mips: add dtb loading support

Kexec for MIPS currently does not support loading devicetrees, unless
they are embedded in the kernel elf file.

Add an option to either pass a new dtb file or - if not specified - to
be generated from existing device tree on the device. As new generic
platforms require a dtb to be passed separately this is required for
such platforms and will be ignored by the kernel otherwise.

Generic kexec infrastructure for dtb support is used.

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Signed-off-by: Simon Horman <horms@verge.net.au>

1 files changed, 31 insertions, 3 deletions

diff --git a/kexec/arch/mips/kexec-elf-mips.c b/kexec/arch/mips/kexec-elf-mips.c
index 7cb06f1..6ca7ca0 100644
--- a/kexec/arch/mips/kexec-elf-mips.c
+++ b/kexec/arch/mips/kexec-elf-mips.c
@@ -29,13 +29,16 @@
 #include "kexec-mips.h"
 #include "crashdump-mips.h"
 #include <arch/options.h>
+#include "../../fs2dt.h"
+#include "../../dt-ops.h"
 
 static const int probe_debug = 0;
 
 #define BOOTLOADER         "kexec"
-#define MAX_COMMAND_LINE   256
 #define UPSZ(X) _ALIGN_UP(sizeof(X), 4)
-static char cmdline_buf[256] = "kexec ";
+
+#define CMDLINE_PREFIX "kexec "
+static char cmdline_buf[COMMAND_LINE_SIZE] = CMDLINE_PREFIX;
 
 int elf_mips_probe(const char *buf, off_t len)
 {
@@ -74,6 +77,10 @@ int elf_mips_load(int argc, char **argv, const char *buf, off_t len,
 	int result;
 	unsigned long cmdline_addr;
 	size_t i;
+	off_t dtb_length;
+	char *dtb_buf;
+	unsigned long long kernel_addr = 0, kernel_size = 0;
+	unsigned long pagesize = getpagesize();
 
 	/* Need to append some command line parameters internally in case of
 	 * taking crash dumps.
@@ -92,8 +99,11 @@ int elf_mips_load(int argc, char **argv, const char *buf, off_t len,
 	for (i = 0; i < ehdr.e_phnum; i++) {
 		struct mem_phdr *phdr;
 		phdr = &ehdr.e_phdr[i];
-		if (phdr->p_type == PT_LOAD)
+		if (phdr->p_type == PT_LOAD) {
 			phdr->p_paddr = virt_to_phys(phdr->p_paddr);
+			kernel_addr = phdr->p_paddr;
+			kernel_size = phdr->p_memsz;
+		}
 	}
 
 	/* Load the Elf data */
@@ -130,10 +140,28 @@ int elf_mips_load(int argc, char **argv, const char *buf, off_t len,
 	else
 		cmdline_addr = 0;
 
+	/* MIPS systems that have been converted to use device tree
+	 * passed through UHI will use commandline in the DTB and
+	 * the DTB passed as a separate buffer. Note that
+	 * CMDLINE_PREFIX is skipped here intentionally, as it is
+	 * used only in the legacy method */
+
+	if (arch_options.dtb_file) {
+		dtb_buf = slurp_file(arch_options.dtb_file, &dtb_length);
+	} else {
+		create_flatten_tree(&dtb_buf, &dtb_length, cmdline_buf + strlen(CMDLINE_PREFIX));
+	}
+
+	/* This is a legacy method for commandline passing used
+	 * currently by Octeon CPUs only */
 	add_buffer(info, cmdline_buf, sizeof(cmdline_buf),
 			sizeof(cmdline_buf), sizeof(void *),
 			cmdline_addr, 0x0fffffff, 1);
 
+	add_buffer(info, dtb_buf, dtb_length, dtb_length, 0,
+		_ALIGN_UP(kernel_addr + kernel_size, pagesize),
+		0x0fffffff, 1);
+
 	return 0;
 }