From 6979118edef2b57c3bb6f401b58a03ab6bb5a54e Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer@pengutronix.de>
Date: Fri, 21 Mar 2014 08:43:00 +0100
Subject: blspec: Check if an entry is compatible with the current machine

When a bootspec entry has the 'devicetree' property specified, check
if the tree is compatible with the currently running machine, otherwise
ignore the entry. This makes it possible to have entries for multiple
machines on an SD card and pick a suitable one.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/blspec.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 79 insertions(+), 2 deletions(-)

(limited to 'common/blspec.c')

diff --git a/common/blspec.c b/common/blspec.c
index 9b4b096a0a..f165b77aaa 100644
--- a/common/blspec.c
+++ b/common/blspec.c
@@ -234,6 +234,78 @@ out:
 	return ret ? ERR_PTR(ret) : mountpath;
 }
 
+/*
+ * entry_is_of_compatible - check if a bootspec entry is compatible with
+ *                          the current machine.
+ *
+ * returns true is the entry is compatible, false otherwise
+ */
+static bool entry_is_of_compatible(struct blspec_entry *entry)
+{
+	const char *devicetree;
+	const char *abspath;
+	size_t size;
+	void *fdt = NULL;
+	int ret;
+	struct device_node *root = NULL, *barebox_root;
+	const char *compat;
+	char *filename;
+
+	/* If we don't have a root node every entry is compatible */
+	barebox_root = of_get_root_node();
+	if (!barebox_root)
+		return true;
+
+	ret = of_property_read_string(barebox_root, "compatible", &compat);
+	if (ret)
+		return false;
+
+	if (entry->rootpath)
+		abspath = entry->rootpath;
+	else
+		abspath = "";
+
+	/* If the entry doesn't specifiy a devicetree we are compatible */
+	devicetree = blspec_entry_var_get(entry, "devicetree");
+	if (!devicetree)
+		return true;
+
+	if (!strcmp(devicetree, "none"))
+		return true;
+
+	filename = asprintf("%s/%s", abspath, devicetree);
+
+	fdt = read_file(filename, &size);
+	if (!fdt) {
+		ret = false;
+		goto out;
+	}
+
+	root = of_unflatten_dtb(NULL, fdt);
+	if (IS_ERR(root)) {
+		ret = PTR_ERR(root);
+		goto out;
+	}
+
+	if (of_device_is_compatible(root, compat)) {
+		ret = true;
+		goto out;
+	}
+
+	pr_info("ignoring entry with incompatible devicetree \"%s\"\n",
+			(char *)of_get_property(root, "compatible", &size));
+
+	ret = false;
+
+out:
+	if (root)
+		of_delete_node(root);
+	free(filename);
+	free(fdt);
+
+	return ret;
+}
+
 /*
  * blspec_scan_directory - scan over a directory
  *
@@ -313,12 +385,17 @@ int blspec_scan_directory(struct blspec *blspec, const char *root)
 			continue;
 		}
 
-		found++;
-
 		entry->rootpath = xstrdup(root);
 		entry->configpath = configname;
 		entry->cdev = get_cdev_by_mountpath(root);
 
+		if (!entry_is_of_compatible(entry)) {
+			blspec_entry_free(entry);
+			continue;
+		}
+
+		found++;
+
 		name = asprintf("%s/%s", dirname, d->d_name);
 		if (entry_default && !strcmp(name, entry_default))
 			entry->boot_default = true;
-- 
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