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/sections.h>
11 #include <asm/unaligned.h>
12 
13 #include "efistub.h"
14 
15 /*
16  * RISC-V requires the kernel image to placed 2 MB aligned base for 64 bit and
17  * 4MB for 32 bit.
18  */
19 #ifdef CONFIG_64BIT
20 #define MIN_KIMG_ALIGN		SZ_2M
21 #else
22 #define MIN_KIMG_ALIGN		SZ_4M
23 #endif
24 
25 typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);
26 
27 static unsigned long hartid;
28 
29 static int get_boot_hartid_from_fdt(void)
30 {
31 	const void *fdt;
32 	int chosen_node, len;
33 	const void *prop;
34 
35 	fdt = get_efi_config_table(DEVICE_TREE_GUID);
36 	if (!fdt)
37 		return -EINVAL;
38 
39 	chosen_node = fdt_path_offset(fdt, "/chosen");
40 	if (chosen_node < 0)
41 		return -EINVAL;
42 
43 	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
44 	if (!prop)
45 		return -EINVAL;
46 
47 	if (len == sizeof(u32))
48 		hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
49 	else if (len == sizeof(u64))
50 		hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
51 	else
52 		return -EINVAL;
53 
54 	return 0;
55 }
56 
57 static efi_status_t get_boot_hartid_from_efi(void)
58 {
59 	efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
60 	struct riscv_efi_boot_protocol *boot_protocol;
61 	efi_status_t status;
62 
63 	status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
64 			     (void **)&boot_protocol);
65 	if (status != EFI_SUCCESS)
66 		return status;
67 	return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
68 }
69 
70 efi_status_t check_platform_features(void)
71 {
72 	efi_status_t status;
73 	int ret;
74 
75 	status = get_boot_hartid_from_efi();
76 	if (status != EFI_SUCCESS) {
77 		ret = get_boot_hartid_from_fdt();
78 		if (ret) {
79 			efi_err("Failed to get boot hartid!\n");
80 			return EFI_UNSUPPORTED;
81 		}
82 	}
83 	return EFI_SUCCESS;
84 }
85 
86 void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
87 				 unsigned long fdt_size)
88 {
89 	unsigned long stext_offset = _start_kernel - _start;
90 	unsigned long kernel_entry = entrypoint + stext_offset;
91 	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
92 
93 	/*
94 	 * Jump to real kernel here with following constraints.
95 	 * 1. MMU should be disabled.
96 	 * 2. a0 should contain hartid
97 	 * 3. a1 should DT address
98 	 */
99 	csr_write(CSR_SATP, 0);
100 	jump_kernel(hartid, fdt);
101 }
102 
103 efi_status_t handle_kernel_image(unsigned long *image_addr,
104 				 unsigned long *image_size,
105 				 unsigned long *reserve_addr,
106 				 unsigned long *reserve_size,
107 				 efi_loaded_image_t *image,
108 				 efi_handle_t image_handle)
109 {
110 	unsigned long kernel_size = 0;
111 	unsigned long preferred_addr;
112 	efi_status_t status;
113 
114 	kernel_size = _edata - _start;
115 	*image_addr = (unsigned long)_start;
116 	*image_size = kernel_size + (_end - _edata);
117 
118 	/*
119 	 * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
120 	 * address where kernel is booted. That's why kernel should boot from
121 	 * as low as possible to avoid wastage of memory. Currently, dram_base
122 	 * is occupied by the firmware. So the preferred address for kernel to
123 	 * boot is next aligned address. If preferred address is not available,
124 	 * relocate_kernel will fall back to efi_low_alloc_above to allocate
125 	 * lowest possible memory region as long as the address and size meets
126 	 * the alignment constraints.
127 	 */
128 	preferred_addr = MIN_KIMG_ALIGN;
129 	status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
130 				     preferred_addr, MIN_KIMG_ALIGN, 0x0);
131 
132 	if (status != EFI_SUCCESS) {
133 		efi_err("Failed to relocate kernel\n");
134 		*image_size = 0;
135 	}
136 	return status;
137 }
138