// SPDX-License-Identifier: GPL-2.0+
/*
 * CompactPCI Hot Plug Driver
 *
 * Copyright (C) 2002,2005 SOMA Networks, Inc.
 * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2001 IBM Corp.
 *
 * All rights reserved.
 *
 * Send feedback to <scottm@somanetworks.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/atomic.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include "cpci_hotplug.h"

#define DRIVER_AUTHOR   "Scott Murray <scottm@somanetworks.com>"
#define DRIVER_DESC     "CompactPCI Hot Plug Core"

#define MY_NAME "cpci_hotplug"

#define dbg(format, arg...)                                     \
        do {                                                    \
                if (cpci_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 DECLARE_RWSEM(list_rwsem);
static LIST_HEAD(slot_list);
static int slots;
static atomic_t extracting;
int cpci_debug;
static struct cpci_hp_controller *controller;
static struct task_struct *cpci_thread;
static int thread_finished;

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 get_power_status(struct hotplug_slot *slot, u8 *value);
static int get_attention_status(struct hotplug_slot *slot, u8 *value);
static int get_adapter_status(struct hotplug_slot *slot, u8 *value);
static int get_latch_status(struct hotplug_slot *slot, u8 *value);

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

static int
enable_slot(struct hotplug_slot *hotplug_slot)
{
        struct slot *slot = to_slot(hotplug_slot);

        dbg("%s - physical_slot = %s", __func__, slot_name(slot));

        return 0;
}

static int
disable_slot(struct hotplug_slot *hotplug_slot)
{
        struct slot *slot = to_slot(hotplug_slot);
        int retval = 0;

        dbg("%s - physical_slot = %s", __func__, slot_name(slot));

        down_write(&list_rwsem);

        /* Unconfigure device */
        dbg("%s - unconfiguring slot %s", __func__, slot_name(slot));
        retval = cpci_unconfigure_slot(slot);
        if (retval) {
                err("%s - could not unconfigure slot %s",
                    __func__, slot_name(slot));
                goto disable_error;
        }
        dbg("%s - finished unconfiguring slot %s", __func__, slot_name(slot));

        /* Clear EXT (by setting it) */
        if (cpci_clear_ext(slot)) {
                err("%s - could not clear EXT for slot %s",
                    __func__, slot_name(slot));
                retval = -ENODEV;
                goto disable_error;
        }
        cpci_led_on(slot);

        slot->adapter_status = 0;

        if (slot->extracting) {
                slot->extracting = 0;
                atomic_dec(&extracting);
        }
disable_error:
        up_write(&list_rwsem);
        return retval;
}

static u8
cpci_get_power_status(struct slot *slot)
{
        return 1;
}

static int
get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
        struct slot *slot = to_slot(hotplug_slot);

        *value = cpci_get_power_status(slot);
        return 0;
}

static int
get_attention_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
        struct slot *slot = to_slot(hotplug_slot);

        *value = cpci_get_attention_status(slot);
        return 0;
}

static int
set_attention_status(struct hotplug_slot *hotplug_slot, u8 status)
{
        return cpci_set_attention_status(to_slot(hotplug_slot), status);
}

static int
get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
        struct slot *slot = to_slot(hotplug_slot);

        *value = slot->adapter_status;
        return 0;
}

static int
get_latch_status(struct hotplug_slot *hotplug_slot, u8 *value)
{
        struct slot *slot = to_slot(hotplug_slot);

        *value = slot->latch_status;
        return 0;
}

static void release_slot(struct slot *slot)
{
        pci_dev_put(slot->dev);
        kfree(slot);
}

#define SLOT_NAME_SIZE  6

int
cpci_hp_register_bus(struct pci_bus *bus, u8 first, u8 last)
{
        struct slot *slot;
        char name[SLOT_NAME_SIZE];
        int status;
        int i;

        if (!(controller && bus))
                return -ENODEV;

        /*
         * Create a structure for each slot, and register that slot
         * with the pci_hotplug subsystem.
         */
        for (i = first; i <= last; ++i) {
                slot = kzalloc_obj(struct slot);
                if (!slot) {
                        status = -ENOMEM;
                        goto error;
                }

                slot->bus = bus;
                slot->number = i;
                slot->devfn = PCI_DEVFN(i, 0);

                snprintf(name, SLOT_NAME_SIZE, "%02x:%02x", bus->number, i);

                slot->hotplug_slot.ops = &cpci_hotplug_slot_ops;

                dbg("registering slot %s", name);
                status = pci_hp_register(&slot->hotplug_slot, bus, i, name);
                if (status) {
                        err("pci_hp_register failed with error %d", status);
                        goto error_slot;
                }
                dbg("slot registered with name: %s", slot_name(slot));

                /* Add slot to our internal list */
                down_write(&list_rwsem);
                list_add(&slot->slot_list, &slot_list);
                slots++;
                up_write(&list_rwsem);
        }
        return 0;
error_slot:
        kfree(slot);
error:
        return status;
}
EXPORT_SYMBOL_GPL(cpci_hp_register_bus);

int
cpci_hp_unregister_bus(struct pci_bus *bus)
{
        struct slot *slot;
        struct slot *tmp;
        int status = 0;

        down_write(&list_rwsem);
        if (!slots) {
                up_write(&list_rwsem);
                return -1;
        }
        list_for_each_entry_safe(slot, tmp, &slot_list, slot_list) {
                if (slot->bus == bus) {
                        list_del(&slot->slot_list);
                        slots--;

                        dbg("deregistering slot %s", slot_name(slot));
                        pci_hp_deregister(&slot->hotplug_slot);
                        release_slot(slot);
                }
        }
        up_write(&list_rwsem);
        return status;
}
EXPORT_SYMBOL_GPL(cpci_hp_unregister_bus);

/* This is the interrupt mode interrupt handler */
static irqreturn_t
cpci_hp_intr(int irq, void *data)
{
        dbg("entered cpci_hp_intr");

        /* Check to see if it was our interrupt */
        if ((controller->irq_flags & IRQF_SHARED) &&
            !controller->ops->check_irq(controller->dev_id)) {
                dbg("exited cpci_hp_intr, not our interrupt");
                return IRQ_NONE;
        }

        /* Disable ENUM interrupt */
        controller->ops->disable_irq();

        /* Trigger processing by the event thread */
        wake_up_process(cpci_thread);
        return IRQ_HANDLED;
}

/*
 * According to PICMG 2.1 R2.0, section 6.3.2, upon
 * initialization, the system driver shall clear the
 * INS bits of the cold-inserted devices.
 */
static int
init_slots(int clear_ins)
{
        struct slot *slot;
        struct pci_dev *dev;

        dbg("%s - enter", __func__);
        down_read(&list_rwsem);
        if (!slots) {
                up_read(&list_rwsem);
                return -1;
        }
        list_for_each_entry(slot, &slot_list, slot_list) {
                dbg("%s - looking at slot %s", __func__, slot_name(slot));
                if (clear_ins && cpci_check_and_clear_ins(slot))
                        dbg("%s - cleared INS for slot %s",
                            __func__, slot_name(slot));
                dev = pci_get_slot(slot->bus, PCI_DEVFN(slot->number, 0));
                if (dev) {
                        slot->adapter_status = 1;
                        slot->latch_status = 1;
                        slot->dev = dev;
                }
        }
        up_read(&list_rwsem);
        dbg("%s - exit", __func__);
        return 0;
}

static int
check_slots(void)
{
        struct slot *slot;
        int extracted;
        int inserted;
        u16 hs_csr;

        down_read(&list_rwsem);
        if (!slots) {
                up_read(&list_rwsem);
                err("no slots registered, shutting down");
                return -1;
        }
        extracted = inserted = 0;
        list_for_each_entry(slot, &slot_list, slot_list) {
                dbg("%s - looking at slot %s", __func__, slot_name(slot));
                if (cpci_check_and_clear_ins(slot)) {
                        /*
                         * Some broken hardware (e.g. PLX 9054AB) asserts
                         * ENUM# twice...
                         */
                        if (slot->dev) {
                                warn("slot %s already inserted",
                                     slot_name(slot));
                                inserted++;
                                continue;
                        }

                        /* Process insertion */
                        dbg("%s - slot %s inserted", __func__, slot_name(slot));

                        /* GSM, debug */
                        hs_csr = cpci_get_hs_csr(slot);
                        dbg("%s - slot %s HS_CSR (1) = %04x",
                            __func__, slot_name(slot), hs_csr);

                        /* Configure device */
                        dbg("%s - configuring slot %s",
                            __func__, slot_name(slot));
                        if (cpci_configure_slot(slot)) {
                                err("%s - could not configure slot %s",
                                    __func__, slot_name(slot));
                                continue;
                        }
                        dbg("%s - finished configuring slot %s",
                            __func__, slot_name(slot));

                        /* GSM, debug */
                        hs_csr = cpci_get_hs_csr(slot);
                        dbg("%s - slot %s HS_CSR (2) = %04x",
                            __func__, slot_name(slot), hs_csr);

                        slot->latch_status = 1;
                        slot->adapter_status = 1;

                        cpci_led_off(slot);

                        /* GSM, debug */
                        hs_csr = cpci_get_hs_csr(slot);
                        dbg("%s - slot %s HS_CSR (3) = %04x",
                            __func__, slot_name(slot), hs_csr);

                        inserted++;
                } else if (cpci_check_ext(slot)) {
                        /* Process extraction request */
                        dbg("%s - slot %s extracted",
                            __func__, slot_name(slot));

                        /* GSM, debug */
                        hs_csr = cpci_get_hs_csr(slot);
                        dbg("%s - slot %s HS_CSR = %04x",
                            __func__, slot_name(slot), hs_csr);

                        if (!slot->extracting) {
                                slot->latch_status = 0;
                                slot->extracting = 1;
                                atomic_inc(&extracting);
                        }
                        extracted++;
                } else if (slot->extracting) {
                        hs_csr = cpci_get_hs_csr(slot);
                        if (hs_csr == 0xffff) {
                                /*
                                 * Hmmm, we're likely hosed at this point, should we
                                 * bother trying to tell the driver or not?
                                 */
                                err("card in slot %s was improperly removed",
                                    slot_name(slot));
                                slot->adapter_status = 0;
                                slot->extracting = 0;
                                atomic_dec(&extracting);
                        }
                }
        }
        up_read(&list_rwsem);
        dbg("inserted=%d, extracted=%d, extracting=%d",
            inserted, extracted, atomic_read(&extracting));
        if (inserted || extracted)
                return extracted;
        else if (!atomic_read(&extracting)) {
                err("cannot find ENUM# source, shutting down");
                return -1;
        }
        return 0;
}

/* This is the interrupt mode worker thread body */
static int
event_thread(void *data)
{
        int rc;

        dbg("%s - event thread started", __func__);
        while (1) {
                dbg("event thread sleeping");
                set_current_state(TASK_INTERRUPTIBLE);
                schedule();
                if (kthread_should_stop())
                        break;
                do {
                        rc = check_slots();
                        if (rc > 0) {
                                /* Give userspace a chance to handle extraction */
                                msleep(500);
                        } else if (rc < 0) {
                                dbg("%s - error checking slots", __func__);
                                thread_finished = 1;
                                goto out;
                        }
                } while (atomic_read(&extracting) && !kthread_should_stop());
                if (kthread_should_stop())
                        break;

                /* Re-enable ENUM# interrupt */
                dbg("%s - re-enabling irq", __func__);
                controller->ops->enable_irq();
        }
 out:
        return 0;
}

/* This is the polling mode worker thread body */
static int
poll_thread(void *data)
{
        int rc;

        while (1) {
                if (kthread_should_stop() || signal_pending(current))
                        break;
                if (controller->ops->query_enum()) {
                        do {
                                rc = check_slots();
                                if (rc > 0) {
                                        /* Give userspace a chance to handle extraction */
                                        msleep(500);
                                } else if (rc < 0) {
                                        dbg("%s - error checking slots", __func__);
                                        thread_finished = 1;
                                        goto out;
                                }
                        } while (atomic_read(&extracting) && !kthread_should_stop());
                }
                msleep(100);
        }
 out:
        return 0;
}

static int
cpci_start_thread(void)
{
        if (controller->irq)
                cpci_thread = kthread_run(event_thread, NULL, "cpci_hp_eventd");
        else
                cpci_thread = kthread_run(poll_thread, NULL, "cpci_hp_polld");
        if (IS_ERR(cpci_thread)) {
                err("Can't start up our thread");
                return PTR_ERR(cpci_thread);
        }
        thread_finished = 0;
        return 0;
}

static void
cpci_stop_thread(void)
{
        kthread_stop(cpci_thread);
        thread_finished = 1;
}

int
cpci_hp_register_controller(struct cpci_hp_controller *new_controller)
{
        int status = 0;

        if (controller)
                return -1;
        if (!(new_controller && new_controller->ops))
                return -EINVAL;
        if (new_controller->irq) {
                if (!(new_controller->ops->enable_irq &&
                     new_controller->ops->disable_irq))
                        status = -EINVAL;
                if (request_irq(new_controller->irq,
                               cpci_hp_intr,
                               new_controller->irq_flags,
                               MY_NAME,
                               new_controller->dev_id)) {
                        err("Can't get irq %d for the hotplug cPCI controller",
                            new_controller->irq);
                        status = -ENODEV;
                }
                dbg("%s - acquired controller irq %d",
                    __func__, new_controller->irq);
        }
        if (!status)
                controller = new_controller;
        return status;
}
EXPORT_SYMBOL_GPL(cpci_hp_register_controller);

static void
cleanup_slots(void)
{
        struct slot *slot;
        struct slot *tmp;

        /*
         * Unregister all of our slots with the pci_hotplug subsystem,
         * and free up all memory that we had allocated.
         */
        down_write(&list_rwsem);
        if (!slots)
                goto cleanup_null;
        list_for_each_entry_safe(slot, tmp, &slot_list, slot_list) {
                list_del(&slot->slot_list);
                pci_hp_deregister(&slot->hotplug_slot);
                release_slot(slot);
        }
cleanup_null:
        up_write(&list_rwsem);
}

int
cpci_hp_unregister_controller(struct cpci_hp_controller *old_controller)
{
        int status = 0;

        if (controller) {
                if (!thread_finished)
                        cpci_stop_thread();
                if (controller->irq)
                        free_irq(controller->irq, controller->dev_id);
                controller = NULL;
                cleanup_slots();
        } else
                status = -ENODEV;
        return status;
}
EXPORT_SYMBOL_GPL(cpci_hp_unregister_controller);

int
cpci_hp_start(void)
{
        static int first = 1;
        int status;

        dbg("%s - enter", __func__);
        if (!controller)
                return -ENODEV;

        down_read(&list_rwsem);
        if (list_empty(&slot_list)) {
                up_read(&list_rwsem);
                return -ENODEV;
        }
        up_read(&list_rwsem);

        status = init_slots(first);
        if (first)
                first = 0;
        if (status)
                return status;

        status = cpci_start_thread();
        if (status)
                return status;
        dbg("%s - thread started", __func__);

        if (controller->irq) {
                /* Start enum interrupt processing */
                dbg("%s - enabling irq", __func__);
                controller->ops->enable_irq();
        }
        dbg("%s - exit", __func__);
        return 0;
}
EXPORT_SYMBOL_GPL(cpci_hp_start);

int
cpci_hp_stop(void)
{
        if (!controller)
                return -ENODEV;
        if (controller->irq) {
                /* Stop enum interrupt processing */
                dbg("%s - disabling irq", __func__);
                controller->ops->disable_irq();
        }
        cpci_stop_thread();
        return 0;
}
EXPORT_SYMBOL_GPL(cpci_hp_stop);

int __init
cpci_hotplug_init(int debug)
{
        cpci_debug = debug;
        return 0;
}