[RFC PATH] of/pci/dma: fix DMA configruation for PCI masters

[Oza Pawandeep via iommu <iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>]

current device frmework and of framework integration assumes dma-ranges
in a way where memory-mapped devices define their dma-ranges.
dma-ranges: (child-bus-address, parent-bus-address, length).

but iproc based SOCs and other SOCs(suc as rcar) have PCI world dma-ranges.
dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;

of_dma_configure is specifically witten to take care of memory mapped devices.
but no implementation exists for pci to take care of pcie based memory ranges.
in fact pci world doesnt seem to define standard dma-ranges

this patch served following purposes

1) exposes intrface to the pci host driver for thir inbound memory ranges

2) provide an interface to callers such as of_dma_get_ranges.
so then the returned size get best possible (largest) dma_mask.
for e.g.
dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
we should get dev->coherent_dma_mask=0x7fffffffff.

3) this patch handles multiple inbound windows and dma-ranges.
it is left to the caller, how it wants to use them.
the new function returns the resources in a standard and unform way

4) this way the callers of of_dma_get_ranges does not need to change.
and

5) leaves scope of adding PCI flag handling for inbound memory
by the new function.

Signed-off-by: Oza Pawandeep <oza.oza-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 02b2903..ec21191 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -6,6 +6,7 @@
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
+#include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/sizes.h>
@@ -829,10 +830,30 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	int len, naddr, nsize, pna;
 	int ret = 0;
 	u64 dmaaddr;
+	struct resource_entry *window;
+	LIST_HEAD(res);
 
 	if (!node)
 		return -EINVAL;
 
+	if (strcmp(np->name, "pci")) {
+		*size = 0;
+		ret = of_pci_get_dma_ranges(np, &res);
+		if (!ret) {
+			resource_list_for_each_entry(window, &res) {
+			struct resource *res_dma = window->res;
+
+			if (*size < resource_size(res_dma)) {
+				*dma_addr = res_dma->start - window->offset;
+				*paddr = res_dma->start;
+				*size = resource_size(res_dma);
+				}
+			}
+		}
+		pci_free_resource_list(&res);
+		goto out;
+	}
+
 	while (1) {
 		naddr = of_n_addr_cells(node);
 		nsize = of_n_size_cells(node);
diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 0ee42c3..2aa9401 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -283,6 +283,83 @@ int of_pci_get_host_bridge_resources(struct device_node *dev,
 	return err;
 }
 EXPORT_SYMBOL_GPL(of_pci_get_host_bridge_resources);
+
+/**
+ * of_pci_get_dma_ranges - Parse PCI host bridge inbound resources from DT
+ * @np: device node of the host bridge having the dma-ranges property
+ * @resources: list where the range of resources will be added after DT parsing
+ *
+ * It is the caller's job to free the @resources list.
+ *
+ * This function will parse the "dma-ranges" property of a
+ * PCI host bridge device node and setup the resource mapping based
+ * on its content.
+ *
+ * It returns zero if the range parsing has been successful or a standard error
+ * value if it failed.
+ */
+
+int of_pci_get_dma_ranges(struct device_node *np, struct list_head *resources)
+{
+	struct device_node *node = of_node_get(np);
+	int rlen;
+	int ret = 0;
+	const int na = 3, ns = 2;
+	struct resource *res;
+	struct of_pci_range_parser parser;
+	struct of_pci_range range;
+
+	if (!node)
+		return -EINVAL;
+
+	parser.node = node;
+	parser.pna = of_n_addr_cells(node);
+	parser.np = parser.pna + na + ns;
+
+	parser.range = of_get_property(node, "dma-ranges", &rlen);
+
+	if (!parser.range) {
+		pr_debug("pcie device has no dma-ranges defined for node(%s)\n",
+			  np->full_name);
+		ret = -ENODEV;
+		goto out;
+	}
+
+	parser.end = parser.range + rlen / sizeof(__be32);
+
+	for_each_of_pci_range(&parser, &range) {
+		/*
+		 * If we failed translation or got a zero-sized region
+		 * then skip this range
+		 */
+		if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
+			continue;
+
+		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+		if (!res) {
+			ret = -ENOMEM;
+			goto parse_failed;
+		}
+
+		ret = of_pci_range_to_resource(&range, np, res);
+		if (ret) {
+			kfree(res);
+			continue;
+		}
+
+		pci_add_resource_offset(resources, res,
+					res->start - range.pci_addr);
+	}
+
+	return ret;
+
+parse_failed:
+	pci_free_resource_list(resources);
+out:
+	of_node_put(node);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_dma_ranges);
 #endif /* CONFIG_OF_ADDRESS */
 
 #ifdef CONFIG_PCI_MSI
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index 0e0974e..617b90d 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -76,6 +76,7 @@ static inline void of_pci_check_probe_only(void) { }
 int of_pci_get_host_bridge_resources(struct device_node *dev,
 			unsigned char busno, unsigned char bus_max,
 			struct list_head *resources, resource_size_t *io_base);
+int of_pci_get_dma_ranges(struct device_node *np, struct list_head *resources);
 #else
 static inline int of_pci_get_host_bridge_resources(struct device_node *dev,
 			unsigned char busno, unsigned char bus_max,
@@ -83,6 +84,12 @@ static inline int of_pci_get_host_bridge_resources(struct device_node *dev,
 {
 	return -EINVAL;
 }
+
+static inline int of_pci_get_dma_ranges(struct device_node *np,
+					struct list_head *resources)
+{
+	return -EINVAL;
+}
 #endif
 
 #if defined(CONFIG_OF) && defined(CONFIG_PCI_MSI)
-- 
1.9.1