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         u64 base, size;
  30
  31         if (!early_efi_keep)
  32                 return 0;
  33
  34         base = boot_params.screen_info.lfb_base;
  35         if (boot_params.screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
  36                 base |= (u64)boot_params.screen_info.ext_lfb_base << 32;
  37         size = boot_params.screen_info.lfb_size;
  38         efi_fb = ioremap(base, size);
  39
  40         return efi_fb ? 0 : -ENOMEM;
  41 }
  42 early_initcall(early_efi_map_fb);
  43
  44 /*
  45  * early_efi_map maps efi framebuffer region [start, start + len -1]
  46  * In case earlyprintk=efi,keep we have the whole framebuffer mapped already
  47  * so just return the offset efi_fb + start.
  48  */
  49 static __ref void *early_efi_map(unsigned long start, unsigned long len)
  50 {
  51         u64 base;
  52
  53         base = boot_params.screen_info.lfb_base;
  54         if (boot_params.screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
  55                 base |= (u64)boot_params.screen_info.ext_lfb_base << 32;
  56
  57         if (efi_fb)
  58                 return (efi_fb + start);
  59         else
  60                 return early_ioremap(base + start, len);
  61 }
  62
  63 static __ref void early_efi_unmap(void *addr, unsigned long len)
  64 {
  65         if (!efi_fb)
  66                 early_iounmap(addr, len);
  67 }
  68
  69 static void early_efi_clear_scanline(unsigned int y)
  70 {
  71         unsigned long *dst;
  72         u16 len;
  73
  74         len = boot_params.screen_info.lfb_linelength;
  75         dst = early_efi_map(y*len, len);
  76         if (!dst)
  77                 return;
  78
  79         memset(dst, 0, len);
  80         early_efi_unmap(dst, len);
  81 }
  82
  83 static void early_efi_scroll_up(void)
  84 {
  85         unsigned long *dst, *src;
  86         u16 len;
  87         u32 i, height;
  88
  89         len = boot_params.screen_info.lfb_linelength;
  90         height = boot_params.screen_info.lfb_height;
  91
  92         for (i = 0; i < height - font->height; i++) {
  93                 dst = early_efi_map(i*len, len);
  94                 if (!dst)
  95                         return;
  96
  97                 src = early_efi_map((i + font->height) * len, len);
  98                 if (!src) {
  99                         early_efi_unmap(dst, len);
 100                         return;
 101                 }
 102
 103                 memmove(dst, src, len);
 104
 105                 early_efi_unmap(src, len);
 106                 early_efi_unmap(dst, len);
 107         }
 108 }
 109
 110 static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
 111 {
 112         const u32 color_black = 0x00000000;
 113         const u32 color_white = 0x00ffffff;
 114         const u8 *src;
 115         u8 s8;
 116         int m;
 117
 118         src = font->data + c * font->height;
 119         s8 = *(src + h);
 120
 121         for (m = 0; m < 8; m++) {
 122                 if ((s8 >> (7 - m)) & 1)
 123                         *dst = color_white;
 124                 else
 125                         *dst = color_black;
 126                 dst++;
 127         }
 128 }
 129
 130 static void
 131 early_efi_write(struct console *con, const char *str, unsigned int num)
 132 {
 133         struct screen_info *si;
 134         unsigned int len;
 135         const char *s;
 136         void *dst;
 137
 138         si = &boot_params.screen_info;
 139         len = si->lfb_linelength;
 140
 141         while (num) {
 142                 unsigned int linemax;
 143                 unsigned int h, count = 0;
 144
 145                 for (s = str; *s && *s != '\n'; s++) {
 146                         if (count == num)
 147                                 break;
 148                         count++;
 149                 }
 150
 151                 linemax = (si->lfb_width - efi_x) / font->width;
 152                 if (count > linemax)
 153                         count = linemax;
 154
 155                 for (h = 0; h < font->height; h++) {
 156                         unsigned int n, x;
 157
 158                         dst = early_efi_map((efi_y + h) * len, len);
 159                         if (!dst)
 160                                 return;
 161
 162                         s = str;
 163                         n = count;
 164                         x = efi_x;
 165
 166                         while (n-- > 0) {
 167                                 early_efi_write_char(dst + x*4, *s, h);
 168                                 x += font->width;
 169                                 s++;
 170                         }
 171
 172                         early_efi_unmap(dst, len);
 173                 }
 174
 175                 num -= count;
 176                 efi_x += count * font->width;
 177                 str += count;
 178
 179                 if (num > 0 && *s == '\n') {
 180                         efi_x = 0;
 181                         efi_y += font->height;
 182                         str++;
 183                         num--;
 184                 }
 185
 186                 if (efi_x + font->width > si->lfb_width) {
 187                         efi_x = 0;
 188                         efi_y += font->height;
 189                 }
 190
 191                 if (efi_y + font->height > si->lfb_height) {
 192                         u32 i;
 193
 194                         efi_y -= font->height;
 195                         early_efi_scroll_up();
 196
 197                         for (i = 0; i < font->height; i++)
 198                                 early_efi_clear_scanline(efi_y + i);
 199                 }
 200         }
 201 }
 202
 203 static __init int early_efi_setup(struct console *con, char *options)
 204 {
 205         struct screen_info *si;
 206         u16 xres, yres;
 207         u32 i;
 208
 209         si = &boot_params.screen_info;
 210         xres = si->lfb_width;
 211         yres = si->lfb_height;
 212
 213         /*
 214          * early_efi_write_char() implicitly assumes a framebuffer with
 215          * 32-bits per pixel.
 216          */
 217         if (si->lfb_depth != 32)
 218                 return -ENODEV;
 219
 220         font = get_default_font(xres, yres, -1, -1);
 221         if (!font)
 222                 return -ENODEV;
 223
 224         efi_y = rounddown(yres, font->height) - font->height;
 225         for (i = 0; i < (yres - efi_y) / font->height; i++)
 226                 early_efi_scroll_up();
 227
 228         /* early_console_register will unset CON_BOOT in case ,keep */
 229         if (!(con->flags & CON_BOOT))
 230                 early_efi_keep = true;
 231         return 0;
 232 }
 233
 234 struct console early_efi_console = {
 235         .name =         "earlyefi",
 236         .write =        early_efi_write,
 237         .setup =        early_efi_setup,
 238         .flags =        CON_PRINTBUFFER,
 239         .index =        -1,
 240 };