If there is no capability for the boot loader to specify a devicetree
blob then this option allows for it to be embedded within the linux
kernel binary itself. This change specifically adds this embedding
support for the m68knommu targets.
Signed-off-by: Greg Ungerer <gerg@xxxxxxxxxxxxxx>
---
arch/m68k/Kconfig.devices | 11 ++++++++++
arch/m68k/kernel/Makefile | 1 +
arch/m68k/kernel/embedded_dtb.S | 19 +++++++++++++++++
arch/m68k/kernel/setup_no.c | 33 ++++++++++++++++++++++++++++++
arch/m68k/kernel/vmlinux-nommu.lds | 9 ++++++++
5 files changed, 73 insertions(+)
create mode 100644 arch/m68k/kernel/embedded_dtb.S
diff --git a/arch/m68k/Kconfig.devices b/arch/m68k/Kconfig.devices
index e6e3efac1840..ea0bce4db639 100644
--- a/arch/m68k/Kconfig.devices
+++ b/arch/m68k/Kconfig.devices
@@ -144,3 +144,14 @@ config SERIAL_CONSOLE
endmenu
endif
+
+config EMBEDDED_DTB
+ bool "Embedded devicetree ELF section"
+ help
+ If there is no capability for the boot loader to specify a
+ devicetree (DTB) then this option allows for it to be embedbed
+ within the linux binary itself. Typically you can do this with
+ something like this:
+
+ objcopy --update-section .embedded_dtb=<filename>.dtb vmlinux
+
diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile
index 6c732ed3998b..04627f13efb6 100644
--- a/arch/m68k/kernel/Makefile
+++ b/arch/m68k/kernel/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_M68K_NONCOHERENT_DMA) += dma.o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_BOOTINFO_PROC) += bootinfo_proc.o
obj-$(CONFIG_UBOOT) += uboot.o
+obj-$(CONFIG_EMBEDDED_DTB) += embedded_dtb.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
diff --git a/arch/m68k/kernel/embedded_dtb.S b/arch/m68k/kernel/embedded_dtb.S
new file mode 100644
index 000000000000..389a63f52770
--- /dev/null
+++ b/arch/m68k/kernel/embedded_dtb.S
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/linkage.h>
+#include <asm/page.h>
+
+/*
+ * If we have a single configured platform then include that fdt now.
+ * Otherwise leave some space so it can be inserted later.
+ */
+.section ".embedded_dtb","aw"
+.balign PAGE_SIZE
+
+#if defined(CONFIG_M520x)
+.incbin "arch/m68k/boot/dts/mcf5208evb.dtb"
+#elif defined(CONFIG_M547x)
+.incbin "arch/m68k/boot/dts/mcf5475evb.dtb"
+#else
+.skip PAGE_SIZE,0
+#endif
diff --git a/arch/m68k/kernel/setup_no.c b/arch/m68k/kernel/setup_no.c
index c926da9d5ec2..50f972c91caa 100644
--- a/arch/m68k/kernel/setup_no.c
+++ b/arch/m68k/kernel/setup_no.c
@@ -33,6 +33,8 @@
#include <linux/initrd.h>
#include <linux/root_dev.h>
#include <linux/rtc.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
#include <asm/setup.h>
#include <asm/bootinfo.h>
@@ -70,6 +72,32 @@ void (*mach_halt)(void);
#define CPU_NAME "UNKNOWN"
#endif
+#ifdef CONFIG_EMBEDDED_DTB
+static void __init m68k_setup_fdt(void)
+{
+ extern void *embedded_dtb;
+ phys_addr_t fdt = (phys_addr_t) &embedded_dtb;
+
+ pr_info("m68k generic DT machine support, FDT blob at 0x%08x\n", fdt);
+ if (!early_init_dt_verify(__va(fdt), fdt)) {
+ pr_err("FDT blob is bad?!\n");
+ return;
+ }
+ early_init_dt_scan_nodes();
+ unflatten_device_tree();
+}
+
+static void __init m68k_dtb_model(void)
+{
+ const char *model;
+ model = of_flat_dt_get_machine_name();
+ if (model)
+ pr_info("DTB reports model \"%s\"\n", model);
+ else
+ pr_warn("DTB has no model type?\n");
+}
+#endif /* CONFIG_EMBEDDED_DTB */
+
/*
* Different cores have different instruction execution timings.
* The old/traditional 68000 cores are basically all the same, at 16.
@@ -166,6 +194,11 @@ void __init setup_arch(char **cmdline_p)
* Get kmalloc into gear.
*/
paging_init();
+
+#ifdef CONFIG_EMBEDDED_DTB
+ m68k_setup_fdt();
+ m68k_dtb_model();
+#endif
}
/*
diff --git a/arch/m68k/kernel/vmlinux-nommu.lds b/arch/m68k/kernel/vmlinux-nommu.lds
index 2624fc18c131..1be3bfe31ba4 100644
--- a/arch/m68k/kernel/vmlinux-nommu.lds
+++ b/arch/m68k/kernel/vmlinux-nommu.lds
@@ -70,6 +70,15 @@ SECTIONS {
INIT_TEXT_SECTION(PAGE_SIZE)
INIT_DATA_SECTION(16)
PERCPU_SECTION(16)
+
+#ifdef CONFIG_EMBEDDED_DTB
+ STRUCT_ALIGN();
+ .embedded_dtb : {
+ embedded_dtb = .;
+ *(.embedded_dtb)
+ KEEP(*(.embedded_dtb))
+ }
+#endif
.m68k_fixup : {
__start_fixup = .;
*(.m68k_fixup)
--
2.43.0
