ubuntu-linux-kernel/arch/x86/platform/efi/early_printk.c

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2024-04-01 15:06:58 +00:00
/*
* Copyright (C) 2013 Intel Corporation; author Matt Fleming
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*/
#include <linux/console.h>
#include <linux/efi.h>
#include <linux/font.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <asm/setup.h>
static const struct font_desc *font;
static u32 efi_x, efi_y;
static void *efi_fb;
static bool early_efi_keep;
/*
* efi earlyprintk need use early_ioremap to map the framebuffer.
* But early_ioremap is not usable for earlyprintk=efi,keep, ioremap should
* be used instead. ioremap will be available after paging_init() which is
* earlier than initcall callbacks. Thus adding this early initcall function
* early_efi_map_fb to map the whole efi framebuffer.
*/
static __init int early_efi_map_fb(void)
{
unsigned long base, size;
if (!early_efi_keep)
return 0;
base = boot_params.screen_info.lfb_base;
size = boot_params.screen_info.lfb_size;
efi_fb = ioremap(base, size);
return efi_fb ? 0 : -ENOMEM;
}
early_initcall(early_efi_map_fb);
/*
* early_efi_map maps efi framebuffer region [start, start + len -1]
* In case earlyprintk=efi,keep we have the whole framebuffer mapped already
* so just return the offset efi_fb + start.
*/
static __ref void *early_efi_map(unsigned long start, unsigned long len)
{
unsigned long base;
base = boot_params.screen_info.lfb_base;
if (efi_fb)
return (efi_fb + start);
else
return early_ioremap(base + start, len);
}
static __ref void early_efi_unmap(void *addr, unsigned long len)
{
if (!efi_fb)
early_iounmap(addr, len);
}
static void early_efi_clear_scanline(unsigned int y)
{
unsigned long *dst;
u16 len;
len = boot_params.screen_info.lfb_linelength;
dst = early_efi_map(y*len, len);
if (!dst)
return;
memset(dst, 0, len);
early_efi_unmap(dst, len);
}
static void early_efi_scroll_up(void)
{
unsigned long *dst, *src;
u16 len;
u32 i, height;
len = boot_params.screen_info.lfb_linelength;
height = boot_params.screen_info.lfb_height;
for (i = 0; i < height - font->height; i++) {
dst = early_efi_map(i*len, len);
if (!dst)
return;
src = early_efi_map((i + font->height) * len, len);
if (!src) {
early_efi_unmap(dst, len);
return;
}
memmove(dst, src, len);
early_efi_unmap(src, len);
early_efi_unmap(dst, len);
}
}
static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
{
const u32 color_black = 0x00000000;
const u32 color_white = 0x00ffffff;
const u8 *src;
u8 s8;
int m;
src = font->data + c * font->height;
s8 = *(src + h);
for (m = 0; m < 8; m++) {
if ((s8 >> (7 - m)) & 1)
*dst = color_white;
else
*dst = color_black;
dst++;
}
}
static void
early_efi_write(struct console *con, const char *str, unsigned int num)
{
struct screen_info *si;
unsigned int len;
const char *s;
void *dst;
si = &boot_params.screen_info;
len = si->lfb_linelength;
while (num) {
unsigned int linemax;
unsigned int h, count = 0;
for (s = str; *s && *s != '\n'; s++) {
if (count == num)
break;
count++;
}
linemax = (si->lfb_width - efi_x) / font->width;
if (count > linemax)
count = linemax;
for (h = 0; h < font->height; h++) {
unsigned int n, x;
dst = early_efi_map((efi_y + h) * len, len);
if (!dst)
return;
s = str;
n = count;
x = efi_x;
while (n-- > 0) {
early_efi_write_char(dst + x*4, *s, h);
x += font->width;
s++;
}
early_efi_unmap(dst, len);
}
num -= count;
efi_x += count * font->width;
str += count;
if (num > 0 && *s == '\n') {
efi_x = 0;
efi_y += font->height;
str++;
num--;
}
if (efi_x >= si->lfb_width) {
efi_x = 0;
efi_y += font->height;
}
if (efi_y + font->height > si->lfb_height) {
u32 i;
efi_y -= font->height;
early_efi_scroll_up();
for (i = 0; i < font->height; i++)
early_efi_clear_scanline(efi_y + i);
}
}
}
static __init int early_efi_setup(struct console *con, char *options)
{
struct screen_info *si;
u16 xres, yres;
u32 i;
si = &boot_params.screen_info;
xres = si->lfb_width;
yres = si->lfb_height;
/*
* early_efi_write_char() implicitly assumes a framebuffer with
* 32-bits per pixel.
*/
if (si->lfb_depth != 32)
return -ENODEV;
font = get_default_font(xres, yres, -1, -1);
if (!font)
return -ENODEV;
efi_y = rounddown(yres, font->height) - font->height;
for (i = 0; i < (yres - efi_y) / font->height; i++)
early_efi_scroll_up();
/* early_console_register will unset CON_BOOT in case ,keep */
if (!(con->flags & CON_BOOT))
early_efi_keep = true;
return 0;
}
struct console early_efi_console = {
.name = "earlyefi",
.write = early_efi_write,
.setup = early_efi_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
};