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
24typedef void __noreturn (*jump_kernel_func)(unsigned int, unsigned long);
25
26static u32 hartid;
27
28static 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
50efi_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
62void __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
79efi_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