[RFC 2/3] 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 |   87 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 87 insertions(+), 0 deletions(-)

diff --git a/arch/x86/platform/olpc/olpc_dt.c b/arch/x86/platform/olpc/olpc_dt.c
index 09cbede..58bba78 100644
--- a/arch/x86/platform/olpc/olpc_dt.c
+++ b/arch/x86/platform/olpc/olpc_dt.c
@@ -22,6 +22,7 @@
 #include <linux/of_platform.h>
 #include <linux/of_pdt.h>
 #include <asm/olpc_ofw.h>
+#include <asm/olpc.h>
 
 static phandle __init olpc_dt_getsibling(phandle node)
 {
@@ -164,6 +165,91 @@ static struct of_pdt_ops prom_olpc_ops __initdata = {
 	.pkg2path = olpc_dt_pkg2path,
 };
 
+static char __init *prom_alloc_string(const char *str, int *len)
+{
+	int _len = strlen(str);
+	char *output = prom_early_alloc(_len + 1);
+
+	strcpy(output, str);
+	if (len)
+		*len = _len;
+	return output;
+}
+
+static void __init prom_alloc_property(struct device_node *node,
+	const char *name, const char *value)
+{
+	struct property *p = prom_early_alloc(sizeof(struct property));
+
+	p->name = prom_alloc_string(name, NULL);
+	p->value = prom_alloc_string(value, &p->length);
+	prom_add_property(node, p);
+}
+
+/* Add dcon device as child of display */
+static void __init add_dcon_node(struct device_node *display)
+{
+	struct device_node *node = prom_early_alloc(sizeof(struct device_node));
+	unsigned long flags;
+
+	kref_init(&node->kref);
+	node->name = prom_alloc_string("dcon", NULL);
+	node->full_name = (char *) node->name;
+	node->parent = display;
+
+	write_lock_irqsave(&devtree_lock, flags);
+	node->sibling = node->parent->child;
+	node->allnext = allnodes;
+	node->parent->child = node;
+	allnodes = node;
+	write_unlock_irqrestore(&devtree_lock, flags);
+
+	prom_alloc_property(node, "compatible", "olpc,xo1-dcon");
+}
+
+static void __init olpc_dt_fixup(void)
+{
+	struct device_node *node;
+
+	/*
+	 * Use battery's compatible property to determine if we're running a
+	 * new-enough firmware. If we have this property, no fixups are needed.
+	 */
+	node = of_find_node_by_name(NULL, "battery");
+	if (node && of_get_property(node, "compatible", NULL)) {
+		of_node_put(node);
+		return;
+	}
+
+	/*
+	 * Add "compatible" property to battery, it was missing from earlier
+	 * firmware releases.
+	 */
+	prom_alloc_property(node, "compatible", "olpc,xo1-battery");
+	of_node_put(node);
+
+	/*
+	 * Mark XO-1 RTC as compatible with olpc,xo1-rtc - this was not done in
+	 * earlier firmware releases.
+	 */
+	node = of_find_node_by_name(NULL, "rtc");
+	if (olpc_platform_info.boardrev < olpc_board_pre(0xd0) && node) {
+		struct property *p = of_get_property(node, "compatible", NULL);
+		prom_remove_property(node, p);
+		prom_alloc_property(node, "compatible", "olpc,xo1-rtc");
+	}
+	of_node_put(node);
+
+	/*
+	 * Add "dcon" device node, it was missing from earlier firmware
+	 * releases.
+	 */
+	node = of_find_node_by_name(NULL, "display");
+	if (node)
+		add_dcon_node(node);
+	of_node_put(node);
+}
+
 void __init olpc_dt_build_devicetree(void)
 {
 	phandle root;
@@ -177,6 +263,7 @@ void __init olpc_dt_build_devicetree(void)
 		return;
 	}
 	of_pdt_build_devicetree(root, &prom_olpc_ops);
+	olpc_dt_fixup();
 
 	pr_info("PROM DT: Built device tree with %u bytes of memory.\n",
 			prom_early_allocated);
-- 
1.7.4