Hi,
now we're able to get a node's memory address. Though, a device tree
may implement so called ranges. Those ranges are used to translate from
one address space to another.
This is used on a few machines, for instance on the raspberry pi:
/ {
#address-cells = <0x1>;
#size-cells = <0x1>;
interrupt-parent = <0x1>;
compatible = "brcm,bcm2710", "brcm,bcm2709";
model = "Raspberry Pi 3 Model B";
[...]
soc {
compatible = "simple-bus";
#address-cells = <0x1>;
#size-cells = <0x1>;
ranges = <0x7e000000 0x3f000000 0x1000000>;
[...]
interrupt-controller@7e00b200 {
compatible = "brcm,bcm2708-armctrl-ic";
reg = <0x7e00b200 0x200>;
interrupt-controller;
#interrupt-cells = <0x2>;
linux,phandle = <0x1>;
phandle = <0x1>;
};
Even though the node's reg is set to 0x7e00b200, the actual address is
0x3f00b200. To get to that address, we need to check the parent's
ranges attribute.
Since I last posted this diff in another thread I have added an
explanatory comment before the function and improved a few comments
inline.
ok?
Patrick
diff --git sys/dev/ofw/fdt.c sys/dev/ofw/fdt.c
index c430a1e..8990afc 100644
--- sys/dev/ofw/fdt.c
+++ sys/dev/ofw/fdt.c
@@ -34,6 +34,7 @@ void *skip_node(void *);
void *fdt_parent_node_recurse(void *, void *);
int fdt_node_property_int(void *, char *, int *);
int fdt_node_property_ints(void *, char *, int *, int);
+int fdt_translate_memory_address(void *, struct fdt_memory *);
#ifdef DEBUG
void fdt_print_node_recurse(void *, int);
#endif
@@ -390,6 +391,108 @@ fdt_parent_node(void *node)
}
/*
+ * Translate memory address depending on parent's range.
+ *
+ * Ranges are a way of mapping one address to another. This ranges attribute
+ * is set on a node's parent. This means if a node does not have a parent,
+ * there's nothing to translate. If it does have a parent and the parent does
+ * not have a ranges attribute, there's nothing to translate either.
+ *
+ * If the parent has a ranges attribute and the attribute is not empty, the
+ * node's memory address has to be in one of the given ranges. This range is
+ * then used to translate the memory address.
+ *
+ * If the parent has a ranges attribute, but the attribute is empty, there's
+ * nothing to translate. But it's not a translation barrier. It can be
treated
+ * as a simple 1:1 mapping.
+ *
+ * Translation does not end here. We need to check if the parent's parent also
+ * has a ranges attribute and ask the same questions again.
+ */
+int
+fdt_translate_memory_address(void *node, struct fdt_memory *mem)
+{
+ void *parent;
+ int pac, psc, ac, sc, ret, rlen, rone, *range;
+ uint64_t from, to, size;
+
+ if (node == NULL || mem == NULL)
+ return 1;
+
+ /* No parent, no translation. */
+ parent = fdt_parent_node(node);
+ if (parent == NULL)
+ return 0;
+
+ /* Extract ranges property from node. */
+ rlen = fdt_node_property(node, "ranges", (char **)&range) / sizeof(int);
+
+ /* No ranges means translation barrier. Translation stops here. */
+ if (range == NULL)
+ return 0;
+
+ /* Empty ranges means 1:1 mapping. Continue translation on parent. */
+ if (rlen <= 0)
+ return fdt_translate_memory_address(parent, mem);
+
+ /* We only support 32-bit (1), and 64-bit (2) wide addresses here. */
+ ret = fdt_node_property_int(parent, "#address-cells", &pac);
+ if (ret != 1 || pac <= 0 || pac > 2)
+ return 1;
+
+ /* We only support 32-bit (1), and 64-bit (2) wide sizes here. */
+ ret = fdt_node_property_int(parent, "#size-cells", &psc);
+ if (ret != 1 || psc <= 0 || psc > 2)
+ return 1;
+
+ /* We only support 32-bit (1), and 64-bit (2) wide addresses here. */
+ ret = fdt_node_property_int(node, "#address-cells", &ac);
+ if (ret <= 0)
+ ac = pac;
+ else if (ret > 1 || ac <= 0 || ac > 2)
+ return 1;
+
+ /* We only support 32-bit (1), and 64-bit (2) wide sizes here. */
+ ret = fdt_node_property_int(node, "#size-cells", &sc);
+ if (ret <= 0)
+ sc = psc;
+ else if (ret > 1 || sc <= 0 || sc > 2)
+ return 1;
+
+ /* Must have at least one range. */
+ rone = pac + ac + sc;
+ if (rlen < rone)
+ return 1;
+
+ /* For each range. */
+ for (; rlen >= rone; rlen -= rone, range += rone) {
+ /* Extract from and size, so we can see if we fit. */
+ from = betoh32(range[0]);
+ if (ac == 2)
+ from = (from << 32) + betoh32(range[1]);
+ size = betoh32(range[ac + pac]);
+ if (sc == 2)
+ size = (size << 32) + betoh32(range[ac + pac + 1]);
+
+ /* Try next, if we're not in the range. */
+ if (mem->addr < from || (mem->addr + mem->size) > (from + size))
+ continue;
+
+ /* All good, extract to address and translate. */
+ to = betoh32(range[ac]);
+ if (pac == 2)
+ to = (to << 32) + betoh32(range[ac + 1]);
+
+ mem->addr -= from;
+ mem->addr += to;
+ return fdt_translate_memory_address(parent, mem);
+ }
+
+ /* To be successful, we must have returned in the for-loop. */
+ return 1;
+}
+
+/*
* Parse the memory address and size of a node.
*/
int
@@ -429,10 +532,7 @@ fdt_get_memory_address(void *node, int idx, struct
fdt_memory *mem)
if (sc == 2)
mem->size = (mem->size << 32) + betoh32(in[off + ac + 1]);
- /* TODO: translate memory address in ranges */
- //return fdt_translate_memory_address(parent, mem);
-
- return 0;
+ return fdt_translate_memory_address(parent, mem);
}
#ifdef DEBUG
