drivers/firmware/efi/earlycon.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013 Intel Corporation; author Matt Fleming
   4  */
   5
   6 #include <linux/console.h>
   7 #include <linux/efi.h>
   8 #include <linux/font.h>
   9 #include <linux/io.h>
  10 #include <linux/kernel.h>
  11 #include <linux/serial_core.h>
  12 #include <linux/screen_info.h>
  13
  14 #include <asm/early_ioremap.h>
  15
  16 static const struct font_desc *font;
  17 static u32 efi_x, efi_y;
  18 static u64 fb_base;
  19 static pgprot_t fb_prot;
  20
  21 static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
  22 {
  23         return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
  24 }
  25
  26 static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
  27 {
  28         early_memunmap(addr, len);
  29 }
  30
  31 static void efi_earlycon_clear_scanline(unsigned int y)
  32 {
  33         unsigned long *dst;
  34         u16 len;
  35
  36         len = screen_info.lfb_linelength;
  37         dst = efi_earlycon_map(y*len, len);
  38         if (!dst)
  39                 return;
  40
  41         memset(dst, 0, len);
  42         efi_earlycon_unmap(dst, len);
  43 }
  44
  45 static void efi_earlycon_scroll_up(void)
  46 {
  47         unsigned long *dst, *src;
  48         u16 len;
  49         u32 i, height;
  50
  51         len = screen_info.lfb_linelength;
  52         height = screen_info.lfb_height;
  53
  54         for (i = 0; i < height - font->height; i++) {
  55                 dst = efi_earlycon_map(i*len, len);
  56                 if (!dst)
  57                         return;
  58
  59                 src = efi_earlycon_map((i + font->height) * len, len);
  60                 if (!src) {
  61                         efi_earlycon_unmap(dst, len);
  62                         return;
  63                 }
  64
  65                 memmove(dst, src, len);
  66
  67                 efi_earlycon_unmap(src, len);
  68                 efi_earlycon_unmap(dst, len);
  69         }
  70 }
  71
  72 static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
  73 {
  74         const u32 color_black = 0x00000000;
  75         const u32 color_white = 0x00ffffff;
  76         const u8 *src;
  77         u8 s8;
  78         int m;
  79
  80         src = font->data + c * font->height;
  81         s8 = *(src + h);
  82
  83         for (m = 0; m < 8; m++) {
  84                 if ((s8 >> (7 - m)) & 1)
  85                         *dst = color_white;
  86                 else
  87                         *dst = color_black;
  88                 dst++;
  89         }
  90 }
  91
  92 static void
  93 efi_earlycon_write(struct console *con, const char *str, unsigned int num)
  94 {
  95         struct screen_info *si;
  96         unsigned int len;
  97         const char *s;
  98         void *dst;
  99
 100         si = &screen_info;
 101         len = si->lfb_linelength;
 102
 103         while (num) {
 104                 unsigned int linemax;
 105                 unsigned int h, count = 0;
 106
 107                 for (s = str; *s && *s != '\n'; s++) {
 108                         if (count == num)
 109                                 break;
 110                         count++;
 111                 }
 112
 113                 linemax = (si->lfb_width - efi_x) / font->width;
 114                 if (count > linemax)
 115                         count = linemax;
 116
 117                 for (h = 0; h < font->height; h++) {
 118                         unsigned int n, x;
 119
 120                         dst = efi_earlycon_map((efi_y + h) * len, len);
 121                         if (!dst)
 122                                 return;
 123
 124                         s = str;
 125                         n = count;
 126                         x = efi_x;
 127
 128                         while (n-- > 0) {
 129                                 efi_earlycon_write_char(dst + x*4, *s, h);
 130                                 x += font->width;
 131                                 s++;
 132                         }
 133
 134                         efi_earlycon_unmap(dst, len);
 135                 }
 136
 137                 num -= count;
 138                 efi_x += count * font->width;
 139                 str += count;
 140
 141                 if (num > 0 && *s == '\n') {
 142                         efi_x = 0;
 143                         efi_y += font->height;
 144                         str++;
 145                         num--;
 146                 }
 147
 148                 if (efi_x + font->width > si->lfb_width) {
 149                         efi_x = 0;
 150                         efi_y += font->height;
 151                 }
 152
 153                 if (efi_y + font->height > si->lfb_height) {
 154                         u32 i;
 155
 156                         efi_y -= font->height;
 157                         efi_earlycon_scroll_up();
 158
 159                         for (i = 0; i < font->height; i++)
 160                                 efi_earlycon_clear_scanline(efi_y + i);
 161                 }
 162         }
 163 }
 164
 165 static int __init efi_earlycon_setup(struct earlycon_device *device,
 166                                      const char *opt)
 167 {
 168         struct screen_info *si;
 169         u16 xres, yres;
 170         u32 i;
 171
 172         if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
 173                 return -ENODEV;
 174
 175         fb_base = screen_info.lfb_base;
 176         if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
 177                 fb_base |= (u64)screen_info.ext_lfb_base << 32;
 178
 179         if (opt && !strcmp(opt, "ram"))
 180                 fb_prot = PAGE_KERNEL;
 181         else
 182                 fb_prot = pgprot_writecombine(PAGE_KERNEL);
 183
 184         si = &screen_info;
 185         xres = si->lfb_width;
 186         yres = si->lfb_height;
 187
 188         /*
 189          * efi_earlycon_write_char() implicitly assumes a framebuffer with
 190          * 32 bits per pixel.
 191          */
 192         if (si->lfb_depth != 32)
 193                 return -ENODEV;
 194
 195         font = get_default_font(xres, yres, -1, -1);
 196         if (!font)
 197                 return -ENODEV;
 198
 199         efi_y = rounddown(yres, font->height) - font->height;
 200         for (i = 0; i < (yres - efi_y) / font->height; i++)
 201                 efi_earlycon_scroll_up();
 202
 203         device->con->write = efi_earlycon_write;
 204         return 0;
 205 }
 206 EARLYCON_DECLARE(efifb, efi_earlycon_setup);