[RFC PATCH 1/2] common: fdt: Add a function for reserving memory without kernel linear mapping

Michael Trimarchi
2020-02-19T18:43:41Z

We need to reserve memory and not put in kernel linear mapping.
This avoid problem during memory remapping from the simple
frame buffer in linux kernel

Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
---
common/fdt_support.c | 40 ++++++++++++++++++++++++++++++++++++++++
include/fdt_support.h | 11 +++++++++++
2 files changed, 51 insertions(+)

diff --git a/common/fdt_support.c b/common/fdt_support.c
index 02cf5c6241..a3662f4358 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -410,6 +410,46 @@ static int fdt_pack_reg(const void *fdt, void *buf, u64 *address, u64 *size,
return p - (char *)buf;
}

+int fdt_fixup_reserved_memory(void *blob, const char *area, u64 start[], u64 size[])
+{
+ int offs, len;
+ const char *subpath;
+ const char *path = "/reserved-memory";
+ fdt32_t address_cells = cpu_to_fdt32(fdt_address_cells(blob, 0));
+ fdt32_t size_cells = cpu_to_fdt32(fdt_size_cells(blob, 0));
+ u8 temp[16]; /* Up to 64-bit address + 64-bit size */
+
+ offs = fdt_path_offset(blob, path);
+ if (offs < 0) {
+ debug("Node %s not found\n", path);
+ path = "/";
+ subpath = "reserved-memory";
+ offs = fdt_path_offset(blob, path);
+ offs = fdt_add_subnode(blob, offs, subpath);
+ if (offs < 0) {
+ printf("Could not create %s%s node.\n", path, subpath);
+ return -1;
+ }
+ path = "/reserved-memory";
+ offs = fdt_path_offset(blob, path);
+
+ fdt_setprop(blob, offs, "#address-cells", &address_cells, sizeof(address_cells));
+ fdt_setprop(blob, offs, "#size-cells", &size_cells, sizeof(size_cells));
+ fdt_setprop(blob, offs, "ranges", NULL, 0);
+ }
+
+ offs = fdt_add_subnode(blob, offs, area ? : "private");
+ if (offs < 0) {
+ printf("Could not create %s%s node.\n", path, subpath);
+ return -1;
+ }
+
+ fdt_setprop(blob, offs, "no-map", NULL, 0);
+ len = fdt_pack_reg(blob, temp, start, size, 1);
+ fdt_setprop(blob, offs, "reg", temp, len);
+ return 0;
+}
+
#if CONFIG_NR_DRAM_BANKS > 4
#define MEMORY_BANKS_MAX CONFIG_NR_DRAM_BANKS
#else
diff --git a/include/fdt_support.h b/include/fdt_support.h
index ba14acd7f6..7c8a280f53 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -93,6 +93,17 @@ void do_fixup_by_compat_u32(void *fdt, const char *compat,
*/
int fdt_fixup_memory(void *blob, u64 start, u64 size);

+/**
+ * Setup the memory reserved node in the DT. Creates one if none was existing before.
+ *
+ * @param blob FDT blob to update
+ * @param area Reserved area name
+ * @param start Begin of DRAM mapping in physical memory
+ * @param size Size of the single memory bank
+ * @return 0 if ok, or -1 or -FDT_ERR_... on error
+ */
+int fdt_fixup_reserved_memory(void *blob, const char *area, u64 start[], u64 size[]);
+
/**
* Fill the DT memory node with multiple memory banks.
* Creates the node if none was existing before.
--
2.17.1