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 int, unsigned long);
25 
26 static u32 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 efi_status_t check_platform_features(void)
51 {
52 	int ret;
53 
54 	ret = get_boot_hartid_from_fdt();
55 	if (ret) {
56 		efi_err("/chosen/boot-hartid missing or invalid!\n");
57 		return EFI_UNSUPPORTED;
58 	}
59 	return EFI_SUCCESS;
60 }
61 
62 void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
63 				 unsigned long fdt_size)
64 {
65 	unsigned long stext_offset = _start_kernel - _start;
66 	unsigned long kernel_entry = entrypoint + stext_offset;
67 	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
68 
69 	/*
70 	 * Jump to real kernel here with following constraints.
71 	 * 1. MMU should be disabled.
72 	 * 2. a0 should contain hartid
73 	 * 3. a1 should DT address
74 	 */
75 	csr_write(CSR_SATP, 0);
76 	jump_kernel(hartid, fdt);
77 }
78 
79 efi_status_t handle_kernel_image(unsigned long *image_addr,
80 				 unsigned long *image_size,
81 				 unsigned long *reserve_addr,
82 				 unsigned long *reserve_size,
83 				 efi_loaded_image_t *image)
84 {
85 	unsigned long kernel_size = 0;
86 	unsigned long preferred_addr;
87 	efi_status_t status;
88 
89 	kernel_size = _edata - _start;
90 	*image_addr = (unsigned long)_start;
91 	*image_size = kernel_size + (_end - _edata);
92 
93 	/*
94 	 * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
95 	 * address where kernel is booted. That's why kernel should boot from
96 	 * as low as possible to avoid wastage of memory. Currently, dram_base
97 	 * is occupied by the firmware. So the preferred address for kernel to
98 	 * boot is next aligned address. If preferred address is not available,
99 	 * relocate_kernel will fall back to efi_low_alloc_above to allocate
100 	 * lowest possible memory region as long as the address and size meets
101 	 * the alignment constraints.
102 	 */
103 	preferred_addr = MIN_KIMG_ALIGN;
104 	status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
105 				     preferred_addr, MIN_KIMG_ALIGN, 0x0);
106 
107 	if (status != EFI_SUCCESS) {
108 		efi_err("Failed to relocate kernel\n");
109 		*image_size = 0;
110 	}
111 	return status;
112 }
113