of: request reserved memory regions so other code can't

Add a new of_reserved_mem_walk that can be used to request
reserved memory regions. This avoids e.g. bootm trying to
place the kernel into a reserved region.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20220609111810.2454588-3-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 72 insertions, 0 deletions

diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index ca8da71cb4..4785128bd9 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_OF_GPIO) += of_gpio.o
 obj-$(CONFIG_OF_PCI) += of_pci.o
 obj-y += partition.o
 obj-y += of_net.o
+obj-y += reserved-mem.o
 obj-$(CONFIG_MTD) += of_mtd.o
 obj-$(CONFIG_OF_BAREBOX_DRIVERS) += barebox.o
 obj-$(CONFIG_OF_OVERLAY) += overlay.o resolver.o of_firmware.o
diff --git a/drivers/of/reserved-mem.c b/drivers/of/reserved-mem.c
new file mode 100644
index 0000000000..34e61dfea3
--- /dev/null
+++ b/drivers/of/reserved-mem.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// SPDX-FileCopyrightText: 2021 Rouven Czerwinski <r.czerwinski@pengutronix.de>, Pengutronix
+
+#include <stdio.h>
+#include <of.h>
+#include <of_address.h>
+
+#define MEMRESERVE_NCELLS	2
+#define MEMRESERVE_FLAGS	(IORESOURCE_MEM | IORESOURCE_EXCLUSIVE)
+
+int of_reserved_mem_walk(int (*handler)(const struct resource *res))
+{
+	struct device_node *node, *child;
+	int ncells = 0;
+	const __be32 *reg;
+	int ret;
+
+	node = of_find_node_by_path("/reserved-memory");
+	if (node) {
+		for_each_available_child_of_node(node, child) {
+			struct resource resource = {};
+
+			/* skip e.g. linux,cma */
+			if (!of_get_property(child, "reg", NULL))
+				continue;
+
+			of_address_to_resource(child, 0, &resource);
+
+			resource.name = child->name;
+			resource.flags = MEMRESERVE_FLAGS;
+
+			ret = handler(&resource);
+			if (ret)
+				return ret;
+		}
+	}
+
+	node = of_find_node_by_path("/memreserve");
+	reg = of_get_property(node, "reg", &ncells);
+	ncells /= sizeof(__be32);
+	if (reg) {
+		char name[sizeof "fdt-memreserve-4294967295"];
+		int i = 0, n = 0;
+
+		while (i < ncells) {
+			struct resource resource = {};
+			u64 size;
+
+			snprintf(name, sizeof(name), "fdt-memreserve-%u", n++);
+			resource.name = name;
+			resource.flags = MEMRESERVE_FLAGS;
+
+			resource.start = of_read_number(reg + i, MEMRESERVE_NCELLS);
+			i += MEMRESERVE_NCELLS;
+
+			size = of_read_number(reg + i, MEMRESERVE_NCELLS);
+			i += MEMRESERVE_NCELLS;
+
+			if (!size)
+				continue;
+
+			resource.end = resource.start + size - 1;
+
+			ret = handler(&resource);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}