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