kernel/arch/x86/platform/efi/early_printk.c

   1 /*
   2  * Copyright (C) 2013 Intel Corporation; author Matt Fleming
   3  *
   4  *  This file is part of the Linux kernel, and is made available under
   5  *  the terms of the GNU General Public License version 2.
   6  */
   7
   8 #include <linux/console.h>
   9 #include <linux/efi.h>
  10 #include <linux/font.h>
  11 #include <linux/io.h>
  12 #include <linux/kernel.h>
  13 #include <asm/setup.h>
  14
  15 static const struct font_desc *font;
  16 static u32 efi_x, efi_y;
  17 static void *efi_fb;
  18 static bool early_efi_keep;
  19
  20 /*
  21  * efi earlyprintk need use early_ioremap to map the framebuffer.
  22  * But early_ioremap is not usable for earlyprintk=efi,keep, ioremap should
  23  * be used instead. ioremap will be available after paging_init() which is
  24  * earlier than initcall callbacks. Thus adding this early initcall function
  25  * early_efi_map_fb to map the whole efi framebuffer.
  26  */
  27 static __init int early_efi_map_fb(void)
  28 {
  29         unsigned long base, size;
  30
  31         if (!early_efi_keep)
  32                 return 0;
  33
  34         base = boot_params.screen_info.lfb_base;
  35         size = boot_params.screen_info.lfb_size;
  36         efi_fb = ioremap(base, size);
  37
  38         return efi_fb ? 0 : -ENOMEM;
  39 }
  40 early_initcall(early_efi_map_fb);
  41
  42 /*
  43  * early_efi_map maps efi framebuffer region [start, start + len -1]
  44  * In case earlyprintk=efi,keep we have the whole framebuffer mapped already
  45  * so just return the offset efi_fb + start.
  46  */
  47 static __init_refok void *early_efi_map(unsigned long start, unsigned long len)
  48 {
  49         unsigned long base;
  50
  51         base = boot_params.screen_info.lfb_base;
  52
  53         if (efi_fb)
  54                 return (efi_fb + start);
  55         else
  56                 return early_ioremap(base + start, len);
  57 }
  58
  59 static __init_refok void early_efi_unmap(void *addr, unsigned long len)
  60 {
  61         if (!efi_fb)
  62                 early_iounmap(addr, len);
  63 }
  64
  65 static void early_efi_clear_scanline(unsigned int y)
  66 {
  67         unsigned long *dst;
  68         u16 len;
  69
  70         len = boot_params.screen_info.lfb_linelength;
  71         dst = early_efi_map(y*len, len);
  72         if (!dst)
  73                 return;
  74
  75         memset(dst, 0, len);
  76         early_efi_unmap(dst, len);
  77 }
  78
  79 static void early_efi_scroll_up(void)
  80 {
  81         unsigned long *dst, *src;
  82         u16 len;
  83         u32 i, height;
  84
  85         len = boot_params.screen_info.lfb_linelength;
  86         height = boot_params.screen_info.lfb_height;
  87
  88         for (i = 0; i < height - font->height; i++) {
  89                 dst = early_efi_map(i*len, len);
  90                 if (!dst)
  91                         return;
  92
  93                 src = early_efi_map((i + font->height) * len, len);
  94                 if (!src) {
  95                         early_efi_unmap(dst, len);
  96                         return;
  97                 }
  98
  99                 memmove(dst, src, len);
 100
 101                 early_efi_unmap(src, len);
 102                 early_efi_unmap(dst, len);
 103         }
 104 }
 105
 106 static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
 107 {
 108         const u32 color_black = 0x00000000;
 109         const u32 color_white = 0x00ffffff;
 110         const u8 *src;
 111         u8 s8;
 112         int m;
 113
 114         src = font->data + c * font->height;
 115         s8 = *(src + h);
 116
 117         for (m = 0; m < 8; m++) {
 118                 if ((s8 >> (7 - m)) & 1)
 119                         *dst = color_white;
 120                 else
 121                         *dst = color_black;
 122                 dst++;
 123         }
 124 }
 125
 126 static void
 127 early_efi_write(struct console *con, const char *str, unsigned int num)
 128 {
 129         struct screen_info *si;
 130         unsigned int len;
 131         const char *s;
 132         void *dst;
 133
 134         si = &boot_params.screen_info;
 135         len = si->lfb_linelength;
 136
 137         while (num) {
 138                 unsigned int linemax;
 139                 unsigned int h, count = 0;
 140
 141                 for (s = str; *s && *s != '\n'; s++) {
 142                         if (count == num)
 143                                 break;
 144                         count++;
 145                 }
 146
 147                 linemax = (si->lfb_width - efi_x) / font->width;
 148                 if (count > linemax)
 149                         count = linemax;
 150
 151                 for (h = 0; h < font->height; h++) {
 152                         unsigned int n, x;
 153
 154                         dst = early_efi_map((efi_y + h) * len, len);
 155                         if (!dst)
 156                                 return;
 157
 158                         s = str;
 159                         n = count;
 160                         x = efi_x;
 161
 162                         while (n-- > 0) {
 163                                 early_efi_write_char(dst + x*4, *s, h);
 164                                 x += font->width;
 165                                 s++;
 166                         }
 167
 168                         early_efi_unmap(dst, len);
 169                 }
 170
 171                 num -= count;
 172                 efi_x += count * font->width;
 173                 str += count;
 174
 175                 if (num > 0 && *s == '\n') {
 176                         efi_x = 0;
 177                         efi_y += font->height;
 178                         str++;
 179                         num--;
 180                 }
 181
 182                 if (efi_x >= si->lfb_width) {
 183                         efi_x = 0;
 184                         efi_y += font->height;
 185                 }
 186
 187                 if (efi_y + font->height > si->lfb_height) {
 188                         u32 i;
 189
 190                         efi_y -= font->height;
 191                         early_efi_scroll_up();
 192
 193                         for (i = 0; i < font->height; i++)
 194                                 early_efi_clear_scanline(efi_y + i);
 195                 }
 196         }
 197 }
 198
 199 static __init int early_efi_setup(struct console *con, char *options)
 200 {
 201         struct screen_info *si;
 202         u16 xres, yres;
 203         u32 i;
 204
 205         si = &boot_params.screen_info;
 206         xres = si->lfb_width;
 207         yres = si->lfb_height;
 208
 209         /*
 210          * early_efi_write_char() implicitly assumes a framebuffer with
 211          * 32-bits per pixel.
 212          */
 213         if (si->lfb_depth != 32)
 214                 return -ENODEV;
 215
 216         font = get_default_font(xres, yres, -1, -1);
 217         if (!font)
 218                 return -ENODEV;
 219
 220         efi_y = rounddown(yres, font->height) - font->height;
 221         for (i = 0; i < (yres - efi_y) / font->height; i++)
 222                 early_efi_scroll_up();
 223
 224         /* early_console_register will unset CON_BOOT in case ,keep */
 225         if (!(con->flags & CON_BOOT))
 226                 early_efi_keep = true;
 227         return 0;
 228 }
 229
 230 struct console early_efi_console = {
 231         .name =         "earlyefi",
 232         .write =        early_efi_write,
 233         .setup =        early_efi_setup,
 234         .flags =        CON_PRINTBUFFER,
 235         .index =        -1,
 236 };