LoongArch: Add FDT booting support from efi system table

Since commit 40cd01a9c324("efi/loongarch: libstub: remove dependency on
flattened DT"), we can parse the FDT from efi system table.

And now, LoongArch is coming to support booting with FDT, so we add the
relevant booting support as well as parameter parsing.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 61 insertions, 1 deletions

diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 53831bcb11ca..f9f5a130710c 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -28,6 +28,9 @@
 #include <linux/sizes.h>
 #include <linux/device.h>
 #include <linux/dma-map-ops.h>
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+#include <linux/of_address.h>
 #include <linux/swiotlb.h>
 
 #include <asm/addrspace.h>
@@ -69,6 +72,7 @@ static const char dmi_empty_string[] = "        ";
  *
  * These are initialized so they are in the .data section
  */
+char init_command_line[COMMAND_LINE_SIZE] __initdata;
 
 static int num_standard_resources;
 static struct resource *standard_resources;
@@ -253,6 +257,58 @@ static void __init arch_parse_crashkernel(void)
 #endif
 }
 
+static void __init fdt_setup(void)
+{
+#ifdef CONFIG_OF_EARLY_FLATTREE
+	void *fdt_pointer;
+
+	/* ACPI-based systems do not require parsing fdt */
+	if (acpi_os_get_root_pointer())
+		return;
+
+	/* Look for a device tree configuration table entry */
+	fdt_pointer = efi_fdt_pointer();
+	if (!fdt_pointer || fdt_check_header(fdt_pointer))
+		return;
+
+	early_init_dt_scan(fdt_pointer);
+	early_init_fdt_reserve_self();
+
+	max_low_pfn = PFN_PHYS(memblock_end_of_DRAM());
+#endif
+}
+
+static void __init bootcmdline_init(char **cmdline_p)
+{
+	/*
+	 * If CONFIG_CMDLINE_FORCE is enabled then initializing the command line
+	 * is trivial - we simply use the built-in command line unconditionally &
+	 * unmodified.
+	 */
+	if (IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
+		strscpy(boot_command_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+		goto out;
+	}
+
+#ifdef CONFIG_OF_FLATTREE
+	/*
+	 * If CONFIG_CMDLINE_BOOTLOADER is enabled and we are in FDT-based system,
+	 * the boot_command_line will be overwritten by early_init_dt_scan_chosen().
+	 * So we need to append init_command_line (the original copy of boot_command_line)
+	 * to boot_command_line.
+	 */
+	if (initial_boot_params) {
+		if (boot_command_line[0])
+			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
+
+		strlcat(boot_command_line, init_command_line, COMMAND_LINE_SIZE);
+	}
+#endif
+
+out:
+	*cmdline_p = boot_command_line;
+}
+
 void __init platform_init(void)
 {
 	arch_reserve_vmcore();
@@ -265,6 +321,7 @@ void __init platform_init(void)
 	acpi_gbl_use_default_register_widths = false;
 	acpi_boot_table_init();
 #endif
+	unflatten_and_copy_device_tree();
 
 #ifdef CONFIG_NUMA
 	init_numa_memory();
@@ -297,6 +354,8 @@ static void __init arch_mem_init(char **cmdline_p)
 
 	check_kernel_sections_mem();
 
+	early_init_fdt_scan_reserved_mem();
+
 	/*
 	 * In order to reduce the possibility of kernel panic when failed to
 	 * get IO TLB memory under CONFIG_SWIOTLB, it is better to allocate
@@ -422,12 +481,13 @@ static void __init prefill_possible_map(void)
 void __init setup_arch(char **cmdline_p)
 {
 	cpu_probe();
-	*cmdline_p = boot_command_line;
 
 	init_environ();
 	efi_init();
+	fdt_setup();
 	memblock_init();
 	pagetable_init();
+	bootcmdline_init(cmdline_p);
 	parse_early_param();
 	reserve_initrd_mem();