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Subject[PATCH] [1/2] POWERPC: IOMMU support for honoring dma_mask
From
Hi,

Paulus -- Ben mentioned being interested in this going into 2.6.17,
since the bcm43xx driver will need it to be usable on G5s with more than
1GB memory.

Built with iseries_defconfig and ppc64_defconfig, boot tested on pSeries
and G5, but I'm away from home so I haven't been able to install an
Airport card in the G5.

Since time is somewhat of essense (if 2.6.17 is still an option), I went
for the choice of sending now and follow up with a small bugfix later
in case something shows up, especially since quick regression tests seem
ok.


Thanks,

Olof


---




Some devices don't support full 32-bit DMA address space, which we currently
assume. Add the required mask-passing to the IOMMU allocators.

Signed-off-by: Olof Johansson <olof@lixom.net>


Index: 2.6/arch/powerpc/kernel/iommu.c
===================================================================
--- 2.6.orig/arch/powerpc/kernel/iommu.c
+++ 2.6/arch/powerpc/kernel/iommu.c
@@ -61,6 +61,7 @@ __setup("iommu=", setup_iommu);
static unsigned long iommu_range_alloc(struct iommu_table *tbl,
unsigned long npages,
unsigned long *handle,
+ unsigned long mask,
unsigned int align_order)
{
unsigned long n, end, i, start;
@@ -97,9 +98,21 @@ static unsigned long iommu_range_alloc(s
*/
if (start >= limit)
start = largealloc ? tbl->it_largehint : tbl->it_hint;
-
+
again:

+ if (limit + tbl->it_offset > mask) {
+ limit = mask - tbl->it_offset + 1;
+ /* If we're constrained on address range, first try
+ * at the masked hint to avoid O(n) search complexity,
+ * but on second pass, start at 0.
+ */
+ if ((start & mask) >= limit || pass > 0)
+ start = 0;
+ else
+ start &= mask;
+ }
+
n = find_next_zero_bit(tbl->it_map, limit, start);

/* Align allocation */
@@ -150,14 +163,14 @@ static unsigned long iommu_range_alloc(s

static dma_addr_t iommu_alloc(struct iommu_table *tbl, void *page,
unsigned int npages, enum dma_data_direction direction,
- unsigned int align_order)
+ unsigned long mask, unsigned int align_order)
{
unsigned long entry, flags;
dma_addr_t ret = DMA_ERROR_CODE;
-
+
spin_lock_irqsave(&(tbl->it_lock), flags);

- entry = iommu_range_alloc(tbl, npages, NULL, align_order);
+ entry = iommu_range_alloc(tbl, npages, NULL, mask, align_order);

if (unlikely(entry == DMA_ERROR_CODE)) {
spin_unlock_irqrestore(&(tbl->it_lock), flags);
@@ -236,7 +249,7 @@ static void iommu_free(struct iommu_tabl

int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
struct scatterlist *sglist, int nelems,
- enum dma_data_direction direction)
+ unsigned long mask, enum dma_data_direction direction)
{
dma_addr_t dma_next = 0, dma_addr;
unsigned long flags;
@@ -274,7 +287,7 @@ int iommu_map_sg(struct device *dev, str
vaddr = (unsigned long)page_address(s->page) + s->offset;
npages = PAGE_ALIGN(vaddr + slen) - (vaddr & PAGE_MASK);
npages >>= PAGE_SHIFT;
- entry = iommu_range_alloc(tbl, npages, &handle, 0);
+ entry = iommu_range_alloc(tbl, npages, &handle, mask >> PAGE_SHIFT, 0);

DBG(" - vaddr: %lx, size: %lx\n", vaddr, slen);

@@ -479,7 +492,8 @@ void iommu_free_table(struct device_node
* byte within the page as vaddr.
*/
dma_addr_t iommu_map_single(struct iommu_table *tbl, void *vaddr,
- size_t size, enum dma_data_direction direction)
+ size_t size, unsigned long mask,
+ enum dma_data_direction direction)
{
dma_addr_t dma_handle = DMA_ERROR_CODE;
unsigned long uaddr;
@@ -492,7 +506,8 @@ dma_addr_t iommu_map_single(struct iommu
npages >>= PAGE_SHIFT;

if (tbl) {
- dma_handle = iommu_alloc(tbl, vaddr, npages, direction, 0);
+ dma_handle = iommu_alloc(tbl, vaddr, npages, direction,
+ mask >> PAGE_SHIFT, 0);
if (dma_handle == DMA_ERROR_CODE) {
if (printk_ratelimit()) {
printk(KERN_INFO "iommu_alloc failed, "
@@ -521,7 +536,7 @@ void iommu_unmap_single(struct iommu_tab
* to the dma address (mapping) of the first page.
*/
void *iommu_alloc_coherent(struct iommu_table *tbl, size_t size,
- dma_addr_t *dma_handle, gfp_t flag)
+ dma_addr_t *dma_handle, unsigned long mask, gfp_t flag)
{
void *ret = NULL;
dma_addr_t mapping;
@@ -551,7 +566,8 @@ void *iommu_alloc_coherent(struct iommu_
memset(ret, 0, size);

/* Set up tces to cover the allocated range */
- mapping = iommu_alloc(tbl, ret, npages, DMA_BIDIRECTIONAL, order);
+ mapping = iommu_alloc(tbl, ret, npages, DMA_BIDIRECTIONAL,
+ mask >> PAGE_SHIFT, order);
if (mapping == DMA_ERROR_CODE) {
free_pages((unsigned long)ret, order);
ret = NULL;
Index: 2.6/arch/powerpc/kernel/vio.c
===================================================================
--- 2.6.orig/arch/powerpc/kernel/vio.c
+++ 2.6/arch/powerpc/kernel/vio.c
@@ -202,7 +202,7 @@ static dma_addr_t vio_map_single(struct
size_t size, enum dma_data_direction direction)
{
return iommu_map_single(to_vio_dev(dev)->iommu_table, vaddr, size,
- direction);
+ ~0ul, direction);
}

static void vio_unmap_single(struct device *dev, dma_addr_t dma_handle,
@@ -216,7 +216,7 @@ static int vio_map_sg(struct device *dev
int nelems, enum dma_data_direction direction)
{
return iommu_map_sg(dev, to_vio_dev(dev)->iommu_table, sglist,
- nelems, direction);
+ nelems, ~0ul, direction);
}

static void vio_unmap_sg(struct device *dev, struct scatterlist *sglist,
@@ -229,7 +229,7 @@ static void *vio_alloc_coherent(struct d
dma_addr_t *dma_handle, gfp_t flag)
{
return iommu_alloc_coherent(to_vio_dev(dev)->iommu_table, size,
- dma_handle, flag);
+ dma_handle, ~0ul, flag);
}

static void vio_free_coherent(struct device *dev, size_t size,
Index: 2.6/include/asm-powerpc/iommu.h
===================================================================
--- 2.6.orig/include/asm-powerpc/iommu.h
+++ 2.6/include/asm-powerpc/iommu.h
@@ -70,17 +70,18 @@ extern void iommu_free_table(struct devi
extern struct iommu_table *iommu_init_table(struct iommu_table * tbl);

extern int iommu_map_sg(struct device *dev, struct iommu_table *tbl,
- struct scatterlist *sglist, int nelems,
+ struct scatterlist *sglist, int nelems, unsigned long mask,
enum dma_data_direction direction);
extern void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
int nelems, enum dma_data_direction direction);

extern void *iommu_alloc_coherent(struct iommu_table *tbl, size_t size,
- dma_addr_t *dma_handle, gfp_t flag);
+ dma_addr_t *dma_handle, unsigned long mask, gfp_t flag);
extern void iommu_free_coherent(struct iommu_table *tbl, size_t size,
void *vaddr, dma_addr_t dma_handle);
extern dma_addr_t iommu_map_single(struct iommu_table *tbl, void *vaddr,
- size_t size, enum dma_data_direction direction);
+ size_t size, unsigned long mask,
+ enum dma_data_direction direction);
extern void iommu_unmap_single(struct iommu_table *tbl, dma_addr_t dma_handle,
size_t size, enum dma_data_direction direction);

Index: 2.6/arch/powerpc/kernel/pci_iommu.c
===================================================================
--- 2.6.orig/arch/powerpc/kernel/pci_iommu.c
+++ 2.6/arch/powerpc/kernel/pci_iommu.c
@@ -59,6 +59,25 @@ static inline struct iommu_table *devnod
}


+static inline unsigned long device_to_mask(struct device *hwdev)
+{
+ struct pci_dev *pdev;
+
+ if (!hwdev) {
+ pdev = ppc64_isabridge_dev;
+ if (!pdev) /* This is the best guess we can do */
+ return 0xfffffffful;
+ } else
+ pdev = to_pci_dev(hwdev);
+
+ if (pdev->dma_mask)
+ return pdev->dma_mask;
+
+ /* Assume devices without mask can take 32 bit addresses */
+ return 0xfffffffful;
+}
+
+
/* Allocates a contiguous real buffer and creates mappings over it.
* Returns the virtual address of the buffer and sets dma_handle
* to the dma address (mapping) of the first page.
@@ -67,7 +86,7 @@ static void *pci_iommu_alloc_coherent(st
dma_addr_t *dma_handle, gfp_t flag)
{
return iommu_alloc_coherent(devnode_table(hwdev), size, dma_handle,
- flag);
+ device_to_mask(hwdev), flag);
}

static void pci_iommu_free_coherent(struct device *hwdev, size_t size,
@@ -86,7 +105,7 @@ static dma_addr_t pci_iommu_map_single(s
size_t size, enum dma_data_direction direction)
{
return iommu_map_single(devnode_table(hwdev), vaddr, size,
- direction);
+ device_to_mask(hwdev), direction);
}


@@ -101,7 +120,7 @@ static int pci_iommu_map_sg(struct devic
int nelems, enum dma_data_direction direction)
{
return iommu_map_sg(pdev, devnode_table(pdev), sglist,
- nelems, direction);
+ nelems, device_to_mask(pdev), direction);
}

static void pci_iommu_unmap_sg(struct device *pdev, struct scatterlist *sglist,
@@ -113,7 +132,19 @@ static void pci_iommu_unmap_sg(struct de
/* We support DMA to/from any memory page via the iommu */
static int pci_iommu_dma_supported(struct device *dev, u64 mask)
{
- return 1;
+ struct iommu_table *tbl = devnode_table(dev);
+
+ if (!tbl || tbl->it_offset > mask) {
+ printk(KERN_INFO "Warning: IOMMU table offset too big for device mask\n");
+ if (tbl)
+ printk(KERN_INFO "mask: 0x%08lx, table offset: 0x%08lx\n",
+ mask, tbl->it_offset);
+ else
+ printk(KERN_INFO "mask: 0x%08lx, table unavailable\n",
+ mask);
+ return 0;
+ } else
+ return 1;
}

void pci_iommu_init(void)
-
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