1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2020 Western Digital Corporation or its affiliates.
4  */
5 
6 #include <linux/efi.h>
7 #include <linux/libfdt.h>
8 
9 #include <asm/efi.h>
10 #include <asm/unaligned.h>
11 
12 #include "efistub.h"
13 
14 typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
15 
16 static unsigned long hartid;
17 
18 static int get_boot_hartid_from_fdt(void)
19 {
20 	const void *fdt;
21 	int chosen_node, len;
22 	const void *prop;
23 
24 	fdt = get_efi_config_table(DEVICE_TREE_GUID);
25 	if (!fdt)
26 		return -EINVAL;
27 
28 	chosen_node = fdt_path_offset(fdt, "/chosen");
29 	if (chosen_node < 0)
30 		return -EINVAL;
31 
32 	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
33 	if (!prop)
34 		return -EINVAL;
35 
36 	if (len == sizeof(u32))
37 		hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
38 	else if (len == sizeof(u64))
39 		hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
40 	else
41 		return -EINVAL;
42 
43 	return 0;
44 }
45 
46 static efi_status_t get_boot_hartid_from_efi(void)
47 {
48 	efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
49 	struct riscv_efi_boot_protocol *boot_protocol;
50 	efi_status_t status;
51 
52 	status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
53 			     (void **)&boot_protocol);
54 	if (status != EFI_SUCCESS)
55 		return status;
56 	return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
57 }
58 
59 efi_status_t check_platform_features(void)
60 {
61 	efi_status_t status;
62 	int ret;
63 
64 	status = get_boot_hartid_from_efi();
65 	if (status != EFI_SUCCESS) {
66 		ret = get_boot_hartid_from_fdt();
67 		if (ret) {
68 			efi_err("Failed to get boot hartid!\n");
69 			return EFI_UNSUPPORTED;
70 		}
71 	}
72 	return EFI_SUCCESS;
73 }
74 
75 unsigned long __weak stext_offset(void)
76 {
77 	/*
78 	 * This fallback definition is used by the EFI zboot stub, which loads
79 	 * the entire image so it can branch via the image header at offset #0.
80 	 */
81 	return 0;
82 }
83 
84 void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
85 				 unsigned long fdt_size)
86 {
87 	unsigned long kernel_entry = entrypoint + stext_offset();
88 	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
89 
90 	/*
91 	 * Jump to real kernel here with following constraints.
92 	 * 1. MMU should be disabled.
93 	 * 2. a0 should contain hartid
94 	 * 3. a1 should DT address
95 	 */
96 	csr_write(CSR_SATP, 0);
97 	jump_kernel(hartid, fdt);
98 }
99