+/*
+ * 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, pci_addr = OF_BAD_ADDR;
+ struct device_node *tmp, *np;
+ const u32 *ranges = NULL;
+ int i, len, best;
+
+ np = dev->archdata.of_node;
+ of_node_get(np);
+ ranges = of_get_property(np, "dma-ranges", &len);
+ while (!ranges && np) {
+ tmp = of_get_parent(np);
+ of_node_put(np);
+ np = tmp;
+ ranges = of_get_property(np, "dma-ranges", &len);
+ }
+
+ if (!ranges) {
+ dev_dbg(dev, "iommu: no dma-ranges found\n");
+ goto out;
+ }
+
+ len /= sizeof(u32);
+
+ /* dma-ranges format:
+ * 1 cell: pci space
+ * 2 cells: pci address
+ * 2 cells: parent address
+ * 2 cells: size
+ */
+ for (i = 0, best = -1, best_size = 0; i < len; i += 7) {
+ cpu_addr = of_translate_dma_address(np, ranges +i + 3);
+ size = of_read_number(ranges + i + 5, 2);
+
+ if (cpu_addr == 0 && size > best_size) {
+ best = i;
+ best_size = size;
+ }
+ }
+
+ if (best >= 0)
+ pci_addr = of_read_number(ranges + best + 1, 2);
+ else
+ dev_dbg(dev, "iommu: no suitable range found!\n");
+
+out:
+ of_node_put(np);
+
+ return pci_addr;
+}
+
+static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask)
+{
+ if (!dev->dma_mask || !dma_supported(dev, dma_mask))
+ return -EIO;
+
+ if (dma_mask == DMA_BIT_MASK(64)) {
+ if (cell_iommu_get_fixed_address(dev) == OF_BAD_ADDR)
+ dev_dbg(dev, "iommu: 64-bit OK, but bad addr\n");
+ else {
+ dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
+ set_dma_ops(dev, &dma_iommu_fixed_ops);
+ cell_dma_dev_setup(dev);
+ }
+ } else {
+ dev_dbg(dev, "iommu: not 64-bit, using default ops\n");
+ set_dma_ops(dev, get_pci_dma_ops());
+ }
+
+ *dev->dma_mask = dma_mask;
+
+ return 0;
+}
+
+static void cell_dma_dev_setup_static(struct device *dev)
+{
+ struct dev_archdata *archdata = &dev->archdata;
+ u64 addr;
+
+ addr = cell_iommu_get_fixed_address(dev) + dma_iommu_fixed_base;
+ archdata->dma_data = (void *)addr;
+
+ dev_dbg(dev, "iommu: fixed addr = %lx\n", addr);
+}
+
+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, *io_pte;
+ int i;
+
+ dma_iommu_fixed_base = fbase;
+
+ /* convert from bytes into page table indices */
+ dbase = dbase >> IOMMU_PAGE_SHIFT;
+ dsize = dsize >> IOMMU_PAGE_SHIFT;
+ fbase = fbase >> IOMMU_PAGE_SHIFT;
+ fsize = fsize >> IOMMU_PAGE_SHIFT;
+
+ pr_debug("iommu: mapping 0x%lx pages from 0x%lx\n", fsize, fbase);
+
+ io_pte = iommu->ptab;
+ base_pte = IOPTE_PP_W | IOPTE_PP_R | IOPTE_M | IOPTE_SO_RW
+ | (cell_iommu_get_ioid(np) & IOPTE_IOID_Mask);
+
+ uaddr = 0;
+ for (i = fbase; i < fbase + fsize; i++, uaddr += IOMMU_PAGE_SIZE) {
+ /* Don't touch the dynamic region */
+ if (i >= dbase && i < (dbase + dsize)) {
+ pr_debug("iommu: static/dynamic overlap, skipping\n");
+ continue;
+ }
+ io_pte[i] = base_pte | (__pa(uaddr) & IOPTE_RPN_Mask);
+ }
+
+ 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");
+ if (!np) {
+ pr_debug("iommu: fixed mapping disabled, no axons found\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_UP(fbase, 1 << IO_SEGMENT_SHIFT);
+ fsize = lmb_phys_mem_size();
+
+ if ((fbase + fsize) <= 0x800000000)
+ 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_UP(hbase, 1 << IO_SEGMENT_SHIFT)) ||
+ (hend != _ALIGN_UP(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;
+ }
+
+ pr_debug("iommu: setting up %d, dynamic window %lx-%lx " \
+ "fixed window %lx-%lx\n", iommu->nid, dbase,
+ dbase + dsize, fbase, fbase + fsize);
+
+ cell_iommu_setup_page_tables(iommu, dbase, dsize, fbase, fsize);
+ 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);
+ }
+
+ dma_iommu_fixed_ops = dma_direct_ops;
+ dma_iommu_fixed_ops.set_dma_mask = dma_set_mask_and_switch;
+
+ dma_iommu_ops.set_dma_mask = dma_set_mask_and_switch;
+ set_pci_dma_ops(&dma_iommu_ops);
+
+ printk(KERN_DEBUG "IOMMU fixed mapping established.\n");
+
+ return 0;
+}
+
+static int iommu_fixed_disabled;
+
+static int __init setup_iommu_fixed(char *str)
+{
+ if (strcmp(str, "off") == 0)
+ iommu_fixed_disabled = 1;
+
+ return 1;
+}
+__setup("iommu_fixed=", setup_iommu_fixed);
+
git.samba.org / sfrench / cifs-2.6.git / commitdiff