LoongArch: Add boot and setup routines

Add basic boot, setup and reset routines for LoongArch. Now, LoongArch
machines use UEFI-based firmware. The firmware passes configuration
information to the kernel via ACPI and DMI/SMBIOS.

Currently an existing interface between the kernel and the bootloader
is implemented. Kernel gets 2 values from the bootloader, passed in
registers a0 and a1; a0 is an "EFI boot flag" distinguishing UEFI and
non-UEFI firmware, while a1 is a pointer to an FDT with systable,
memmap, cmdline and initrd information.

The standard UEFI boot protocol (EFISTUB) will be added later.

Cc: linux-efi@vger.kernel.org
Cc: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Co-developed-by: Yun Liu <liuyun@loongson.cn>
Signed-off-by: Yun Liu <liuyun@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 72 insertions, 0 deletions

diff --git a/arch/loongarch/kernel/efi.c b/arch/loongarch/kernel/efi.c
new file mode 100644
index 000000000000..a50b60c587fa
--- /dev/null
+++ b/arch/loongarch/kernel/efi.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * EFI initialization
+ *
+ * Author: Jianmin Lv <lvjianmin@loongson.cn>
+ *         Huacai Chen <chenhuacai@loongson.cn>
+ *
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/acpi.h>
+#include <linux/efi.h>
+#include <linux/efi-bgrt.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/kobject.h>
+#include <linux/memblock.h>
+#include <linux/reboot.h>
+#include <linux/uaccess.h>
+
+#include <asm/early_ioremap.h>
+#include <asm/efi.h>
+#include <asm/loongson.h>
+
+static unsigned long efi_nr_tables;
+static unsigned long efi_config_table;
+
+static efi_system_table_t *efi_systab;
+static efi_config_table_type_t arch_tables[] __initdata = {{},};
+
+void __init efi_runtime_init(void)
+{
+	if (!efi_enabled(EFI_BOOT))
+		return;
+
+	if (efi_runtime_disabled()) {
+		pr_info("EFI runtime services will be disabled.\n");
+		return;
+	}
+
+	efi.runtime = (efi_runtime_services_t *)efi_systab->runtime;
+	efi.runtime_version = (unsigned int)efi.runtime->hdr.revision;
+
+	efi_native_runtime_setup();
+	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+}
+
+void __init efi_init(void)
+{
+	int size;
+	void *config_tables;
+
+	if (!efi_system_table)
+		return;
+
+	efi_systab = (efi_system_table_t *)early_memremap_ro(efi_system_table, sizeof(*efi_systab));
+	if (!efi_systab) {
+		pr_err("Can't find EFI system table.\n");
+		return;
+	}
+
+	set_bit(EFI_64BIT, &efi.flags);
+	efi_nr_tables	 = efi_systab->nr_tables;
+	efi_config_table = (unsigned long)efi_systab->tables;
+
+	size = sizeof(efi_config_table_t);
+	config_tables = early_memremap(efi_config_table, efi_nr_tables * size);
+	efi_config_parse_tables(config_tables, efi_systab->nr_tables, arch_tables);
+	early_memunmap(config_tables, efi_nr_tables * size);
+}