/*
 * 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 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 struct pci_hp_callback_ops hp_ops = {
        .create_slot = init_pci_slot,
        .remove_slot = exit_pci_slot,
};

static void __init init_pci_slots(void)
{
        struct zpci_dev *zdev;

        /*
         * 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);
        }
        mutex_unlock(&zpci_list_lock);
}

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)
{
        if (!s390_pci_probe)
                return -EOPNOTSUPP;

        zpci_register_hp_ops(&hp_ops);
        init_pci_slots();

        return 0;
}

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

module_init(pci_hotplug_s390_init);
module_exit(pci_hotplug_s390_exit);