/*
 * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
 * Author: Joerg Roedel <joerg.roedel@amd.com>
 *         Leo Duran <leo.duran@amd.com>
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/scatterlist.h>
#include <linux/dma-mapping.h>
#include <linux/iommu-helper.h>
#include <linux/iommu.h>
#include <asm/proto.h>
#include <asm/iommu.h>
#include <asm/gart.h>
#include <asm/amd_iommu_types.h>
#include <asm/amd_iommu.h>

#define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))

#define EXIT_LOOP_COUNT 10000000

static DEFINE_RWLOCK(amd_iommu_devtable_lock);

/* A list of preallocated protection domains */
static LIST_HEAD(iommu_pd_list);
static DEFINE_SPINLOCK(iommu_pd_list_lock);

/*
 * Domain for untranslated devices - only allocated
 * if iommu=pt passed on kernel cmd line.
 */
static struct protection_domain *pt_domain;

static struct iommu_ops amd_iommu_ops;

/*
 * general struct to manage commands send to an IOMMU
 */
struct iommu_cmd {
        u32 data[4];
};

static int dma_ops_unity_map(struct dma_ops_domain *dma_dom,
                             struct unity_map_entry *e);
static struct dma_ops_domain *find_protection_domain(u16 devid);
static u64 *alloc_pte(struct protection_domain *domain,
                      unsigned long address, int end_lvl,
                      u64 **pte_page, gfp_t gfp);
static void dma_ops_reserve_addresses(struct dma_ops_domain *dom,
                                      unsigned long start_page,
                                      unsigned int pages);
static void reset_iommu_command_buffer(struct amd_iommu *iommu);
static u64 *fetch_pte(struct protection_domain *domain,
                      unsigned long address, int map_size);
static void update_domain(struct protection_domain *domain);

#ifdef CONFIG_AMD_IOMMU_STATS

/*
 * Initialization code for statistics collection
 */

DECLARE_STATS_COUNTER(compl_wait);
DECLARE_STATS_COUNTER(cnt_map_single);
DECLARE_STATS_COUNTER(cnt_unmap_single);
DECLARE_STATS_COUNTER(cnt_map_sg);
DECLARE_STATS_COUNTER(cnt_unmap_sg);
DECLARE_STATS_COUNTER(cnt_alloc_coherent);
DECLARE_STATS_COUNTER(cnt_free_coherent);
DECLARE_STATS_COUNTER(cross_page);
DECLARE_STATS_COUNTER(domain_flush_single);
DECLARE_STATS_COUNTER(domain_flush_all);
DECLARE_STATS_COUNTER(alloced_io_mem);
DECLARE_STATS_COUNTER(total_map_requests);

static struct dentry *stats_dir;
static struct dentry *de_isolate;
static struct dentry *de_fflush;

static void amd_iommu_stats_add(struct __iommu_counter *cnt)
{
        if (stats_dir == NULL)
                return;

        cnt->dent = debugfs_create_u64(cnt->name, 0444, stats_dir,
                                       &cnt->value);
}

static void amd_iommu_stats_init(void)
{
        stats_dir = debugfs_create_dir("amd-iommu", NULL);
        if (stats_dir == NULL)
                return;

        de_isolate = debugfs_create_bool("isolation", 0444, stats_dir,
                                         (u32 *)&amd_iommu_isolate);

        de_fflush  = debugfs_create_bool("fullflush", 0444, stats_dir,
                                         (u32 *)&amd_iommu_unmap_flush);

        amd_iommu_stats_add(&compl_wait);
        amd_iommu_stats_add(&cnt_map_single);
        amd_iommu_stats_add(&cnt_unmap_single);
        amd_iommu_stats_add(&cnt_map_sg);
        amd_iommu_stats_add(&cnt_unmap_sg);
        amd_iommu_stats_add(&cnt_alloc_coherent);
        amd_iommu_stats_add(&cnt_free_coherent);
        amd_iommu_stats_add(&cross_page);
        amd_iommu_stats_add(&domain_flush_single);
        amd_iommu_stats_add(&domain_flush_all);
        amd_iommu_stats_add(&alloced_io_mem);
        amd_iommu_stats_add(&total_map_requests);
}

#endif

/* returns !0 if the IOMMU is caching non-present entries in its TLB */
static int iommu_has_npcache(struct amd_iommu *iommu)
{
        return iommu->cap & (1UL << IOMMU_CAP_NPCACHE);
}

/****************************************************************************
 *
 * Interrupt handling functions
 *
 ****************************************************************************/

static void dump_dte_entry(u16 devid)
{
        int i;

        for (i = 0; i < 8; ++i)
                pr_err("AMD-Vi: DTE[%d]: %08x\n", i,
                        amd_iommu_dev_table[devid].data[i]);
}

static void dump_command(unsigned long phys_addr)
{
        struct iommu_cmd *cmd = phys_to_virt(phys_addr);
        int i;

        for (i = 0; i < 4; ++i)
                pr_err("AMD-Vi: CMD[%d]: %08x\n", i, cmd->data[i]);
}

static void iommu_print_event(struct amd_iommu *iommu, void *__evt)
{
        u32 *event = __evt;
        int type  = (event[1] >> EVENT_TYPE_SHIFT)  & EVENT_TYPE_MASK;
        int devid = (event[0] >> EVENT_DEVID_SHIFT) & EVENT_DEVID_MASK;
        int domid = (event[1] >> EVENT_DOMID_SHIFT) & EVENT_DOMID_MASK;
        int flags = (event[1] >> EVENT_FLAGS_SHIFT) & EVENT_FLAGS_MASK;
        u64 address = (u64)(((u64)event[3]) << 32) | event[2];

        printk(KERN_ERR "AMD-Vi: Event logged [");

        switch (type) {
        case EVENT_TYPE_ILL_DEV:
                printk("ILLEGAL_DEV_TABLE_ENTRY device=%02x:%02x.%x "
                       "address=0x%016llx flags=0x%04x]\n",
                       PCI_BUS(devid), PCI_SLOT(devid), PCI_FUNC(devid),
                       address, flags);
                dump_dte_entry(devid);
                break;
        case EVENT_TYPE_IO_FAULT:
                printk("IO_PAGE_FAULT device=%02x:%02x.%x "
                       "domain=0x%04x address=0x%016llx flags=0x%04x]\n",
                       PCI_BUS(devid), PCI_SLOT(devid), PCI_FUNC(devid),
                       domid, address, flags);
                break;
        case EVENT_TYPE_DEV_TAB_ERR:
                printk("DEV_TAB_HARDWARE_ERROR device=%02x:%02x.%x "
                       "address=0x%016llx flags=0x%04x]\n",
                       PCI_BUS(devid), PCI_SLOT(devid), PCI_FUNC(devid),
                       address, flags);
                break;
        case EVENT_TYPE_PAGE_TAB_ERR:
                printk("PAGE_TAB_HARDWARE_ERROR device=%02x:%02x.%x "
                       "domain=0x%04x address=0x%016llx flags=0x%04x]\n",
                       PCI_BUS(devid), PCI_SLOT(devid), PCI_FUNC(devid),
                       domid, address, flags);
                break;
        case EVENT_TYPE_ILL_CMD:
                printk("ILLEGAL_COMMAND_ERROR address=0x%016llx]\n", address);
                reset_iommu_command_buffer(iommu);
                dump_command(address);
                break;
        case EVENT_TYPE_CMD_HARD_ERR:
                printk("COMMAND_HARDWARE_ERROR address=0x%016llx "
                       "flags=0x%04x]\n", address, flags);
                break;
        case EVENT_TYPE_IOTLB_INV_TO:
                printk("IOTLB_INV_TIMEOUT device=%02x:%02x.%x "
                       "address=0x%016llx]\n",
                       PCI_BUS(devid), PCI_SLOT(devid), PCI_FUNC(devid),
                       address);
                break;
        case EVENT_TYPE_INV_DEV_REQ:
                printk("INVALID_DEVICE_REQUEST device=%02x:%02x.%x "
                       "address=0x%016llx flags=0x%04x]\n",
                       PCI_BUS(devid), PCI_SLOT(devid), PCI_FUNC(devid),
                       address, flags);
                break;
        default:
                printk(KERN_ERR "UNKNOWN type=0x%02x]\n", type);
        }
}

static void iommu_poll_events(struct amd_iommu *iommu)
{
        u32 head, tail;
        unsigned long flags;

        spin_lock_irqsave(&iommu->lock, flags);

        head = readl(iommu->mmio_base + MMIO_EVT_HEAD_OFFSET);
        tail = readl(iommu->mmio_base + MMIO_EVT_TAIL_OFFSET);

        while (head != tail) {
                iommu_print_event(iommu, iommu->evt_buf + head);
                head = (head + EVENT_ENTRY_SIZE) % iommu->evt_buf_size;
        }

        writel(head, iommu->mmio_base + MMIO_EVT_HEAD_OFFSET);

        spin_unlock_irqrestore(&iommu->lock, flags);
}

irqreturn_t amd_iommu_int_handler(int irq, void *data)
{
        struct amd_iommu *iommu;

        for_each_iommu(iommu)
                iommu_poll_events(iommu);

        return IRQ_HANDLED;
}

/****************************************************************************
 *
 * IOMMU command queuing functions
 *
 ****************************************************************************/

/*
 * Writes the command to the IOMMUs command buffer and informs the
 * hardware about the new command. Must be called with iommu->lock held.
 */
static int __iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
{
        u32 tail, head;
        u8 *target;

        tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
        target = iommu->cmd_buf + tail;
        memcpy_toio(target, cmd, sizeof(*cmd));
        tail = (tail + sizeof(*cmd)) % iommu->cmd_buf_size;
        head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
        if (tail == head)
                return -ENOMEM;
        writel(tail, iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);

        return 0;
}

/*
 * General queuing function for commands. Takes iommu->lock and calls
 * __iommu_queue_command().
 */
static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
{
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&iommu->lock, flags);
        ret = __iommu_queue_command(iommu, cmd);
        if (!ret)
                iommu->need_sync = true;
        spin_unlock_irqrestore(&iommu->lock, flags);

        return ret;
}

/*
 * This function waits until an IOMMU has completed a completion
 * wait command
 */
static void __iommu_wait_for_completion(struct amd_iommu *iommu)
{
        int ready = 0;
        unsigned status = 0;
        unsigned long i = 0;

        INC_STATS_COUNTER(compl_wait);

        while (!ready && (i < EXIT_LOOP_COUNT)) {
                ++i;
                /* wait for the bit to become one */
                status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
                ready = status & MMIO_STATUS_COM_WAIT_INT_MASK;
        }

        /* set bit back to zero */
        status &= ~MMIO_STATUS_COM_WAIT_INT_MASK;
        writel(status, iommu->mmio_base + MMIO_STATUS_OFFSET);

        if (unlikely(i == EXIT_LOOP_COUNT)) {
                spin_unlock(&iommu->lock);
                reset_iommu_command_buffer(iommu);
                spin_lock(&iommu->lock);
        }
}

/*
 * This function queues a completion wait command into the command
 * buffer of an IOMMU
 */
static int __iommu_completion_wait(struct amd_iommu *iommu)
{
        struct iommu_cmd cmd;

         memset(&cmd, 0, sizeof(cmd));
         cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
         CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT);

         return __iommu_queue_command(iommu, &cmd);
}

/*
 * This function is called whenever we need to ensure that the IOMMU has
 * completed execution of all commands we sent. It sends a
 * COMPLETION_WAIT command and waits for it to finish. The IOMMU informs
 * us about that by writing a value to a physical address we pass with
 * the command.
 */
static int iommu_completion_wait(struct amd_iommu *iommu)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&iommu->lock, flags);

        if (!iommu->need_sync)
                goto out;

        ret = __iommu_completion_wait(iommu);

        iommu->need_sync = false;

        if (ret)
                goto out;

        __iommu_wait_for_completion(iommu);

out:
        spin_unlock_irqrestore(&iommu->lock, flags);

        return 0;
}

/*
 * Command send function for invalidating a device table entry
 */
static int iommu_queue_inv_dev_entry(struct amd_iommu *iommu, u16 devid)
{
        struct iommu_cmd cmd;
        int ret;

        BUG_ON(iommu == NULL);

        memset(&cmd, 0, sizeof(cmd));
        CMD_SET_TYPE(&cmd, CMD_INV_DEV_ENTRY);
        cmd.data[0] = devid;

        ret = iommu_queue_command(iommu, &cmd);

        return ret;
}

static void __iommu_build_inv_iommu_pages(struct iommu_cmd *cmd, u64 address,
                                          u16 domid, int pde, int s)
{
        memset(cmd, 0, sizeof(*cmd));
        address &= PAGE_MASK;
        CMD_SET_TYPE(cmd, CMD_INV_IOMMU_PAGES);
        cmd->data[1] |= domid;
        cmd->data[2] = lower_32_bits(address);
        cmd->data[3] = upper_32_bits(address);
        if (s) /* size bit - we flush more than one 4kb page */
                cmd->data[2] |= CMD_INV_IOMMU_PAGES_SIZE_MASK;
        if (pde) /* PDE bit - we wan't flush everything not only the PTEs */
                cmd->data[2] |= CMD_INV_IOMMU_PAGES_PDE_MASK;
}

/*
 * Generic command send function for invalidaing TLB entries
 */
static int iommu_queue_inv_iommu_pages(struct amd_iommu *iommu,
                u64 address, u16 domid, int pde, int s)
{
        struct iommu_cmd cmd;
        int ret;

        __iommu_build_inv_iommu_pages(&cmd, address, domid, pde, s);

        ret = iommu_queue_command(iommu, &cmd);

        return ret;
}

/*
 * TLB invalidation function which is called from the mapping functions.
 * It invalidates a single PTE if the range to flush is within a single
 * page. Otherwise it flushes the whole TLB of the IOMMU.
 */
static int iommu_flush_pages(struct amd_iommu *iommu, u16 domid,
                u64 address, size_t size)
{
        int s = 0;
        unsigned pages = iommu_num_pages(address, size, PAGE_SIZE);

        address &= PAGE_MASK;

        if (pages > 1) {
                /*
                 * If we have to flush more than one page, flush all
                 * TLB entries for this domain
                 */
                address = CMD_INV_IOMMU_ALL_PAGES_ADDRESS;
                s = 1;
        }

        iommu_queue_inv_iommu_pages(iommu, address, domid, 0, s);

        return 0;
}

/* Flush the whole IO/TLB for a given protection domain */
static void iommu_flush_tlb(struct amd_iommu *iommu, u16 domid)
{
        u64 address = CMD_INV_IOMMU_ALL_PAGES_ADDRESS;

        INC_STATS_COUNTER(domain_flush_single);

        iommu_queue_inv_iommu_pages(iommu, address, domid, 0, 1);
}

/* Flush the whole IO/TLB for a given protection domain - including PDE */
static void iommu_flush_tlb_pde(struct amd_iommu *iommu, u16 domid)
{
       u64 address = CMD_INV_IOMMU_ALL_PAGES_ADDRESS;

       INC_STATS_COUNTER(domain_flush_single);

       iommu_queue_inv_iommu_pages(iommu, address, domid, 1, 1);
}

/*
 * This function flushes one domain on one IOMMU
 */
static void flush_domain_on_iommu(struct amd_iommu *iommu, u16 domid)
{
        struct iommu_cmd cmd;
        unsigned long flags;

        __iommu_build_inv_iommu_pages(&cmd, CMD_INV_IOMMU_ALL_PAGES_ADDRESS,
                                      domid, 1, 1);

        spin_lock_irqsave(&iommu->lock, flags);
        __iommu_queue_command(iommu, &cmd);
        __iommu_completion_wait(iommu);
        __iommu_wait_for_completion(iommu);
        spin_unlock_irqrestore(&iommu->lock, flags);
}

static void flush_all_domains_on_iommu(struct amd_iommu *iommu)
{
        int i;

        for (i = 1; i < MAX_DOMAIN_ID; ++i) {
                if (!test_bit(i, amd_iommu_pd_alloc_bitmap))
                        continue;
                flush_domain_on_iommu(iommu, i);
        }

}

/*
 * This function is used to flush the IO/TLB for a given protection domain
 * on every IOMMU in the system
 */
static void iommu_flush_domain(u16 domid)
{
        struct amd_iommu *iommu;

        INC_STATS_COUNTER(domain_flush_all);

        for_each_iommu(iommu)
                flush_domain_on_iommu(iommu, domid);
}

void amd_iommu_flush_all_domains(void)
{
        struct amd_iommu *iommu;

        for_each_iommu(iommu)
                flush_all_domains_on_iommu(iommu);
}

static void flush_all_devices_for_iommu(struct amd_iommu *iommu)
{
        int i;

        for (i = 0; i <= amd_iommu_last_bdf; ++i) {
                if (iommu != amd_iommu_rlookup_table[i])
                        continue;

                iommu_queue_inv_dev_entry(iommu, i);
                iommu_completion_wait(iommu);
        }
}

static void flush_devices_by_domain(struct protection_domain *domain)
{
        struct amd_iommu *iommu;
        int i;

        for (i = 0; i <= amd_iommu_last_bdf; ++i) {
                if ((domain == NULL && amd_iommu_pd_table[i] == NULL) ||
                    (amd_iommu_pd_table[i] != domain))
                        continue;

                iommu = amd_iommu_rlookup_table[i];
                if (!iommu)
                        continue;

                iommu_queue_inv_dev_entry(iommu, i);
                iommu_completion_wait(iommu);
        }
}

static void reset_iommu_command_buffer(struct amd_iommu *iommu)
{
        pr_err("AMD-Vi: Resetting IOMMU command buffer\n");

        if (iommu->reset_in_progress)
                panic("AMD-Vi: ILLEGAL_COMMAND_ERROR while resetting command buffer\n");

        iommu->reset_in_progress = true;

        amd_iommu_reset_cmd_buffer(iommu);
        flush_all_devices_for_iommu(iommu);
        flush_all_domains_on_iommu(iommu);

        iommu->reset_in_progress = false;
}

void amd_iommu_flush_all_devices(void)
{
        flush_devices_by_domain(NULL);
}

/****************************************************************************
 *
 * The functions below are used the create the page table mappings for
 * unity mapped regions.
 *
 ****************************************************************************/

/*
 * Generic mapping functions. It maps a physical address into a DMA
 * address space. It allocates the page table pages if necessary.
 * In the future it can be extended to a generic mapping function
 * supporting all features of AMD IOMMU page tables like level skipping
 * and full 64 bit address spaces.
 */
static int iommu_map_page(struct protection_domain *dom,
                          unsigned long bus_addr,
                          unsigned long phys_addr,
                          int prot,
                          int map_size)
{
        u64 __pte, *pte;

        bus_addr  = PAGE_ALIGN(bus_addr);
        phys_addr = PAGE_ALIGN(phys_addr);

        BUG_ON(!PM_ALIGNED(map_size, bus_addr));
        BUG_ON(!PM_ALIGNED(map_size, phys_addr));

        if (!(prot & IOMMU_PROT_MASK))
                return -EINVAL;

        pte = alloc_pte(dom, bus_addr, map_size, NULL, GFP_KERNEL);

        if (IOMMU_PTE_PRESENT(*pte))
                return -EBUSY;

        __pte = phys_addr | IOMMU_PTE_P;
        if (prot & IOMMU_PROT_IR)
                __pte |= IOMMU_PTE_IR;
        if (prot & IOMMU_PROT_IW)
                __pte |= IOMMU_PTE_IW;

        *pte = __pte;

        update_domain(dom);

        return 0;
}

static void iommu_unmap_page(struct protection_domain *dom,
                             unsigned long bus_addr, int map_size)
{
        u64 *pte = fetch_pte(dom, bus_addr, map_size);

        if (pte)
                *pte = 0;
}

/*
 * This function checks if a specific unity mapping entry is needed for
 * this specific IOMMU.
 */
static int iommu_for_unity_map(struct amd_iommu *iommu,
                               struct unity_map_entry *entry)
{
        u16 bdf, i;

        for (i = entry->devid_start; i <= entry->devid_end; ++i) {
                bdf = amd_iommu_alias_table[i];
                if (amd_iommu_rlookup_table[bdf] == iommu)
                        return 1;
        }

        return 0;
}

/*
 * Init the unity mappings for a specific IOMMU in the system
 *
 * Basically iterates over all unity mapping entries and applies them to
 * the default domain DMA of that IOMMU if necessary.
 */
static int iommu_init_unity_mappings(struct amd_iommu *iommu)
{
        struct unity_map_entry *entry;
        int ret;

        list_for_each_entry(entry, &amd_iommu_unity_map, list) {
                if (!iommu_for_unity_map(iommu, entry))
                        continue;
                ret = dma_ops_unity_map(iommu->default_dom, entry);
                if (ret)
                        return ret;
        }

        return 0;
}

/*
 * This function actually applies the mapping to the page table of the
 * dma_ops domain.
 */
static int dma_ops_unity_map(struct dma_ops_domain *dma_dom,
                             struct unity_map_entry *e)
{
        u64 addr;
        int ret;

        for (addr = e->address_start; addr < e->address_end;
             addr += PAGE_SIZE) {
                ret = iommu_map_page(&dma_dom->domain, addr, addr, e->prot,
                                     PM_MAP_4k);
                if (ret)
                        return ret;
                /*
                 * if unity mapping is in aperture range mark the page
                 * as allocated in the aperture
                 */
                if (addr < dma_dom->aperture_size)
                        __set_bit(addr >> PAGE_SHIFT,
                                  dma_dom->aperture[0]->bitmap);
        }

        return 0;
}

/*
 * Inits the unity mappings required for a specific device
 */
static int init_unity_mappings_for_device(struct dma_ops_domain *dma_dom,
                                          u16 devid)
{
        struct unity_map_entry *e;
        int ret;

        list_for_each_entry(e, &amd_iommu_unity_map, list) {
                if (!(devid >= e->devid_start && devid <= e->devid_end))
                        continue;
                ret = dma_ops_unity_map(dma_dom, e);
                if (ret)
                        return ret;
        }

        return 0;
}

/****************************************************************************
 *
 * The next functions belong to the address allocator for the dma_ops
 * interface functions. They work like the allocators in the other IOMMU
 * drivers. Its basically a bitmap which marks the allocated pages in
 * the aperture. Maybe it could be enhanced in the future to a more
 * efficient allocator.
 *
 ****************************************************************************/

/*
 * The address allocator core functions.
 *
 * called with domain->lock held
 */

/*
 * This function checks if there is a PTE for a given dma address. If
 * there is one, it returns the pointer to it.
 */
static u64 *fetch_pte(struct protection_domain *domain,
                      unsigned long address, int map_size)
{
        int level;
        u64 *pte;

        level =  domain->mode - 1;
        pte   = &domain->pt_root[PM_LEVEL_INDEX(level, address)];

        while (level > map_size) {
                if (!IOMMU_PTE_PRESENT(*pte))
                        return NULL;

                level -= 1;

                pte = IOMMU_PTE_PAGE(*pte);
                pte = &pte[PM_LEVEL_INDEX(level, address)];

                if ((PM_PTE_LEVEL(*pte) == 0) && level != map_size) {
                        pte = NULL;
                        break;
                }
        }

        return pte;
}

/*
 * This function is used to add a new aperture range to an existing
 * aperture in case of dma_ops domain allocation or address allocation
 * failure.
 */
static int alloc_new_range(struct amd_iommu *iommu,
                           struct dma_ops_domain *dma_dom,
                           bool populate, gfp_t gfp)
{
        int index = dma_dom->aperture_size >> APERTURE_RANGE_SHIFT;
        int i;

#ifdef CONFIG_IOMMU_STRESS
        populate = false;
#endif

        if (index >= APERTURE_MAX_RANGES)
                return -ENOMEM;

        dma_dom->aperture[index] = kzalloc(sizeof(struct aperture_range), gfp);
        if (!dma_dom->aperture[index])
                return -ENOMEM;

        dma_dom->aperture[index]->bitmap = (void *)get_zeroed_page(gfp);
        if (!dma_dom->aperture[index]->bitmap)
                goto out_free;

        dma_dom->aperture[index]->offset = dma_dom->aperture_size;

        if (populate) {
                unsigned long address = dma_dom->aperture_size;
                int i, num_ptes = APERTURE_RANGE_PAGES / 512;
                u64 *pte, *pte_page;

                for (i = 0; i < num_ptes; ++i) {
                        pte = alloc_pte(&dma_dom->domain, address, PM_MAP_4k,
                                        &pte_page, gfp);
                        if (!pte)
                                goto out_free;

                        dma_dom->aperture[index]->pte_pages[i] = pte_page;

                        address += APERTURE_RANGE_SIZE / 64;
                }
        }

        dma_dom->aperture_size += APERTURE_RANGE_SIZE;

        /* Intialize the exclusion range if necessary */
        if (iommu->exclusion_start &&
            iommu->exclusion_start >= dma_dom->aperture[index]->offset &&
            iommu->exclusion_start < dma_dom->aperture_size) {
                unsigned long startpage = iommu->exclusion_start >> PAGE_SHIFT;
                int pages = iommu_num_pages(iommu->exclusion_start,
                                            iommu->exclusion_length,
                                            PAGE_SIZE);
                dma_ops_reserve_addresses(dma_dom, startpage, pages);
        }

        /*
         * Check for areas already mapped as present in the new aperture
         * range and mark those pages as reserved in the allocator. Such
         * mappings may already exist as a result of requested unity
         * mappings for devices.
         */
        for (i = dma_dom->aperture[index]->offset;
             i < dma_dom->aperture_size;
             i += PAGE_SIZE) {
                u64 *pte = fetch_pte(&dma_dom->domain, i, PM_MAP_4k);
                if (!pte || !IOMMU_PTE_PRESENT(*pte))
                        continue;

                dma_ops_reserve_addresses(dma_dom, i << PAGE_SHIFT, 1);
        }

        update_domain(&dma_dom->domain);

        return 0;

out_free:
        update_domain(&dma_dom->domain);

        free_page((unsigned long)dma_dom->aperture[index]->bitmap);

        kfree(dma_dom->aperture[index]);
        dma_dom->aperture[index] = NULL;

        return -ENOMEM;
}

static unsigned long dma_ops_area_alloc(struct device *dev,
                                        struct dma_ops_domain *dom,
                                        unsigned int pages,
                                        unsigned long align_mask,
                                        u64 dma_mask,
                                        unsigned long start)
{
        unsigned long next_bit = dom->next_address % APERTURE_RANGE_SIZE;
        int max_index = dom->aperture_size >> APERTURE_RANGE_SHIFT;
        int i = start >> APERTURE_RANGE_SHIFT;
        unsigned long boundary_size;
        unsigned long address = -1;
        unsigned long limit;

        next_bit >>= PAGE_SHIFT;

        boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
                        PAGE_SIZE) >> PAGE_SHIFT;

        for (;i < max_index; ++i) {
                unsigned long offset = dom->aperture[i]->offset >> PAGE_SHIFT;

                if (dom->aperture[i]->offset >= dma_mask)
                        break;

                limit = iommu_device_max_index(APERTURE_RANGE_PAGES, offset,
                                               dma_mask >> PAGE_SHIFT);

                address = iommu_area_alloc(dom->aperture[i]->bitmap,
                                           limit, next_bit, pages, 0,
                                            boundary_size, align_mask);
                if (address != -1) {
                        address = dom->aperture[i]->offset +
                                  (address << PAGE_SHIFT);
                        dom->next_address = address + (pages << PAGE_SHIFT);
                        break;
                }

                next_bit = 0;
        }

        return address;
}

static unsigned long dma_ops_alloc_addresses(struct device *dev,
                                             struct dma_ops_domain *dom,
                                             unsigned int pages,
                                             unsigned long align_mask,
                                             u64 dma_mask)
{
        unsigned long address;

#ifdef CONFIG_IOMMU_STRESS
        dom->next_address = 0;
        dom->need_flush = true;
#endif

        address = dma_ops_area_alloc(dev, dom, pages, align_mask,
                                     dma_mask, dom->next_address);

        if (address == -1) {
                dom->next_address = 0;
                address = dma_ops_area_alloc(dev, dom, pages, align_mask,
                                             dma_mask, 0);
                dom->need_flush = true;
        }

        if (unlikely(address == -1))
                address = bad_dma_address;

        WARN_ON((address + (PAGE_SIZE*pages)) > dom->aperture_size);

        return address;
}

/*
 * The address free function.
 *
 * called with domain->lock held
 */
static void dma_ops_free_addresses(struct dma_ops_domain *dom,
                                   unsigned long address,
                                   unsigned int pages)
{
        unsigned i = address >> APERTURE_RANGE_SHIFT;
        struct aperture_range *range = dom->aperture[i];

        BUG_ON(i >= APERTURE_MAX_RANGES || range == NULL);

#ifdef CONFIG_IOMMU_STRESS
        if (i < 4)
                return;
#endif

        if (address >= dom->next_address)
                dom->need_flush = true;

        address = (address % APERTURE_RANGE_SIZE) >> PAGE_SHIFT;

        iommu_area_free(range->bitmap, address, pages);

}

/****************************************************************************
 *
 * The next functions belong to the domain allocation. A domain is
 * allocated for every IOMMU as the default domain. If device isolation
 * is enabled, every device get its own domain. The most important thing
 * about domains is the page table mapping the DMA address space they
 * contain.
 *
 ****************************************************************************/

static u16 domain_id_alloc(void)
{
        unsigned long flags;
        int id;

        write_lock_irqsave(&amd_iommu_devtable_lock, flags);
        id = find_first_zero_bit(amd_iommu_pd_alloc_bitmap, MAX_DOMAIN_ID);
        BUG_ON(id == 0);
        if (id > 0 && id < MAX_DOMAIN_ID)
                __set_bit(id, amd_iommu_pd_alloc_bitmap);
        else
                id = 0;
        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

        return id;
}

static void domain_id_free(int id)
{
        unsigned long flags;

        write_lock_irqsave(&amd_iommu_devtable_lock, flags);
        if (id > 0 && id < MAX_DOMAIN_ID)
                __clear_bit(id, amd_iommu_pd_alloc_bitmap);
        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

}

/*
 * Used to reserve address ranges in the aperture (e.g. for exclusion
 * ranges.
 */
static void dma_ops_reserve_addresses(struct dma_ops_domain *dom,
                                      unsigned long start_page,
                                      unsigned int pages)
{
        unsigned int i, last_page = dom->aperture_size >> PAGE_SHIFT;

        if (start_page + pages > last_page)
                pages = last_page - start_page;

        for (i = start_page; i < start_page + pages; ++i) {
                int index = i / APERTURE_RANGE_PAGES;
                int page  = i % APERTURE_RANGE_PAGES;
                __set_bit(page, dom->aperture[index]->bitmap);
        }
}

static void free_pagetable(struct protection_domain *domain)
{
        int i, j;
        u64 *p1, *p2, *p3;

        p1 = domain->pt_root;

        if (!p1)
                return;

        for (i = 0; i < 512; ++i) {
                if (!IOMMU_PTE_PRESENT(p1[i]))
                        continue;

                p2 = IOMMU_PTE_PAGE(p1[i]);
                for (j = 0; j < 512; ++j) {
                        if (!IOMMU_PTE_PRESENT(p2[j]))
                                continue;
                        p3 = IOMMU_PTE_PAGE(p2[j]);
                        free_page((unsigned long)p3);
                }

                free_page((unsigned long)p2);
        }

        free_page((unsigned long)p1);

        domain->pt_root = NULL;
}

/*
 * Free a domain, only used if something went wrong in the
 * allocation path and we need to free an already allocated page table
 */
static void dma_ops_domain_free(struct dma_ops_domain *dom)
{
        int i;

        if (!dom)
                return;

        free_pagetable(&dom->domain);

        for (i = 0; i < APERTURE_MAX_RANGES; ++i) {
                if (!dom->aperture[i])
                        continue;
                free_page((unsigned long)dom->aperture[i]->bitmap);
                kfree(dom->aperture[i]);
        }

        kfree(dom);
}

/*
 * Allocates a new protection domain usable for the dma_ops functions.
 * It also intializes the page table and the address allocator data
 * structures required for the dma_ops interface
 */
static struct dma_ops_domain *dma_ops_domain_alloc(struct amd_iommu *iommu)
{
        struct dma_ops_domain *dma_dom;

        dma_dom = kzalloc(sizeof(struct dma_ops_domain), GFP_KERNEL);
        if (!dma_dom)
                return NULL;

        spin_lock_init(&dma_dom->domain.lock);

        dma_dom->domain.id = domain_id_alloc();
        if (dma_dom->domain.id == 0)
                goto free_dma_dom;
        dma_dom->domain.mode = PAGE_MODE_2_LEVEL;
        dma_dom->domain.pt_root = (void *)get_zeroed_page(GFP_KERNEL);
        dma_dom->domain.flags = PD_DMA_OPS_MASK;
        dma_dom->domain.priv = dma_dom;
        if (!dma_dom->domain.pt_root)
                goto free_dma_dom;

        dma_dom->need_flush = false;
        dma_dom->target_dev = 0xffff;

        if (alloc_new_range(iommu, dma_dom, true, GFP_KERNEL))
                goto free_dma_dom;

        /*
         * mark the first page as allocated so we never return 0 as
         * a valid dma-address. So we can use 0 as error value
         */
        dma_dom->aperture[0]->bitmap[0] = 1;
        dma_dom->next_address = 0;


        return dma_dom;

free_dma_dom:
        dma_ops_domain_free(dma_dom);

        return NULL;
}

/*
 * little helper function to check whether a given protection domain is a
 * dma_ops domain
 */
static bool dma_ops_domain(struct protection_domain *domain)
{
        return domain->flags & PD_DMA_OPS_MASK;
}

/*
 * Find out the protection domain structure for a given PCI device. This
 * will give us the pointer to the page table root for example.
 */
static struct protection_domain *domain_for_device(u16 devid)
{
        struct protection_domain *dom;
        unsigned long flags;

        read_lock_irqsave(&amd_iommu_devtable_lock, flags);
        dom = amd_iommu_pd_table[devid];
        read_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

        return dom;
}

static void set_dte_entry(u16 devid, struct protection_domain *domain)
{
        u64 pte_root = virt_to_phys(domain->pt_root);

        pte_root |= (domain->mode & DEV_ENTRY_MODE_MASK)
                    << DEV_ENTRY_MODE_SHIFT;
        pte_root |= IOMMU_PTE_IR | IOMMU_PTE_IW | IOMMU_PTE_P | IOMMU_PTE_TV;

        amd_iommu_dev_table[devid].data[2] = domain->id;
        amd_iommu_dev_table[devid].data[1] = upper_32_bits(pte_root);
        amd_iommu_dev_table[devid].data[0] = lower_32_bits(pte_root);

        amd_iommu_pd_table[devid] = domain;
}

/*
 * If a device is not yet associated with a domain, this function does
 * assigns it visible for the hardware
 */
static void __attach_device(struct amd_iommu *iommu,
                            struct protection_domain *domain,
                            u16 devid)
{
        /* lock domain */
        spin_lock(&domain->lock);

        /* update DTE entry */
        set_dte_entry(devid, domain);

        domain->dev_cnt += 1;

        /* ready */
        spin_unlock(&domain->lock);
}

/*
 * If a device is not yet associated with a domain, this function does
 * assigns it visible for the hardware
 */
static void attach_device(struct amd_iommu *iommu,
                          struct protection_domain *domain,
                          u16 devid)
{
        unsigned long flags;

        write_lock_irqsave(&amd_iommu_devtable_lock, flags);
        __attach_device(iommu, domain, devid);
        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

        /*
         * We might boot into a crash-kernel here. The crashed kernel
         * left the caches in the IOMMU dirty. So we have to flush
         * here to evict all dirty stuff.
         */
        iommu_queue_inv_dev_entry(iommu, devid);
        iommu_flush_tlb_pde(iommu, domain->id);
}

/*
 * Removes a device from a protection domain (unlocked)
 */
static void __detach_device(struct protection_domain *domain, u16 devid)
{

        /* lock domain */
        spin_lock(&domain->lock);

        /* remove domain from the lookup table */
        amd_iommu_pd_table[devid] = NULL;

        /* remove entry from the device table seen by the hardware */
        amd_iommu_dev_table[devid].data[0] = IOMMU_PTE_P | IOMMU_PTE_TV;
        amd_iommu_dev_table[devid].data[1] = 0;
        amd_iommu_dev_table[devid].data[2] = 0;

        amd_iommu_apply_erratum_63(devid);

        /* decrease reference counter */
        domain->dev_cnt -= 1;

        /* ready */
        spin_unlock(&domain->lock);

        /*
         * If we run in passthrough mode the device must be assigned to the
         * passthrough domain if it is detached from any other domain
         */
        if (iommu_pass_through) {
                struct amd_iommu *iommu = amd_iommu_rlookup_table[devid];
                __attach_device(iommu, pt_domain, devid);
        }
}

/*
 * Removes a device from a protection domain (with devtable_lock held)
 */
static void detach_device(struct protection_domain *domain, u16 devid)
{
        unsigned long flags;

        /* lock device table */
        write_lock_irqsave(&amd_iommu_devtable_lock, flags);
        __detach_device(domain, devid);
        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
}

static int device_change_notifier(struct notifier_block *nb,
                                  unsigned long action, void *data)
{
        struct device *dev = data;
        struct pci_dev *pdev = to_pci_dev(dev);
        u16 devid = calc_devid(pdev->bus->number, pdev->devfn);
        struct protection_domain *domain;
        struct dma_ops_domain *dma_domain;
        struct amd_iommu *iommu;
        unsigned long flags;

        if (devid > amd_iommu_last_bdf)
                goto out;

        devid = amd_iommu_alias_table[devid];

        iommu = amd_iommu_rlookup_table[devid];
        if (iommu == NULL)
                goto out;

        domain = domain_for_device(devid);

        if (domain && !dma_ops_domain(domain))
                WARN_ONCE(1, "AMD IOMMU WARNING: device %s already bound "
                          "to a non-dma-ops domain\n", dev_name(dev));

        switch (action) {
        case BUS_NOTIFY_UNBOUND_DRIVER:
                if (!domain)
                        goto out;
                if (iommu_pass_through)
                        break;
                detach_device(domain, devid);
                break;
        case BUS_NOTIFY_ADD_DEVICE:
                /* allocate a protection domain if a device is added */
                dma_domain = find_protection_domain(devid);
                if (dma_domain)
                        goto out;
                dma_domain = dma_ops_domain_alloc(iommu);
                if (!dma_domain)
                        goto out;
                dma_domain->target_dev = devid;

                spin_lock_irqsave(&iommu_pd_list_lock, flags);
                list_add_tail(&dma_domain->list, &iommu_pd_list);
                spin_unlock_irqrestore(&iommu_pd_list_lock, flags);

                break;
        default:
                goto out;
        }

        iommu_queue_inv_dev_entry(iommu, devid);
        iommu_completion_wait(iommu);

out:
        return 0;
}

static struct notifier_block device_nb = {
        .notifier_call = device_change_notifier,
};

/*****************************************************************************
 *
 * The next functions belong to the dma_ops mapping/unmapping code.
 *
 *****************************************************************************/

/*
 * This function checks if the driver got a valid device from the caller to
 * avoid dereferencing invalid pointers.
 */
static bool check_device(struct device *dev)
{
        if (!dev || !dev->dma_mask)
                return false;

        return true;
}

/*
 * In this function the list of preallocated protection domains is traversed to
 * find the domain for a specific device
 */
static struct dma_ops_domain *find_protection_domain(u16 devid)
{
        struct dma_ops_domain *entry, *ret = NULL;
        unsigned long flags;

        if (list_empty(&iommu_pd_list))
                return NULL;

        spin_lock_irqsave(&iommu_pd_list_lock, flags);

        list_for_each_entry(entry, &iommu_pd_list, list) {
                if (entry->target_dev == devid) {
                        ret = entry;
                        break;
                }
        }

        spin_unlock_irqrestore(&iommu_pd_list_lock, flags);

        return ret;
}

/*
 * In the dma_ops path we only have the struct device. This function
 * finds the corresponding IOMMU, the protection domain and the
 * requestor id for a given device.
 * If the device is not yet associated with a domain this is also done
 * in this function.
 */
static int get_device_resources(struct device *dev,
                                struct amd_iommu **iommu,
                                struct protection_domain **domain,
                                u16 *bdf)
{
        struct dma_ops_domain *dma_dom;
        struct pci_dev *pcidev;
        u16 _bdf;

        *iommu = NULL;
        *domain = NULL;
        *bdf = 0xffff;

        if (dev->bus != &pci_bus_type)
                return 0;

        pcidev = to_pci_dev(dev);
        _bdf = calc_devid(pcidev->bus->number, pcidev->devfn);

        /* device not translated by any IOMMU in the system? */
        if (_bdf > amd_iommu_last_bdf)
                return 0;

        *bdf = amd_iommu_alias_table[_bdf];

        *iommu = amd_iommu_rlookup_table[*bdf];
        if (*iommu == NULL)
                return 0;
        *domain = domain_for_device(*bdf);
        if (*domain == NULL) {
                dma_dom = find_protection_domain(*bdf);
                if (!dma_dom)
                        dma_dom = (*iommu)->default_dom;
                *domain = &dma_dom->domain;
                attach_device(*iommu, *domain, *bdf);
                DUMP_printk("Using protection domain %d for device %s\n",
                            (*domain)->id, dev_name(dev));
        }

        if (domain_for_device(_bdf) == NULL)
                attach_device(*iommu, *domain, _bdf);

        return 1;
}

static void update_device_table(struct protection_domain *domain)
{
        unsigned long flags;
        int i;

        for (i = 0; i <= amd_iommu_last_bdf; ++i) {
                if (amd_iommu_pd_table[i] != domain)
                        continue;
                write_lock_irqsave(&amd_iommu_devtable_lock, flags);
                set_dte_entry(i, domain);
                write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
        }
}

static void update_domain(struct protection_domain *domain)
{
        if (!domain->updated)
                return;

        update_device_table(domain);
        flush_devices_by_domain(domain);
        iommu_flush_domain(domain->id);

        domain->updated = false;
}

/*
 * This function is used to add another level to an IO page table. Adding
 * another level increases the size of the address space by 9 bits to a size up
 * to 64 bits.
 */
static bool increase_address_space(struct protection_domain *domain,
                                   gfp_t gfp)
{
        u64 *pte;

        if (domain->mode == PAGE_MODE_6_LEVEL)
                /* address space already 64 bit large */
                return false;

        pte = (void *)get_zeroed_page(gfp);
        if (!pte)
                return false;

        *pte             = PM_LEVEL_PDE(domain->mode,
                                        virt_to_phys(domain->pt_root));
        domain->pt_root  = pte;
        domain->mode    += 1;
        domain->updated  = true;

        return true;
}

static u64 *alloc_pte(struct protection_domain *domain,
                      unsigned long address,
                      int end_lvl,
                      u64 **pte_page,
                      gfp_t gfp)
{
        u64 *pte, *page;
        int level;

        while (address > PM_LEVEL_SIZE(domain->mode))
                increase_address_space(domain, gfp);

        level =  domain->mode - 1;
        pte   = &domain->pt_root[PM_LEVEL_INDEX(level, address)];

        while (level > end_lvl) {
                if (!IOMMU_PTE_PRESENT(*pte)) {
                        page = (u64 *)get_zeroed_page(gfp);
                        if (!page)
                                return NULL;
                        *pte = PM_LEVEL_PDE(level, virt_to_phys(page));
                }

                level -= 1;

                pte = IOMMU_PTE_PAGE(*pte);

                if (pte_page && level == end_lvl)
                        *pte_page = pte;

                pte = &pte[PM_LEVEL_INDEX(level, address)];
        }

        return pte;
}

/*
 * This function fetches the PTE for a given address in the aperture
 */
static u64* dma_ops_get_pte(struct dma_ops_domain *dom,
                            unsigned long address)
{
        struct aperture_range *aperture;
        u64 *pte, *pte_page;

        aperture = dom->aperture[APERTURE_RANGE_INDEX(address)];
        if (!aperture)
                return NULL;

        pte = aperture->pte_pages[APERTURE_PAGE_INDEX(address)];
        if (!pte) {
                pte = alloc_pte(&dom->domain, address, PM_MAP_4k, &pte_page,
                                GFP_ATOMIC);
                aperture->pte_pages[APERTURE_PAGE_INDEX(address)] = pte_page;
        } else
                pte += PM_LEVEL_INDEX(0, address);

        update_domain(&dom->domain);

        return pte;
}

/*
 * This is the generic map function. It maps one 4kb page at paddr to
 * the given address in the DMA address space for the domain.
 */
static dma_addr_t dma_ops_domain_map(struct amd_iommu *iommu,
                                     struct dma_ops_domain *dom,
                                     unsigned long address,
                                     phys_addr_t paddr,
                                     int direction)
{
        u64 *pte, __pte;

        WARN_ON(address > dom->aperture_size);

        paddr &= PAGE_MASK;

        pte  = dma_ops_get_pte(dom, address);
        if (!pte)
                return bad_dma_address;

        __pte = paddr | IOMMU_PTE_P | IOMMU_PTE_FC;

        if (direction == DMA_TO_DEVICE)
                __pte |= IOMMU_PTE_IR;
        else if (direction == DMA_FROM_DEVICE)
                __pte |= IOMMU_PTE_IW;
        else if (direction == DMA_BIDIRECTIONAL)
                __pte |= IOMMU_PTE_IR | IOMMU_PTE_IW;

        WARN_ON(*pte);

        *pte = __pte;

        return (dma_addr_t)address;
}

/*
 * The generic unmapping function for on page in the DMA address space.
 */
static void dma_ops_domain_unmap(struct amd_iommu *iommu,
                                 struct dma_ops_domain *dom,
                                 unsigned long address)
{
        struct aperture_range *aperture;
        u64 *pte;

        if (address >= dom->aperture_size)
                return;

        aperture = dom->aperture[APERTURE_RANGE_INDEX(address)];
        if (!aperture)
                return;

        pte  = aperture->pte_pages[APERTURE_PAGE_INDEX(address)];
        if (!pte)
                return;

        pte += PM_LEVEL_INDEX(0, address);

        WARN_ON(!*pte);

        *pte = 0ULL;
}

/*
 * This function contains common code for mapping of a physically
 * contiguous memory region into DMA address space. It is used by all
 * mapping functions provided with this IOMMU driver.
 * Must be called with the domain lock held.
 */
static dma_addr_t __map_single(struct device *dev,
                               struct amd_iommu *iommu,
                               struct dma_ops_domain *dma_dom,
                               phys_addr_t paddr,
                               size_t size,
                               int dir,
                               bool align,
                               u64 dma_mask)
{
        dma_addr_t offset = paddr & ~PAGE_MASK;
        dma_addr_t address, start, ret;
        unsigned int pages;
        unsigned long align_mask = 0;
        int i;

        pages = iommu_num_pages(paddr, size, PAGE_SIZE);
        paddr &= PAGE_MASK;

        INC_STATS_COUNTER(total_map_requests);

        if (pages > 1)
                INC_STATS_COUNTER(cross_page);

        if (align)
                align_mask = (1UL << get_order(size)) - 1;

retry:
        address = dma_ops_alloc_addresses(dev, dma_dom, pages, align_mask,
                                          dma_mask);
        if (unlikely(address == bad_dma_address)) {
                /*
                 * setting next_address here will let the address
                 * allocator only scan the new allocated range in the
                 * first run. This is a small optimization.
                 */
                dma_dom->next_address = dma_dom->aperture_size;

                if (alloc_new_range(iommu, dma_dom, false, GFP_ATOMIC))
                        goto out;

                /*
                 * aperture was sucessfully enlarged by 128 MB, try
                 * allocation again
                 */
                goto retry;
        }

        start = address;
        for (i = 0; i < pages; ++i) {
                ret = dma_ops_domain_map(iommu, dma_dom, start, paddr, dir);
                if (ret == bad_dma_address)
                        goto out_unmap;

                paddr += PAGE_SIZE;
                start += PAGE_SIZE;
        }
        address += offset;

        ADD_STATS_COUNTER(alloced_io_mem, size);

        if (unlikely(dma_dom->need_flush && !amd_iommu_unmap_flush)) {
                iommu_flush_tlb(iommu, dma_dom->domain.id);
                dma_dom->need_flush = false;
        } else if (unlikely(iommu_has_npcache(iommu)))
                iommu_flush_pages(iommu, dma_dom->domain.id, address, size);

out:
        return address;

out_unmap:

        for (--i; i >= 0; --i) {
                start -= PAGE_SIZE;
                dma_ops_domain_unmap(iommu, dma_dom, start);
        }

        dma_ops_free_addresses(dma_dom, address, pages);

        return bad_dma_address;
}

/*
 * Does the reverse of the __map_single function. Must be called with
 * the domain lock held too
 */
static void __unmap_single(struct amd_iommu *iommu,
                           struct dma_ops_domain *dma_dom,
                           dma_addr_t dma_addr,
                           size_t size,
                           int dir)
{
        dma_addr_t i, start;
        unsigned int pages;

        if ((dma_addr == bad_dma_address) ||
            (dma_addr + size > dma_dom->aperture_size))
                return;

        pages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
        dma_addr &= PAGE_MASK;
        start = dma_addr;

        for (i = 0; i < pages; ++i) {
                dma_ops_domain_unmap(iommu, dma_dom, start);
                start += PAGE_SIZE;
        }

        SUB_STATS_COUNTER(alloced_io_mem, size);

        dma_ops_free_addresses(dma_dom, dma_addr, pages);

        if (amd_iommu_unmap_flush || dma_dom->need_flush) {
                iommu_flush_pages(iommu, dma_dom->domain.id, dma_addr, size);
                dma_dom->need_flush = false;
        }
}

/*
 * The exported map_single function for dma_ops.
 */
static dma_addr_t map_page(struct device *dev, struct page *page,
                           unsigned long offset, size_t size,
                           enum dma_data_direction dir,
                           struct dma_attrs *attrs)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;
        dma_addr_t addr;
        u64 dma_mask;
        phys_addr_t paddr = page_to_phys(page) + offset;

        INC_STATS_COUNTER(cnt_map_single);

        if (!check_device(dev))
                return bad_dma_address;

        dma_mask = *dev->dma_mask;

        get_device_resources(dev, &iommu, &domain, &devid);

        if (iommu == NULL || domain == NULL)
                /* device not handled by any AMD IOMMU */
                return (dma_addr_t)paddr;

        if (!dma_ops_domain(domain))
                return bad_dma_address;

        spin_lock_irqsave(&domain->lock, flags);
        addr = __map_single(dev, iommu, domain->priv, paddr, size, dir, false,
                            dma_mask);
        if (addr == bad_dma_address)
                goto out;

        iommu_completion_wait(iommu);

out:
        spin_unlock_irqrestore(&domain->lock, flags);

        return addr;
}

/*
 * The exported unmap_single function for dma_ops.
 */
static void unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
                       enum dma_data_direction dir, struct dma_attrs *attrs)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;

        INC_STATS_COUNTER(cnt_unmap_single);

        if (!check_device(dev) ||
            !get_device_resources(dev, &iommu, &domain, &devid))
                /* device not handled by any AMD IOMMU */
                return;

        if (!dma_ops_domain(domain))
                return;

        spin_lock_irqsave(&domain->lock, flags);

        __unmap_single(iommu, domain->priv, dma_addr, size, dir);

        iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);
}

/*
 * This is a special map_sg function which is used if we should map a
 * device which is not handled by an AMD IOMMU in the system.
 */
static int map_sg_no_iommu(struct device *dev, struct scatterlist *sglist,
                           int nelems, int dir)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sglist, s, nelems, i) {
                s->dma_address = (dma_addr_t)sg_phys(s);
                s->dma_length  = s->length;
        }

        return nelems;
}

/*
 * The exported map_sg function for dma_ops (handles scatter-gather
 * lists).
 */
static int map_sg(struct device *dev, struct scatterlist *sglist,
                  int nelems, enum dma_data_direction dir,
                  struct dma_attrs *attrs)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;
        int i;
        struct scatterlist *s;
        phys_addr_t paddr;
        int mapped_elems = 0;
        u64 dma_mask;

        INC_STATS_COUNTER(cnt_map_sg);

        if (!check_device(dev))
                return 0;

        dma_mask = *dev->dma_mask;

        get_device_resources(dev, &iommu, &domain, &devid);

        if (!iommu || !domain)
                return map_sg_no_iommu(dev, sglist, nelems, dir);

        if (!dma_ops_domain(domain))
                return 0;

        spin_lock_irqsave(&domain->lock, flags);

        for_each_sg(sglist, s, nelems, i) {
                paddr = sg_phys(s);

                s->dma_address = __map_single(dev, iommu, domain->priv,
                                              paddr, s->length, dir, false,
                                              dma_mask);

                if (s->dma_address) {
                        s->dma_length = s->length;
                        mapped_elems++;
                } else
                        goto unmap;
        }

        iommu_completion_wait(iommu);

out:
        spin_unlock_irqrestore(&domain->lock, flags);

        return mapped_elems;
unmap:
        for_each_sg(sglist, s, mapped_elems, i) {
                if (s->dma_address)
                        __unmap_single(iommu, domain->priv, s->dma_address,
                                       s->dma_length, dir);
                s->dma_address = s->dma_length = 0;
        }

        mapped_elems = 0;

        goto out;
}

/*
 * The exported map_sg function for dma_ops (handles scatter-gather
 * lists).
 */
static void unmap_sg(struct device *dev, struct scatterlist *sglist,
                     int nelems, enum dma_data_direction dir,
                     struct dma_attrs *attrs)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        struct scatterlist *s;
        u16 devid;
        int i;

        INC_STATS_COUNTER(cnt_unmap_sg);

        if (!check_device(dev) ||
            !get_device_resources(dev, &iommu, &domain, &devid))
                return;

        if (!dma_ops_domain(domain))
                return;

        spin_lock_irqsave(&domain->lock, flags);

        for_each_sg(sglist, s, nelems, i) {
                __unmap_single(iommu, domain->priv, s->dma_address,
                               s->dma_length, dir);
                s->dma_address = s->dma_length = 0;
        }

        iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);
}

/*
 * The exported alloc_coherent function for dma_ops.
 */
static void *alloc_coherent(struct device *dev, size_t size,
                            dma_addr_t *dma_addr, gfp_t flag)
{
        unsigned long flags;
        void *virt_addr;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;
        phys_addr_t paddr;
        u64 dma_mask = dev->coherent_dma_mask;

        INC_STATS_COUNTER(cnt_alloc_coherent);

        if (!check_device(dev))
                return NULL;

        if (!get_device_resources(dev, &iommu, &domain, &devid))
                flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);

        flag |= __GFP_ZERO;
        virt_addr = (void *)__get_free_pages(flag, get_order(size));
        if (!virt_addr)
                return NULL;

        paddr = virt_to_phys(virt_addr);

        if (!iommu || !domain) {
                *dma_addr = (dma_addr_t)paddr;
                return virt_addr;
        }

        if (!dma_ops_domain(domain))
                goto out_free;

        if (!dma_mask)
                dma_mask = *dev->dma_mask;

        spin_lock_irqsave(&domain->lock, flags);

        *dma_addr = __map_single(dev, iommu, domain->priv, paddr,
                                 size, DMA_BIDIRECTIONAL, true, dma_mask);

        if (*dma_addr == bad_dma_address) {
                spin_unlock_irqrestore(&domain->lock, flags);
                goto out_free;
        }

        iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);

        return virt_addr;

out_free:

        free_pages((unsigned long)virt_addr, get_order(size));

        return NULL;
}

/*
 * The exported free_coherent function for dma_ops.
 */
static void free_coherent(struct device *dev, size_t size,
                          void *virt_addr, dma_addr_t dma_addr)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;

        INC_STATS_COUNTER(cnt_free_coherent);

        if (!check_device(dev))
                return;

        get_device_resources(dev, &iommu, &domain, &devid);

        if (!iommu || !domain)
                goto free_mem;

        if (!dma_ops_domain(domain))
                goto free_mem;

        spin_lock_irqsave(&domain->lock, flags);

        __unmap_single(iommu, domain->priv, dma_addr, size, DMA_BIDIRECTIONAL);

        iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);

free_mem:
        free_pages((unsigned long)virt_addr, get_order(size));
}

/*
 * This function is called by the DMA layer to find out if we can handle a
 * particular device. It is part of the dma_ops.
 */
static int amd_iommu_dma_supported(struct device *dev, u64 mask)
{
        u16 bdf;
        struct pci_dev *pcidev;

        /* No device or no PCI device */
        if (!dev || dev->bus != &pci_bus_type)
                return 0;

        pcidev = to_pci_dev(dev);

        bdf = calc_devid(pcidev->bus->number, pcidev->devfn);

        /* Out of our scope? */
        if (bdf > amd_iommu_last_bdf)
                return 0;

        return 1;
}

/*
 * The function for pre-allocating protection domains.
 *
 * If the driver core informs the DMA layer if a driver grabs a device
 * we don't need to preallocate the protection domains anymore.
 * For now we have to.
 */
static void prealloc_protection_domains(void)
{
        struct pci_dev *dev = NULL;
        struct dma_ops_domain *dma_dom;
        struct amd_iommu *iommu;
        u16 devid;

        while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
                devid = calc_devid(dev->bus->number, dev->devfn);
                if (devid > amd_iommu_last_bdf)
                        continue;
                devid = amd_iommu_alias_table[devid];
                if (domain_for_device(devid))
                        continue;
                iommu = amd_iommu_rlookup_table[devid];
                if (!iommu)
                        continue;
                dma_dom = dma_ops_domain_alloc(iommu);
                if (!dma_dom)
                        continue;
                init_unity_mappings_for_device(dma_dom, devid);
                dma_dom->target_dev = devid;

                list_add_tail(&dma_dom->list, &iommu_pd_list);
        }
}

static struct dma_map_ops amd_iommu_dma_ops = {
        .alloc_coherent = alloc_coherent,
        .free_coherent = free_coherent,
        .map_page = map_page,
        .unmap_page = unmap_page,
        .map_sg = map_sg,
        .unmap_sg = unmap_sg,
        .dma_supported = amd_iommu_dma_supported,
};

/*
 * The function which clues the AMD IOMMU driver into dma_ops.
 */
int __init amd_iommu_init_dma_ops(void)
{
        struct amd_iommu *iommu;
        int ret;

        /*
         * first allocate a default protection domain for every IOMMU we
         * found in the system. Devices not assigned to any other
         * protection domain will be assigned to the default one.
         */
        for_each_iommu(iommu) {
                iommu->default_dom = dma_ops_domain_alloc(iommu);
                if (iommu->default_dom == NULL)
                        return -ENOMEM;
                iommu->default_dom->domain.flags |= PD_DEFAULT_MASK;
                ret = iommu_init_unity_mappings(iommu);
                if (ret)
                        goto free_domains;
        }

        /*
         * If device isolation is enabled, pre-allocate the protection
         * domains for each device.
         */
        if (amd_iommu_isolate)
                prealloc_protection_domains();

        iommu_detected = 1;
        force_iommu = 1;
        bad_dma_address = 0;
#ifdef CONFIG_GART_IOMMU
        gart_iommu_aperture_disabled = 1;
        gart_iommu_aperture = 0;
#endif

        /* Make the driver finally visible to the drivers */
        dma_ops = &amd_iommu_dma_ops;

        register_iommu(&amd_iommu_ops);

        bus_register_notifier(&pci_bus_type, &device_nb);

        amd_iommu_stats_init();

        return 0;

free_domains:

        for_each_iommu(iommu) {
                if (iommu->default_dom)
                        dma_ops_domain_free(iommu->default_dom);
        }

        return ret;
}

/*****************************************************************************
 *
 * The following functions belong to the exported interface of AMD IOMMU
 *
 * This interface allows access to lower level functions of the IOMMU
 * like protection domain handling and assignement of devices to domains
 * which is not possible with the dma_ops interface.
 *
 *****************************************************************************/

static void cleanup_domain(struct protection_domain *domain)
{
        unsigned long flags;
        u16 devid;

        write_lock_irqsave(&amd_iommu_devtable_lock, flags);

        for (devid = 0; devid <= amd_iommu_last_bdf; ++devid)
                if (amd_iommu_pd_table[devid] == domain)
                        __detach_device(domain, devid);

        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
}

static void protection_domain_free(struct protection_domain *domain)
{
        if (!domain)
                return;

        if (domain->id)
                domain_id_free(domain->id);

        kfree(domain);
}

static struct protection_domain *protection_domain_alloc(void)
{
        struct protection_domain *domain;

        domain = kzalloc(sizeof(*domain), GFP_KERNEL);
        if (!domain)
                return NULL;

        spin_lock_init(&domain->lock);
        domain->id = domain_id_alloc();
        if (!domain->id)
                goto out_err;

        return domain;

out_err:
        kfree(domain);

        return NULL;
}

static int amd_iommu_domain_init(struct iommu_domain *dom)
{
        struct protection_domain *domain;

        domain = protection_domain_alloc();
        if (!domain)
                goto out_free;

        domain->mode    = PAGE_MODE_3_LEVEL;
        domain->pt_root = (void *)get_zeroed_page(GFP_KERNEL);
        if (!domain->pt_root)
                goto out_free;

        dom->priv = domain;

        return 0;

out_free:
        protection_domain_free(domain);

        return -ENOMEM;
}

static void amd_iommu_domain_destroy(struct iommu_domain *dom)
{
        struct protection_domain *domain = dom->priv;

        if (!domain)
                return;

        if (domain->dev_cnt > 0)
                cleanup_domain(domain);

        BUG_ON(domain->dev_cnt != 0);

        free_pagetable(domain);

        domain_id_free(domain->id);

        kfree(domain);

        dom->priv = NULL;
}

static void amd_iommu_detach_device(struct iommu_domain *dom,
                                    struct device *dev)
{
        struct protection_domain *domain = dom->priv;
        struct amd_iommu *iommu;
        struct pci_dev *pdev;
        u16 devid;

        if (dev->bus != &pci_bus_type)
                return;

        pdev = to_pci_dev(dev);

        devid = calc_devid(pdev->bus->number, pdev->devfn);

        if (devid > 0)
                detach_device(domain, devid);

        iommu = amd_iommu_rlookup_table[devid];
        if (!iommu)
                return;

        iommu_queue_inv_dev_entry(iommu, devid);
        iommu_completion_wait(iommu);
}

static int amd_iommu_attach_device(struct iommu_domain *dom,
                                   struct device *dev)
{
        struct protection_domain *domain = dom->priv;
        struct protection_domain *old_domain;
        struct amd_iommu *iommu;
        struct pci_dev *pdev;
        u16 devid;

        if (dev->bus != &pci_bus_type)
                return -EINVAL;

        pdev = to_pci_dev(dev);

        devid = calc_devid(pdev->bus->number, pdev->devfn);

        if (devid >= amd_iommu_last_bdf ||
                        devid != amd_iommu_alias_table[devid])
                return -EINVAL;

        iommu = amd_iommu_rlookup_table[devid];
        if (!iommu)
                return -EINVAL;

        old_domain = domain_for_device(devid);
        if (old_domain)
                detach_device(old_domain, devid);

        attach_device(iommu, domain, devid);

        iommu_completion_wait(iommu);

        return 0;
}

static int amd_iommu_map_range(struct iommu_domain *dom,
                               unsigned long iova, phys_addr_t paddr,
                               size_t size, int iommu_prot)
{
        struct protection_domain *domain = dom->priv;
        unsigned long i,  npages = iommu_num_pages(paddr, size, PAGE_SIZE);
        int prot = 0;
        int ret;

        if (iommu_prot & IOMMU_READ)
                prot |= IOMMU_PROT_IR;
        if (iommu_prot & IOMMU_WRITE)
                prot |= IOMMU_PROT_IW;

        iova  &= PAGE_MASK;
        paddr &= PAGE_MASK;

        for (i = 0; i < npages; ++i) {
                ret = iommu_map_page(domain, iova, paddr, prot, PM_MAP_4k);
                if (ret)
                        return ret;

                iova  += PAGE_SIZE;
                paddr += PAGE_SIZE;
        }

        return 0;
}

static void amd_iommu_unmap_range(struct iommu_domain *dom,
                                  unsigned long iova, size_t size)
{

        struct protection_domain *domain = dom->priv;
        unsigned long i,  npages = iommu_num_pages(iova, size, PAGE_SIZE);

        iova  &= PAGE_MASK;

        for (i = 0; i < npages; ++i) {
                iommu_unmap_page(domain, iova, PM_MAP_4k);
                iova  += PAGE_SIZE;
        }

        iommu_flush_domain(domain->id);
}

static phys_addr_t amd_iommu_iova_to_phys(struct iommu_domain *dom,
                                          unsigned long iova)
{
        struct protection_domain *domain = dom->priv;
        unsigned long offset = iova & ~PAGE_MASK;
        phys_addr_t paddr;
        u64 *pte;

        pte = fetch_pte(domain, iova, PM_MAP_4k);

        if (!pte || !IOMMU_PTE_PRESENT(*pte))
                return 0;

        paddr  = *pte & IOMMU_PAGE_MASK;
        paddr |= offset;

        return paddr;
}

static int amd_iommu_domain_has_cap(struct iommu_domain *domain,
                                    unsigned long cap)
{
        return 0;
}

static struct iommu_ops amd_iommu_ops = {
        .domain_init = amd_iommu_domain_init,
        .domain_destroy = amd_iommu_domain_destroy,
        .attach_dev = amd_iommu_attach_device,
        .detach_dev = amd_iommu_detach_device,
        .map = amd_iommu_map_range,
        .unmap = amd_iommu_unmap_range,
        .iova_to_phys = amd_iommu_iova_to_phys,
        .domain_has_cap = amd_iommu_domain_has_cap,
};

/*****************************************************************************
 *
 * The next functions do a basic initialization of IOMMU for pass through
 * mode
 *
 * In passthrough mode the IOMMU is initialized and enabled but not used for
 * DMA-API translation.
 *
 *****************************************************************************/

int __init amd_iommu_init_passthrough(void)
{
        struct pci_dev *dev = NULL;
        u16 devid, devid2;

        /* allocate passthroug domain */
        pt_domain = protection_domain_alloc();
        if (!pt_domain)
                return -ENOMEM;

        pt_domain->mode |= PAGE_MODE_NONE;

        while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
                struct amd_iommu *iommu;

                devid = calc_devid(dev->bus->number, dev->devfn);
                if (devid > amd_iommu_last_bdf)
                        continue;

                devid2 = amd_iommu_alias_table[devid];

                iommu = amd_iommu_rlookup_table[devid2];
                if (!iommu)
                        continue;

                __attach_device(iommu, pt_domain, devid);
                __attach_device(iommu, pt_domain, devid2);
        }

        pr_info("AMD-Vi: Initialized for Passthrough Mode\n");

        return 0;
}