tile pci: enable IOMMU to support DMA for legacy devices

This change uses the TRIO IOMMU to map the PCI DMA space and physical
memory at different addresses.  We also now use the dma_mapping_ops
to provide support for non-PCI DMA, PCIe DMA (64-bit) and legacy PCI
DMA (32-bit).  We use the kernel's software I/O TLB framework
(i.e. bounce buffers) for the legacy 32-bit PCI device support since
there are a limited number of TLB entries in the IOMMU and it is
non-trivial to handle indexing, searching, matching, etc.  For 32-bit
devices the performance impact of bounce buffers should not be a concern.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 58 insertions, 55 deletions

diff --git a/arch/tile/kernel/pci_gx.c b/arch/tile/kernel/pci_gx.c
index 1b996bb628f1..27f7ab021137 100644
--- a/arch/tile/kernel/pci_gx.c
+++ b/arch/tile/kernel/pci_gx.c
@@ -40,22 +40,8 @@
 #include <arch/sim.h>
 
 /*
- * Initialization flow and process
- * -------------------------------
- *
- * This files containes the routines to search for PCI buses,
+ * This file containes the routines to search for PCI buses,
  * enumerate the buses, and configure any attached devices.
- *
- * There are two entry points here:
- * 1) tile_pci_init
- *    This sets up the pci_controller structs, and opens the
- *    FDs to the hypervisor.  This is called from setup_arch() early
- *    in the boot process.
- * 2) pcibios_init
- *    This probes the PCI bus(es) for any attached hardware.  It's
- *    called by subsys_initcall.  All of the real work is done by the
- *    generic Linux PCI layer.
- *
  */
 
 #define DEBUG_PCI_CFG	0
@@ -110,6 +96,21 @@ static struct pci_ops tile_cfg_ops;
 /* Mask of CPUs that should receive PCIe interrupts. */
 static struct cpumask intr_cpus_map;
 
+/* PCI I/O space support is not implemented. */
+static struct resource pci_ioport_resource = {
+	.name	= "PCI IO",
+	.start	= 0,
+	.end	= 0,
+	.flags	= IORESOURCE_IO,
+};
+
+static struct resource pci_iomem_resource = {
+	.name	= "PCI mem",
+	.start	= TILE_PCI_MEM_START,
+	.end	= TILE_PCI_MEM_END,
+	.flags	= IORESOURCE_MEM,
+};
+
 /*
  * We don't need to worry about the alignment of resources.
  */
@@ -334,8 +335,6 @@ free_irqs:
 }
 
 /*
- * First initialization entry point, called from setup_arch().
- *
  * Find valid controllers and fill in pci_controller structs for each
  * of them.
  *
@@ -583,10 +582,7 @@ static int __devinit setup_pcie_rc_delay(char *str)
 early_param("pcie_rc_delay", setup_pcie_rc_delay);
 
 /*
- * Second PCI initialization entry point, called by subsys_initcall.
- *
- * The controllers have been set up by the time we get here, by a call to
- * tile_pci_init.
+ * PCI initialization entry point, called by subsys_initcall.
  */
 int __init pcibios_init(void)
 {
@@ -594,15 +590,13 @@ int __init pcibios_init(void)
 	LIST_HEAD(resources);
 	int i;
 
+	tile_pci_init();
+
 	if (num_rc_controllers == 0 && num_ep_controllers == 0)
 		return 0;
 
-	pr_info("PCI: Probing PCI hardware\n");
-
 	/*
 	 * We loop over all the TRIO shims and set up the MMIO mappings.
-	 * This step can't be done in tile_pci_init because the MM subsystem
-	 * hasn't been initialized then.
 	 */
 	for (i = 0; i < TILEGX_NUM_TRIO; i++) {
 		gxio_trio_context_t *context = &trio_contexts[i];
@@ -645,9 +639,7 @@ int __init pcibios_init(void)
 		unsigned int class_code_revision;
 		int trio_index;
 		int mac;
-#ifndef USE_SHARED_PCIE_CONFIG_REGION
 		int ret;
-#endif
 
 		if (trio_context->fd < 0)
 			continue;
@@ -802,8 +794,6 @@ int __init pcibios_init(void)
 			pr_err("PCI: PCI CFG PIO alloc failure for mac %d "
 				"on TRIO %d, give up\n", mac, trio_index);
 
-			/* TBD: cleanup ... */
-
 			continue;
 		}
 
@@ -819,8 +809,6 @@ int __init pcibios_init(void)
 			pr_err("PCI: PCI CFG PIO init failure for mac %d "
 				"on TRIO %d, give up\n", mac, trio_index);
 
-			/* TBD: cleanup ... */
-
 			continue;
 		}
 
@@ -837,8 +825,6 @@ int __init pcibios_init(void)
 			pr_err("PCI: PIO map failure for mac %d on TRIO %d\n",
 				mac, trio_index);
 
-			/* TBD: cleanup ... */
-
 			continue;
 		}
 
@@ -852,7 +838,14 @@ int __init pcibios_init(void)
 			continue;
 		}
 
-		pci_add_resource(&resources, &iomem_resource);
+		/*
+		 * The PCI memory resource is located above the PA space.
+		 * The memory range for the PCI root bus should not overlap
+		 * with the physical RAM
+		 */
+		pci_add_resource_offset(&resources, &iomem_resource,
+					1ULL << CHIP_PA_WIDTH());
+
 		bus = pci_scan_root_bus(NULL, 0, controller->ops,
 					controller, &resources);
 		controller->root_bus = bus;
@@ -923,11 +916,6 @@ int __init pcibios_init(void)
 		}
 
 		/*
-		 * We always assign 32-bit PCI bus BAR ranges.
-		 */
-		BUG_ON(bus_address_hi != 0);
-
-		/*
 		 * Alloc a PIO region for PCI memory access for each RC port.
 		 */
 		ret = gxio_trio_alloc_pio_regions(trio_context, 1, 0, 0);
@@ -936,8 +924,6 @@ int __init pcibios_init(void)
 				"give up\n", controller->trio_index,
 				controller->mac);
 
-			/* TBD: cleanup ... */
-
 			continue;
 		}
 
@@ -950,15 +936,13 @@ int __init pcibios_init(void)
 		ret = gxio_trio_init_pio_region_aux(trio_context,
 						    controller->pio_mem_index,
 						    controller->mac,
-						    bus_address_hi,
+						    0,
 						    0);
 		if (ret < 0) {
 			pr_err("PCI: MEM PIO init failure on TRIO %d mac %d, "
 				"give up\n", controller->trio_index,
 				controller->mac);
 
-			/* TBD: cleanup ... */
-
 			continue;
 		}
 
@@ -980,8 +964,6 @@ int __init pcibios_init(void)
 					controller->trio_index,
 					controller->mac, j);
 
-				/* TBD: cleanup ... */
-
 				goto alloc_mem_map_failed;
 			}
 
@@ -991,9 +973,13 @@ int __init pcibios_init(void)
 			 * Initialize the Mem-Map and the I/O MMU so that all
 			 * the physical memory can be accessed by the endpoint
 			 * devices. The base bus address is set to the base CPA
-			 * of this memory controller, so is the base VA. The
+			 * of this memory controller plus an offset (see pci.h).
+			 * The region's base VA is set to the base CPA. The
 			 * I/O MMU table essentially translates the CPA to
-			 * the real PA.
+			 * the real PA. Implicitly, for node 0, we create
+			 * a separate Mem-Map region that serves as the inbound
+			 * window for legacy 32-bit devices. This is a direct
+			 * map of the low 4GB CPA space.
 			 */
 			ret = gxio_trio_init_memory_map_mmu_aux(trio_context,
 				controller->mem_maps[j],
@@ -1001,7 +987,8 @@ int __init pcibios_init(void)
 				nr_pages << PAGE_SHIFT,
 				trio_context->asid,
 				controller->mac,
-				start_pfn << PAGE_SHIFT,
+				(start_pfn << PAGE_SHIFT) +
+				TILE_PCI_MEM_MAP_BASE_OFFSET,
 				j,
 				GXIO_TRIO_ORDER_MODE_UNORDERED);
 			if (ret < 0) {
@@ -1010,11 +997,8 @@ int __init pcibios_init(void)
 					controller->trio_index,
 					controller->mac, j);
 
-				/* TBD: cleanup ... */
-
 				goto alloc_mem_map_failed;
 			}
-
 			continue;
 
 alloc_mem_map_failed:
@@ -1028,11 +1012,19 @@ alloc_mem_map_failed:
 subsys_initcall(pcibios_init);
 
 /*
- * No bus fixups needed.
+ * PCI scan code calls the arch specific pcibios_fixup_bus() each time it scans
+ * a new bridge. Called after each bus is probed, but before its children are
+ * examined.
  */
 void __devinit pcibios_fixup_bus(struct pci_bus *bus)
 {
-	/* Nothing needs to be done. */
+	struct pci_dev *dev = bus->self;
+
+	if (!dev) {
+		/* This is the root bus. */
+		bus->resource[0] = &pci_ioport_resource;
+		bus->resource[1] = &pci_iomem_resource;
+	}
 }
 
 /*
@@ -1069,6 +1061,17 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
 	return pci_enable_resources(dev, mask);
 }
 
+/* Called for each device after PCI setup is done. */
+static void __init
+pcibios_fixup_final(struct pci_dev *pdev)
+{
+	set_dma_ops(&pdev->dev, gx_pci_dma_map_ops);
+	set_dma_offset(&pdev->dev, TILE_PCI_MEM_MAP_BASE_OFFSET);
+	pdev->dev.archdata.max_direct_dma_addr =
+		TILE_PCI_MAX_DIRECT_DMA_ADDRESS;
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_ANY_ID, PCI_ANY_ID, pcibios_fixup_final);
+
 /* Map a PCI MMIO bus address into VA space. */
 void __iomem *ioremap(resource_size_t phys_addr, unsigned long size)
 {
@@ -1127,7 +1130,7 @@ got_it:
 	 * We need to keep the PCI bus address's in-page offset in the VA.
 	 */
 	return iorpc_ioremap(trio_fd, offset, size) +
-					(phys_addr & (PAGE_SIZE - 1));
+		(phys_addr & (PAGE_SIZE - 1));
 }
 EXPORT_SYMBOL(ioremap);