Add configurability via devicetree

This adds the possibility to configure the place for the environment
from the devicetree and to partition devices from the devicetree.

Configuration has the general form of devices with a regular compatible
property. This allows to later add additional drivers or drivers with
different behaviour (for example to add support for redundant environment).

The configuration is all in the /chosen/barebox/ hierarchy of the
devicetree. This separates the configuration from the hardware
description. Also it makes it possible to store the configuration
in a completely separate devicetree (or devicetree overlay). For
the same reason all configuration is done using nodepathes rather
than phandles.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 155 insertions, 0 deletions

diff --git a/drivers/of/of_path.c b/drivers/of/of_path.c
new file mode 100644
index 0000000000..ab8618e23d
--- /dev/null
+++ b/drivers/of/of_path.c
@@ -0,0 +1,155 @@
+/*
+ * of_path.c
+ *
+ * Copyright (c) 2013 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <of.h>
+
+struct of_path {
+	struct cdev *cdev;
+	struct device_d *dev;
+};
+
+struct of_path_type {
+	const char *name;
+	int (*parse)(struct of_path *op, const char *str);
+};
+
+/**
+ * of_path_type_partname - find a partition based on physical device and
+ *                         partition name
+ * @op: of_path context
+ * @name: the partition name to find
+ */
+static int of_path_type_partname(struct of_path *op, const char *name)
+{
+	if (!op->dev)
+		return -EINVAL;
+
+	op->cdev = device_find_partition(op->dev, name);
+	if (op->cdev) {
+		pr_debug("%s: found part '%s'\n", __func__, name);
+		return 0;
+	} else {
+		pr_debug("%s: cannot find part '%s'\n", __func__, name);
+		return -ENODEV;
+	}
+}
+
+static struct of_path_type of_path_types[] = {
+	{
+		.name = "partname",
+		.parse = of_path_type_partname,
+	},
+};
+
+static int of_path_parse_one(struct of_path *op, const char *str)
+{
+	int i, ret;
+	char *name, *desc;
+
+	pr_debug("parsing: %s\n", str);
+
+	name = xstrdup(str);
+	desc = strchr(name, ':');
+	if (!desc) {
+		free(name);
+		return -EINVAL;
+	}
+
+	*desc = 0;
+	desc++;
+
+	for (i = 0; i < ARRAY_SIZE(of_path_types); i++) {
+		if (!strcmp(of_path_types[i].name, name)) {
+			ret = of_path_types[i].parse(op, desc);
+			goto out;
+		}
+	}
+
+	ret = -EINVAL;
+out:
+	free(name);
+
+	return ret;
+}
+
+/**
+ * of_find_path - translate a path description in the devicetree to a barebox
+ *                path
+ *
+ * @node: the node containing the property with the path description
+ * @propname: the property name of the path description
+ * @outpath: if this function returns 0 outpath will contain the path belonging
+ *           to the input path description. Must be freed with free().
+ *
+ * pathes in the devicetree have the form of a multistring property. The first
+ * string contains the full path to the physical device containing the path.
+ * The remaining strings have the form "<type>:<options>". Currently supported
+ * for <type> are:
+ *
+ * partname:<partname> - find a partition by its partition name. For mtd
+ *                       partitions this is the label. For DOS partitions
+ *                       this is the number beginning with 0.
+ *
+ * examples:
+ *
+ * device-path = &mmc0, "partname:0";
+ * device-path = &norflash, "partname:barebox-environment";
+ */
+int of_find_path(struct device_node *node, const char *propname, char **outpath)
+{
+	struct of_path op = {};
+	struct device_node *rnode;
+	const char *path, *str;
+	int i, len, ret;
+
+	path = of_get_property(node, propname, &len);
+	if (!path)
+		return -EINVAL;
+
+	rnode = of_find_node_by_path(path);
+	if (!rnode)
+		return -ENODEV;
+
+	op.dev = of_find_device_by_node_path(rnode->full_name);
+	if (!op.dev)
+		return -ENODEV;
+
+	device_detect(op.dev);
+
+	i = 1;
+
+	while (1) {
+		ret = of_property_read_string_index(node, propname, i++, &str);
+		if (ret)
+			break;
+
+		ret = of_path_parse_one(&op, str);
+		if (ret)
+			return ret;
+	}
+
+	if (!op.cdev)
+		return -ENOENT;
+
+	*outpath = asprintf("/dev/%s", op.cdev->name);
+
+	return 0;
+}