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  /*
   * Fake PCI Hot Plug Controller Driver
   *
   * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   * Copyright (C) 2003 IBM Corp.
   * Copyright (C) 2003 Rolf Eike Beer <eike-kernel@sf-tec.de>
   *
   * Based on ideas and code from:
   *         Vladimir Kondratiev <vladimir.kondratiev@intel.com>
  *        Rolf Eike Beer <eike-kernel@sf-tec.de>
  *
  * All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, version 2 of the License.
  *
  * Send feedback to <greg@kroah.com>
  */
 
 /*
  *
  * This driver will "emulate" removing PCI devices from the system.  If
  * the "power" file is written to with "0" then the specified PCI device
  * will be completely removed from the kernel.
  *
  * WARNING, this does NOT turn off the power to the PCI device.  This is
  * a "logical" removal, not a physical or electrical removal.
  *
  * Use this module at your own risk, you have been warned!
  *
  * Enabling PCI devices is left as an exercise for the reader...
  *
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/pci_hotplug.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include "../pci.h"
 
 #if !defined(MODULE)
         #define MY_NAME        "fakephp"
 #else
         #define MY_NAME        THIS_MODULE->name
 #endif
 
 #define dbg(format, arg...)                                        \
         do {                                                        \
                 if (debug)                                        \
                         printk(KERN_DEBUG "%s: " format,        \
                                 MY_NAME , ## arg);                 \
         } while (0)
 #define err(format, arg...) printk(KERN_ERR "%s: " format, MY_NAME , ## arg)
 #define info(format, arg...) printk(KERN_INFO "%s: " format, MY_NAME , ## arg)
 
 #define DRIVER_AUTHOR        "Greg Kroah-Hartman <greg@kroah.com>"
 #define DRIVER_DESC        "Fake PCI Hot Plug Controller Driver"
 
 struct dummy_slot {
         struct list_head node;
         struct hotplug_slot *slot;
         struct pci_dev *dev;
         struct work_struct remove_work;
         unsigned long removed;
 };
 
 static int debug;
 static int dup_slots;
 static LIST_HEAD(slot_list);
 static struct workqueue_struct *dummyphp_wq;
 
 static void pci_rescan_worker(struct work_struct *work);
 static DECLARE_WORK(pci_rescan_work, pci_rescan_worker);
 
 static int enable_slot (struct hotplug_slot *slot);
 static int disable_slot (struct hotplug_slot *slot);
 
 static struct hotplug_slot_ops dummy_hotplug_slot_ops = {
         .owner                        = THIS_MODULE,
         .enable_slot                = enable_slot,
         .disable_slot                = disable_slot,
 };
 
 static void dummy_release(struct hotplug_slot *slot)
 {
         struct dummy_slot *dslot = slot->private;
 
         list_del(&dslot->node);
         kfree(dslot->slot->info);
         kfree(dslot->slot);
         pci_dev_put(dslot->dev);
         kfree(dslot);
 }
 
 #define SLOT_NAME_SIZE        8

static int add_slot(struct pci_dev *dev)
{
        struct dummy_slot *dslot;
        struct hotplug_slot *slot;
        char name[SLOT_NAME_SIZE];
        int retval = -ENOMEM;
        static int count = 1;

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

        slot->info = kzalloc(sizeof(struct hotplug_slot_info), GFP_KERNEL);
        if (!slot->info)
                goto error_slot;

        slot->info->power_status = 1;
        slot->info->max_bus_speed = PCI_SPEED_UNKNOWN;
        slot->info->cur_bus_speed = PCI_SPEED_UNKNOWN;

        dslot = kzalloc(sizeof(struct dummy_slot), GFP_KERNEL);
        if (!dslot)
                goto error_info;

        if (dup_slots)
                snprintf(name, SLOT_NAME_SIZE, "fake");
        else
                snprintf(name, SLOT_NAME_SIZE, "fake%d", count++);
        dbg("slot->name = %s\n", name);
        slot->ops = &dummy_hotplug_slot_ops;
        slot->release = &dummy_release;
        slot->private = dslot;

        retval = pci_hp_register(slot, dev->bus, PCI_SLOT(dev->devfn), name);
        if (retval) {
                err("pci_hp_register failed with error %d\n", retval);
                goto error_dslot;
        }

        dbg("slot->name = %s\n", hotplug_slot_name(slot));
        dslot->slot = slot;
        dslot->dev = pci_dev_get(dev);
        list_add (&dslot->node, &slot_list);
        return retval;

error_dslot:
        kfree(dslot);
error_info:
        kfree(slot->info);
error_slot:
        kfree(slot);
error:
        return retval;
}

static int __init pci_scan_buses(void)
{
        struct pci_dev *dev = NULL;
        int lastslot = 0;

        while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
                if (PCI_FUNC(dev->devfn) > 0 &&
                                lastslot == PCI_SLOT(dev->devfn))
                        continue;
                lastslot = PCI_SLOT(dev->devfn);
                add_slot(dev);
        }

        return 0;
}

static void remove_slot(struct dummy_slot *dslot)
{
        int retval;

        dbg("removing slot %s\n", hotplug_slot_name(dslot->slot));
        retval = pci_hp_deregister(dslot->slot);
        if (retval)
                err("Problem unregistering a slot %s\n",
                        hotplug_slot_name(dslot->slot));
}

/* called from the single-threaded workqueue handler to remove a slot */
static void remove_slot_worker(struct work_struct *work)
{
        struct dummy_slot *dslot =
                container_of(work, struct dummy_slot, remove_work);
        remove_slot(dslot);
}

/**
 * pci_rescan_slot - Rescan slot
 * @temp: Device template. Should be set: bus and devfn.
 *
 * Tries hard not to re-enable already existing devices;
 * also handles scanning of subfunctions.
 */
static void pci_rescan_slot(struct pci_dev *temp)
{
        struct pci_bus *bus = temp->bus;
        struct pci_dev *dev;
        int func;
        int retval;
        u8 hdr_type;

        if (!pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type)) {
                temp->hdr_type = hdr_type & 0x7f;
                if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
                        pci_dev_put(dev);
                else {
                        dev = pci_scan_single_device(bus, temp->devfn);
                        if (dev) {
                                dbg("New device on %s function %x:%x\n",
                                        bus->name, temp->devfn >> 3,
                                        temp->devfn & 7);
                                retval = pci_bus_add_device(dev);
                                if (retval)
                                        dev_err(&dev->dev, "error adding "
                                                "device, continuing.\n");
                                else
                                        add_slot(dev);
                        }
                }
                /* multifunction device? */
                if (!(hdr_type & 0x80))
                        return;

                /* continue scanning for other functions */
                for (func = 1, temp->devfn++; func < 8; func++, temp->devfn++) {
                        if (pci_read_config_byte(temp, PCI_HEADER_TYPE, &hdr_type))
                                continue;
                        temp->hdr_type = hdr_type & 0x7f;

                        if ((dev = pci_get_slot(bus, temp->devfn)) != NULL)
                                pci_dev_put(dev);
                        else {
                                dev = pci_scan_single_device(bus, temp->devfn);
                                if (dev) {
                                        dbg("New device on %s function %x:%x\n",
                                                bus->name, temp->devfn >> 3,
                                                temp->devfn & 7);
                                        retval = pci_bus_add_device(dev);
                                        if (retval)
                                                dev_err(&dev->dev, "error adding "
                                                        "device, continuing.\n");
                                        else
                                                add_slot(dev);
                                }
                        }
                }
        }
}


/**
 * pci_rescan_bus - Rescan PCI bus
 * @bus: the PCI bus to rescan
 *
 * Call pci_rescan_slot for each possible function of the bus.
 */
static void pci_rescan_bus(const struct pci_bus *bus)
{
        unsigned int devfn;
        struct pci_dev *dev;
        dev = alloc_pci_dev();
        if (!dev)
                return;

        dev->bus = (struct pci_bus*)bus;
        dev->sysdata = bus->sysdata;
        for (devfn = 0; devfn < 0x100; devfn += 8) {
                dev->devfn = devfn;
                pci_rescan_slot(dev);
        }
        kfree(dev);
}

/* recursively scan all buses */
static void pci_rescan_buses(const struct list_head *list)
{
        const struct list_head *l;
        list_for_each(l,list) {
                const struct pci_bus *b = pci_bus_b(l);
                pci_rescan_bus(b);
                pci_rescan_buses(&b->children);
        }
}

/* initiate rescan of all pci buses */
static inline void pci_rescan(void) {
        pci_rescan_buses(&pci_root_buses);
}

/* called from the single-threaded workqueue handler to rescan all pci buses */
static void pci_rescan_worker(struct work_struct *work)
{
        pci_rescan();
}

static int enable_slot(struct hotplug_slot *hotplug_slot)
{
        /* mis-use enable_slot for rescanning of the pci bus */
        cancel_work_sync(&pci_rescan_work);
        queue_work(dummyphp_wq, &pci_rescan_work);
        return 0;
}

static int disable_slot(struct hotplug_slot *slot)
{
        struct dummy_slot *dslot;
        struct pci_dev *dev;
        int func;

        if (!slot)
                return -ENODEV;
        dslot = slot->private;

        dbg("%s - physical_slot = %s\n", __func__, hotplug_slot_name(slot));

        for (func = 7; func >= 0; func--) {
                dev = pci_get_slot(dslot->dev->bus, dslot->dev->devfn + func);
                if (!dev)
                        continue;

                if (test_and_set_bit(0, &dslot->removed)) {
                        dbg("Slot already scheduled for removal\n");
                        return -ENODEV;
                }

                /* remove the device from the pci core */
                pci_remove_bus_device(dev);

                /* queue work item to blow away this sysfs entry and other
                 * parts.
                 */
                INIT_WORK(&dslot->remove_work, remove_slot_worker);
                queue_work(dummyphp_wq, &dslot->remove_work);

                pci_dev_put(dev);
        }
        return 0;
}

static void cleanup_slots (void)
{
        struct list_head *tmp;
        struct list_head *next;
        struct dummy_slot *dslot;

        destroy_workqueue(dummyphp_wq);
        list_for_each_safe (tmp, next, &slot_list) {
                dslot = list_entry (tmp, struct dummy_slot, node);
                remove_slot(dslot);
        }
        
}

static int __init dummyphp_init(void)
{
        info(DRIVER_DESC "\n");

        dummyphp_wq = create_singlethread_workqueue(MY_NAME);
        if (!dummyphp_wq)
                return -ENOMEM;

        return pci_scan_buses();
}


static void __exit dummyphp_exit(void)
{
        cleanup_slots();
}

module_init(dummyphp_init);
module_exit(dummyphp_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
module_param(dup_slots, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(dup_slots, "Force duplicate slot names for debugging");