[RFC v2] OLPC: add missing elements to device tree

[Daniel Drake]

In response to new device tree code in the kernel, OLPC will start
using it for probing of certain devices. However, some firmware fixes
are needed to put the devicetree into a usable state.

Retain compatibility with old firmware by fixing up the device tree
at boot-time if it does not contain the new nodes/properties that
we need for probing.

Signed-off-by: Daniel Drake <dsd at laptop.org>
---
 arch/x86/platform/olpc/olpc_dt.c |  104 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 104 insertions(+), 0 deletions(-)

v2: ask OpenFirmware to adjust the tree instead of manipulating the tree
on the linux level.

diff --git a/arch/x86/platform/olpc/olpc_dt.c b/arch/x86/platform/olpc/olpc_dt.c
index 24f2598..d6ee929 100644
--- a/arch/x86/platform/olpc/olpc_dt.c
+++ b/arch/x86/platform/olpc/olpc_dt.c
@@ -21,6 +21,7 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/of_pdt.h>
+#include <asm/olpc.h>
 #include <asm/olpc_ofw.h>
 
 static phandle __init olpc_dt_getsibling(phandle node)
@@ -164,6 +165,107 @@ static struct of_pdt_ops prom_olpc_ops __initdata = {
 	.pkg2path = olpc_dt_pkg2path,
 };
 
+static phandle __init olpc_dt_finddevice(const char *path)
+{
+	phandle node;
+	const void *args[] = { path };
+	void *res[] = { &node };
+
+	if (olpc_ofw("finddevice", args, res)) {
+		pr_err("olpc_dt: finddevice failed!\n");
+		return 0;
+	}
+
+	if ((s32) node == -1)
+		return 0;
+
+	return node;
+}
+
+static int __init olpc_dt_interpret(const char *words)
+{
+	int result;
+	const void *args[] = { words };
+	void *res[] = { &result };
+
+	if (olpc_ofw("interpret", args, res)) {
+		pr_err("olpc_dt: interpret failed!\n");
+		return -1;
+	}
+
+	return result;
+}
+
+/*
+ * Extract board revision directly from OFW device tree.
+ * We can't use olpc_platform_info because that hasn't been set up yet.
+ */
+static u32 __init olpc_dt_get_board_revision(void)
+{
+	phandle node;
+	__be32 rev;
+	int r;
+
+	node = olpc_dt_finddevice("/");
+	if (!node)
+		return 0;
+
+	r = olpc_dt_getproperty(node, "board-revision-int",
+				(char *) &rev, sizeof(rev));
+	if (r < 0)
+		return 0;
+
+	return be32_to_cpu(rev);
+}
+
+void __init olpc_dt_fixup(void)
+{
+	int r;
+	char buf[64];
+	phandle node;
+	u32 board_rev;
+
+	node = olpc_dt_finddevice("/battery at 0");
+	if (!node)
+		return;
+
+	/*
+	 * If the battery node has a compatible property, we are running a new
+	 * enough firmware and don't have fixups to make.
+	 */
+	r = olpc_dt_getproperty(node, "compatible", buf, sizeof(buf));
+	if (r > 0)
+		return;
+
+	pr_info("PROM DT: Old firmware detected, applying fixes\n");
+
+	/* Add olpc,xo1-battery compatible marker to battery node */
+	olpc_dt_interpret("\" /battery at 0\" find-device"
+		" \" olpc,xo1-battery\" +compatible"
+		" device-end");
+
+	board_rev = olpc_dt_get_board_revision();
+	if (!board_rev)
+		return;
+
+	if (board_rev >= olpc_board_pre(0xd0)) {
+		/* XO-1.5: add dcon device */
+		olpc_dt_interpret("\" /pci/display at 1\" find-device"
+			" new-device"
+			" \" dcon\" device-name \" olpc,xo1-dcon\" +compatible"
+			" finish-device device-end");
+	} else {
+		/* XO-1: add dcon device, mark RTC as olpc,xo1-rtc */
+		olpc_dt_interpret("\" /pci/display at 1,1\" find-device"
+			" new-device"
+			" \" dcon\" device-name \" olpc,xo1-dcon\" +compatible"
+			" finish-device device-end"
+			" \" /rtc\" find-device"
+			" \" olpc,xo1-rtc\" +compatible"
+			" device-end");
+	}
+}
+
 void __init olpc_dt_build_devicetree(void)
 {
 	phandle root;
@@ -171,6 +273,8 @@ void __init olpc_dt_build_devicetree(void)
 	if (!olpc_ofw_is_installed())
 		return;
 
+	olpc_dt_fixup();
+
 	root = olpc_dt_getsibling(0);
 	if (!root) {
 		pr_err("PROM: unable to get root node from OFW!\n");
-- 
1.7.4