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 u32 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 U32_MAX;
37 
38 	chosen_node = fdt_path_offset(fdt, "/chosen");
39 	if (chosen_node < 0)
40 		return U32_MAX;
41 
42 	prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
43 	if (!prop || len != sizeof(u32))
44 		return U32_MAX;
45 
46 	return fdt32_to_cpu(*prop);
47 }
48 
49 efi_status_t check_platform_features(void)
50 {
51 	hartid = get_boot_hartid_from_fdt();
52 	if (hartid == U32_MAX) {
53 		efi_err("/chosen/boot-hartid missing or invalid!\n");
54 		return EFI_UNSUPPORTED;
55 	}
56 	return EFI_SUCCESS;
57 }
58 
59 void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
60 				 unsigned long fdt_size)
61 {
62 	unsigned long stext_offset = _start_kernel - _start;
63 	unsigned long kernel_entry = entrypoint + stext_offset;
64 	jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;
65 
66 	/*
67 	 * Jump to real kernel here with following constraints.
68 	 * 1. MMU should be disabled.
69 	 * 2. a0 should contain hartid
70 	 * 3. a1 should DT address
71 	 */
72 	csr_write(CSR_SATP, 0);
73 	jump_kernel(hartid, fdt);
74 }
75 
76 efi_status_t handle_kernel_image(unsigned long *image_addr,
77 				 unsigned long *image_size,
78 				 unsigned long *reserve_addr,
79 				 unsigned long *reserve_size,
80 				 efi_loaded_image_t *image)
81 {
82 	unsigned long kernel_size = 0;
83 	unsigned long preferred_addr;
84 	efi_status_t status;
85 
86 	kernel_size = _edata - _start;
87 	*image_addr = (unsigned long)_start;
88 	*image_size = kernel_size + (_end - _edata);
89 
90 	/*
91 	 * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical
92 	 * address where kernel is booted. That's why kernel should boot from
93 	 * as low as possible to avoid wastage of memory. Currently, dram_base
94 	 * is occupied by the firmware. So the preferred address for kernel to
95 	 * boot is next aligned address. If preferred address is not available,
96 	 * relocate_kernel will fall back to efi_low_alloc_above to allocate
97 	 * lowest possible memory region as long as the address and size meets
98 	 * the alignment constraints.
99 	 */
100 	preferred_addr = MIN_KIMG_ALIGN;
101 	status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
102 				     preferred_addr, MIN_KIMG_ALIGN, 0x0);
103 
104 	if (status != EFI_SUCCESS) {
105 		efi_err("Failed to relocate kernel\n");
106 		*image_size = 0;
107 	}
108 	return status;
109 }
110