1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/efi.h>
4 #include <linux/sysfb.h>
5
6 #include <asm/efi.h>
7
8 #include "efistub.h"
9
10 /*
11 * There are two ways of populating the core kernel's sysfb_primary_display
12 * via the stub:
13 *
14 * - using a configuration table, which relies on the EFI init code to
15 * locate the table and copy the contents; or
16 *
17 * - by linking directly to the core kernel's copy of the global symbol.
18 *
19 * The latter is preferred because it makes the EFIFB earlycon available very
20 * early, but it only works if the EFI stub is part of the core kernel image
21 * itself. The zboot decompressor can only use the configuration table
22 * approach.
23 */
24
25 static efi_guid_t primary_display_guid = LINUX_EFI_PRIMARY_DISPLAY_TABLE_GUID;
26
__alloc_primary_display(void)27 struct sysfb_display_info *__alloc_primary_display(void)
28 {
29 struct sysfb_display_info *dpy;
30 efi_status_t status;
31
32 status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
33 sizeof(*dpy), (void **)&dpy);
34
35 if (status != EFI_SUCCESS)
36 return NULL;
37
38 memset(dpy, 0, sizeof(*dpy));
39
40 status = efi_bs_call(install_configuration_table,
41 &primary_display_guid, dpy);
42 if (status == EFI_SUCCESS)
43 return dpy;
44
45 efi_bs_call(free_pool, dpy);
46 return NULL;
47 }
48
free_primary_display(struct sysfb_display_info * dpy)49 void free_primary_display(struct sysfb_display_info *dpy)
50 {
51 if (!dpy)
52 return;
53
54 efi_bs_call(install_configuration_table, &primary_display_guid, NULL);
55 efi_bs_call(free_pool, dpy);
56 }
57