/*
 * PCI Hot Plug Controller Driver for System z
 *
 * Copyright 2012 IBM Corp.
 *
 * Author(s):
 *   Jan Glauber <jang@linux.vnet.ibm.com>
 */

#define COMPONENT "zPCI hpc"
#define pr_fmt(fmt) COMPONENT ": " fmt

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

#define SLOT_NAME_SIZE	10
static LIST_HEAD(s390_hotplug_slot_list);

MODULE_AUTHOR("Jan Glauber <jang@linux.vnet.ibm.com");
MODULE_DESCRIPTION("Hot Plug PCI Controller for System z");
MODULE_LICENSE("GPL");

static int zpci_fn_configured(enum zpci_state state)
{
	return state == ZPCI_FN_STATE_CONFIGURED ||
	       state == ZPCI_FN_STATE_ONLINE;
}

/*
 * struct slot - slot information for each *physical* slot
 */
struct slot {
	struct list_head slot_list;
	struct hotplug_slot *hotplug_slot;
	struct zpci_dev *zdev;
};

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

	if (slot->zdev->state != ZPCI_FN_STATE_STANDBY)
		return -EIO;

	rc = sclp_pci_configure(slot->zdev->fid);
	if (!rc) {
		slot->zdev->state = ZPCI_FN_STATE_CONFIGURED;
		/* automatically scan the device after is was configured */
		zpci_enable_device(slot->zdev);
		zpci_scan_device(slot->zdev);
	}
	return rc;
}

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

	if (!zpci_fn_configured(slot->zdev->state))
		return -EIO;

	/* TODO: we rely on the user to unbind/remove the device, is that plausible
	 *	 or do we need to trigger that here?
	 */
	rc = sclp_pci_deconfigure(slot->zdev->fid);
	if (!rc) {
		/* Fixme: better call List-PCI to find the disabled FH
		   for the FID since the FH should be opaque... */
		slot->zdev->fh &= 0x7fffffff;
		slot->zdev->state = ZPCI_FN_STATE_STANDBY;
	}
	return rc;
}

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

	switch (slot->zdev->state) {
	case ZPCI_FN_STATE_STANDBY:
		*value = 0;
		break;
	default:
		*value = 1;
		break;
	}
	return 0;
}

static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
	/* if the slot exits it always contains a function */
	*value = 1;
	return 0;
}

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

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

static struct hotplug_slot_ops s390_hotplug_slot_ops = {
	.enable_slot =		enable_slot,
	.disable_slot =		disable_slot,
	.get_power_status =	get_power_status,
	.get_adapter_status =	get_adapter_status,
};

static int init_pci_slot(struct zpci_dev *zdev)
{
	struct hotplug_slot *hotplug_slot;
	struct hotplug_slot_info *info;
	char name[SLOT_NAME_SIZE];
	struct slot *slot;
	int rc;

	if (!zdev)
		return 0;

	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
	if (!slot)
		goto error;

	hotplug_slot = kzalloc(sizeof(*hotplug_slot), GFP_KERNEL);
	if (!hotplug_slot)
		goto error_hp;
	hotplug_slot->private = slot;

	slot->hotplug_slot = hotplug_slot;
	slot->zdev = zdev;

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info)
		goto error_info;
	hotplug_slot->info = info;

	hotplug_slot->ops = &s390_hotplug_slot_ops;
	hotplug_slot->release = &release_slot;

	get_power_status(hotplug_slot, &info->power_status);
	get_adapter_status(hotplug_slot, &info->adapter_status);

	snprintf(name, SLOT_NAME_SIZE, "%08x", zdev->fid);
	rc = pci_hp_register(slot->hotplug_slot, zdev->bus,
			     ZPCI_DEVFN, name);
	if (rc) {
		pr_err("pci_hp_register failed with error %d\n", rc);
		goto error_reg;
	}
	list_add(&slot->slot_list, &s390_hotplug_slot_list);
	return 0;

error_reg:
	kfree(info);
error_info:
	kfree(hotplug_slot);
error_hp:
	kfree(slot);
error:
	return -ENOMEM;
}

static int __init init_pci_slots(void)
{
	struct zpci_dev *zdev;
	int device = 0;

	/*
	 * Create a structure for each slot, and register that slot
	 * with the pci_hotplug subsystem.
	 */
	mutex_lock(&zpci_list_lock);
	list_for_each_entry(zdev, &zpci_list, entry) {
		init_pci_slot(zdev);
		device++;
	}

	mutex_unlock(&zpci_list_lock);
	return (device) ? 0 : -ENODEV;
}

static void exit_pci_slot(struct zpci_dev *zdev)
{
	struct list_head *tmp, *n;
	struct slot *slot;

	list_for_each_safe(tmp, n, &s390_hotplug_slot_list) {
		slot = list_entry(tmp, struct slot, slot_list);
		if (slot->zdev != zdev)
			continue;
		list_del(&slot->slot_list);
		pci_hp_deregister(slot->hotplug_slot);
	}
}

static void __exit exit_pci_slots(void)
{
	struct list_head *tmp, *n;
	struct slot *slot;

	/*
	 * 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_safe(tmp, n, &s390_hotplug_slot_list) {
		slot = list_entry(tmp, struct slot, slot_list);
		list_del(&slot->slot_list);
		pci_hp_deregister(slot->hotplug_slot);
	}
}

static int __init pci_hotplug_s390_init(void)
{
	/*
	 * 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.
	 */

	if (!pci_probe)
		return -EOPNOTSUPP;

	/* register callbacks for slot handling from arch code */
	mutex_lock(&zpci_list_lock);
	hotplug_ops.create_slot = init_pci_slot;
	hotplug_ops.remove_slot = exit_pci_slot;
	mutex_unlock(&zpci_list_lock);
	pr_info("registered hotplug slot callbacks\n");
	return init_pci_slots();
}

static void __exit pci_hotplug_s390_exit(void)
{
	exit_pci_slots();
}

module_init(pci_hotplug_s390_init);
module_exit(pci_hotplug_s390_exit);