/*
 * 8259 interrupt controller emulation
 *
 * Copyright (c) 2003-2004 Fabrice Bellard
 * Copyright (c) 2007 Intel Corporation
 * Copyright 2009 Red Hat, Inc. and/or its affiliates.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * Authors:
 *   Yaozu (Eddie) Dong <Eddie.dong@intel.com>
 *   Port from Qemu.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/bitops.h>

#include "ioapic.h"
#include "irq.h"

#include <linux/kvm_host.h>
#include "trace.h"

#define pr_pic_unimpl(fmt, ...) \
        pr_err_ratelimited("pic: " fmt, ## __VA_ARGS__)

static void pic_irq_request(struct kvm *kvm, int level);

static void pic_lock(struct kvm_pic *s)
        __acquires(&s->lock)
{
        spin_lock(&s->lock);
}

static void pic_unlock(struct kvm_pic *s)
        __releases(&s->lock)
{
        bool wakeup = s->wakeup_needed;
        struct kvm_vcpu *vcpu;
        unsigned long i;

        s->wakeup_needed = false;

        spin_unlock(&s->lock);

        if (wakeup) {
                kvm_for_each_vcpu(i, vcpu, s->kvm) {
                        if (kvm_apic_accept_pic_intr(vcpu)) {
                                kvm_make_request(KVM_REQ_EVENT, vcpu);
                                kvm_vcpu_kick(vcpu);
                                return;
                        }
                }
        }
}

static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
{
        s->isr &= ~(1 << irq);
        if (s != &s->pics_state->pics[0])
                irq += 8;
        /*
         * We are dropping lock while calling ack notifiers since ack
         * notifier callbacks for assigned devices call into PIC recursively.
         * Other interrupt may be delivered to PIC while lock is dropped but
         * it should be safe since PIC state is already updated at this stage.
         */
        pic_unlock(s->pics_state);
        kvm_notify_acked_irq(s->pics_state->kvm, SELECT_PIC(irq), irq);
        pic_lock(s->pics_state);
}

/*
 * set irq level. If an edge is detected, then the IRR is set to 1
 */
static inline int pic_set_irq1(struct kvm_kpic_state *s, int irq, int level)
{
        int mask, ret = 1;
        mask = 1 << irq;
        if (s->elcr & mask)     /* level triggered */
                if (level) {
                        ret = !(s->irr & mask);
                        s->irr |= mask;
                        s->last_irr |= mask;
                } else {
                        s->irr &= ~mask;
                        s->last_irr &= ~mask;
                }
        else    /* edge triggered */
                if (level) {
                        if ((s->last_irr & mask) == 0) {
                                ret = !(s->irr & mask);
                                s->irr |= mask;
                        }
                        s->last_irr |= mask;
                } else
                        s->last_irr &= ~mask;

        return (s->imr & mask) ? -1 : ret;
}

/*
 * return the highest priority found in mask (highest = smallest
 * number). Return 8 if no irq
 */
static inline int get_priority(struct kvm_kpic_state *s, int mask)
{
        int priority;
        if (mask == 0)
                return 8;
        priority = 0;
        while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0)
                priority++;
        return priority;
}

/*
 * return the pic wanted interrupt. return -1 if none
 */
static int pic_get_irq(struct kvm_kpic_state *s)
{
        int mask, cur_priority, priority;

        mask = s->irr & ~s->imr;
        priority = get_priority(s, mask);
        if (priority == 8)
                return -1;
        /*
         * compute current priority. If special fully nested mode on the
         * master, the IRQ coming from the slave is not taken into account
         * for the priority computation.
         */
        mask = s->isr;
        if (s->special_fully_nested_mode && s == &s->pics_state->pics[0])
                mask &= ~(1 << 2);
        cur_priority = get_priority(s, mask);
        if (priority < cur_priority)
                /*
                 * higher priority found: an irq should be generated
                 */
                return (priority + s->priority_add) & 7;
        else
                return -1;
}

/*
 * raise irq to CPU if necessary. must be called every time the active
 * irq may change
 */
static void pic_update_irq(struct kvm_pic *s)
{
        int irq2, irq;

        irq2 = pic_get_irq(&s->pics[1]);
        if (irq2 >= 0) {
                /*
                 * if irq request by slave pic, signal master PIC
                 */
                pic_set_irq1(&s->pics[0], 2, 1);
                pic_set_irq1(&s->pics[0], 2, 0);
        }
        irq = pic_get_irq(&s->pics[0]);
        pic_irq_request(s->kvm, irq >= 0);
}

void kvm_pic_update_irq(struct kvm_pic *s)
{
        pic_lock(s);
        pic_update_irq(s);
        pic_unlock(s);
}

int kvm_pic_set_irq(struct kvm_kernel_irq_routing_entry *e, struct kvm *kvm,
                    int irq_source_id, int level, bool line_status)
{
        struct kvm_pic *s = kvm->arch.vpic;
        int irq = e->irqchip.pin;
        int ret, irq_level;

        BUG_ON(irq < 0 || irq >= PIC_NUM_PINS);

        pic_lock(s);
        irq_level = __kvm_irq_line_state(&s->irq_states[irq],
                                         irq_source_id, level);
        ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, irq_level);
        pic_update_irq(s);
        trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
                              s->pics[irq >> 3].imr, ret == 0);
        pic_unlock(s);

        return ret;
}

/*
 * acknowledge interrupt 'irq'
 */
static inline void pic_intack(struct kvm_kpic_state *s, int irq)
{
        s->isr |= 1 << irq;
        /*
         * We don't clear a level sensitive interrupt here
         */
        if (!(s->elcr & (1 << irq)))
                s->irr &= ~(1 << irq);

        if (s->auto_eoi) {
                if (s->rotate_on_auto_eoi)
                        s->priority_add = (irq + 1) & 7;
                pic_clear_isr(s, irq);
        }

}

int kvm_pic_read_irq(struct kvm *kvm)
{
        int irq, irq2, intno;
        struct kvm_pic *s = kvm->arch.vpic;

        s->output = 0;

        pic_lock(s);
        irq = pic_get_irq(&s->pics[0]);
        if (irq >= 0) {
                pic_intack(&s->pics[0], irq);
                if (irq == 2) {
                        irq2 = pic_get_irq(&s->pics[1]);
                        if (irq2 >= 0)
                                pic_intack(&s->pics[1], irq2);
                        else
                                /*
                                 * spurious IRQ on slave controller
                                 */
                                irq2 = 7;
                        intno = s->pics[1].irq_base + irq2;
                } else
                        intno = s->pics[0].irq_base + irq;
        } else {
                /*
                 * spurious IRQ on host controller
                 */
                irq = 7;
                intno = s->pics[0].irq_base + irq;
        }
        pic_update_irq(s);
        pic_unlock(s);

        return intno;
}

static void kvm_pic_reset(struct kvm_kpic_state *s)
{
        int irq;
        unsigned long i;
        struct kvm_vcpu *vcpu;
        u8 edge_irr = s->irr & ~s->elcr;
        bool found = false;

        s->last_irr = 0;
        s->irr &= s->elcr;
        s->imr = 0;
        s->priority_add = 0;
        s->special_mask = 0;
        s->read_reg_select = 0;
        if (!s->init4) {
                s->special_fully_nested_mode = 0;
                s->auto_eoi = 0;
        }
        s->init_state = 1;

        kvm_for_each_vcpu(i, vcpu, s->pics_state->kvm)
                if (kvm_apic_accept_pic_intr(vcpu)) {
                        found = true;
                        break;
                }


        if (!found)
                return;

        for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
                if (edge_irr & (1 << irq))
                        pic_clear_isr(s, irq);
}

static void pic_ioport_write(void *opaque, u32 addr, u32 val)
{
        struct kvm_kpic_state *s = opaque;
        int priority, cmd, irq;

        addr &= 1;
        if (addr == 0) {
                if (val & 0x10) {
                        s->init4 = val & 1;
                        if (val & 0x02)
                                pr_pic_unimpl("single mode not supported");
                        if (val & 0x08)
                                pr_pic_unimpl(
                                                "level sensitive irq not supported");
                        kvm_pic_reset(s);
                } else if (val & 0x08) {
                        if (val & 0x04)
                                s->poll = 1;
                        if (val & 0x02)
                                s->read_reg_select = val & 1;
                        if (val & 0x40)
                                s->special_mask = (val >> 5) & 1;
                } else {
                        cmd = val >> 5;
                        switch (cmd) {
                        case 0:
                        case 4:
                                s->rotate_on_auto_eoi = cmd >> 2;
                                break;
                        case 1: /* end of interrupt */
                        case 5:
                                priority = get_priority(s, s->isr);
                                if (priority != 8) {
                                        irq = (priority + s->priority_add) & 7;
                                        if (cmd == 5)
                                                s->priority_add = (irq + 1) & 7;
                                        pic_clear_isr(s, irq);
                                        pic_update_irq(s->pics_state);
                                }
                                break;
                        case 3:
                                irq = val & 7;
                                pic_clear_isr(s, irq);
                                pic_update_irq(s->pics_state);
                                break;
                        case 6:
                                s->priority_add = (val + 1) & 7;
                                pic_update_irq(s->pics_state);
                                break;
                        case 7:
                                irq = val & 7;
                                s->priority_add = (irq + 1) & 7;
                                pic_clear_isr(s, irq);
                                pic_update_irq(s->pics_state);
                                break;
                        default:
                                break;  /* no operation */
                        }
                }
        } else
                switch (s->init_state) {
                case 0: { /* normal mode */
                        u8 imr_diff = s->imr ^ val,
                                off = (s == &s->pics_state->pics[0]) ? 0 : 8;
                        s->imr = val;
                        for (irq = 0; irq < PIC_NUM_PINS/2; irq++)
                                if (imr_diff & (1 << irq))
                                        kvm_fire_mask_notifiers(
                                                s->pics_state->kvm,
                                                SELECT_PIC(irq + off),
                                                irq + off,
                                                !!(s->imr & (1 << irq)));
                        pic_update_irq(s->pics_state);
                        break;
                }
                case 1:
                        s->irq_base = val & 0xf8;
                        s->init_state = 2;
                        break;
                case 2:
                        if (s->init4)
                                s->init_state = 3;
                        else
                                s->init_state = 0;
                        break;
                case 3:
                        s->special_fully_nested_mode = (val >> 4) & 1;
                        s->auto_eoi = (val >> 1) & 1;
                        s->init_state = 0;
                        break;
                }
}

static u32 pic_poll_read(struct kvm_kpic_state *s, u32 addr1)
{
        int ret;

        ret = pic_get_irq(s);
        if (ret >= 0) {
                if (addr1 >> 7) {
                        s->pics_state->pics[0].isr &= ~(1 << 2);
                        s->pics_state->pics[0].irr &= ~(1 << 2);
                }
                s->irr &= ~(1 << ret);
                pic_clear_isr(s, ret);
                if (addr1 >> 7 || ret != 2)
                        pic_update_irq(s->pics_state);
                /* Bit 7 is 1, means there's an interrupt */
                ret |= 0x80;
        } else {
                /* Bit 7 is 0, means there's no interrupt */
                ret = 0x07;
                pic_update_irq(s->pics_state);
        }

        return ret;
}

static u32 pic_ioport_read(void *opaque, u32 addr)
{
        struct kvm_kpic_state *s = opaque;
        int ret;

        if (s->poll) {
                ret = pic_poll_read(s, addr);
                s->poll = 0;
        } else
                if ((addr & 1) == 0)
                        if (s->read_reg_select)
                                ret = s->isr;
                        else
                                ret = s->irr;
                else
                        ret = s->imr;
        return ret;
}

static void elcr_ioport_write(void *opaque, u32 val)
{
        struct kvm_kpic_state *s = opaque;
        s->elcr = val & s->elcr_mask;
}

static u32 elcr_ioport_read(void *opaque)
{
        struct kvm_kpic_state *s = opaque;
        return s->elcr;
}

static int picdev_write(struct kvm_pic *s,
                         gpa_t addr, int len, const void *val)
{
        unsigned char data = *(unsigned char *)val;

        if (len != 1) {
                pr_pic_unimpl("non byte write\n");
                return 0;
        }
        switch (addr) {
        case 0x20:
        case 0x21:
                pic_lock(s);
                pic_ioport_write(&s->pics[0], addr, data);
                pic_unlock(s);
                break;
        case 0xa0:
        case 0xa1:
                pic_lock(s);
                pic_ioport_write(&s->pics[1], addr, data);
                pic_unlock(s);
                break;
        case 0x4d0:
        case 0x4d1:
                pic_lock(s);
                elcr_ioport_write(&s->pics[addr & 1], data);
                pic_unlock(s);
                break;
        default:
                return -EOPNOTSUPP;
        }
        return 0;
}

static int picdev_read(struct kvm_pic *s,
                       gpa_t addr, int len, void *val)
{
        unsigned char *data = (unsigned char *)val;

        if (len != 1) {
                memset(val, 0, len);
                pr_pic_unimpl("non byte read\n");
                return 0;
        }
        switch (addr) {
        case 0x20:
        case 0x21:
        case 0xa0:
        case 0xa1:
                pic_lock(s);
                *data = pic_ioport_read(&s->pics[addr >> 7], addr);
                pic_unlock(s);
                break;
        case 0x4d0:
        case 0x4d1:
                pic_lock(s);
                *data = elcr_ioport_read(&s->pics[addr & 1]);
                pic_unlock(s);
                break;
        default:
                return -EOPNOTSUPP;
        }
        return 0;
}

static int picdev_master_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
                               gpa_t addr, int len, const void *val)
{
        return picdev_write(container_of(dev, struct kvm_pic, dev_master),
                            addr, len, val);
}

static int picdev_master_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
                              gpa_t addr, int len, void *val)
{
        return picdev_read(container_of(dev, struct kvm_pic, dev_master),
                            addr, len, val);
}

static int picdev_slave_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
                              gpa_t addr, int len, const void *val)
{
        return picdev_write(container_of(dev, struct kvm_pic, dev_slave),
                            addr, len, val);
}

static int picdev_slave_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
                             gpa_t addr, int len, void *val)
{
        return picdev_read(container_of(dev, struct kvm_pic, dev_slave),
                            addr, len, val);
}

static int picdev_elcr_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
                             gpa_t addr, int len, const void *val)
{
        return picdev_write(container_of(dev, struct kvm_pic, dev_elcr),
                            addr, len, val);
}

static int picdev_elcr_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
                            gpa_t addr, int len, void *val)
{
        return picdev_read(container_of(dev, struct kvm_pic, dev_elcr),
                            addr, len, val);
}

/*
 * callback when PIC0 irq status changed
 */
static void pic_irq_request(struct kvm *kvm, int level)
{
        struct kvm_pic *s = kvm->arch.vpic;

        if (!s->output && level)
                s->wakeup_needed = true;
        s->output = level;
}

static const struct kvm_io_device_ops picdev_master_ops = {
        .read     = picdev_master_read,
        .write    = picdev_master_write,
};

static const struct kvm_io_device_ops picdev_slave_ops = {
        .read     = picdev_slave_read,
        .write    = picdev_slave_write,
};

static const struct kvm_io_device_ops picdev_elcr_ops = {
        .read     = picdev_elcr_read,
        .write    = picdev_elcr_write,
};

int kvm_pic_init(struct kvm *kvm)
{
        struct kvm_pic *s;
        int ret;

        s = kzalloc_obj(struct kvm_pic, GFP_KERNEL_ACCOUNT);
        if (!s)
                return -ENOMEM;
        spin_lock_init(&s->lock);
        s->kvm = kvm;
        s->pics[0].elcr_mask = 0xf8;
        s->pics[1].elcr_mask = 0xde;
        s->pics[0].pics_state = s;
        s->pics[1].pics_state = s;

        /*
         * Initialize PIO device
         */
        kvm_iodevice_init(&s->dev_master, &picdev_master_ops);
        kvm_iodevice_init(&s->dev_slave, &picdev_slave_ops);
        kvm_iodevice_init(&s->dev_elcr, &picdev_elcr_ops);
        mutex_lock(&kvm->slots_lock);
        ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x20, 2,
                                      &s->dev_master);
        if (ret < 0)
                goto fail_unlock;

        ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0xa0, 2, &s->dev_slave);
        if (ret < 0)
                goto fail_unreg_2;

        ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, 0x4d0, 2, &s->dev_elcr);
        if (ret < 0)
                goto fail_unreg_1;

        mutex_unlock(&kvm->slots_lock);

        kvm->arch.vpic = s;

        return 0;

fail_unreg_1:
        kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_slave);

fail_unreg_2:
        kvm_io_bus_unregister_dev(kvm, KVM_PIO_BUS, &s->dev_master);

fail_unlock:
        mutex_unlock(&kvm->slots_lock);

        kfree(s);

        return ret;
}

void kvm_pic_destroy(struct kvm *kvm)
{
        struct kvm_pic *vpic = kvm->arch.vpic;

        if (!vpic)
                return;

        mutex_lock(&kvm->slots_lock);
        kvm_io_bus_unregister_dev(vpic->kvm, KVM_PIO_BUS, &vpic->dev_master);
        kvm_io_bus_unregister_dev(vpic->kvm, KVM_PIO_BUS, &vpic->dev_slave);
        kvm_io_bus_unregister_dev(vpic->kvm, KVM_PIO_BUS, &vpic->dev_elcr);
        mutex_unlock(&kvm->slots_lock);

        kvm->arch.vpic = NULL;
        kfree(vpic);
}