[PATCH v2 7/8] mips: generic: add fdt fixup for Realtek reference board

Chris Packham
2024-06-24T01:23:15Z

The bootloader used on the Realtek RTL9302C boards is an ancient vendor
fork of U-Boot that doesn't understand device trees. So to run a modern
kernel it is necessary use one of the APPENDED_DTB options.

When appending the DTB the inintrd information, if present, needs to be
inserted into the /chosen device tree node. The bootloader provides the
initrd start/size via the firmware environment. Add a fdt fixup that
will update the device tree with the initrd information.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
Changes in v2:
- update compatible string

arch/mips/generic/Makefile | 1 +
arch/mips/generic/board-realtek.c | 81 +++++++++++++++++++++++++++++++
2 files changed, 82 insertions(+)
create mode 100644 arch/mips/generic/board-realtek.c

diff --git a/arch/mips/generic/Makefile b/arch/mips/generic/Makefile
index 56011d738441..ea0e4ad5e600 100644
--- a/arch/mips/generic/Makefile
+++ b/arch/mips/generic/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_LEGACY_BOARD_SEAD3) += board-sead3.o
obj-$(CONFIG_LEGACY_BOARD_OCELOT) += board-ocelot.o
obj-$(CONFIG_MACH_INGENIC) += board-ingenic.o
obj-$(CONFIG_VIRT_BOARD_RANCHU) += board-ranchu.o
+obj-$(CONFIG_MACH_REALTEK_RTL) += board-realtek.o
diff --git a/arch/mips/generic/board-realtek.c b/arch/mips/generic/board-realtek.c
new file mode 100644
index 000000000000..29234ab9bc64
--- /dev/null
+++ b/arch/mips/generic/board-realtek.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 Allied Telesis
+ */
+
+#include <linux/errno.h>
+#include <linux/libfdt.h>
+#include <linux/of_address.h>
+#include <linux/types.h>
+
+#include <asm/fw/fw.h>
+#include <asm/machine.h>
+
+static __init int realtek_add_initrd(void *fdt)
+{
+ int node, err;
+ u32 start, size;
+
+ node = fdt_path_offset(fdt, "/chosen");
+ if (node < 0) {
+ pr_err("/chosen node not found\n");
+ return -ENOENT;
+ }
+
+ start = fw_getenvl("initrd_start");
+ size = fw_getenvl("initrd_size");
+
+ if (start == 0 && size == 0)
+ return 0;
+
+ pr_info("Adding initrd info from environment\n");
+
+ err = fdt_setprop_u32(fdt, node, "linux,initrd-start", start);
+ if (err) {
+ pr_err("unable to set initrd-start: %d\n", err);
+ return err;
+ }
+
+ err = fdt_setprop_u32(fdt, node, "linux,initrd-end", start + size);
+ if (err) {
+ pr_err("unable to set initrd-end: %d\n", err);
+ return err;
+ }
+
+ return 0;
+}
+
+static const struct mips_fdt_fixup realtek_fdt_fixups[] __initconst = {
+ { realtek_add_initrd, "add initrd" },
+ {},
+};
+
+static __init const void *realtek_fixup_fdt(const void *fdt, const void *match_data)
+{
+ static unsigned char fdt_buf[16 << 10] __initdata;
+ int err;
+
+ if (fdt_check_header(fdt))
+ panic("Corrupt DT");
+
+ fw_init_cmdline();
+
+ err = apply_mips_fdt_fixups(fdt_buf, sizeof(fdt_buf), fdt, realtek_fdt_fixups);
+ if (err)
+ panic("Unable to fixup FDT: %d", err);
+
+ return fdt_buf;
+
+}
+
+static const struct of_device_id realtek_of_match[] __initconst = {
+ {
+ .compatible = "realtek,rtl9302-soc",
+ },
+ {}
+};
+
+MIPS_MACHINE(realtek) = {
+ .matches = realtek_of_match,
+ .fixup_fdt = realtek_fixup_fdt,
+};
--
2.45.2