[RFC][PATCH] add FDT address translation

[Walter Goossens <waltergoossens-CmkmPbn3yAE@public.gmane.org>]

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This patch adds address translations to fdt. Needed when the early 
console is connected to a simple-bus that has address translation enabled.

To be honest, I'm not too happy about this solution but it works and 
most code is stolen from other parts of the fdt code, so I'm probably 
not doing too weird stuff :)
What do you guys think of this?

Greetz Walter

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diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index c1360e0..d586efe 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -538,6 +538,161 @@ 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 = (u32 *)of_get_flat_dt_prop(node,"ranges",&size);
+
+	if(size==0) {
+		pr_debug("No translation possible/necessary\n");
+		return 0;
+	}
+
+	prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
+	if (prop)
+		size_cells = be32_to_cpup(prop);
+	pr_debug("size_cells = %x\n", size_cells);
+
+	prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
+	if (prop)
+		addr_cells = be32_to_cpup(prop);
+	pr_debug("addr_cells = %x\n", addr_cells);
+
+	if(parent) {
+		prop = of_get_flat_dt_prop(parent, "#address-cells", NULL);
+		if (prop)
+			paddr_cells = be32_to_cpup(prop);
+		pr_debug("paddr_cells = %x\n", paddr_cells);
+	}
+	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;
+	}
+	pr_debug("FDT-Ranges:\n");
+	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;
+	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) == '/') {
+			char *lp, *np;
+			for (lp = NULL, np = pathp; *np; np++)
+				if ((*np) == '/')
+					lp = np+1;
+			if (lp != NULL)
+				pathp = lp;
+		}
+		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 gooed 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;
+}
+int __init early_init_dt_translate_address(unsigned long node, u64 *address)
+{
+	unsigned long p = ((unsigned long)initial_boot_params) +
+			be32_to_cpu(initial_boot_params->off_dt_struct);
+	return of_scan_flat_dt_ranges(&p, 0, node, address,0);
+}
+
 
 /**
  * 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 7bbf5b3..92e8694 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -82,6 +82,8 @@ extern void early_init_dt_add_memory_arch(u64 base, u64 size);
 extern u64 early_init_dt_alloc_memory_arch(u64 size, u64 align);
 extern u64 dt_mem_next_cell(int s, __be32 **cellp);
 
+extern int early_init_dt_translate_address(unsigned long node, u64 *address);
+
 /*
  * 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

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