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authorVincent Whitchurch <vincent.whitchurch@axis.com>2021-12-08 16:11:23 +0100
committerRichard Weinberger <richard@nod.at>2021-12-22 20:35:01 +0100
commitb31297f04e86e4115ece79ca530d8ae1c454db75 (patch)
tree0de0a845d29525262d48d3b81c829a855806ff23 /arch/um
parent361640b4fdc86167b0c25d8e73c08dcaa4ecd28a (diff)
um: Add devicetree support
Add a dtb=<filename> option to boot UML with a devicetree blob. This can be used for testing driver code using UML. Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> [rw: Add dependency on CONFIG_OF] Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/Kconfig1
-rw-r--r--arch/um/kernel/Makefile1
-rw-r--r--arch/um/kernel/dtb.c41
-rw-r--r--arch/um/kernel/um_arch.c3
-rw-r--r--arch/um/kernel/um_arch.h6
5 files changed, 52 insertions, 0 deletions
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index aafdbb6e8059..b233db4f42b2 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -18,6 +18,7 @@ config UML
select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_BUGVERBOSE
select NO_DMA if !UML_DMA_EMULATION
+ select OF_EARLY_FLATTREE if OF
select GENERIC_IRQ_SHOW
select GENERIC_CPU_DEVICES
select HAVE_GCC_PLUGINS
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index 4ab4a0011043..1c2d4b29a3d4 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -22,6 +22,7 @@ obj-y += load_file.o
obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
obj-$(CONFIG_GPROF) += gprof_syms.o
+obj-$(CONFIG_OF) += dtb.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_GENERIC_PCI_IOMAP) += ioport.o
diff --git a/arch/um/kernel/dtb.c b/arch/um/kernel/dtb.c
new file mode 100644
index 000000000000..ca69d72025f3
--- /dev/null
+++ b/arch/um/kernel/dtb.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/init.h>
+#include <linux/of_fdt.h>
+#include <linux/printk.h>
+#include <linux/memblock.h>
+#include <init.h>
+
+#include "um_arch.h"
+
+static char *dtb __initdata;
+
+void uml_dtb_init(void)
+{
+ long long size;
+ void *area;
+
+ area = uml_load_file(dtb, &size);
+ if (!area)
+ return;
+
+ if (!early_init_dt_scan(area)) {
+ pr_err("invalid DTB %s\n", dtb);
+ memblock_free(area, size);
+ return;
+ }
+
+ unflatten_device_tree();
+ early_init_fdt_scan_reserved_mem();
+}
+
+static int __init uml_dtb_setup(char *line, int *add)
+{
+ dtb = line;
+ return 0;
+}
+
+__uml_setup("dtb=", uml_dtb_setup,
+"dtb=<file>\n"
+" Boot the kernel with the devicetree blob from the specified file.\n"
+);
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 54447690de11..abceeabe29b9 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -29,6 +29,8 @@
#include <mem_user.h>
#include <os.h>
+#include "um_arch.h"
+
#define DEFAULT_COMMAND_LINE_ROOT "root=98:0"
#define DEFAULT_COMMAND_LINE_CONSOLE "console=tty"
@@ -407,6 +409,7 @@ void __init setup_arch(char **cmdline_p)
stack_protections((unsigned long) &init_thread_info);
setup_physmem(uml_physmem, uml_reserved, physmem_size, highmem);
mem_total_pages(physmem_size, iomem_size, highmem);
+ uml_dtb_init();
read_initrd();
paging_init();
diff --git a/arch/um/kernel/um_arch.h b/arch/um/kernel/um_arch.h
index b195df3a09a0..1e07fb7ee35e 100644
--- a/arch/um/kernel/um_arch.h
+++ b/arch/um/kernel/um_arch.h
@@ -5,4 +5,10 @@
extern void * __init uml_load_file(const char *filename, unsigned long long *size);
+#ifdef CONFIG_OF
+extern void __init uml_dtb_init(void);
+#else
+static inline void uml_dtb_init(void) { }
+#endif
+
#endif