fdt: Support for ISA busses

Support ISA busses in much the same way as Linux does. This allows for
ISA bus addresses to be translated, and only if CONFIG_OF_ISA_BUS is
selected in order to avoid including the code in builds which won't need
it.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

2 files changed, 121 insertions, 3 deletions

diff --git a/common/fdt_support.c b/common/fdt_support.c
index 42e5d8a..96b5d0a 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -964,10 +964,21 @@ static void of_dump_addr(const char *s, const fdt32_t *addr, int na)
 static void of_dump_addr(const char *s, const fdt32_t *addr, int na) { }
 #endif
 
-/* Callbacks for bus specific translators */
+/**
+ * struct of_bus - Callbacks for bus specific translators
+ * @match:	Return non-zero if the node whose parent is at
+ *		parentoffset in the FDT blob corresponds to a bus
+ *		of this type, otherwise return zero. If NULL a match
+ *		is assumed.
+ *
+ * Each bus type will include a struct of_bus in the of_busses array,
+ * providing implementations of some or all of the functions used to
+ * match the bus & handle address translation for its children.
+ */
 struct of_bus {
 	const char	*name;
 	const char	*addresses;
+	int		(*match)(void *blob, int parentoffset);
 	void		(*count_cells)(void *blob, int parentoffset,
 				int *addrc, int *sizec);
 	u64		(*map)(fdt32_t *addr, const fdt32_t *range,
@@ -1022,8 +1033,70 @@ static int of_bus_default_translate(fdt32_t *addr, u64 offset, int na)
 	return 0;
 }
 
+#ifdef CONFIG_OF_ISA_BUS
+
+/* ISA bus translator */
+static int of_bus_isa_match(void *blob, int parentoffset)
+{
+	const char *name;
+
+	name = fdt_get_name(blob, parentoffset, NULL);
+	if (!name)
+		return 0;
+
+	return !strcmp(name, "isa");
+}
+
+static void of_bus_isa_count_cells(void *blob, int parentoffset,
+				   int *addrc, int *sizec)
+{
+	if (addrc)
+		*addrc = 2;
+	if (sizec)
+		*sizec = 1;
+}
+
+static u64 of_bus_isa_map(fdt32_t *addr, const fdt32_t *range,
+			  int na, int ns, int pna)
+{
+	u64 cp, s, da;
+
+	/* Check address type match */
+	if ((addr[0] ^ range[0]) & cpu_to_be32(1))
+		return OF_BAD_ADDR;
+
+	cp = of_read_number(range + 1, na - 1);
+	s  = of_read_number(range + na + pna, ns);
+	da = of_read_number(addr + 1, na - 1);
+
+	debug("OF: ISA map, cp=%" PRIu64 ", s=%" PRIu64
+	      ", da=%" PRIu64 "\n", cp, s, da);
+
+	if (da < cp || da >= (cp + s))
+		return OF_BAD_ADDR;
+	return da - cp;
+}
+
+static int of_bus_isa_translate(fdt32_t *addr, u64 offset, int na)
+{
+	return of_bus_default_translate(addr + 1, offset, na - 1);
+}
+
+#endif /* CONFIG_OF_ISA_BUS */
+
 /* Array of bus specific translators */
 static struct of_bus of_busses[] = {
+#ifdef CONFIG_OF_ISA_BUS
+	/* ISA */
+	{
+		.name = "isa",
+		.addresses = "reg",
+		.match = of_bus_isa_match,
+		.count_cells = of_bus_isa_count_cells,
+		.map = of_bus_isa_map,
+		.translate = of_bus_isa_translate,
+	},
+#endif /* CONFIG_OF_ISA_BUS */
 	/* Default */
 	{
 		.name = "default",
@@ -1034,6 +1107,28 @@ static struct of_bus of_busses[] = {
 	},
 };
 
+static struct of_bus *of_match_bus(void *blob, int parentoffset)
+{
+	struct of_bus *bus;
+
+	if (ARRAY_SIZE(of_busses) == 1)
+		return of_busses;
+
+	for (bus = of_busses; bus; bus++) {
+		if (!bus->match || bus->match(blob, parentoffset))
+			return bus;
+	}
+
+	/*
+	 * We should always have matched the default bus at least, since
+	 * it has a NULL match field. If we didn't then it somehow isn't
+	 * in the of_busses array or something equally catastrophic has
+	 * gone wrong.
+	 */
+	assert(0);
+	return NULL;
+}
+
 static int of_translate_one(void * blob, int parent, struct of_bus *bus,
 			    struct of_bus *pbus, fdt32_t *addr,
 			    int na, int ns, int pna, const char *rprop)
@@ -1113,7 +1208,7 @@ static u64 __of_translate_address(void *blob, int node_offset, const fdt32_t *in
 	parent = fdt_parent_offset(blob, node_offset);
 	if (parent < 0)
 		goto bail;
-	bus = &of_busses[0];
+	bus = of_match_bus(blob, parent);
 
 	/* Cound address cells & copy address locally */
 	bus->count_cells(blob, parent, &na, &ns);
@@ -1142,7 +1237,7 @@ static u64 __of_translate_address(void *blob, int node_offset, const fdt32_t *in
 		}
 
 		/* Get new parent bus and counts */
-		pbus = &of_busses[0];
+		pbus = of_match_bus(blob, parent);
 		pbus->count_cells(blob, parent, &pna, &pns);
 		if (!OF_CHECK_COUNTS(pna, pns)) {
 			printf("%s: Bad cell count for %s\n", __FUNCTION__,
diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig
index c5c9d2a..8749561 100644
--- a/drivers/core/Kconfig
+++ b/drivers/core/Kconfig
@@ -178,4 +178,27 @@ config SPL_OF_TRANSLATE
 	  used for the address translation. This function is faster and
 	  smaller in size than fdt_translate_address().
 
+config OF_ISA_BUS
+	bool
+	depends on OF_TRANSLATE
+	help
+	  Is this option is enabled then support for the ISA bus will
+	  be included for addresses read from DT. This is something that
+	  should be known to be required or not based upon the board
+	  being targetted, and whether or not it makes use of an ISA bus.
+
+	  The bus is matched based upon its node name equalling "isa". The
+	  busses #address-cells should equal 2, with the first cell being
+	  used to hold flags & flag 0x1 indicating that the address range
+	  should be accessed using I/O port in/out accessors. The second
+	  cell holds the offset into ISA bus address space. The #size-cells
+	  property should equal 1, and of course holds the size of the
+	  address range used by a device.
+
+	  If this option is not enabled then support for the ISA bus is
+	  not included and any such busses used in DT will be treated as
+	  typical simple-bus compatible busses. This will lead to
+	  mistranslation of device addresses, so ensure that this is
+	  enabled if your board does include an ISA bus.
+
 endmenu