/*
 * Copyright 2014 IBM Corp.
 *
 * 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; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <misc/cxl.h>
#include <linux/msi.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/sched/mm.h>

#include "cxl.h"

/*
 * Since we want to track memory mappings to be able to force-unmap
 * when the AFU is no longer reachable, we need an inode. For devices
 * opened through the cxl user API, this is not a problem, but a
 * userland process can also get a cxl fd through the cxl_get_fd()
 * API, which is used by the cxlflash driver.
 *
 * Therefore we implement our own simple pseudo-filesystem and inode
 * allocator. We don't use the anonymous inode, as we need the
 * meta-data associated with it (address_space) and it is shared by
 * other drivers/processes, so it could lead to cxl unmapping VMAs
 * from random processes.
 */

#define CXL_PSEUDO_FS_MAGIC     0x1697697f

static int cxl_fs_cnt;
static struct vfsmount *cxl_vfs_mount;

static const struct dentry_operations cxl_fs_dops = {
        .d_dname        = simple_dname,
};

static struct dentry *cxl_fs_mount(struct file_system_type *fs_type, int flags,
                                const char *dev_name, void *data)
{
        return mount_pseudo(fs_type, "cxl:", NULL, &cxl_fs_dops,
                        CXL_PSEUDO_FS_MAGIC);
}

static struct file_system_type cxl_fs_type = {
        .name           = "cxl",
        .owner          = THIS_MODULE,
        .mount          = cxl_fs_mount,
        .kill_sb        = kill_anon_super,
};


void cxl_release_mapping(struct cxl_context *ctx)
{
        if (ctx->kernelapi && ctx->mapping)
                simple_release_fs(&cxl_vfs_mount, &cxl_fs_cnt);
}

static struct file *cxl_getfile(const char *name,
                                const struct file_operations *fops,
                                void *priv, int flags)
{
        struct qstr this;
        struct path path;
        struct file *file;
        struct inode *inode = NULL;
        int rc;

        /* strongly inspired by anon_inode_getfile() */

        if (fops->owner && !try_module_get(fops->owner))
                return ERR_PTR(-ENOENT);

        rc = simple_pin_fs(&cxl_fs_type, &cxl_vfs_mount, &cxl_fs_cnt);
        if (rc < 0) {
                pr_err("Cannot mount cxl pseudo filesystem: %d\n", rc);
                file = ERR_PTR(rc);
                goto err_module;
        }

        inode = alloc_anon_inode(cxl_vfs_mount->mnt_sb);
        if (IS_ERR(inode)) {
                file = ERR_CAST(inode);
                goto err_fs;
        }

        file = ERR_PTR(-ENOMEM);
        this.name = name;
        this.len = strlen(name);
        this.hash = 0;
        path.dentry = d_alloc_pseudo(cxl_vfs_mount->mnt_sb, &this);
        if (!path.dentry)
                goto err_inode;

        path.mnt = mntget(cxl_vfs_mount);
        d_instantiate(path.dentry, inode);

        file = alloc_file(&path, OPEN_FMODE(flags), fops);
        if (IS_ERR(file))
                goto err_dput;
        file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
        file->private_data = priv;

        return file;

err_dput:
        path_put(&path);
err_inode:
        iput(inode);
err_fs:
        simple_release_fs(&cxl_vfs_mount, &cxl_fs_cnt);
err_module:
        module_put(fops->owner);
        return file;
}

struct cxl_context *cxl_dev_context_init(struct pci_dev *dev)
{
        struct cxl_afu *afu;
        struct cxl_context  *ctx;
        int rc;

        afu = cxl_pci_to_afu(dev);
        if (IS_ERR(afu))
                return ERR_CAST(afu);

        ctx = cxl_context_alloc();
        if (!ctx)
                return ERR_PTR(-ENOMEM);

        ctx->kernelapi = true;

        /* Make it a slave context.  We can promote it later? */
        rc = cxl_context_init(ctx, afu, false);
        if (rc)
                goto err_ctx;

        return ctx;

err_ctx:
        kfree(ctx);
        return ERR_PTR(rc);
}
EXPORT_SYMBOL_GPL(cxl_dev_context_init);

struct cxl_context *cxl_get_context(struct pci_dev *dev)
{
        return dev->dev.archdata.cxl_ctx;
}
EXPORT_SYMBOL_GPL(cxl_get_context);

int cxl_release_context(struct cxl_context *ctx)
{
        if (ctx->status >= STARTED)
                return -EBUSY;

        cxl_context_free(ctx);

        return 0;
}
EXPORT_SYMBOL_GPL(cxl_release_context);

static irq_hw_number_t cxl_find_afu_irq(struct cxl_context *ctx, int num)
{
        __u16 range;
        int r;

        for (r = 0; r < CXL_IRQ_RANGES; r++) {
                range = ctx->irqs.range[r];
                if (num < range) {
                        return ctx->irqs.offset[r] + num;
                }
                num -= range;
        }
        return 0;
}

int _cxl_next_msi_hwirq(struct pci_dev *pdev, struct cxl_context **ctx, int *afu_irq)
{
        if (*ctx == NULL || *afu_irq == 0) {
                *afu_irq = 1;
                *ctx = cxl_get_context(pdev);
        } else {
                (*afu_irq)++;
                if (*afu_irq > cxl_get_max_irqs_per_process(pdev)) {
                        *ctx = list_next_entry(*ctx, extra_irq_contexts);
                        *afu_irq = 1;
                }
        }
        return cxl_find_afu_irq(*ctx, *afu_irq);
}
/* Exported via cxl_base */

int cxl_set_priv(struct cxl_context *ctx, void *priv)
{
        if (!ctx)
                return -EINVAL;

        ctx->priv = priv;

        return 0;
}
EXPORT_SYMBOL_GPL(cxl_set_priv);

void *cxl_get_priv(struct cxl_context *ctx)
{
        if (!ctx)
                return ERR_PTR(-EINVAL);

        return ctx->priv;
}
EXPORT_SYMBOL_GPL(cxl_get_priv);

int cxl_allocate_afu_irqs(struct cxl_context *ctx, int num)
{
        int res;
        irq_hw_number_t hwirq;

        if (num == 0)
                num = ctx->afu->pp_irqs;
        res = afu_allocate_irqs(ctx, num);
        if (res)
                return res;

        if (!cpu_has_feature(CPU_FTR_HVMODE)) {
                /* In a guest, the PSL interrupt is not multiplexed. It was
                 * allocated above, and we need to set its handler
                 */
                hwirq = cxl_find_afu_irq(ctx, 0);
                if (hwirq)
                        cxl_map_irq(ctx->afu->adapter, hwirq, cxl_ops->psl_interrupt, ctx, "psl");
        }

        if (ctx->status == STARTED) {
                if (cxl_ops->update_ivtes)
                        cxl_ops->update_ivtes(ctx);
                else WARN(1, "BUG: cxl_allocate_afu_irqs must be called prior to starting the context on this platform\n");
        }

        return res;
}
EXPORT_SYMBOL_GPL(cxl_allocate_afu_irqs);

void cxl_free_afu_irqs(struct cxl_context *ctx)
{
        irq_hw_number_t hwirq;
        unsigned int virq;

        if (!cpu_has_feature(CPU_FTR_HVMODE)) {
                hwirq = cxl_find_afu_irq(ctx, 0);
                if (hwirq) {
                        virq = irq_find_mapping(NULL, hwirq);
                        if (virq)
                                cxl_unmap_irq(virq, ctx);
                }
        }
        afu_irq_name_free(ctx);
        cxl_ops->release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
}
EXPORT_SYMBOL_GPL(cxl_free_afu_irqs);

int cxl_map_afu_irq(struct cxl_context *ctx, int num,
                    irq_handler_t handler, void *cookie, char *name)
{
        irq_hw_number_t hwirq;

        /*
         * Find interrupt we are to register.
         */
        hwirq = cxl_find_afu_irq(ctx, num);
        if (!hwirq)
                return -ENOENT;

        return cxl_map_irq(ctx->afu->adapter, hwirq, handler, cookie, name);
}
EXPORT_SYMBOL_GPL(cxl_map_afu_irq);

void cxl_unmap_afu_irq(struct cxl_context *ctx, int num, void *cookie)
{
        irq_hw_number_t hwirq;
        unsigned int virq;

        hwirq = cxl_find_afu_irq(ctx, num);
        if (!hwirq)
                return;

        virq = irq_find_mapping(NULL, hwirq);
        if (virq)
                cxl_unmap_irq(virq, cookie);
}
EXPORT_SYMBOL_GPL(cxl_unmap_afu_irq);

/*
 * Start a context
 * Code here similar to afu_ioctl_start_work().
 */
int cxl_start_context(struct cxl_context *ctx, u64 wed,
                      struct task_struct *task)
{
        int rc = 0;
        bool kernel = true;

        pr_devel("%s: pe: %i\n", __func__, ctx->pe);

        mutex_lock(&ctx->status_mutex);
        if (ctx->status == STARTED)
                goto out; /* already started */

        /*
         * Increment the mapped context count for adapter. This also checks
         * if adapter_context_lock is taken.
         */
        rc = cxl_adapter_context_get(ctx->afu->adapter);
        if (rc)
                goto out;

        if (task) {
                ctx->pid = get_task_pid(task, PIDTYPE_PID);
                kernel = false;
                ctx->real_mode = false;

                /* acquire a reference to the task's mm */
                ctx->mm = get_task_mm(current);

                /* ensure this mm_struct can't be freed */
                cxl_context_mm_count_get(ctx);

                /* decrement the use count */
                if (ctx->mm)
                        mmput(ctx->mm);
        }

        /*
         * Increment driver use count. Enables global TLBIs for hash
         * and callbacks to handle the segment table
         */
        cxl_ctx_get();

        if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) {
                put_pid(ctx->pid);
                ctx->pid = NULL;
                cxl_adapter_context_put(ctx->afu->adapter);
                cxl_ctx_put();
                if (task)
                        cxl_context_mm_count_put(ctx);
                goto out;
        }

        ctx->status = STARTED;
out:
        mutex_unlock(&ctx->status_mutex);
        return rc;
}
EXPORT_SYMBOL_GPL(cxl_start_context);

int cxl_process_element(struct cxl_context *ctx)
{
        return ctx->external_pe;
}
EXPORT_SYMBOL_GPL(cxl_process_element);

/* Stop a context.  Returns 0 on success, otherwise -Errno */
int cxl_stop_context(struct cxl_context *ctx)
{
        return __detach_context(ctx);
}
EXPORT_SYMBOL_GPL(cxl_stop_context);

void cxl_set_master(struct cxl_context *ctx)
{
        ctx->master = true;
}
EXPORT_SYMBOL_GPL(cxl_set_master);

int cxl_set_translation_mode(struct cxl_context *ctx, bool real_mode)
{
        if (ctx->status == STARTED) {
                /*
                 * We could potentially update the PE and issue an update LLCMD
                 * to support this, but it doesn't seem to have a good use case
                 * since it's trivial to just create a second kernel context
                 * with different translation modes, so until someone convinces
                 * me otherwise:
                 */
                return -EBUSY;
        }

        ctx->real_mode = real_mode;
        return 0;
}
EXPORT_SYMBOL_GPL(cxl_set_translation_mode);

/* wrappers around afu_* file ops which are EXPORTED */
int cxl_fd_open(struct inode *inode, struct file *file)
{
        return afu_open(inode, file);
}
EXPORT_SYMBOL_GPL(cxl_fd_open);
int cxl_fd_release(struct inode *inode, struct file *file)
{
        return afu_release(inode, file);
}
EXPORT_SYMBOL_GPL(cxl_fd_release);
long cxl_fd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        return afu_ioctl(file, cmd, arg);
}
EXPORT_SYMBOL_GPL(cxl_fd_ioctl);
int cxl_fd_mmap(struct file *file, struct vm_area_struct *vm)
{
        return afu_mmap(file, vm);
}
EXPORT_SYMBOL_GPL(cxl_fd_mmap);
unsigned int cxl_fd_poll(struct file *file, struct poll_table_struct *poll)
{
        return afu_poll(file, poll);
}
EXPORT_SYMBOL_GPL(cxl_fd_poll);
ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
                        loff_t *off)
{
        return afu_read(file, buf, count, off);
}
EXPORT_SYMBOL_GPL(cxl_fd_read);

#define PATCH_FOPS(NAME) if (!fops->NAME) fops->NAME = afu_fops.NAME

/* Get a struct file and fd for a context and attach the ops */
struct file *cxl_get_fd(struct cxl_context *ctx, struct file_operations *fops,
                        int *fd)
{
        struct file *file;
        int rc, flags, fdtmp;
        char *name = NULL;

        /* only allow one per context */
        if (ctx->mapping)
                return ERR_PTR(-EEXIST);

        flags = O_RDWR | O_CLOEXEC;

        /* This code is similar to anon_inode_getfd() */
        rc = get_unused_fd_flags(flags);
        if (rc < 0)
                return ERR_PTR(rc);
        fdtmp = rc;

        /*
         * Patch the file ops.  Needs to be careful that this is rentrant safe.
         */
        if (fops) {
                PATCH_FOPS(open);
                PATCH_FOPS(poll);
                PATCH_FOPS(read);
                PATCH_FOPS(release);
                PATCH_FOPS(unlocked_ioctl);
                PATCH_FOPS(compat_ioctl);
                PATCH_FOPS(mmap);
        } else /* use default ops */
                fops = (struct file_operations *)&afu_fops;

        name = kasprintf(GFP_KERNEL, "cxl:%d", ctx->pe);
        file = cxl_getfile(name, fops, ctx, flags);
        kfree(name);
        if (IS_ERR(file))
                goto err_fd;

        cxl_context_set_mapping(ctx, file->f_mapping);
        *fd = fdtmp;
        return file;

err_fd:
        put_unused_fd(fdtmp);
        return NULL;
}
EXPORT_SYMBOL_GPL(cxl_get_fd);

struct cxl_context *cxl_fops_get_context(struct file *file)
{
        return file->private_data;
}
EXPORT_SYMBOL_GPL(cxl_fops_get_context);

void cxl_set_driver_ops(struct cxl_context *ctx,
                        struct cxl_afu_driver_ops *ops)
{
        WARN_ON(!ops->fetch_event || !ops->event_delivered);
        atomic_set(&ctx->afu_driver_events, 0);
        ctx->afu_driver_ops = ops;
}
EXPORT_SYMBOL_GPL(cxl_set_driver_ops);

void cxl_context_events_pending(struct cxl_context *ctx,
                                unsigned int new_events)
{
        atomic_add(new_events, &ctx->afu_driver_events);
        wake_up_all(&ctx->wq);
}
EXPORT_SYMBOL_GPL(cxl_context_events_pending);

int cxl_start_work(struct cxl_context *ctx,
                   struct cxl_ioctl_start_work *work)
{
        int rc;

        /* code taken from afu_ioctl_start_work */
        if (!(work->flags & CXL_START_WORK_NUM_IRQS))
                work->num_interrupts = ctx->afu->pp_irqs;
        else if ((work->num_interrupts < ctx->afu->pp_irqs) ||
                 (work->num_interrupts > ctx->afu->irqs_max)) {
                return -EINVAL;
        }

        rc = afu_register_irqs(ctx, work->num_interrupts);
        if (rc)
                return rc;

        rc = cxl_start_context(ctx, work->work_element_descriptor, current);
        if (rc < 0) {
                afu_release_irqs(ctx, ctx);
                return rc;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(cxl_start_work);

void __iomem *cxl_psa_map(struct cxl_context *ctx)
{
        if (ctx->status != STARTED)
                return NULL;

        pr_devel("%s: psn_phys%llx size:%llx\n",
                __func__, ctx->psn_phys, ctx->psn_size);
        return ioremap(ctx->psn_phys, ctx->psn_size);
}
EXPORT_SYMBOL_GPL(cxl_psa_map);

void cxl_psa_unmap(void __iomem *addr)
{
        iounmap(addr);
}
EXPORT_SYMBOL_GPL(cxl_psa_unmap);

int cxl_afu_reset(struct cxl_context *ctx)
{
        struct cxl_afu *afu = ctx->afu;
        int rc;

        rc = cxl_ops->afu_reset(afu);
        if (rc)
                return rc;

        return cxl_ops->afu_check_and_enable(afu);
}
EXPORT_SYMBOL_GPL(cxl_afu_reset);

void cxl_perst_reloads_same_image(struct cxl_afu *afu,
                                  bool perst_reloads_same_image)
{
        afu->adapter->perst_same_image = perst_reloads_same_image;
}
EXPORT_SYMBOL_GPL(cxl_perst_reloads_same_image);

ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count)
{
        struct cxl_afu *afu = cxl_pci_to_afu(dev);
        if (IS_ERR(afu))
                return -ENODEV;

        return cxl_ops->read_adapter_vpd(afu->adapter, buf, count);
}
EXPORT_SYMBOL_GPL(cxl_read_adapter_vpd);

int cxl_set_max_irqs_per_process(struct pci_dev *dev, int irqs)
{
        struct cxl_afu *afu = cxl_pci_to_afu(dev);
        if (IS_ERR(afu))
                return -ENODEV;

        if (irqs > afu->adapter->user_irqs)
                return -EINVAL;

        /* Limit user_irqs to prevent the user increasing this via sysfs */
        afu->adapter->user_irqs = irqs;
        afu->irqs_max = irqs;

        return 0;
}
EXPORT_SYMBOL_GPL(cxl_set_max_irqs_per_process);

int cxl_get_max_irqs_per_process(struct pci_dev *dev)
{
        struct cxl_afu *afu = cxl_pci_to_afu(dev);
        if (IS_ERR(afu))
                return -ENODEV;

        return afu->irqs_max;
}
EXPORT_SYMBOL_GPL(cxl_get_max_irqs_per_process);

/*
 * This is a special interrupt allocation routine called from the PHB's MSI
 * setup function. When capi interrupts are allocated in this manner they must
 * still be associated with a running context, but since the MSI APIs have no
 * way to specify this we use the default context associated with the device.
 *
 * The Mellanox CX4 has a hardware limitation that restricts the maximum AFU
 * interrupt number, so in order to overcome this their driver informs us of
 * the restriction by setting the maximum interrupts per context, and we
 * allocate additional contexts as necessary so that we can keep the AFU
 * interrupt number within the supported range.
 */
int _cxl_cx4_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
{
        struct cxl_context *ctx, *new_ctx, *default_ctx;
        int remaining;
        int rc;

        ctx = default_ctx = cxl_get_context(pdev);
        if (WARN_ON(!default_ctx))
                return -ENODEV;

        remaining = nvec;
        while (remaining > 0) {
                rc = cxl_allocate_afu_irqs(ctx, min(remaining, ctx->afu->irqs_max));
                if (rc) {
                        pr_warn("%s: Failed to find enough free MSIs\n", pci_name(pdev));
                        return rc;
                }
                remaining -= ctx->afu->irqs_max;

                if (ctx != default_ctx && default_ctx->status == STARTED) {
                        WARN_ON(cxl_start_context(ctx,
                                be64_to_cpu(default_ctx->elem->common.wed),
                                NULL));
                }

                if (remaining > 0) {
                        new_ctx = cxl_dev_context_init(pdev);
                        if (IS_ERR(new_ctx)) {
                                pr_warn("%s: Failed to allocate enough contexts for MSIs\n", pci_name(pdev));
                                return -ENOSPC;
                        }
                        list_add(&new_ctx->extra_irq_contexts, &ctx->extra_irq_contexts);
                        ctx = new_ctx;
                }
        }

        return 0;
}
/* Exported via cxl_base */

void _cxl_cx4_teardown_msi_irqs(struct pci_dev *pdev)
{
        struct cxl_context *ctx, *pos, *tmp;

        ctx = cxl_get_context(pdev);
        if (WARN_ON(!ctx))
                return;

        cxl_free_afu_irqs(ctx);
        list_for_each_entry_safe(pos, tmp, &ctx->extra_irq_contexts, extra_irq_contexts) {
                cxl_stop_context(pos);
                cxl_free_afu_irqs(pos);
                list_del(&pos->extra_irq_contexts);
                cxl_release_context(pos);
        }
}
/* Exported via cxl_base */