IB/ipath: Improved support for PowerPC

Signed-off-by: Bryan O'Sullivan <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

8 files changed, 198 insertions, 73 deletions

diff --git a/drivers/infiniband/hw/ipath/ipath_driver.c b/drivers/infiniband/hw/ipath/ipath_driver.c
index 467816043d10..68fc9b5a4ad8 100644
--- a/drivers/infiniband/hw/ipath/ipath_driver.c
+++ b/drivers/infiniband/hw/ipath/ipath_driver.c
@@ -755,8 +755,8 @@ static void get_rhf_errstring(u32 err, char *msg, size_t len)
 static inline void *ipath_get_egrbuf(struct ipath_devdata *dd, u32 bufnum,
                                      int err)
 {
-        return dd->ipath_port0_skbs ?
-                (void *)dd->ipath_port0_skbs[bufnum]->data : NULL;
+        return dd->ipath_port0_skbinfo ?
+                (void *) dd->ipath_port0_skbinfo[bufnum].skb->data : NULL;
 }
 
 /**
@@ -778,31 +778,34 @@ struct sk_buff *ipath_alloc_skb(struct ipath_devdata *dd,
          */
 
         /*
-         * We need 4 extra bytes for unaligned transfer copying
+         * We need 2 extra bytes for ipath_ether data sent in the
+         * key header.  In order to keep everything dword aligned,
+         * we'll reserve 4 bytes.
          */
+        len = dd->ipath_ibmaxlen + 4;
+
         if (dd->ipath_flags & IPATH_4BYTE_TID) {
-                /* we need a 4KB multiple alignment, and there is no way
+                /* We need a 2KB multiple alignment, and there is no way
                  * to do it except to allocate extra and then skb_reserve
                  * enough to bring it up to the right alignment.
                  */
-                len = dd->ipath_ibmaxlen + 4 + (1 << 11) - 1;
+                len += 2047;
         }
-        else
-                len = dd->ipath_ibmaxlen + 4;
+
         skb = __dev_alloc_skb(len, gfp_mask);
         if (!skb) {
                 ipath_dev_err(dd, "Failed to allocate skbuff, length %u\n",
                               len);
                 goto bail;
         }
+
+        skb_reserve(skb, 4);
+
         if (dd->ipath_flags & IPATH_4BYTE_TID) {
-                u32 una = ((1 << 11) - 1) & (unsigned long)(skb->data + 4);
+                u32 una = (unsigned long)skb->data & 2047;
                 if (una)
-                        skb_reserve(skb, 4 + (1 << 11) - una);
-                else
-                        skb_reserve(skb, 4);
-        } else
-                skb_reserve(skb, 4);
+                        skb_reserve(skb, 2048 - una);
+        }
 
 bail:
         return skb;
@@ -1345,8 +1348,9 @@ int ipath_create_rcvhdrq(struct ipath_devdata *dd,
                 ipath_cdbg(VERBOSE, "reuse port %d rcvhdrq @%p %llx phys; "
                            "hdrtailaddr@%p %llx physical\n",
                            pd->port_port, pd->port_rcvhdrq,
-                           pd->port_rcvhdrq_phys, pd->port_rcvhdrtail_kvaddr,
-                           (unsigned long long)pd->port_rcvhdrqtailaddr_phys);
+                           (unsigned long long) pd->port_rcvhdrq_phys,
+                           pd->port_rcvhdrtail_kvaddr, (unsigned long long)
+                           pd->port_rcvhdrqtailaddr_phys);
 
         /* clear for security and sanity on each use */
         memset(pd->port_rcvhdrq, 0, pd->port_rcvhdrq_size);
@@ -1827,17 +1831,22 @@ void ipath_free_pddata(struct ipath_devdata *dd, struct ipath_portdata *pd)
                 kfree(pd->port_rcvegrbuf_phys);
                 pd->port_rcvegrbuf_phys = NULL;
                 pd->port_rcvegrbuf_chunks = 0;
-        } else if (pd->port_port == 0 && dd->ipath_port0_skbs) {
+        } else if (pd->port_port == 0 && dd->ipath_port0_skbinfo) {
                 unsigned e;
-                struct sk_buff **skbs = dd->ipath_port0_skbs;
+                struct ipath_skbinfo *skbinfo = dd->ipath_port0_skbinfo;
 
-                dd->ipath_port0_skbs = NULL;
-                ipath_cdbg(VERBOSE, "free closed port %d ipath_port0_skbs "
-                           "@ %p\n", pd->port_port, skbs);
+                dd->ipath_port0_skbinfo = NULL;
+                ipath_cdbg(VERBOSE, "free closed port %d "
+                           "ipath_port0_skbinfo @ %p\n", pd->port_port,
+                           skbinfo);
                 for (e = 0; e < dd->ipath_rcvegrcnt; e++)
-                        if (skbs[e])
-                                dev_kfree_skb(skbs[e]);
-                vfree(skbs);
+                if (skbinfo[e].skb) {
+                        pci_unmap_single(dd->pcidev, skbinfo[e].phys,
+                                         dd->ipath_ibmaxlen,
+                                         PCI_DMA_FROMDEVICE);
+                        dev_kfree_skb(skbinfo[e].skb);
+                }
+                vfree(skbinfo);
         }
         kfree(pd->port_tid_pg_list);
         vfree(pd->subport_uregbase);
@@ -1934,7 +1943,7 @@ static void cleanup_device(struct ipath_devdata *dd)
 
         if (dd->ipath_pioavailregs_dma) {
                 dma_free_coherent(&dd->pcidev->dev, PAGE_SIZE,
-                                  dd->ipath_pioavailregs_dma,
+                                  (void *) dd->ipath_pioavailregs_dma,
                                   dd->ipath_pioavailregs_phys);
                 dd->ipath_pioavailregs_dma = NULL;
         }
@@ -1947,6 +1956,7 @@ static void cleanup_device(struct ipath_devdata *dd)
 
         if (dd->ipath_pageshadow) {
                 struct page **tmpp = dd->ipath_pageshadow;
+                dma_addr_t *tmpd = dd->ipath_physshadow;
                 int i, cnt = 0;
 
                 ipath_cdbg(VERBOSE, "Unlocking any expTID pages still "
@@ -1957,6 +1967,8 @@ static void cleanup_device(struct ipath_devdata *dd)
                         for (i = port_tidbase; i < maxtid; i++) {
                                 if (!tmpp[i])
                                         continue;
+                                pci_unmap_page(dd->pcidev, tmpd[i],
+                                               PAGE_SIZE, PCI_DMA_FROMDEVICE);
                                 ipath_release_user_pages(&tmpp[i], 1);
                                 tmpp[i] = NULL;
                                 cnt++;
diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c
index d4fc4118ddd5..64221b937762 100644
--- a/drivers/infiniband/hw/ipath/ipath_file_ops.c
+++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c
@@ -364,11 +364,14 @@ static int ipath_tid_update(struct ipath_portdata *pd, struct file *fp,
                            "vaddr %lx\n", i, tid + tidoff, vaddr);
                 /* we "know" system pages and TID pages are same size */
                 dd->ipath_pageshadow[porttid + tid] = pagep[i];
+                dd->ipath_physshadow[porttid + tid] = ipath_map_page(
+                        dd->pcidev, pagep[i], 0, PAGE_SIZE,
+                        PCI_DMA_FROMDEVICE);
                 /*
                  * don't need atomic or it's overhead
                  */
                 __set_bit(tid, tidmap);
-                physaddr = page_to_phys(pagep[i]);
+                physaddr = dd->ipath_physshadow[porttid + tid];
                 ipath_stats.sps_pagelocks++;
                 ipath_cdbg(VERBOSE,
                            "TID %u, vaddr %lx, physaddr %llx pgp %p\n",
@@ -402,6 +405,9 @@ static int ipath_tid_update(struct ipath_portdata *pd, struct file *fp,
                                            tid);
                                 dd->ipath_f_put_tid(dd, &tidbase[tid], 1,
                                                     dd->ipath_tidinvalid);
+                                pci_unmap_page(dd->pcidev,
+                                        dd->ipath_physshadow[porttid + tid],
+                                        PAGE_SIZE, PCI_DMA_FROMDEVICE);
                                 dd->ipath_pageshadow[porttid + tid] = NULL;
                                 ipath_stats.sps_pageunlocks++;
                         }
@@ -515,6 +521,9 @@ static int ipath_tid_free(struct ipath_portdata *pd, unsigned subport,
                                    pd->port_pid, tid);
                         dd->ipath_f_put_tid(dd, &tidbase[tid], 1,
                                             dd->ipath_tidinvalid);
+                        pci_unmap_page(dd->pcidev,
+                                dd->ipath_physshadow[porttid + tid],
+                                PAGE_SIZE, PCI_DMA_FROMDEVICE);
                         ipath_release_user_pages(
                                 &dd->ipath_pageshadow[porttid + tid], 1);
                         dd->ipath_pageshadow[porttid + tid] = NULL;
@@ -711,7 +720,7 @@ static int ipath_manage_rcvq(struct ipath_portdata *pd, unsigned subport,
                  * updated and correct itself, even in the face of software
                  * bugs.
                  */
-                *pd->port_rcvhdrtail_kvaddr = 0;
+                *(volatile u64 *)pd->port_rcvhdrtail_kvaddr = 0;
                 set_bit(INFINIPATH_R_PORTENABLE_SHIFT + pd->port_port,
                         &dd->ipath_rcvctrl);
         } else
@@ -923,11 +932,11 @@ bail:
 
 /* common code for the mappings on dma_alloc_coherent mem */
 static int ipath_mmap_mem(struct vm_area_struct *vma,
-                             struct ipath_portdata *pd, unsigned len,
-                             int write_ok, dma_addr_t addr, char *what)
+        struct ipath_portdata *pd, unsigned len, int write_ok,
+        void *kvaddr, char *what)
 {
         struct ipath_devdata *dd = pd->port_dd;
-        unsigned pfn = (unsigned long)addr >> PAGE_SHIFT;
+        unsigned long pfn;
         int ret;
 
         if ((vma->vm_end - vma->vm_start) > len) {
@@ -950,17 +959,17 @@ static int ipath_mmap_mem(struct vm_area_struct *vma,
                 vma->vm_flags &= ~VM_MAYWRITE;
         }
 
+        pfn = virt_to_phys(kvaddr) >> PAGE_SHIFT;
         ret = remap_pfn_range(vma, vma->vm_start, pfn,
                               len, vma->vm_page_prot);
         if (ret)
-                dev_info(&dd->pcidev->dev,
-                         "%s port%u mmap of %lx, %x bytes r%c failed: %d\n",
-                         what, pd->port_port, (unsigned long)addr, len,
-                         write_ok?'w':'o', ret);
+                dev_info(&dd->pcidev->dev, "%s port%u mmap of %lx, %x "
+                         "bytes r%c failed: %d\n", what, pd->port_port,
+                         pfn, len, write_ok?'w':'o', ret);
         else
-                ipath_cdbg(VERBOSE, "%s port%u mmaped %lx, %x bytes r%c\n",
-                        what, pd->port_port, (unsigned long)addr, len,
-                         write_ok?'w':'o');
+                ipath_cdbg(VERBOSE, "%s port%u mmaped %lx, %x bytes "
+                           "r%c\n", what, pd->port_port, pfn, len,
+                           write_ok?'w':'o');
 bail:
         return ret;
 }
@@ -1049,7 +1058,7 @@ static int mmap_rcvegrbufs(struct vm_area_struct *vma,
         struct ipath_devdata *dd = pd->port_dd;
         unsigned long start, size;
         size_t total_size, i;
-        dma_addr_t *phys;
+        unsigned long pfn;
         int ret;
 
         size = pd->port_rcvegrbuf_size;
@@ -1073,11 +1082,11 @@ static int mmap_rcvegrbufs(struct vm_area_struct *vma,
         vma->vm_flags &= ~VM_MAYWRITE;
 
         start = vma->vm_start;
-        phys = pd->port_rcvegrbuf_phys;
 
         for (i = 0; i < pd->port_rcvegrbuf_chunks; i++, start += size) {
-                ret = remap_pfn_range(vma, start, phys[i] >> PAGE_SHIFT,
-                                      size, vma->vm_page_prot);
+                pfn = virt_to_phys(pd->port_rcvegrbuf[i]) >> PAGE_SHIFT;
+                ret = remap_pfn_range(vma, start, pfn, size,
+                                      vma->vm_page_prot);
                 if (ret < 0)
                         goto bail;
         }
@@ -1290,7 +1299,7 @@ static int ipath_mmap(struct file *fp, struct vm_area_struct *vma)
         else if (pgaddr == dd->ipath_pioavailregs_phys)
                 /* in-memory copy of pioavail registers */
                 ret = ipath_mmap_mem(vma, pd, PAGE_SIZE, 0,
-                                     dd->ipath_pioavailregs_phys,
+                                     (void *) dd->ipath_pioavailregs_dma,
                                      "pioavail registers");
         else if (subport_fp(fp))
                 /* Subports don't mmap the physical receive buffers */
@@ -1304,12 +1313,12 @@ static int ipath_mmap(struct file *fp, struct vm_area_struct *vma)
                  * from an i/o perspective.
                  */
                 ret = ipath_mmap_mem(vma, pd, pd->port_rcvhdrq_size, 1,
-                                     pd->port_rcvhdrq_phys,
+                                     pd->port_rcvhdrq,
                                      "rcvhdrq");
         else if (pgaddr == (u64) pd->port_rcvhdrqtailaddr_phys)
                 /* in-memory copy of rcvhdrq tail register */
                 ret = ipath_mmap_mem(vma, pd, PAGE_SIZE, 0,
-                                     pd->port_rcvhdrqtailaddr_phys,
+                                     pd->port_rcvhdrtail_kvaddr,
                                      "rcvhdrq tail");
         else
                 ret = -EINVAL;
@@ -1802,7 +1811,7 @@ static int ipath_do_user_init(struct file *fp,
          * We explictly set the in-memory copy to 0 beforehand, so we don't
          * have to wait to be sure the DMA update has happened.
          */
-        *pd->port_rcvhdrtail_kvaddr = 0ULL;
+        *(volatile u64 *)pd->port_rcvhdrtail_kvaddr = 0ULL;
         set_bit(INFINIPATH_R_PORTENABLE_SHIFT + pd->port_port,
                 &dd->ipath_rcvctrl);
         ipath_write_kreg(dd, dd->ipath_kregs->kr_rcvctrl,
@@ -1832,6 +1841,8 @@ static void unlock_expected_tids(struct ipath_portdata *pd)
                 if (!dd->ipath_pageshadow[i])
                         continue;
 
+                pci_unmap_page(dd->pcidev, dd->ipath_physshadow[i],
+                        PAGE_SIZE, PCI_DMA_FROMDEVICE);
                 ipath_release_user_pages_on_close(&dd->ipath_pageshadow[i],
                                                   1);
                 dd->ipath_pageshadow[i] = NULL;
@@ -1936,14 +1947,14 @@ static int ipath_close(struct inode *in, struct file *fp)
                 i = dd->ipath_pbufsport * (port - 1);
                 ipath_disarm_piobufs(dd, i, dd->ipath_pbufsport);
 
+                dd->ipath_f_clear_tids(dd, pd->port_port);
+
                 if (dd->ipath_pageshadow)
                         unlock_expected_tids(pd);
                 ipath_stats.sps_ports--;
                 ipath_cdbg(PROC, "%s[%u] closed port %u:%u\n",
                            pd->port_comm, pd->port_pid,
                            dd->ipath_unit, port);
-
-                dd->ipath_f_clear_tids(dd, pd->port_port);
         }
 
         pd->port_pid = 0;
diff --git a/drivers/infiniband/hw/ipath/ipath_iba6120.c b/drivers/infiniband/hw/ipath/ipath_iba6120.c
index ac5cbe27c068..08a44dd9ed6f 100644
--- a/drivers/infiniband/hw/ipath/ipath_iba6120.c
+++ b/drivers/infiniband/hw/ipath/ipath_iba6120.c
@@ -1113,7 +1113,7 @@ static void ipath_pe_put_tid_2(struct ipath_devdata *dd, u64 __iomem *tidptr,
         if (pa != dd->ipath_tidinvalid) {
                 if (pa & ((1U << 11) - 1)) {
                         dev_info(&dd->pcidev->dev, "BUG: physaddr %lx "
-                                 "not 4KB aligned!\n", pa);
+                                 "not 2KB aligned!\n", pa);
                         return;
                 }
                 pa >>= 11;
diff --git a/drivers/infiniband/hw/ipath/ipath_init_chip.c b/drivers/infiniband/hw/ipath/ipath_init_chip.c
index 44669dc2e22d..d819cca524cd 100644
--- a/drivers/infiniband/hw/ipath/ipath_init_chip.c
+++ b/drivers/infiniband/hw/ipath/ipath_init_chip.c
@@ -88,13 +88,13 @@ MODULE_PARM_DESC(kpiobufs, "Set number of PIO buffers for driver");
 static int create_port0_egr(struct ipath_devdata *dd)
 {
         unsigned e, egrcnt;
-        struct sk_buff **skbs;
+        struct ipath_skbinfo *skbinfo;
         int ret;
 
         egrcnt = dd->ipath_rcvegrcnt;
 
-        skbs = vmalloc(sizeof(*dd->ipath_port0_skbs) * egrcnt);
-        if (skbs == NULL) {
+        skbinfo = vmalloc(sizeof(*dd->ipath_port0_skbinfo) * egrcnt);
+        if (skbinfo == NULL) {
                 ipath_dev_err(dd, "allocation error for eager TID "
                               "skb array\n");
                 ret = -ENOMEM;
@@ -109,13 +109,13 @@ static int create_port0_egr(struct ipath_devdata *dd)
                  * 4 bytes so that the data buffer stays word aligned.
                  * See ipath_kreceive() for more details.
                  */
-                skbs[e] = ipath_alloc_skb(dd, GFP_KERNEL);
-                if (!skbs[e]) {
+                skbinfo[e].skb = ipath_alloc_skb(dd, GFP_KERNEL);
+                if (!skbinfo[e].skb) {
                         ipath_dev_err(dd, "SKB allocation error for "
                                       "eager TID %u\n", e);
                         while (e != 0)
-                                dev_kfree_skb(skbs[--e]);
-                        vfree(skbs);
+                                dev_kfree_skb(skbinfo[--e].skb);
+                        vfree(skbinfo);
                         ret = -ENOMEM;
                         goto bail;
                 }
@@ -124,14 +124,17 @@ static int create_port0_egr(struct ipath_devdata *dd)
          * After loop above, so we can test non-NULL to see if ready
          * to use at receive, etc.
          */
-        dd->ipath_port0_skbs = skbs;
+        dd->ipath_port0_skbinfo = skbinfo;
 
         for (e = 0; e < egrcnt; e++) {
-                unsigned long phys =
-                        virt_to_phys(dd->ipath_port0_skbs[e]->data);
+                dd->ipath_port0_skbinfo[e].phys =
+                  ipath_map_single(dd->pcidev,
+                                   dd->ipath_port0_skbinfo[e].skb->data,
+                                   dd->ipath_ibmaxlen, PCI_DMA_FROMDEVICE);
                 dd->ipath_f_put_tid(dd, e + (u64 __iomem *)
                                     ((char __iomem *) dd->ipath_kregbase +
-                                     dd->ipath_rcvegrbase), 0, phys);
+                                     dd->ipath_rcvegrbase), 0,
+                                    dd->ipath_port0_skbinfo[e].phys);
         }
 
         ret = 0;
@@ -432,16 +435,33 @@ done:
  */
 static void init_shadow_tids(struct ipath_devdata *dd)
 {
-        dd->ipath_pageshadow = (struct page **)
-                vmalloc(dd->ipath_cfgports * dd->ipath_rcvtidcnt *
+        struct page **pages;
+        dma_addr_t *addrs;
+
+        pages = vmalloc(dd->ipath_cfgports * dd->ipath_rcvtidcnt *
                         sizeof(struct page *));
-        if (!dd->ipath_pageshadow)
+        if (!pages) {
                 ipath_dev_err(dd, "failed to allocate shadow page * "
                               "array, no expected sends!\n");
-        else
-                memset(dd->ipath_pageshadow, 0,
-                       dd->ipath_cfgports * dd->ipath_rcvtidcnt *
-                       sizeof(struct page *));
+                dd->ipath_pageshadow = NULL;
+                return;
+        }
+
+        addrs = vmalloc(dd->ipath_cfgports * dd->ipath_rcvtidcnt *
+                        sizeof(dma_addr_t));
+        if (!addrs) {
+                ipath_dev_err(dd, "failed to allocate shadow dma handle "
+                              "array, no expected sends!\n");
+                vfree(dd->ipath_pageshadow);
+                dd->ipath_pageshadow = NULL;
+                return;
+        }
+
+        memset(pages, 0, dd->ipath_cfgports * dd->ipath_rcvtidcnt *
+               sizeof(struct page *));
+
+        dd->ipath_pageshadow = pages;
+        dd->ipath_physshadow = addrs;
 }
 
 static void enable_chip(struct ipath_devdata *dd,
diff --git a/drivers/infiniband/hw/ipath/ipath_intr.c b/drivers/infiniband/hw/ipath/ipath_intr.c
index 54b3dbc8195a..f4d8aafc6306 100644
--- a/drivers/infiniband/hw/ipath/ipath_intr.c
+++ b/drivers/infiniband/hw/ipath/ipath_intr.c
@@ -605,7 +605,7 @@ static int handle_errors(struct ipath_devdata *dd, ipath_err_t errs)
                                  * don't report same point multiple times,
                                  * except kernel
                                  */
-                                tl = (u32) * pd->port_rcvhdrtail_kvaddr;
+                                tl = *(u64 *) pd->port_rcvhdrtail_kvaddr;
                                 if (tl == dd->ipath_lastrcvhdrqtails[i])
                                         continue;
                                 hd = ipath_read_ureg32(dd, ur_rcvhdrhead,
diff --git a/drivers/infiniband/hw/ipath/ipath_kernel.h b/drivers/infiniband/hw/ipath/ipath_kernel.h
index 96e2bd8fb5f8..2a0e9a430634 100644
--- a/drivers/infiniband/hw/ipath/ipath_kernel.h
+++ b/drivers/infiniband/hw/ipath/ipath_kernel.h
@@ -39,6 +39,8 @@
  */
 
 #include <linux/interrupt.h>
+#include <linux/pci.h>
+#include <linux/dma-mapping.h>
 #include <asm/io.h>
 
 #include "ipath_common.h"
@@ -62,7 +64,7 @@ struct ipath_portdata {
         /* rcvhdrq base, needs mmap before useful */
         void *port_rcvhdrq;
         /* kernel virtual address where hdrqtail is updated */
-        volatile __le64 *port_rcvhdrtail_kvaddr;
+        void *port_rcvhdrtail_kvaddr;
         /*
          * temp buffer for expected send setup, allocated at open, instead
          * of each setup call
@@ -146,6 +148,11 @@ struct _ipath_layer {
         void *l_arg;
 };
 
+struct ipath_skbinfo {
+        struct sk_buff *skb;
+        dma_addr_t phys;
+};
+
 struct ipath_devdata {
         struct list_head ipath_list;
 
@@ -168,7 +175,7 @@ struct ipath_devdata {
         /* ipath_cfgports pointers */
         struct ipath_portdata **ipath_pd;
         /* sk_buffs used by port 0 eager receive queue */
-        struct sk_buff **ipath_port0_skbs;
+        struct ipath_skbinfo *ipath_port0_skbinfo;
         /* kvirt address of 1st 2k pio buffer */
         void __iomem *ipath_pio2kbase;
         /* kvirt address of 1st 4k pio buffer */
@@ -335,6 +342,8 @@ struct ipath_devdata {
         u64 *ipath_tidsimshadow;
         /* shadow copy of struct page *'s for exp tid pages */
         struct page **ipath_pageshadow;
+        /* shadow copy of dma handles for exp tid pages */
+        dma_addr_t *ipath_physshadow;
         /* lock to workaround chip bug 9437 */
         spinlock_t ipath_tid_lock;
 
@@ -865,6 +874,13 @@ int ipathfs_add_device(struct ipath_devdata *);
 int ipathfs_remove_device(struct ipath_devdata *);
 
 /*
+ * dma_addr wrappers - all 0's invalid for hw
+ */
+dma_addr_t ipath_map_page(struct pci_dev *, struct page *, unsigned long,
+                          size_t, int);
+dma_addr_t ipath_map_single(struct pci_dev *, void *, size_t, int);
+
+/*
  * Flush write combining store buffers (if present) and perform a write
  * barrier.
  */
diff --git a/drivers/infiniband/hw/ipath/ipath_user_pages.c b/drivers/infiniband/hw/ipath/ipath_user_pages.c
index e32fca9faf80..413754b1d8a2 100644
--- a/drivers/infiniband/hw/ipath/ipath_user_pages.c
+++ b/drivers/infiniband/hw/ipath/ipath_user_pages.c
@@ -90,6 +90,62 @@ bail:
 }
 
 /**
+ * ipath_map_page - a safety wrapper around pci_map_page()
+ *
+ * A dma_addr of all 0's is interpreted by the chip as "disabled".
+ * Unfortunately, it can also be a valid dma_addr returned on some
+ * architectures.
+ *
+ * The powerpc iommu assigns dma_addrs in ascending order, so we don't
+ * have to bother with retries or mapping a dummy page to insure we
+ * don't just get the same mapping again.
+ *
+ * I'm sure we won't be so lucky with other iommu's, so FIXME.
+ */
+dma_addr_t ipath_map_page(struct pci_dev *hwdev, struct page *page,
+        unsigned long offset, size_t size, int direction)
+{
+        dma_addr_t phys;
+
+        phys = pci_map_page(hwdev, page, offset, size, direction);
+
+        if (phys == 0) {
+                pci_unmap_page(hwdev, phys, size, direction);
+                phys = pci_map_page(hwdev, page, offset, size, direction);
+                /*
+                 * FIXME: If we get 0 again, we should keep this page,
+                 * map another, then free the 0 page.
+                 */
+        }
+
+        return phys;
+}
+
+/**
+ * ipath_map_single - a safety wrapper around pci_map_single()
+ *
+ * Same idea as ipath_map_page().
+ */
+dma_addr_t ipath_map_single(struct pci_dev *hwdev, void *ptr, size_t size,
+        int direction)
+{
+        dma_addr_t phys;
+
+        phys = pci_map_single(hwdev, ptr, size, direction);
+
+        if (phys == 0) {
+                pci_unmap_single(hwdev, phys, size, direction);
+                phys = pci_map_single(hwdev, ptr, size, direction);
+                /*
+                 * FIXME: If we get 0 again, we should keep this page,
+                 * map another, then free the 0 page.
+                 */
+        }
+
+        return phys;
+}
+
+/**
  * ipath_get_user_pages - lock user pages into memory
  * @start_page: the start page
  * @num_pages: the number of pages
diff --git a/drivers/infiniband/hw/ipath/ipath_wc_ppc64.c b/drivers/infiniband/hw/ipath/ipath_wc_ppc64.c
index 036fde662aa9..0095bb70f34e 100644
--- a/drivers/infiniband/hw/ipath/ipath_wc_ppc64.c
+++ b/drivers/infiniband/hw/ipath/ipath_wc_ppc64.c
@@ -38,13 +38,23 @@
 #include "ipath_kernel.h"
 
 /**
- * ipath_unordered_wc - indicate whether write combining is ordered
+ * ipath_enable_wc - enable write combining for MMIO writes to the device
+ * @dd: infinipath device
  *
- * PowerPC systems (at least those in the 970 processor family)
- * write partially filled store buffers in address order, but will write
- * completely filled store buffers in "random" order, and therefore must
- * have serialization for correctness with current InfiniPath chips.
+ * Nothing to do on PowerPC, so just return without error.
+ */
+int ipath_enable_wc(struct ipath_devdata *dd)
+{
+        return 0;
+}
+
+/**
+ * ipath_unordered_wc - indicate whether write combining is unordered
  *
+ * Because our performance depends on our ability to do write
+ * combining mmio writes in the most efficient way, we need to
+ * know if we are on a processor that may reorder stores when
+ * write combining.
  */
 int ipath_unordered_wc(void)
 {