// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * IOMMU implementation for Cell Broadband Processor Architecture
 *
 * (C) Copyright IBM Corporation 2006-2008
 *
 * Author: Jeremy Kerr <jk@ozlabs.org>
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/slab.h>
#include <linux/memblock.h>

#include <asm/prom.h>
#include <asm/iommu.h>
#include <asm/machdep.h>
#include <asm/pci-bridge.h>
#include <asm/udbg.h>
#include <asm/firmware.h>
#include <asm/cell-regs.h>

#include "cell.h"
#include "interrupt.h"

/* Define CELL_IOMMU_REAL_UNMAP to actually unmap non-used pages
 * instead of leaving them mapped to some dummy page. This can be
 * enabled once the appropriate workarounds for spider bugs have
 * been enabled
 */
#define CELL_IOMMU_REAL_UNMAP

/* Define CELL_IOMMU_STRICT_PROTECTION to enforce protection of
 * IO PTEs based on the transfer direction. That can be enabled
 * once spider-net has been fixed to pass the correct direction
 * to the DMA mapping functions
 */
#define CELL_IOMMU_STRICT_PROTECTION


#define NR_IOMMUS                       2

/* IOC mmap registers */
#define IOC_Reg_Size                    0x2000

#define IOC_IOPT_CacheInvd              0x908
#define IOC_IOPT_CacheInvd_NE_Mask      0xffe0000000000000ul
#define IOC_IOPT_CacheInvd_IOPTE_Mask   0x000003fffffffff8ul
#define IOC_IOPT_CacheInvd_Busy         0x0000000000000001ul

#define IOC_IOST_Origin                 0x918
#define IOC_IOST_Origin_E               0x8000000000000000ul
#define IOC_IOST_Origin_HW              0x0000000000000800ul
#define IOC_IOST_Origin_HL              0x0000000000000400ul

#define IOC_IO_ExcpStat                 0x920
#define IOC_IO_ExcpStat_V               0x8000000000000000ul
#define IOC_IO_ExcpStat_SPF_Mask        0x6000000000000000ul
#define IOC_IO_ExcpStat_SPF_S           0x6000000000000000ul
#define IOC_IO_ExcpStat_SPF_P           0x2000000000000000ul
#define IOC_IO_ExcpStat_ADDR_Mask       0x00000007fffff000ul
#define IOC_IO_ExcpStat_RW_Mask         0x0000000000000800ul
#define IOC_IO_ExcpStat_IOID_Mask       0x00000000000007fful

#define IOC_IO_ExcpMask                 0x928
#define IOC_IO_ExcpMask_SFE             0x4000000000000000ul
#define IOC_IO_ExcpMask_PFE             0x2000000000000000ul

#define IOC_IOCmd_Offset                0x1000

#define IOC_IOCmd_Cfg                   0xc00
#define IOC_IOCmd_Cfg_TE                0x0000800000000000ul


/* Segment table entries */
#define IOSTE_V                 0x8000000000000000ul /* valid */
#define IOSTE_H                 0x4000000000000000ul /* cache hint */
#define IOSTE_PT_Base_RPN_Mask  0x3ffffffffffff000ul /* base RPN of IOPT */
#define IOSTE_NPPT_Mask         0x0000000000000fe0ul /* no. pages in IOPT */
#define IOSTE_PS_Mask           0x0000000000000007ul /* page size */
#define IOSTE_PS_4K             0x0000000000000001ul /*   - 4kB  */
#define IOSTE_PS_64K            0x0000000000000003ul /*   - 64kB */
#define IOSTE_PS_1M             0x0000000000000005ul /*   - 1MB  */
#define IOSTE_PS_16M            0x0000000000000007ul /*   - 16MB */


/* IOMMU sizing */
#define IO_SEGMENT_SHIFT        28
#define IO_PAGENO_BITS(shift)   (IO_SEGMENT_SHIFT - (shift))

/* The high bit needs to be set on every DMA address */
#define SPIDER_DMA_OFFSET       0x80000000ul

struct iommu_window {
        struct list_head list;
        struct cbe_iommu *iommu;
        unsigned long offset;
        unsigned long size;
        unsigned int ioid;
        struct iommu_table table;
};

#define NAMESIZE 8
struct cbe_iommu {
        int nid;
        char name[NAMESIZE];
        void __iomem *xlate_regs;
        void __iomem *cmd_regs;
        unsigned long *stab;
        unsigned long *ptab;
        void *pad_page;
        struct list_head windows;
};

/* Static array of iommus, one per node
 *   each contains a list of windows, keyed from dma_window property
 *   - on bus setup, look for a matching window, or create one
 *   - on dev setup, assign iommu_table ptr
 */
static struct cbe_iommu iommus[NR_IOMMUS];
static int cbe_nr_iommus;

static void invalidate_tce_cache(struct cbe_iommu *iommu, unsigned long *pte,
                long n_ptes)
{
        u64 __iomem *reg;
        u64 val;
        long n;

        reg = iommu->xlate_regs + IOC_IOPT_CacheInvd;

        while (n_ptes > 0) {
                /* we can invalidate up to 1 << 11 PTEs at once */
                n = min(n_ptes, 1l << 11);
                val = (((n /*- 1*/) << 53) & IOC_IOPT_CacheInvd_NE_Mask)
                        | (__pa(pte) & IOC_IOPT_CacheInvd_IOPTE_Mask)
                        | IOC_IOPT_CacheInvd_Busy;

                out_be64(reg, val);
                while (in_be64(reg) & IOC_IOPT_CacheInvd_Busy)
                        ;

                n_ptes -= n;
                pte += n;
        }
}

static int tce_build_cell(struct iommu_table *tbl, long index, long npages,
                unsigned long uaddr, enum dma_data_direction direction,
                unsigned long attrs)
{
        int i;
        unsigned long *io_pte, base_pte;
        struct iommu_window *window =
                container_of(tbl, struct iommu_window, table);

        /* implementing proper protection causes problems with the spidernet
         * driver - check mapping directions later, but allow read & write by
         * default for now.*/
#ifdef CELL_IOMMU_STRICT_PROTECTION
        /* to avoid referencing a global, we use a trick here to setup the
         * protection bit. "prot" is setup to be 3 fields of 4 bits appended
         * together for each of the 3 supported direction values. It is then
         * shifted left so that the fields matching the desired direction
         * lands on the appropriate bits, and other bits are masked out.
         */
        const unsigned long prot = 0xc48;
        base_pte =
                ((prot << (52 + 4 * direction)) &
                 (CBE_IOPTE_PP_W | CBE_IOPTE_PP_R)) |
                CBE_IOPTE_M | CBE_IOPTE_SO_RW |
                (window->ioid & CBE_IOPTE_IOID_Mask);
#else
        base_pte = CBE_IOPTE_PP_W | CBE_IOPTE_PP_R | CBE_IOPTE_M |
                CBE_IOPTE_SO_RW | (window->ioid & CBE_IOPTE_IOID_Mask);
#endif
        if (unlikely(attrs & DMA_ATTR_WEAK_ORDERING))
                base_pte &= ~CBE_IOPTE_SO_RW;

        io_pte = (unsigned long *)tbl->it_base + (index - tbl->it_offset);

        for (i = 0; i < npages; i++, uaddr += (1 << tbl->it_page_shift))
                io_pte[i] = base_pte | (__pa(uaddr) & CBE_IOPTE_RPN_Mask);

        mb();

        invalidate_tce_cache(window->iommu, io_pte, npages);

        pr_debug("tce_build_cell(index=%lx,n=%lx,dir=%d,base_pte=%lx)\n",
                 index, npages, direction, base_pte);
        return 0;
}

static void tce_free_cell(struct iommu_table *tbl, long index, long npages)
{

        int i;
        unsigned long *io_pte, pte;
        struct iommu_window *window =
                container_of(tbl, struct iommu_window, table);

        pr_debug("tce_free_cell(index=%lx,n=%lx)\n", index, npages);

#ifdef CELL_IOMMU_REAL_UNMAP
        pte = 0;
#else
        /* spider bridge does PCI reads after freeing - insert a mapping
         * to a scratch page instead of an invalid entry */
        pte = CBE_IOPTE_PP_R | CBE_IOPTE_M | CBE_IOPTE_SO_RW |
                __pa(window->iommu->pad_page) |
                (window->ioid & CBE_IOPTE_IOID_Mask);
#endif

        io_pte = (unsigned long *)tbl->it_base + (index - tbl->it_offset);

        for (i = 0; i < npages; i++)
                io_pte[i] = pte;

        mb();

        invalidate_tce_cache(window->iommu, io_pte, npages);
}

static irqreturn_t ioc_interrupt(int irq, void *data)
{
        unsigned long stat, spf;
        struct cbe_iommu *iommu = data;

        stat = in_be64(iommu->xlate_regs + IOC_IO_ExcpStat);
        spf = stat & IOC_IO_ExcpStat_SPF_Mask;

        /* Might want to rate limit it */
        printk(KERN_ERR "iommu: DMA exception 0x%016lx\n", stat);
        printk(KERN_ERR "  V=%d, SPF=[%c%c], RW=%s, IOID=0x%04x\n",
               !!(stat & IOC_IO_ExcpStat_V),
               (spf == IOC_IO_ExcpStat_SPF_S) ? 'S' : ' ',
               (spf == IOC_IO_ExcpStat_SPF_P) ? 'P' : ' ',
               (stat & IOC_IO_ExcpStat_RW_Mask) ? "Read" : "Write",
               (unsigned int)(stat & IOC_IO_ExcpStat_IOID_Mask));
        printk(KERN_ERR "  page=0x%016lx\n",
               stat & IOC_IO_ExcpStat_ADDR_Mask);

        /* clear interrupt */
        stat &= ~IOC_IO_ExcpStat_V;
        out_be64(iommu->xlate_regs + IOC_IO_ExcpStat, stat);

        return IRQ_HANDLED;
}

static int cell_iommu_find_ioc(int nid, unsigned long *base)
{
        struct device_node *np;
        struct resource r;

        *base = 0;

        /* First look for new style /be nodes */
        for_each_node_by_name(np, "ioc") {
                if (of_node_to_nid(np) != nid)
                        continue;
                if (of_address_to_resource(np, 0, &r)) {
                        printk(KERN_ERR "iommu: can't get address for %pOF\n",
                               np);
                        continue;
                }
                *base = r.start;
                of_node_put(np);
                return 0;
        }

        /* Ok, let's try the old way */
        for_each_node_by_type(np, "cpu") {
                const unsigned int *nidp;
                const unsigned long *tmp;

                nidp = of_get_property(np, "node-id", NULL);
                if (nidp && *nidp == nid) {
                        tmp = of_get_property(np, "ioc-translation", NULL);
                        if (tmp) {
                                *base = *tmp;
                                of_node_put(np);
                                return 0;
                        }
                }
        }

        return -ENODEV;
}

static void cell_iommu_setup_stab(struct cbe_iommu *iommu,
                                unsigned long dbase, unsigned long dsize,
                                unsigned long fbase, unsigned long fsize)
{
        struct page *page;
        unsigned long segments, stab_size;

        segments = max(dbase + dsize, fbase + fsize) >> IO_SEGMENT_SHIFT;

        pr_debug("%s: iommu[%d]: segments: %lu\n",
                        __func__, iommu->nid, segments);

        /* set up the segment table */
        stab_size = segments * sizeof(unsigned long);
        page = alloc_pages_node(iommu->nid, GFP_KERNEL, get_order(stab_size));
        BUG_ON(!page);
        iommu->stab = page_address(page);
        memset(iommu->stab, 0, stab_size);
}

static unsigned long *cell_iommu_alloc_ptab(struct cbe_iommu *iommu,
                unsigned long base, unsigned long size, unsigned long gap_base,
                unsigned long gap_size, unsigned long page_shift)
{
        struct page *page;
        int i;
        unsigned long reg, segments, pages_per_segment, ptab_size,
                      n_pte_pages, start_seg, *ptab;

        start_seg = base >> IO_SEGMENT_SHIFT;
        segments  = size >> IO_SEGMENT_SHIFT;
        pages_per_segment = 1ull << IO_PAGENO_BITS(page_shift);
        /* PTEs for each segment must start on a 4K boundary */
        pages_per_segment = max(pages_per_segment,
                                (1 << 12) / sizeof(unsigned long));

        ptab_size = segments * pages_per_segment * sizeof(unsigned long);
        pr_debug("%s: iommu[%d]: ptab_size: %lu, order: %d\n", __func__,
                        iommu->nid, ptab_size, get_order(ptab_size));
        page = alloc_pages_node(iommu->nid, GFP_KERNEL, get_order(ptab_size));
        BUG_ON(!page);

        ptab = page_address(page);
        memset(ptab, 0, ptab_size);

        /* number of 4K pages needed for a page table */
        n_pte_pages = (pages_per_segment * sizeof(unsigned long)) >> 12;

        pr_debug("%s: iommu[%d]: stab at %p, ptab at %p, n_pte_pages: %lu\n",
                        __func__, iommu->nid, iommu->stab, ptab,
                        n_pte_pages);

        /* initialise the STEs */
        reg = IOSTE_V | ((n_pte_pages - 1) << 5);

        switch (page_shift) {
        case 12: reg |= IOSTE_PS_4K;  break;
        case 16: reg |= IOSTE_PS_64K; break;
        case 20: reg |= IOSTE_PS_1M;  break;
        case 24: reg |= IOSTE_PS_16M; break;
        default: BUG();
        }

        gap_base = gap_base >> IO_SEGMENT_SHIFT;
        gap_size = gap_size >> IO_SEGMENT_SHIFT;

        pr_debug("Setting up IOMMU stab:\n");
        for (i = start_seg; i < (start_seg + segments); i++) {
                if (i >= gap_base && i < (gap_base + gap_size)) {
                        pr_debug("\toverlap at %d, skipping\n", i);
                        continue;
                }
                iommu->stab[i] = reg | (__pa(ptab) + (n_pte_pages << 12) *
                                        (i - start_seg));
                pr_debug("\t[%d] 0x%016lx\n", i, iommu->stab[i]);
        }

        return ptab;
}

static void cell_iommu_enable_hardware(struct cbe_iommu *iommu)
{
        int ret;
        unsigned long reg, xlate_base;
        unsigned int virq;

        if (cell_iommu_find_ioc(iommu->nid, &xlate_base))
                panic("%s: missing IOC register mappings for node %d\n",
                      __func__, iommu->nid);

        iommu->xlate_regs = ioremap(xlate_base, IOC_Reg_Size);
        iommu->cmd_regs = iommu->xlate_regs + IOC_IOCmd_Offset;

        /* ensure that the STEs have updated */
        mb();

        /* setup interrupts for the iommu. */
        reg = in_be64(iommu->xlate_regs + IOC_IO_ExcpStat);
        out_be64(iommu->xlate_regs + IOC_IO_ExcpStat,
                        reg & ~IOC_IO_ExcpStat_V);
        out_be64(iommu->xlate_regs + IOC_IO_ExcpMask,
                        IOC_IO_ExcpMask_PFE | IOC_IO_ExcpMask_SFE);

        virq = irq_create_mapping(NULL,
                        IIC_IRQ_IOEX_ATI | (iommu->nid << IIC_IRQ_NODE_SHIFT));
        BUG_ON(!virq);

        ret = request_irq(virq, ioc_interrupt, 0, iommu->name, iommu);
        BUG_ON(ret);

        /* set the IOC segment table origin register (and turn on the iommu) */
        reg = IOC_IOST_Origin_E | __pa(iommu->stab) | IOC_IOST_Origin_HW;
        out_be64(iommu->xlate_regs + IOC_IOST_Origin, reg);
        in_be64(iommu->xlate_regs + IOC_IOST_Origin);

        /* turn on IO translation */
        reg = in_be64(iommu->cmd_regs + IOC_IOCmd_Cfg) | IOC_IOCmd_Cfg_TE;
        out_be64(iommu->cmd_regs + IOC_IOCmd_Cfg, reg);
}

static void cell_iommu_setup_hardware(struct cbe_iommu *iommu,
        unsigned long base, unsigned long size)
{
        cell_iommu_setup_stab(iommu, base, size, 0, 0);
        iommu->ptab = cell_iommu_alloc_ptab(iommu, base, size, 0, 0,
                                            IOMMU_PAGE_SHIFT_4K);
        cell_iommu_enable_hardware(iommu);
}

#if 0/* Unused for now */
static struct iommu_window *find_window(struct cbe_iommu *iommu,
                unsigned long offset, unsigned long size)
{
        struct iommu_window *window;

        /* todo: check for overlapping (but not equal) windows) */

        list_for_each_entry(window, &(iommu->windows), list) {
                if (window->offset == offset && window->size == size)
                        return window;
        }

        return NULL;
}
#endif

static inline u32 cell_iommu_get_ioid(struct device_node *np)
{
        const u32 *ioid;

        ioid = of_get_property(np, "ioid", NULL);
        if (ioid == NULL) {
                printk(KERN_WARNING "iommu: missing ioid for %pOF using 0\n",
                       np);
                return 0;
        }

        return *ioid;
}

static struct iommu_table_ops cell_iommu_ops = {
        .set = tce_build_cell,
        .clear = tce_free_cell
};

static struct iommu_window * __init
cell_iommu_setup_window(struct cbe_iommu *iommu, struct device_node *np,
                        unsigned long offset, unsigned long size,
                        unsigned long pte_offset)
{
        struct iommu_window *window;
        struct page *page;
        u32 ioid;

        ioid = cell_iommu_get_ioid(np);

        window = kzalloc_node(sizeof(*window), GFP_KERNEL, iommu->nid);
        BUG_ON(window == NULL);

        window->offset = offset;
        window->size = size;
        window->ioid = ioid;
        window->iommu = iommu;

        window->table.it_blocksize = 16;
        window->table.it_base = (unsigned long)iommu->ptab;
        window->table.it_index = iommu->nid;
        window->table.it_page_shift = IOMMU_PAGE_SHIFT_4K;
        window->table.it_offset =
                (offset >> window->table.it_page_shift) + pte_offset;
        window->table.it_size = size >> window->table.it_page_shift;
        window->table.it_ops = &cell_iommu_ops;

        if (!iommu_init_table(&window->table, iommu->nid, 0, 0))
                panic("Failed to initialize iommu table");

        pr_debug("\tioid      %d\n", window->ioid);
        pr_debug("\tblocksize %ld\n", window->table.it_blocksize);
        pr_debug("\tbase      0x%016lx\n", window->table.it_base);
        pr_debug("\toffset    0x%lx\n", window->table.it_offset);
        pr_debug("\tsize      %ld\n", window->table.it_size);

        list_add(&window->list, &iommu->windows);

        if (offset != 0)
                return window;

        /* We need to map and reserve the first IOMMU page since it's used
         * by the spider workaround. In theory, we only need to do that when
         * running on spider but it doesn't really matter.
         *
         * This code also assumes that we have a window that starts at 0,
         * which is the case on all spider based blades.
         */
        page = alloc_pages_node(iommu->nid, GFP_KERNEL, 0);
        BUG_ON(!page);
        iommu->pad_page = page_address(page);
        clear_page(iommu->pad_page);

        __set_bit(0, window->table.it_map);
        tce_build_cell(&window->table, window->table.it_offset, 1,
                       (unsigned long)iommu->pad_page, DMA_TO_DEVICE, 0);

        return window;
}

static struct cbe_iommu *cell_iommu_for_node(int nid)
{
        int i;

        for (i = 0; i < cbe_nr_iommus; i++)
                if (iommus[i].nid == nid)
                        return &iommus[i];
        return NULL;
}

static unsigned long cell_dma_nommu_offset;

static unsigned long dma_iommu_fixed_base;
static bool cell_iommu_enabled;

/* iommu_fixed_is_weak is set if booted with iommu_fixed=weak */
bool iommu_fixed_is_weak;

static struct iommu_table *cell_get_iommu_table(struct device *dev)
{
        struct iommu_window *window;
        struct cbe_iommu *iommu;

        /* Current implementation uses the first window available in that
         * node's iommu. We -might- do something smarter later though it may
         * never be necessary
         */
        iommu = cell_iommu_for_node(dev_to_node(dev));
        if (iommu == NULL || list_empty(&iommu->windows)) {
                dev_err(dev, "iommu: missing iommu for %pOF (node %d)\n",
                       dev->of_node, dev_to_node(dev));
                return NULL;
        }
        window = list_entry(iommu->windows.next, struct iommu_window, list);

        return &window->table;
}

static u64 cell_iommu_get_fixed_address(struct device *dev);

static void cell_dma_dev_setup(struct device *dev)
{
        if (cell_iommu_enabled) {
                u64 addr = cell_iommu_get_fixed_address(dev);

                if (addr != OF_BAD_ADDR)
                        dev->archdata.dma_offset = addr + dma_iommu_fixed_base;
                set_iommu_table_base(dev, cell_get_iommu_table(dev));
        } else {
                dev->archdata.dma_offset = cell_dma_nommu_offset;
        }
}

static void cell_pci_dma_dev_setup(struct pci_dev *dev)
{
        cell_dma_dev_setup(&dev->dev);
}

static int cell_of_bus_notify(struct notifier_block *nb, unsigned long action,
                              void *data)
{
        struct device *dev = data;

        /* We are only intereted in device addition */
        if (action != BUS_NOTIFY_ADD_DEVICE)
                return 0;

        if (cell_iommu_enabled)
                dev->dma_ops = &dma_iommu_ops;
        cell_dma_dev_setup(dev);
        return 0;
}

static struct notifier_block cell_of_bus_notifier = {
        .notifier_call = cell_of_bus_notify
};

static int __init cell_iommu_get_window(struct device_node *np,
                                         unsigned long *base,
                                         unsigned long *size)
{
        const __be32 *dma_window;
        unsigned long index;

        /* Use ibm,dma-window if available, else, hard code ! */
        dma_window = of_get_property(np, "ibm,dma-window", NULL);
        if (dma_window == NULL) {
                *base = 0;
                *size = 0x80000000u;
                return -ENODEV;
        }

        of_parse_dma_window(np, dma_window, &index, base, size);
        return 0;
}

static struct cbe_iommu * __init cell_iommu_alloc(struct device_node *np)
{
        struct cbe_iommu *iommu;
        int nid, i;

        /* Get node ID */
        nid = of_node_to_nid(np);
        if (nid < 0) {
                printk(KERN_ERR "iommu: failed to get node for %pOF\n",
                       np);
                return NULL;
        }
        pr_debug("iommu: setting up iommu for node %d (%pOF)\n",
                 nid, np);

        /* XXX todo: If we can have multiple windows on the same IOMMU, which
         * isn't the case today, we probably want here to check whether the
         * iommu for that node is already setup.
         * However, there might be issue with getting the size right so let's
         * ignore that for now. We might want to completely get rid of the
         * multiple window support since the cell iommu supports per-page ioids
         */

        if (cbe_nr_iommus >= NR_IOMMUS) {
                printk(KERN_ERR "iommu: too many IOMMUs detected ! (%pOF)\n",
                       np);
                return NULL;
        }

        /* Init base fields */
        i = cbe_nr_iommus++;
        iommu = &iommus[i];
        iommu->stab = NULL;
        iommu->nid = nid;
        snprintf(iommu->name, sizeof(iommu->name), "iommu%d", i);
        INIT_LIST_HEAD(&iommu->windows);

        return iommu;
}

static void __init cell_iommu_init_one(struct device_node *np,
                                       unsigned long offset)
{
        struct cbe_iommu *iommu;
        unsigned long base, size;

        iommu = cell_iommu_alloc(np);
        if (!iommu)
                return;

        /* Obtain a window for it */
        cell_iommu_get_window(np, &base, &size);

        pr_debug("\ttranslating window 0x%lx...0x%lx\n",
                 base, base + size - 1);

        /* Initialize the hardware */
        cell_iommu_setup_hardware(iommu, base, size);

        /* Setup the iommu_table */
        cell_iommu_setup_window(iommu, np, base, size,
                                offset >> IOMMU_PAGE_SHIFT_4K);
}

static void __init cell_disable_iommus(void)
{
        int node;
        unsigned long base, val;
        void __iomem *xregs, *cregs;

        /* Make sure IOC translation is disabled on all nodes */
        for_each_online_node(node) {
                if (cell_iommu_find_ioc(node, &base))
                        continue;
                xregs = ioremap(base, IOC_Reg_Size);
                if (xregs == NULL)
                        continue;
                cregs = xregs + IOC_IOCmd_Offset;

                pr_debug("iommu: cleaning up iommu on node %d\n", node);

                out_be64(xregs + IOC_IOST_Origin, 0);
                (void)in_be64(xregs + IOC_IOST_Origin);
                val = in_be64(cregs + IOC_IOCmd_Cfg);
                val &= ~IOC_IOCmd_Cfg_TE;
                out_be64(cregs + IOC_IOCmd_Cfg, val);
                (void)in_be64(cregs + IOC_IOCmd_Cfg);

                iounmap(xregs);
        }
}

static int __init cell_iommu_init_disabled(void)
{
        struct device_node *np = NULL;
        unsigned long base = 0, size;

        /* When no iommu is present, we use direct DMA ops */

        /* First make sure all IOC translation is turned off */
        cell_disable_iommus();

        /* If we have no Axon, we set up the spider DMA magic offset */
        if (of_find_node_by_name(NULL, "axon") == NULL)
                cell_dma_nommu_offset = SPIDER_DMA_OFFSET;

        /* Now we need to check to see where the memory is mapped
         * in PCI space. We assume that all busses use the same dma
         * window which is always the case so far on Cell, thus we
         * pick up the first pci-internal node we can find and check
         * the DMA window from there.
         */
        for_each_node_by_name(np, "axon") {
                if (np->parent == NULL || np->parent->parent != NULL)
                        continue;
                if (cell_iommu_get_window(np, &base, &size) == 0)
                        break;
        }
        if (np == NULL) {
                for_each_node_by_name(np, "pci-internal") {
                        if (np->parent == NULL || np->parent->parent != NULL)
                                continue;
                        if (cell_iommu_get_window(np, &base, &size) == 0)
                                break;
                }
        }
        of_node_put(np);

        /* If we found a DMA window, we check if it's big enough to enclose
         * all of physical memory. If not, we force enable IOMMU
         */
        if (np && size < memblock_end_of_DRAM()) {
                printk(KERN_WARNING "iommu: force-enabled, dma window"
                       " (%ldMB) smaller than total memory (%lldMB)\n",
                       size >> 20, memblock_end_of_DRAM() >> 20);
                return -ENODEV;
        }

        cell_dma_nommu_offset += base;

        if (cell_dma_nommu_offset != 0)
                cell_pci_controller_ops.dma_dev_setup = cell_pci_dma_dev_setup;

        printk("iommu: disabled, direct DMA offset is 0x%lx\n",
               cell_dma_nommu_offset);

        return 0;
}

/*
 *  Fixed IOMMU mapping support
 *
 *  This code adds support for setting up a fixed IOMMU mapping on certain
 *  cell machines. For 64-bit devices this avoids the performance overhead of
 *  mapping and unmapping pages at runtime. 32-bit devices are unable to use
 *  the fixed mapping.
 *
 *  The fixed mapping is established at boot, and maps all of physical memory
 *  1:1 into device space at some offset. On machines with < 30 GB of memory
 *  we setup the fixed mapping immediately above the normal IOMMU window.
 *
 *  For example a machine with 4GB of memory would end up with the normal
 *  IOMMU window from 0-2GB and the fixed mapping window from 2GB to 6GB. In
 *  this case a 64-bit device wishing to DMA to 1GB would be told to DMA to
 *  3GB, plus any offset required by firmware. The firmware offset is encoded
 *  in the "dma-ranges" property.
 *
 *  On machines with 30GB or more of memory, we are unable to place the fixed
 *  mapping above the normal IOMMU window as we would run out of address space.
 *  Instead we move the normal IOMMU window to coincide with the hash page
 *  table, this region does not need to be part of the fixed mapping as no
 *  device should ever be DMA'ing to it. We then setup the fixed mapping
 *  from 0 to 32GB.
 */

static u64 cell_iommu_get_fixed_address(struct device *dev)
{
        u64 cpu_addr, size, best_size, dev_addr = OF_BAD_ADDR;
        struct device_node *np;
        const u32 *ranges = NULL;
        int i, len, best, naddr, nsize, pna, range_size;

        /* We can be called for platform devices that have no of_node */
        np = of_node_get(dev->of_node);
        if (!np)
                goto out;

        while (1) {
                naddr = of_n_addr_cells(np);
                nsize = of_n_size_cells(np);
                np = of_get_next_parent(np);
                if (!np)
                        break;

                ranges = of_get_property(np, "dma-ranges", &len);

                /* Ignore empty ranges, they imply no translation required */
                if (ranges && len > 0)
                        break;
        }

        if (!ranges) {
                dev_dbg(dev, "iommu: no dma-ranges found\n");
                goto out;
        }

        len /= sizeof(u32);

        pna = of_n_addr_cells(np);
        range_size = naddr + nsize + pna;

        /* dma-ranges format:
         * child addr   : naddr cells
         * parent addr  : pna cells
         * size         : nsize cells
         */
        for (i = 0, best = -1, best_size = 0; i < len; i += range_size) {
                cpu_addr = of_translate_dma_address(np, ranges + i + naddr);
                size = of_read_number(ranges + i + naddr + pna, nsize);

                if (cpu_addr == 0 && size > best_size) {
                        best = i;
                        best_size = size;
                }
        }

        if (best >= 0) {
                dev_addr = of_read_number(ranges + best, naddr);
        } else
                dev_dbg(dev, "iommu: no suitable range found!\n");

out:
        of_node_put(np);

        return dev_addr;
}

static bool cell_pci_iommu_bypass_supported(struct pci_dev *pdev, u64 mask)
{
        return mask == DMA_BIT_MASK(64) &&
                cell_iommu_get_fixed_address(&pdev->dev) != OF_BAD_ADDR;
}

static void insert_16M_pte(unsigned long addr, unsigned long *ptab,
                           unsigned long base_pte)
{
        unsigned long segment, offset;

        segment = addr >> IO_SEGMENT_SHIFT;
        offset = (addr >> 24) - (segment << IO_PAGENO_BITS(24));
        ptab = ptab + (segment * (1 << 12) / sizeof(unsigned long));

        pr_debug("iommu: addr %lx ptab %p segment %lx offset %lx\n",
                  addr, ptab, segment, offset);

        ptab[offset] = base_pte | (__pa(addr) & CBE_IOPTE_RPN_Mask);
}

static void cell_iommu_setup_fixed_ptab(struct cbe_iommu *iommu,
        struct device_node *np, unsigned long dbase, unsigned long dsize,
        unsigned long fbase, unsigned long fsize)
{
        unsigned long base_pte, uaddr, ioaddr, *ptab;

        ptab = cell_iommu_alloc_ptab(iommu, fbase, fsize, dbase, dsize, 24);

        dma_iommu_fixed_base = fbase;

        pr_debug("iommu: mapping 0x%lx pages from 0x%lx\n", fsize, fbase);

        base_pte = CBE_IOPTE_PP_W | CBE_IOPTE_PP_R | CBE_IOPTE_M |
                (cell_iommu_get_ioid(np) & CBE_IOPTE_IOID_Mask);

        if (iommu_fixed_is_weak)
                pr_info("IOMMU: Using weak ordering for fixed mapping\n");
        else {
                pr_info("IOMMU: Using strong ordering for fixed mapping\n");
                base_pte |= CBE_IOPTE_SO_RW;
        }

        for (uaddr = 0; uaddr < fsize; uaddr += (1 << 24)) {
                /* Don't touch the dynamic region */
                ioaddr = uaddr + fbase;
                if (ioaddr >= dbase && ioaddr < (dbase + dsize)) {
                        pr_debug("iommu: fixed/dynamic overlap, skipping\n");
                        continue;
                }

                insert_16M_pte(uaddr, ptab, base_pte);
        }

        mb();
}

static int __init cell_iommu_fixed_mapping_init(void)
{
        unsigned long dbase, dsize, fbase, fsize, hbase, hend;
        struct cbe_iommu *iommu;
        struct device_node *np;

        /* The fixed mapping is only supported on axon machines */
        np = of_find_node_by_name(NULL, "axon");
        of_node_put(np);

        if (!np) {
                pr_debug("iommu: fixed mapping disabled, no axons found\n");
                return -1;
        }

        /* We must have dma-ranges properties for fixed mapping to work */
        np = of_find_node_with_property(NULL, "dma-ranges");
        of_node_put(np);

        if (!np) {
                pr_debug("iommu: no dma-ranges found, no fixed mapping\n");
                return -1;
        }

        /* The default setup is to have the fixed mapping sit after the
         * dynamic region, so find the top of the largest IOMMU window
         * on any axon, then add the size of RAM and that's our max value.
         * If that is > 32GB we have to do other shennanigans.
         */
        fbase = 0;
        for_each_node_by_name(np, "axon") {
                cell_iommu_get_window(np, &dbase, &dsize);
                fbase = max(fbase, dbase + dsize);
        }

        fbase = ALIGN(fbase, 1 << IO_SEGMENT_SHIFT);
        fsize = memblock_phys_mem_size();

        if ((fbase + fsize) <= 0x800000000ul)
                hbase = 0; /* use the device tree window */
        else {
                /* If we're over 32 GB we need to cheat. We can't map all of
                 * RAM with the fixed mapping, and also fit the dynamic
                 * region. So try to place the dynamic region where the hash
                 * table sits, drivers never need to DMA to it, we don't
                 * need a fixed mapping for that area.
                 */
                if (!htab_address) {
                        pr_debug("iommu: htab is NULL, on LPAR? Huh?\n");
                        return -1;
                }
                hbase = __pa(htab_address);
                hend  = hbase + htab_size_bytes;

                /* The window must start and end on a segment boundary */
                if ((hbase != ALIGN(hbase, 1 << IO_SEGMENT_SHIFT)) ||
                    (hend != ALIGN(hend, 1 << IO_SEGMENT_SHIFT))) {
                        pr_debug("iommu: hash window not segment aligned\n");
                        return -1;
                }

                /* Check the hash window fits inside the real DMA window */
                for_each_node_by_name(np, "axon") {
                        cell_iommu_get_window(np, &dbase, &dsize);

                        if (hbase < dbase || (hend > (dbase + dsize))) {
                                pr_debug("iommu: hash window doesn't fit in"
                                         "real DMA window\n");
                                return -1;
                        }
                }

                fbase = 0;
        }

        /* Setup the dynamic regions */
        for_each_node_by_name(np, "axon") {
                iommu = cell_iommu_alloc(np);
                BUG_ON(!iommu);

                if (hbase == 0)
                        cell_iommu_get_window(np, &dbase, &dsize);
                else {
                        dbase = hbase;
                        dsize = htab_size_bytes;
                }

                printk(KERN_DEBUG "iommu: node %d, dynamic window 0x%lx-0x%lx "
                        "fixed window 0x%lx-0x%lx\n", iommu->nid, dbase,

                         dbase + dsize, fbase, fbase + fsize);

                cell_iommu_setup_stab(iommu, dbase, dsize, fbase, fsize);
                iommu->ptab = cell_iommu_alloc_ptab(iommu, dbase, dsize, 0, 0,
                                                    IOMMU_PAGE_SHIFT_4K);
                cell_iommu_setup_fixed_ptab(iommu, np, dbase, dsize,
                                             fbase, fsize);
                cell_iommu_enable_hardware(iommu);
                cell_iommu_setup_window(iommu, np, dbase, dsize, 0);
        }

        cell_pci_controller_ops.iommu_bypass_supported =
                cell_pci_iommu_bypass_supported;
        return 0;
}

static int iommu_fixed_disabled;

static int __init setup_iommu_fixed(char *str)
{
        struct device_node *pciep;

        if (strcmp(str, "off") == 0)
                iommu_fixed_disabled = 1;

        /* If we can find a pcie-endpoint in the device tree assume that
         * we're on a triblade or a CAB so by default the fixed mapping
         * should be set to be weakly ordered; but only if the boot
         * option WASN'T set for strong ordering
         */
        pciep = of_find_node_by_type(NULL, "pcie-endpoint");

        if (strcmp(str, "weak") == 0 || (pciep && strcmp(str, "strong") != 0))
                iommu_fixed_is_weak = true;

        of_node_put(pciep);

        return 1;
}
__setup("iommu_fixed=", setup_iommu_fixed);

static int __init cell_iommu_init(void)
{
        struct device_node *np;

        /* If IOMMU is disabled or we have little enough RAM to not need
         * to enable it, we setup a direct mapping.
         *
         * Note: should we make sure we have the IOMMU actually disabled ?
         */
        if (iommu_is_off ||
            (!iommu_force_on && memblock_end_of_DRAM() <= 0x80000000ull))
                if (cell_iommu_init_disabled() == 0)
                        goto bail;

        /* Setup various callbacks */
        cell_pci_controller_ops.dma_dev_setup = cell_pci_dma_dev_setup;

        if (!iommu_fixed_disabled && cell_iommu_fixed_mapping_init() == 0)
                goto done;

        /* Create an iommu for each /axon node.  */
        for_each_node_by_name(np, "axon") {
                if (np->parent == NULL || np->parent->parent != NULL)
                        continue;
                cell_iommu_init_one(np, 0);
        }

        /* Create an iommu for each toplevel /pci-internal node for
         * old hardware/firmware
         */
        for_each_node_by_name(np, "pci-internal") {
                if (np->parent == NULL || np->parent->parent != NULL)
                        continue;
                cell_iommu_init_one(np, SPIDER_DMA_OFFSET);
        }
 done:
        /* Setup default PCI iommu ops */
        set_pci_dma_ops(&dma_iommu_ops);
        cell_iommu_enabled = true;
 bail:
        /* Register callbacks on OF platform device addition/removal
         * to handle linking them to the right DMA operations
         */
        bus_register_notifier(&platform_bus_type, &cell_of_bus_notifier);

        return 0;
}
machine_arch_initcall(cell, cell_iommu_init);