[PATCH] of/fdt: Add FDT address translation

[Ley Foon Tan <lftan@altera.com>]

This patch adds address translation to fdt. It is needed when the early
console is connected to a simple-bus (bridge) that has address translation
enabled.

Walter Goossens have submitted first version of patch previously. This
patch resolved the feedback from first submission and some enhancements
on translation functions.

Reviewed-by: Walter Goossens <waltergoossens@home.nl>
Signed-off-by: Ley Foon Tan <lftan@altera.com>
---
 drivers/of/fdt.c       |  188 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_fdt.h |    2 +
 2 files changed, 190 insertions(+), 0 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 808be06..74cc1bc 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -695,6 +695,194 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 	/* break now */
 	return 1;
 }
+/**
+ * flat_dt_translate_address - Translate an address using the ranges property
+ *
+ * This function converts address from "node address-space" to "parent address-
+ * space"
+ */
+static int __init flat_dt_translate_address(unsigned long node,
+		unsigned long parent, u64 *address)
+{
+	unsigned long size = 0;
+	__be32 *prop;
+	__be32 *ranges;
+	int size_cells = 0;
+	int addr_cells = 0;
+	int paddr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
+
+	ranges = of_get_flat_dt_prop(node, "ranges", &size);
+
+	if (!ranges) {
+		pr_warn("Address cannot be translated\n");
+		return -EINVAL;
+	}
+
+	if (!size) {
+		pr_debug("No translation possible/necessary\n");
+		return 0;
+	}
+
+	prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
+	if (!prop)
+		return -EINVAL;
+	size_cells = be32_to_cpup(prop);
+
+	prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
+	if (!prop)
+		return -EINVAL;
+	addr_cells = be32_to_cpup(prop);
+
+	if (parent) {
+		prop = of_get_flat_dt_prop(parent, "#address-cells", NULL);
+		if (prop)
+			paddr_cells = be32_to_cpup(prop);
+	}
+	if ((addr_cells <= 0) || (size_cells <= 0) ||
+		(addr_cells > 2) || (size_cells > 2) || (paddr_cells > 2)) {
+		pr_warn("Translation not possible in fdt. Invalid address.\n");
+		*address = 0;
+		return -1;
+	}
+
+	while (size > 0) {
+		u64 from, to, tsize;
+		from = be32_to_cpup(ranges++);
+		size -= 4;
+		if (addr_cells == 2) {
+			from += (((u64)be32_to_cpup(ranges++)) << 32);
+			size -= 4;
+		}
+		to = be32_to_cpup(ranges++);
+		size -= 4;
+		if (paddr_cells == 2) {
+			to += (((u64)be32_to_cpup(ranges++)) << 32);
+			size -= 4;
+		}
+		tsize = be32_to_cpup(ranges++);
+		size -= 4;
+		if (size_cells == 2) {
+			tsize += (((u64)be32_to_cpup(ranges++)) << 32);
+			size -= 4;
+		}
+		pr_debug("  From %llX To %llX Size %llX\n", from, to, tsize);
+		if ((*address >= from) && (*address < (from + tsize)))
+			*address += (to - from);
+	}
+	return 1;
+}
+
+static int __init of_scan_flat_dt_ranges(unsigned long *pnode,
+				unsigned long parent, unsigned long target,
+				u64 *address, int ignore)
+{
+	int rc = 0;
+	int depth = -1;
+	const char *pathp;
+	unsigned long p = *pnode;
+	do {
+		u32 tag = be32_to_cpup((__be32 *)p);
+
+		p += 4;
+		if (tag == OF_DT_END_NODE) {
+			if (depth--)
+				break;
+			else
+				continue;
+		}
+		if (tag == OF_DT_NOP)
+			continue;
+		if (tag == OF_DT_END)
+			break;
+		if (tag == OF_DT_PROP) {
+			u32 sz = be32_to_cpup((__be32 *)p);
+			p += 8;
+			if (be32_to_cpu(initial_boot_params->version) < 0x10)
+				p = ALIGN(p, sz >= 8 ? 8 : 4);
+			p += sz;
+			p = ALIGN(p, 4);
+			continue;
+		}
+		if (tag != OF_DT_BEGIN_NODE) {
+			pr_err("Invalid tag %x in flat device tree!\n", tag);
+			return -EINVAL;
+		}
+		pathp = (char *)p;
+		p = ALIGN(p + strlen(pathp) + 1, 4);
+		if ((*pathp) == '/')
+			pathp = kbasename(pathp);
+		if ((ignore == 0) && (p == target)) {
+			rc = 1;
+			ignore++;
+			pr_debug("Found target. Start address translation\n");
+		}
+		if (depth) {
+			int res;
+			*pnode = p;
+			res = of_scan_flat_dt_ranges(pnode, p, target,
+							address, ignore);
+			if (res < 0) {
+				/* Something bad happened */
+				return -1;
+			} else if (res > 0) {
+				/* Something good happened. Translate. */
+				rc++;
+				pr_debug("translate %08lX %s\n", p, pathp);
+				if (flat_dt_translate_address(p, parent,
+						address) < 0)
+					return -1;
+			}
+			p = *pnode;
+		} else
+			depth++;
+	} while (1);
+
+	*pnode = p;
+	return rc;
+}
+/**
+ * of_get_flat_dt_address - get address from a node
+ * @node: targeted node
+ *
+ * Returns address or OF_BAD_ADDR if error.
+ */
+u64 __init of_get_flat_dt_address(unsigned long node)
+{
+	__be32 *valp;
+	u64 addr = OF_BAD_ADDR;
+	unsigned long sz;
+
+	valp = of_get_flat_dt_prop(node, "reg", &sz);
+	if (valp) {
+		if (sz == 1)
+			addr = be32_to_cpu(valp[0]);
+		 else if (sz == 2)
+			addr = (((u64)be32_to_cpu(valp[0]) << 32)) |
+				be32_to_cpu(valp[1]);
+	}
+	return addr;
+}
+
+/**
+ * of_get_flat_dt_translated_address - get translated address from a node
+ * @node: targeted node
+ *
+ * Returns translated address or OF_BAD_ADDR if error.
+ */
+u64 __init of_get_flat_dt_translated_address(unsigned long node)
+{
+	unsigned long p = of_get_flat_dt_root();
+	u64 addr64;
+	int rc;
+
+	addr64 = of_get_flat_dt_address(node);
+	if (addr64 != OF_BAD_ADDR) {
+		rc = of_scan_flat_dt_ranges(&p, 0, node, &addr64, 0);
+		if (rc > 0)
+			return addr64;
+	}
+	return OF_BAD_ADDR;
+}
 
 /**
  * unflatten_device_tree - create tree of device_nodes from flat blob
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index ed136ad..48046ed 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -100,6 +100,8 @@ extern void early_init_dt_add_memory_arch(u64 base, u64 size);
 extern void * early_init_dt_alloc_memory_arch(u64 size, u64 align);
 extern u64 dt_mem_next_cell(int s, __be32 **cellp);
 
+extern u64 __init of_get_flat_dt_address(unsigned long node);
+extern u64 __init of_get_flat_dt_translated_address(unsigned long node);
 /*
  * If BLK_DEV_INITRD, the fdt early init code will call this function,
  * to be provided by the arch code. start and end are specified as
-- 
1.7.7.4