
		}
		hotplug_slot->info = info;

		slot->number = i;

		hotplug_slot->name = slot->name;
		hotplug_slot->private = slot;
		hotplug_slot->release = &release_slot;
		make_slot_name(slot);
		hotplug_slot->ops = &skel_hotplug_slot_ops;

		/*
		 * Initialize the slot info structure with some known
		 * good values.
		 */
		get_power_status(hotplug_slot, &info->power_status);
		get_attention_status(hotplug_slot, &info->attention_status);
		get_latch_status(hotplug_slot, &info->latch_status);
		get_adapter_status(hotplug_slot, &info->adapter_status);

		dbg("registering slot %d\n", i);
		retval = pci_hp_register(slot->hotplug_slot);
		if (retval) {
			err("pci_hp_register failed with error %d\n", retval);
			goto error_info;
		}

		/* add slot to our internal list */
		list_add(&slot->slot_list, &slot_list);
	}

	return 0;
error_info:
	kfree(info);
error_hpslot:
	kfree(hotplug_slot);
error_slot:
	kfree(slot);
error:
	return retval;
}

static void __exit cleanup_slots(void)
{
	struct slot *slot, *next;

	/*
	 * Unregister all of our slots with the pci_hotplug subsystem.
	 * Memory will be freed in release_slot() callback after slot's
	 * lifespan is finished.
	 */
	list_for_each_entry_safe(slot, next, &slot_list, slot_list) {
		list_del(&slot->slot_list);
		pci_hp_deregister(slot->hotplug_slot);
	}
}

static int __init pcihp_skel_init(void)
{
	int retval;

	info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
	/*
	 * Do specific initialization stuff for your driver here
	 * like initializing your controller hardware (if any) and
	 * determining the number of slots you have in the system
	 * right now.
	 */
	num_slots = 5;

	return init_slots();
}

static void __exit pcihp_skel_exit(void)
{
	/*
	 * Clean everything up.
	 */
	cleanup_slots();
}

module_init(pcihp_skel_init);
module_exit(pcihp_skel_exit);