/*
 *  pci_slot.c - ACPI PCI Slot Driver
 *
 *  The code here is heavily leveraged from the acpiphp module.
 *  Thanks to Matthew Wilcox <matthew@wil.cx> for much guidance.
 *  Thanks to Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> for code
 *  review and fixes.
 *
 *  Copyright (C) 2007-2008 Hewlett-Packard Development Company, L.P.
 *      Alex Chiang <achiang@hp.com>
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms and conditions of the GNU General Public License,
 *  version 2, as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/acpi.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
#include <linux/dmi.h>

static int debug;
static int check_sta_before_sun;

#define DRIVER_VERSION  "0.1"
#define DRIVER_AUTHOR   "Alex Chiang <achiang@hp.com>"
#define DRIVER_DESC     "ACPI PCI Slot Detection Driver"
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_PARM_DESC(debug, "Debugging mode enabled or not");
module_param(debug, bool, 0644);

#define _COMPONENT              ACPI_PCI_COMPONENT
ACPI_MODULE_NAME("pci_slot");

#define MY_NAME "pci_slot"
#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 dbg(format, arg...)                                     \
        do {                                                    \
                if (debug)                                      \
                        printk(KERN_DEBUG "%s: " format,        \
                                MY_NAME , ## arg);              \
        } while (0)

#define SLOT_NAME_SIZE 21               /* Inspired by #define in acpiphp.h */

struct acpi_pci_slot {
        acpi_handle root_handle;        /* handle of the root bridge */
        struct pci_slot *pci_slot;      /* corresponding pci_slot */
        struct list_head list;          /* node in the list of slots */
};

static int acpi_pci_slot_add(acpi_handle handle);
static void acpi_pci_slot_remove(acpi_handle handle);

static LIST_HEAD(slot_list);
static DEFINE_MUTEX(slot_list_lock);
static struct acpi_pci_driver acpi_pci_slot_driver = {
        .add = acpi_pci_slot_add,
        .remove = acpi_pci_slot_remove,
};

static int
check_slot(acpi_handle handle, unsigned long long *sun)
{
        int device = -1;
        unsigned long long adr, sta;
        acpi_status status;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
        dbg("Checking slot on path: %s\n", (char *)buffer.pointer);

        if (check_sta_before_sun) {
                /* If SxFy doesn't have _STA, we just assume it's there */
                status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
                if (ACPI_SUCCESS(status) && !(sta & ACPI_STA_DEVICE_PRESENT))
                        goto out;
        }

        status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
        if (ACPI_FAILURE(status)) {
                dbg("_ADR returned %d on %s\n", status, (char *)buffer.pointer);
                goto out;
        }

        /* No _SUN == not a slot == bail */
        status = acpi_evaluate_integer(handle, "_SUN", NULL, sun);
        if (ACPI_FAILURE(status)) {
                dbg("_SUN returned %d on %s\n", status, (char *)buffer.pointer);
                goto out;
        }

        device = (adr >> 16) & 0xffff;
out:
        kfree(buffer.pointer);
        return device;
}

struct callback_args {
        acpi_walk_callback      user_function;  /* only for walk_p2p_bridge */
        struct pci_bus          *pci_bus;
        acpi_handle             root_handle;
};

/*
 * register_slot
 *
 * Called once for each SxFy object in the namespace. Don't worry about
 * calling pci_create_slot multiple times for the same pci_bus:device,
 * since each subsequent call simply bumps the refcount on the pci_slot.
 *
 * The number of calls to pci_destroy_slot from unregister_slot is
 * symmetrical.
 */
static acpi_status
register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
{
        int device;
        unsigned long long sun;
        char name[SLOT_NAME_SIZE];
        struct acpi_pci_slot *slot;
        struct pci_slot *pci_slot;
        struct callback_args *parent_context = context;
        struct pci_bus *pci_bus = parent_context->pci_bus;

        device = check_slot(handle, &sun);
        if (device < 0)
                return AE_OK;

        slot = kmalloc(sizeof(*slot), GFP_KERNEL);
        if (!slot) {
                err("%s: cannot allocate memory\n", __func__);
                return AE_OK;
        }

        snprintf(name, sizeof(name), "%llu", sun);
        pci_slot = pci_create_slot(pci_bus, device, name, NULL);
        if (IS_ERR(pci_slot)) {
                err("pci_create_slot returned %ld\n", PTR_ERR(pci_slot));
                kfree(slot);
                return AE_OK;
        }

        slot->root_handle = parent_context->root_handle;
        slot->pci_slot = pci_slot;
        INIT_LIST_HEAD(&slot->list);
        mutex_lock(&slot_list_lock);
        list_add(&slot->list, &slot_list);
        mutex_unlock(&slot_list_lock);

        get_device(&pci_bus->dev);

        dbg("pci_slot: %p, pci_bus: %x, device: %d, name: %s\n",
                pci_slot, pci_bus->number, device, name);

        return AE_OK;
}

/*
 * walk_p2p_bridge - discover and walk p2p bridges
 * @handle: points to an acpi_pci_root
 * @context: p2p_bridge_context pointer
 *
 * Note that when we call ourselves recursively, we pass a different
 * value of pci_bus in the child_context.
 */
static acpi_status
walk_p2p_bridge(acpi_handle handle, u32 lvl, void *context, void **rv)
{
        int device, function;
        unsigned long long adr;
        acpi_status status;
        acpi_handle dummy_handle;
        acpi_walk_callback user_function;

        struct pci_dev *dev;
        struct pci_bus *pci_bus;
        struct callback_args child_context;
        struct callback_args *parent_context = context;

        pci_bus = parent_context->pci_bus;
        user_function = parent_context->user_function;

        status = acpi_get_handle(handle, "_ADR", &dummy_handle);
        if (ACPI_FAILURE(status))
                return AE_OK;

        status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
        if (ACPI_FAILURE(status))
                return AE_OK;

        device = (adr >> 16) & 0xffff;
        function = adr & 0xffff;

        dev = pci_get_slot(pci_bus, PCI_DEVFN(device, function));
        if (!dev || !dev->subordinate)
                goto out;

        child_context.pci_bus = dev->subordinate;
        child_context.user_function = user_function;
        child_context.root_handle = parent_context->root_handle;

        dbg("p2p bridge walk, pci_bus = %x\n", dev->subordinate->number);
        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
                                     user_function, NULL, &child_context, NULL);
        if (ACPI_FAILURE(status))
                goto out;

        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
                                     walk_p2p_bridge, NULL, &child_context, NULL);
out:
        pci_dev_put(dev);
        return AE_OK;
}

/*
 * walk_root_bridge - generic root bridge walker
 * @handle: points to an acpi_pci_root
 * @user_function: user callback for slot objects
 *
 * Call user_function for all objects underneath this root bridge.
 * Walk p2p bridges underneath us and call user_function on those too.
 */
static int
walk_root_bridge(acpi_handle handle, acpi_walk_callback user_function)
{
        int seg, bus;
        unsigned long long tmp;
        acpi_status status;
        acpi_handle dummy_handle;
        struct pci_bus *pci_bus;
        struct callback_args context;

        /* If the bridge doesn't have _STA, we assume it is always there */
        status = acpi_get_handle(handle, "_STA", &dummy_handle);
        if (ACPI_SUCCESS(status)) {
                status = acpi_evaluate_integer(handle, "_STA", NULL, &tmp);
                if (ACPI_FAILURE(status)) {
                        info("%s: _STA evaluation failure\n", __func__);
                        return 0;
                }
                if ((tmp & ACPI_STA_DEVICE_FUNCTIONING) == 0)
                        /* don't register this object */
                        return 0;
        }

        status = acpi_evaluate_integer(handle, "_SEG", NULL, &tmp);
        seg = ACPI_SUCCESS(status) ? tmp : 0;

        status = acpi_evaluate_integer(handle, "_BBN", NULL, &tmp);
        bus = ACPI_SUCCESS(status) ? tmp : 0;

        pci_bus = pci_find_bus(seg, bus);
        if (!pci_bus)
                return 0;

        context.pci_bus = pci_bus;
        context.user_function = user_function;
        context.root_handle = handle;

        dbg("root bridge walk, pci_bus = %x\n", pci_bus->number);
        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
                                     user_function, NULL, &context, NULL);
        if (ACPI_FAILURE(status))
                return status;

        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, (u32)1,
                                     walk_p2p_bridge, NULL, &context, NULL);
        if (ACPI_FAILURE(status))
                err("%s: walk_p2p_bridge failure - %d\n", __func__, status);

        return status;
}

/*
 * acpi_pci_slot_add
 * @handle: points to an acpi_pci_root
 */
static int
acpi_pci_slot_add(acpi_handle handle)
{
        acpi_status status;

        status = walk_root_bridge(handle, register_slot);
        if (ACPI_FAILURE(status))
                err("%s: register_slot failure - %d\n", __func__, status);

        return status;
}

/*
 * acpi_pci_slot_remove
 * @handle: points to an acpi_pci_root
 */
static void
acpi_pci_slot_remove(acpi_handle handle)
{
        struct acpi_pci_slot *slot, *tmp;
        struct pci_bus *pbus;

        mutex_lock(&slot_list_lock);
        list_for_each_entry_safe(slot, tmp, &slot_list, list) {
                if (slot->root_handle == handle) {
                        list_del(&slot->list);
                        pbus = slot->pci_slot->bus;
                        pci_destroy_slot(slot->pci_slot);
                        put_device(&pbus->dev);
                        kfree(slot);
                }
        }
        mutex_unlock(&slot_list_lock);
}

static int do_sta_before_sun(const struct dmi_system_id *d)
{
        info("%s detected: will evaluate _STA before calling _SUN\n", d->ident);
        check_sta_before_sun = 1;
        return 0;
}

static struct dmi_system_id acpi_pci_slot_dmi_table[] __initdata = {
        /*
         * Fujitsu Primequest machines will return 1023 to indicate an
         * error if the _SUN method is evaluated on SxFy objects that
         * are not present (as indicated by _STA), so for those machines,
         * we want to check _STA before evaluating _SUN.
         */
        {
         .callback = do_sta_before_sun,
         .ident = "Fujitsu PRIMEQUEST",
         .matches = {
                DMI_MATCH(DMI_BIOS_VENDOR, "FUJITSU LIMITED"),
                DMI_MATCH(DMI_BIOS_VERSION, "PRIMEQUEST"),
                },
        },
        {}
};

static int __init
acpi_pci_slot_init(void)
{
        dmi_check_system(acpi_pci_slot_dmi_table);
        acpi_pci_register_driver(&acpi_pci_slot_driver);
        return 0;
}

static void __exit
acpi_pci_slot_exit(void)
{
        acpi_pci_unregister_driver(&acpi_pci_slot_driver);
}

module_init(acpi_pci_slot_init);
module_exit(acpi_pci_slot_exit);