/*
 * Copyright (C) 2016 Linaro
 * Author: Christoffer Dall <christoffer.dall@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/interrupt.h>
#include <linux/kvm_host.h>
#include <linux/seq_file.h>
#include <kvm/arm_vgic.h>
#include <asm/kvm_mmu.h>
#include "vgic.h"

/*
 * Structure to control looping through the entire vgic state.  We start at
 * zero for each field and move upwards.  So, if dist_id is 0 we print the
 * distributor info.  When dist_id is 1, we have already printed it and move
 * on.
 *
 * When vcpu_id < nr_cpus we print the vcpu info until vcpu_id == nr_cpus and
 * so on.
 */
struct vgic_state_iter {
        int nr_cpus;
        int nr_spis;
        int dist_id;
        int vcpu_id;
        int intid;
};

static void iter_next(struct vgic_state_iter *iter)
{
        if (iter->dist_id == 0) {
                iter->dist_id++;
                return;
        }

        iter->intid++;
        if (iter->intid == VGIC_NR_PRIVATE_IRQS &&
            ++iter->vcpu_id < iter->nr_cpus)
                iter->intid = 0;
}

static void iter_init(struct kvm *kvm, struct vgic_state_iter *iter,
                      loff_t pos)
{
        int nr_cpus = atomic_read(&kvm->online_vcpus);

        memset(iter, 0, sizeof(*iter));

        iter->nr_cpus = nr_cpus;
        iter->nr_spis = kvm->arch.vgic.nr_spis;

        /* Fast forward to the right position if needed */
        while (pos--)
                iter_next(iter);
}

static bool end_of_vgic(struct vgic_state_iter *iter)
{
        return iter->dist_id > 0 &&
                iter->vcpu_id == iter->nr_cpus &&
                (iter->intid - VGIC_NR_PRIVATE_IRQS) == iter->nr_spis;
}

static void *vgic_debug_start(struct seq_file *s, loff_t *pos)
{
        struct kvm *kvm = (struct kvm *)s->private;
        struct vgic_state_iter *iter;

        mutex_lock(&kvm->lock);
        iter = kvm->arch.vgic.iter;
        if (iter) {
                iter = ERR_PTR(-EBUSY);
                goto out;
        }

        iter = kmalloc(sizeof(*iter), GFP_KERNEL);
        if (!iter) {
                iter = ERR_PTR(-ENOMEM);
                goto out;
        }

        iter_init(kvm, iter, *pos);
        kvm->arch.vgic.iter = iter;

        if (end_of_vgic(iter))
                iter = NULL;
out:
        mutex_unlock(&kvm->lock);
        return iter;
}

static void *vgic_debug_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct kvm *kvm = (struct kvm *)s->private;
        struct vgic_state_iter *iter = kvm->arch.vgic.iter;

        ++*pos;
        iter_next(iter);
        if (end_of_vgic(iter))
                iter = NULL;
        return iter;
}

static void vgic_debug_stop(struct seq_file *s, void *v)
{
        struct kvm *kvm = (struct kvm *)s->private;
        struct vgic_state_iter *iter;

        /*
         * If the seq file wasn't properly opened, there's nothing to clearn
         * up.
         */
        if (IS_ERR(v))
                return;

        mutex_lock(&kvm->lock);
        iter = kvm->arch.vgic.iter;
        kfree(iter);
        kvm->arch.vgic.iter = NULL;
        mutex_unlock(&kvm->lock);
}

static void print_dist_state(struct seq_file *s, struct vgic_dist *dist)
{
        seq_printf(s, "Distributor\n");
        seq_printf(s, "===========\n");
        seq_printf(s, "vgic_model:\t%s\n",
                   (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) ?
                   "GICv3" : "GICv2");
        seq_printf(s, "nr_spis:\t%d\n", dist->nr_spis);
        seq_printf(s, "enabled:\t%d\n", dist->enabled);
        seq_printf(s, "\n");

        seq_printf(s, "P=pending_latch, L=line_level, A=active\n");
        seq_printf(s, "E=enabled, H=hw, C=config (level=1, edge=0)\n");
}

static void print_header(struct seq_file *s, struct vgic_irq *irq,
                         struct kvm_vcpu *vcpu)
{
        int id = 0;
        char *hdr = "SPI ";

        if (vcpu) {
                hdr = "VCPU";
                id = vcpu->vcpu_id;
        }

        seq_printf(s, "\n");
        seq_printf(s, "%s%2d TYP   ID TGT_ID PLAEHC     HWID   TARGET SRC PRI VCPU_ID\n", hdr, id);
        seq_printf(s, "---------------------------------------------------------------\n");
}

static void print_irq_state(struct seq_file *s, struct vgic_irq *irq,
                            struct kvm_vcpu *vcpu)
{
        char *type;
        if (irq->intid < VGIC_NR_SGIS)
                type = "SGI";
        else if (irq->intid < VGIC_NR_PRIVATE_IRQS)
                type = "PPI";
        else
                type = "SPI";

        if (irq->intid ==0 || irq->intid == VGIC_NR_PRIVATE_IRQS)
                print_header(s, irq, vcpu);

        seq_printf(s, "       %s %4d "
                      "    %2d "
                      "%d%d%d%d%d%d "
                      "%8d "
                      "%8x "
                      " %2x "
                      "%3d "
                      "     %2d "
                      "\n",
                        type, irq->intid,
                        (irq->target_vcpu) ? irq->target_vcpu->vcpu_id : -1,
                        irq->pending_latch,
                        irq->line_level,
                        irq->active,
                        irq->enabled,
                        irq->hw,
                        irq->config == VGIC_CONFIG_LEVEL,
                        irq->hwintid,
                        irq->mpidr,
                        irq->source,
                        irq->priority,
                        (irq->vcpu) ? irq->vcpu->vcpu_id : -1);

}

static int vgic_debug_show(struct seq_file *s, void *v)
{
        struct kvm *kvm = (struct kvm *)s->private;
        struct vgic_state_iter *iter = (struct vgic_state_iter *)v;
        struct vgic_irq *irq;
        struct kvm_vcpu *vcpu = NULL;

        if (iter->dist_id == 0) {
                print_dist_state(s, &kvm->arch.vgic);
                return 0;
        }

        if (!kvm->arch.vgic.initialized)
                return 0;

        if (iter->vcpu_id < iter->nr_cpus) {
                vcpu = kvm_get_vcpu(kvm, iter->vcpu_id);
                irq = &vcpu->arch.vgic_cpu.private_irqs[iter->intid];
        } else {
                irq = &kvm->arch.vgic.spis[iter->intid - VGIC_NR_PRIVATE_IRQS];
        }

        spin_lock(&irq->irq_lock);
        print_irq_state(s, irq, vcpu);
        spin_unlock(&irq->irq_lock);

        return 0;
}

static const struct seq_operations vgic_debug_seq_ops = {
        .start = vgic_debug_start,
        .next  = vgic_debug_next,
        .stop  = vgic_debug_stop,
        .show  = vgic_debug_show
};

static int debug_open(struct inode *inode, struct file *file)
{
        int ret;
        ret = seq_open(file, &vgic_debug_seq_ops);
        if (!ret) {
                struct seq_file *seq;
                /* seq_open will have modified file->private_data */
                seq = file->private_data;
                seq->private = inode->i_private;
        }

        return ret;
};

static const struct file_operations vgic_debug_fops = {
        .owner   = THIS_MODULE,
        .open    = debug_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release
};

int vgic_debug_init(struct kvm *kvm)
{
        if (!kvm->debugfs_dentry)
                return -ENOENT;

        if (!debugfs_create_file("vgic-state", 0444,
                                 kvm->debugfs_dentry,
                                 kvm,
                                 &vgic_debug_fops))
                return -ENOMEM;

        return 0;
}

int vgic_debug_destroy(struct kvm *kvm)
{
        return 0;
}