/*
 * Copyright (c) 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2013 Cisco Systems.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * 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.
 */

#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/sched.h>
#include <linux/hugetlb.h>
#include <linux/dma-attrs.h>
#include <linux/iommu.h>
#include <linux/workqueue.h>
#include <linux/list.h>
#include <linux/pci.h>

#include "usnic_log.h"
#include "usnic_uiom.h"
#include "usnic_uiom_interval_tree.h"

static struct workqueue_struct *usnic_uiom_wq;

#define USNIC_UIOM_PAGE_CHUNK                                           \
        ((PAGE_SIZE - offsetof(struct usnic_uiom_chunk, page_list))     /\
        ((void *) &((struct usnic_uiom_chunk *) 0)->page_list[1] -      \
        (void *) &((struct usnic_uiom_chunk *) 0)->page_list[0]))

static void usnic_uiom_reg_account(struct work_struct *work)
{
        struct usnic_uiom_reg *umem = container_of(work,
                                                struct usnic_uiom_reg, work);

        down_write(&umem->mm->mmap_sem);
        umem->mm->locked_vm -= umem->diff;
        up_write(&umem->mm->mmap_sem);
        mmput(umem->mm);
        kfree(umem);
}

static int usnic_uiom_dma_fault(struct iommu_domain *domain,
                                struct device *dev,
                                unsigned long iova, int flags,
                                void *token)
{
        usnic_err("Device %s iommu fault domain 0x%pK va 0x%lx flags 0x%x\n",
                dev_name(dev),
                domain, iova, flags);
        return -ENOSYS;
}

static void usnic_uiom_put_pages(struct list_head *chunk_list, int dirty)
{
        struct usnic_uiom_chunk *chunk, *tmp;
        struct page *page;
        struct scatterlist *sg;
        int i;
        dma_addr_t pa;

        list_for_each_entry_safe(chunk, tmp, chunk_list, list) {
                for_each_sg(chunk->page_list, sg, chunk->nents, i) {
                        page = sg_page(sg);
                        pa = sg_phys(sg);
                        if (dirty)
                                set_page_dirty_lock(page);
                        put_page(page);
                        usnic_dbg("pa: %pa\n", &pa);
                }
                kfree(chunk);
        }
}

static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
                                int dmasync, struct list_head *chunk_list)
{
        struct page **page_list;
        struct scatterlist *sg;
        struct usnic_uiom_chunk *chunk;
        unsigned long locked;
        unsigned long lock_limit;
        unsigned long cur_base;
        unsigned long npages;
        int ret;
        int off;
        int i;
        int flags;
        dma_addr_t pa;
        DEFINE_DMA_ATTRS(attrs);

        if (dmasync)
                dma_set_attr(DMA_ATTR_WRITE_BARRIER, &attrs);

        if (!can_do_mlock())
                return -EPERM;

        INIT_LIST_HEAD(chunk_list);

        page_list = (struct page **) __get_free_page(GFP_KERNEL);
        if (!page_list)
                return -ENOMEM;

        npages = PAGE_ALIGN(size + (addr & ~PAGE_MASK)) >> PAGE_SHIFT;

        down_write(&current->mm->mmap_sem);

        locked = npages + current->mm->locked_vm;
        lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

        if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
                ret = -ENOMEM;
                goto out;
        }

        flags = IOMMU_READ | IOMMU_CACHE;
        flags |= (writable) ? IOMMU_WRITE : 0;
        cur_base = addr & PAGE_MASK;
        ret = 0;

        while (npages) {
                ret = get_user_pages(current, current->mm, cur_base,
                                        min_t(unsigned long, npages,
                                        PAGE_SIZE / sizeof(struct page *)),
                                        1, !writable, page_list, NULL);

                if (ret < 0)
                        goto out;

                npages -= ret;
                off = 0;

                while (ret) {
                        chunk = kmalloc(sizeof(*chunk) +
                                        sizeof(struct scatterlist) *
                                        min_t(int, ret, USNIC_UIOM_PAGE_CHUNK),
                                        GFP_KERNEL);
                        if (!chunk) {
                                ret = -ENOMEM;
                                goto out;
                        }

                        chunk->nents = min_t(int, ret, USNIC_UIOM_PAGE_CHUNK);
                        sg_init_table(chunk->page_list, chunk->nents);
                        for_each_sg(chunk->page_list, sg, chunk->nents, i) {
                                sg_set_page(sg, page_list[i + off],
                                                PAGE_SIZE, 0);
                                pa = sg_phys(sg);
                                usnic_dbg("va: 0x%lx pa: %pa\n",
                                                cur_base + i*PAGE_SIZE, &pa);
                        }
                        cur_base += chunk->nents * PAGE_SIZE;
                        ret -= chunk->nents;
                        off += chunk->nents;
                        list_add_tail(&chunk->list, chunk_list);
                }

                ret = 0;
        }

out:
        if (ret < 0)
                usnic_uiom_put_pages(chunk_list, 0);
        else
                current->mm->locked_vm = locked;

        up_write(&current->mm->mmap_sem);
        free_page((unsigned long) page_list);
        return ret;
}

static void usnic_uiom_unmap_sorted_intervals(struct list_head *intervals,
                                                struct usnic_uiom_pd *pd)
{
        struct usnic_uiom_interval_node *interval, *tmp;
        long unsigned va, size;

        list_for_each_entry_safe(interval, tmp, intervals, link) {
                va = interval->start << PAGE_SHIFT;
                size = ((interval->last - interval->start) + 1) << PAGE_SHIFT;
                while (size > 0) {
                        /* Workaround for RH 970401 */
                        usnic_dbg("va 0x%lx size 0x%lx", va, PAGE_SIZE);
                        iommu_unmap(pd->domain, va, PAGE_SIZE);
                        va += PAGE_SIZE;
                        size -= PAGE_SIZE;
                }
        }
}

static void __usnic_uiom_reg_release(struct usnic_uiom_pd *pd,
                                        struct usnic_uiom_reg *uiomr,
                                        int dirty)
{
        int npages;
        unsigned long vpn_start, vpn_last;
        struct usnic_uiom_interval_node *interval, *tmp;
        int writable = 0;
        LIST_HEAD(rm_intervals);

        npages = PAGE_ALIGN(uiomr->length + uiomr->offset) >> PAGE_SHIFT;
        vpn_start = (uiomr->va & PAGE_MASK) >> PAGE_SHIFT;
        vpn_last = vpn_start + npages - 1;

        spin_lock(&pd->lock);
        usnic_uiom_remove_interval(&pd->rb_root, vpn_start,
                                        vpn_last, &rm_intervals);
        usnic_uiom_unmap_sorted_intervals(&rm_intervals, pd);

        list_for_each_entry_safe(interval, tmp, &rm_intervals, link) {
                if (interval->flags & IOMMU_WRITE)
                        writable = 1;
                list_del(&interval->link);
                kfree(interval);
        }

        usnic_uiom_put_pages(&uiomr->chunk_list, dirty & writable);
        spin_unlock(&pd->lock);
}

static int usnic_uiom_map_sorted_intervals(struct list_head *intervals,
                                                struct usnic_uiom_reg *uiomr)
{
        int i, err;
        size_t size;
        struct usnic_uiom_chunk *chunk;
        struct usnic_uiom_interval_node *interval_node;
        dma_addr_t pa;
        dma_addr_t pa_start = 0;
        dma_addr_t pa_end = 0;
        long int va_start = -EINVAL;
        struct usnic_uiom_pd *pd = uiomr->pd;
        long int va = uiomr->va & PAGE_MASK;
        int flags = IOMMU_READ | IOMMU_CACHE;

        flags |= (uiomr->writable) ? IOMMU_WRITE : 0;
        chunk = list_first_entry(&uiomr->chunk_list, struct usnic_uiom_chunk,
                                                                        list);
        list_for_each_entry(interval_node, intervals, link) {
iter_chunk:
                for (i = 0; i < chunk->nents; i++, va += PAGE_SIZE) {
                        pa = sg_phys(&chunk->page_list[i]);
                        if ((va >> PAGE_SHIFT) < interval_node->start)
                                continue;

                        if ((va >> PAGE_SHIFT) == interval_node->start) {
                                /* First page of the interval */
                                va_start = va;
                                pa_start = pa;
                                pa_end = pa;
                        }

                        WARN_ON(va_start == -EINVAL);

                        if ((pa_end + PAGE_SIZE != pa) &&
                                        (pa != pa_start)) {
                                /* PAs are not contiguous */
                                size = pa_end - pa_start + PAGE_SIZE;
                                usnic_dbg("va 0x%lx pa %pa size 0x%zx flags 0x%x",
                                        va_start, &pa_start, size, flags);
                                err = iommu_map(pd->domain, va_start, pa_start,
                                                        size, flags);
                                if (err) {
                                        usnic_err("Failed to map va 0x%lx pa %pa size 0x%zx with err %d\n",
                                                va_start, &pa_start, size, err);
                                        goto err_out;
                                }
                                va_start = va;
                                pa_start = pa;
                                pa_end = pa;
                        }

                        if ((va >> PAGE_SHIFT) == interval_node->last) {
                                /* Last page of the interval */
                                size = pa - pa_start + PAGE_SIZE;
                                usnic_dbg("va 0x%lx pa %pa size 0x%zx flags 0x%x\n",
                                        va_start, &pa_start, size, flags);
                                err = iommu_map(pd->domain, va_start, pa_start,
                                                size, flags);
                                if (err) {
                                        usnic_err("Failed to map va 0x%lx pa %pa size 0x%zx with err %d\n",
                                                va_start, &pa_start, size, err);
                                        goto err_out;
                                }
                                break;
                        }

                        if (pa != pa_start)
                                pa_end += PAGE_SIZE;
                }

                if (i == chunk->nents) {
                        /*
                         * Hit last entry of the chunk,
                         * hence advance to next chunk
                         */
                        chunk = list_first_entry(&chunk->list,
                                                        struct usnic_uiom_chunk,
                                                        list);
                        goto iter_chunk;
                }
        }

        return 0;

err_out:
        usnic_uiom_unmap_sorted_intervals(intervals, pd);
        return err;
}

struct usnic_uiom_reg *usnic_uiom_reg_get(struct usnic_uiom_pd *pd,
                                                unsigned long addr, size_t size,
                                                int writable, int dmasync)
{
        struct usnic_uiom_reg *uiomr;
        unsigned long va_base, vpn_start, vpn_last;
        unsigned long npages;
        int offset, err;
        LIST_HEAD(sorted_diff_intervals);

        /*
         * Intel IOMMU map throws an error if a translation entry is
         * changed from read to write.  This module may not unmap
         * and then remap the entry after fixing the permission
         * b/c this open up a small windows where hw DMA may page fault
         * Hence, make all entries to be writable.
         */
        writable = 1;

        va_base = addr & PAGE_MASK;
        offset = addr & ~PAGE_MASK;
        npages = PAGE_ALIGN(size + offset) >> PAGE_SHIFT;
        vpn_start = (addr & PAGE_MASK) >> PAGE_SHIFT;
        vpn_last = vpn_start + npages - 1;

        uiomr = kmalloc(sizeof(*uiomr), GFP_KERNEL);
        if (!uiomr)
                return ERR_PTR(-ENOMEM);

        uiomr->va = va_base;
        uiomr->offset = offset;
        uiomr->length = size;
        uiomr->writable = writable;
        uiomr->pd = pd;

        err = usnic_uiom_get_pages(addr, size, writable, dmasync,
                                        &uiomr->chunk_list);
        if (err) {
                usnic_err("Failed get_pages vpn [0x%lx,0x%lx] err %d\n",
                                vpn_start, vpn_last, err);
                goto out_free_uiomr;
        }

        spin_lock(&pd->lock);
        err = usnic_uiom_get_intervals_diff(vpn_start, vpn_last,
                                                (writable) ? IOMMU_WRITE : 0,
                                                IOMMU_WRITE,
                                                &pd->rb_root,
                                                &sorted_diff_intervals);
        if (err) {
                usnic_err("Failed disjoint interval vpn [0x%lx,0x%lx] err %d\n",
                                                vpn_start, vpn_last, err);
                goto out_put_pages;
        }

        err = usnic_uiom_map_sorted_intervals(&sorted_diff_intervals, uiomr);
        if (err) {
                usnic_err("Failed map interval vpn [0x%lx,0x%lx] err %d\n",
                                                vpn_start, vpn_last, err);
                goto out_put_intervals;

        }

        err = usnic_uiom_insert_interval(&pd->rb_root, vpn_start, vpn_last,
                                        (writable) ? IOMMU_WRITE : 0);
        if (err) {
                usnic_err("Failed insert interval vpn [0x%lx,0x%lx] err %d\n",
                                                vpn_start, vpn_last, err);
                goto out_unmap_intervals;
        }

        usnic_uiom_put_interval_set(&sorted_diff_intervals);
        spin_unlock(&pd->lock);

        return uiomr;

out_unmap_intervals:
        usnic_uiom_unmap_sorted_intervals(&sorted_diff_intervals, pd);
out_put_intervals:
        usnic_uiom_put_interval_set(&sorted_diff_intervals);
out_put_pages:
        usnic_uiom_put_pages(&uiomr->chunk_list, 0);
        spin_unlock(&pd->lock);
out_free_uiomr:
        kfree(uiomr);
        return ERR_PTR(err);
}

void usnic_uiom_reg_release(struct usnic_uiom_reg *uiomr, int closing)
{
        struct mm_struct *mm;
        unsigned long diff;

        __usnic_uiom_reg_release(uiomr->pd, uiomr, 1);

        mm = get_task_mm(current);
        if (!mm) {
                kfree(uiomr);
                return;
        }

        diff = PAGE_ALIGN(uiomr->length + uiomr->offset) >> PAGE_SHIFT;

        /*
         * We may be called with the mm's mmap_sem already held.  This
         * can happen when a userspace munmap() is the call that drops
         * the last reference to our file and calls our release
         * method.  If there are memory regions to destroy, we'll end
         * up here and not be able to take the mmap_sem.  In that case
         * we defer the vm_locked accounting to the system workqueue.
         */
        if (closing) {
                if (!down_write_trylock(&mm->mmap_sem)) {
                        INIT_WORK(&uiomr->work, usnic_uiom_reg_account);
                        uiomr->mm = mm;
                        uiomr->diff = diff;

                        queue_work(usnic_uiom_wq, &uiomr->work);
                        return;
                }
        } else
                down_write(&mm->mmap_sem);

        current->mm->locked_vm -= diff;
        up_write(&mm->mmap_sem);
        mmput(mm);
        kfree(uiomr);
}

struct usnic_uiom_pd *usnic_uiom_alloc_pd(void)
{
        struct usnic_uiom_pd *pd;
        void *domain;

        pd = kzalloc(sizeof(*pd), GFP_KERNEL);
        if (!pd)
                return ERR_PTR(-ENOMEM);

        pd->domain = domain = iommu_domain_alloc(&pci_bus_type);
        if (IS_ERR_OR_NULL(domain)) {
                usnic_err("Failed to allocate IOMMU domain with err %ld\n",
                                PTR_ERR(pd->domain));
                kfree(pd);
                return ERR_PTR(domain ? PTR_ERR(domain) : -ENOMEM);
        }

        iommu_set_fault_handler(pd->domain, usnic_uiom_dma_fault, NULL);

        spin_lock_init(&pd->lock);
        INIT_LIST_HEAD(&pd->devs);

        return pd;
}

void usnic_uiom_dealloc_pd(struct usnic_uiom_pd *pd)
{
        iommu_domain_free(pd->domain);
        kfree(pd);
}

int usnic_uiom_attach_dev_to_pd(struct usnic_uiom_pd *pd, struct device *dev)
{
        struct usnic_uiom_dev *uiom_dev;
        int err;

        uiom_dev = kzalloc(sizeof(*uiom_dev), GFP_ATOMIC);
        if (!uiom_dev)
                return -ENOMEM;
        uiom_dev->dev = dev;

        err = iommu_attach_device(pd->domain, dev);
        if (err)
                goto out_free_dev;

        if (!iommu_capable(dev->bus, IOMMU_CAP_CACHE_COHERENCY)) {
                usnic_err("IOMMU of %s does not support cache coherency\n",
                                dev_name(dev));
                err = -EINVAL;
                goto out_detach_device;
        }

        spin_lock(&pd->lock);
        list_add_tail(&uiom_dev->link, &pd->devs);
        pd->dev_cnt++;
        spin_unlock(&pd->lock);

        return 0;

out_detach_device:
        iommu_detach_device(pd->domain, dev);
out_free_dev:
        kfree(uiom_dev);
        return err;
}

void usnic_uiom_detach_dev_from_pd(struct usnic_uiom_pd *pd, struct device *dev)
{
        struct usnic_uiom_dev *uiom_dev;
        int found = 0;

        spin_lock(&pd->lock);
        list_for_each_entry(uiom_dev, &pd->devs, link) {
                if (uiom_dev->dev == dev) {
                        found = 1;
                        break;
                }
        }

        if (!found) {
                usnic_err("Unable to free dev %s - not found\n",
                                dev_name(dev));
                spin_unlock(&pd->lock);
                return;
        }

        list_del(&uiom_dev->link);
        pd->dev_cnt--;
        spin_unlock(&pd->lock);

        return iommu_detach_device(pd->domain, dev);
}

struct device **usnic_uiom_get_dev_list(struct usnic_uiom_pd *pd)
{
        struct usnic_uiom_dev *uiom_dev;
        struct device **devs;
        int i = 0;

        spin_lock(&pd->lock);
        devs = kcalloc(pd->dev_cnt + 1, sizeof(*devs), GFP_ATOMIC);
        if (!devs) {
                devs = ERR_PTR(-ENOMEM);
                goto out;
        }

        list_for_each_entry(uiom_dev, &pd->devs, link) {
                devs[i++] = uiom_dev->dev;
        }
out:
        spin_unlock(&pd->lock);
        return devs;
}

void usnic_uiom_free_dev_list(struct device **devs)
{
        kfree(devs);
}

int usnic_uiom_init(char *drv_name)
{
        if (!iommu_present(&pci_bus_type)) {
                usnic_err("IOMMU required but not present or enabled.  USNIC QPs will not function w/o enabling IOMMU\n");
                return -EPERM;
        }

        usnic_uiom_wq = create_workqueue(drv_name);
        if (!usnic_uiom_wq) {
                usnic_err("Unable to alloc wq for drv %s\n", drv_name);
                return -ENOMEM;
        }

        return 0;
}

void usnic_uiom_fini(void)
{
        flush_workqueue(usnic_uiom_wq);
        destroy_workqueue(usnic_uiom_wq);
}