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 #include <linux/string.h>
  14
  15 #include <asm/early_ioremap.h>
  16
  17 static const struct console *earlycon_console __initdata;
  18 static const struct font_desc *font;
  19 static u16 cur_line_y, max_line_y;
  20 static u32 efi_x_array[1024];
  21 static u32 efi_x, efi_y;
  22 static u64 fb_base;
  23 static bool fb_wb;
  24 static void *efi_fb;
  25
  26 /*
  27  * EFI earlycon needs to use early_memremap() to map the framebuffer.
  28  * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
  29  * memremap() should be used instead. memremap() will be available after
  30  * paging_init() which is earlier than initcall callbacks. Thus adding this
  31  * early initcall function early_efi_map_fb() to map the whole EFI framebuffer.
  32  */
  33 static int __init efi_earlycon_remap_fb(void)
  34 {
  35         /* bail if there is no bootconsole or it was unregistered already */
  36         if (!earlycon_console || !console_is_registered(earlycon_console))
  37                 return 0;
  38
  39         efi_fb = memremap(fb_base, screen_info.lfb_size,
  40                           fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
  41
  42         return efi_fb ? 0 : -ENOMEM;
  43 }
  44 early_initcall(efi_earlycon_remap_fb);
  45
  46 static int __init efi_earlycon_unmap_fb(void)
  47 {
  48         /* unmap the bootconsole fb unless keep_bootcon left it registered */
  49         if (efi_fb && !console_is_registered(earlycon_console))
  50                 memunmap(efi_fb);
  51         return 0;
  52 }
  53 late_initcall(efi_earlycon_unmap_fb);
  54
  55 static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
  56 {
  57         pgprot_t fb_prot;
  58
  59         if (efi_fb)
  60                 return efi_fb + start;
  61
  62         fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
  63         return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
  64 }
  65
  66 static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
  67 {
  68         if (efi_fb)
  69                 return;
  70
  71         early_memunmap(addr, len);
  72 }
  73
  74 static void efi_earlycon_clear_scanline(unsigned int y)
  75 {
  76         unsigned long *dst;
  77         u16 len;
  78
  79         len = screen_info.lfb_linelength;
  80         dst = efi_earlycon_map(y*len, len);
  81         if (!dst)
  82                 return;
  83
  84         memset(dst, 0, len);
  85         efi_earlycon_unmap(dst, len);
  86 }
  87
  88 static void efi_earlycon_scroll_up(void)
  89 {
  90         unsigned long *dst, *src;
  91         u16 maxlen = 0;
  92         u16 len;
  93         u32 i, height;
  94
  95         /* Find the cached maximum x coordinate */
  96         for (i = 0; i < max_line_y; i++) {
  97                 if (efi_x_array[i] > maxlen)
  98                         maxlen = efi_x_array[i];
  99         }
 100         maxlen *= 4;
 101
 102         len = screen_info.lfb_linelength;
 103         height = screen_info.lfb_height;
 104
 105         for (i = 0; i < height - font->height; i++) {
 106                 dst = efi_earlycon_map(i*len, len);
 107                 if (!dst)
 108                         return;
 109
 110                 src = efi_earlycon_map((i + font->height) * len, len);
 111                 if (!src) {
 112                         efi_earlycon_unmap(dst, len);
 113                         return;
 114                 }
 115
 116                 memmove(dst, src, maxlen);
 117
 118                 efi_earlycon_unmap(src, len);
 119                 efi_earlycon_unmap(dst, len);
 120         }
 121 }
 122
 123 static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
 124 {
 125         const u32 color_black = 0x00000000;
 126         const u32 color_white = 0x00ffffff;
 127         const u8 *src;
 128         int m, n, bytes;
 129         u8 x;
 130
 131         bytes = BITS_TO_BYTES(font->width);
 132         src = font->data + c * font->height * bytes + h * bytes;
 133
 134         for (m = 0; m < font->width; m++) {
 135                 n = m % 8;
 136                 x = *(src + m / 8);
 137                 if ((x >> (7 - n)) & 1)
 138                         *dst = color_white;
 139                 else
 140                         *dst = color_black;
 141                 dst++;
 142         }
 143 }
 144
 145 static void
 146 efi_earlycon_write(struct console *con, const char *str, unsigned int num)
 147 {
 148         struct screen_info *si;
 149         u32 cur_efi_x = efi_x;
 150         unsigned int len;
 151         const char *s;
 152         void *dst;
 153
 154         si = &screen_info;
 155         len = si->lfb_linelength;
 156
 157         while (num) {
 158                 unsigned int linemax = (si->lfb_width - efi_x) / font->width;
 159                 unsigned int h, count;
 160
 161                 count = strnchrnul(str, num, '\n') - str;
 162                 if (count > linemax)
 163                         count = linemax;
 164
 165                 for (h = 0; h < font->height; h++) {
 166                         unsigned int n, x;
 167
 168                         dst = efi_earlycon_map((efi_y + h) * len, len);
 169                         if (!dst)
 170                                 return;
 171
 172                         s = str;
 173                         n = count;
 174                         x = efi_x;
 175
 176                         while (n-- > 0) {
 177                                 efi_earlycon_write_char(dst + x*4, *s, h);
 178                                 x += font->width;
 179                                 s++;
 180                         }
 181
 182                         efi_earlycon_unmap(dst, len);
 183                 }
 184
 185                 num -= count;
 186                 efi_x += count * font->width;
 187                 str += count;
 188
 189                 if (num > 0 && *s == '\n') {
 190                         cur_efi_x = efi_x;
 191                         efi_x = 0;
 192                         efi_y += font->height;
 193                         str++;
 194                         num--;
 195                 }
 196
 197                 if (efi_x + font->width > si->lfb_width) {
 198                         cur_efi_x = efi_x;
 199                         efi_x = 0;
 200                         efi_y += font->height;
 201                 }
 202
 203                 if (efi_y + font->height > si->lfb_height) {
 204                         u32 i;
 205
 206                         efi_x_array[cur_line_y] = cur_efi_x;
 207                         cur_line_y = (cur_line_y + 1) % max_line_y;
 208
 209                         efi_y -= font->height;
 210                         efi_earlycon_scroll_up();
 211
 212                         for (i = 0; i < font->height; i++)
 213                                 efi_earlycon_clear_scanline(efi_y + i);
 214                 }
 215         }
 216 }
 217
 218 static bool __initdata fb_probed;
 219
 220 void __init efi_earlycon_reprobe(void)
 221 {
 222         if (fb_probed)
 223                 setup_earlycon("efifb");
 224 }
 225
 226 static int __init efi_earlycon_setup(struct earlycon_device *device,
 227                                      const char *opt)
 228 {
 229         struct screen_info *si;
 230         u16 xres, yres;
 231         u32 i;
 232
 233         fb_wb = opt && !strcmp(opt, "ram");
 234
 235         if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI) {
 236                 fb_probed = true;
 237                 return -ENODEV;
 238         }
 239
 240         fb_base = screen_info.lfb_base;
 241         if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
 242                 fb_base |= (u64)screen_info.ext_lfb_base << 32;
 243
 244         si = &screen_info;
 245         xres = si->lfb_width;
 246         yres = si->lfb_height;
 247
 248         /*
 249          * efi_earlycon_write_char() implicitly assumes a framebuffer with
 250          * 32 bits per pixel.
 251          */
 252         if (si->lfb_depth != 32)
 253                 return -ENODEV;
 254
 255         font = get_default_font(xres, yres, NULL, NULL);
 256         if (!font)
 257                 return -ENODEV;
 258
 259         /* Fill the cache with maximum possible value of x coordinate */
 260         memset32(efi_x_array, rounddown(xres, font->width), ARRAY_SIZE(efi_x_array));
 261         efi_y = rounddown(yres, font->height);
 262
 263         /* Make sure we have cache for the x coordinate for the full screen */
 264         max_line_y = efi_y / font->height + 1;
 265         cur_line_y = 0;
 266
 267         efi_y -= font->height;
 268         for (i = 0; i < (yres - efi_y) / font->height; i++)
 269                 efi_earlycon_scroll_up();
 270
 271         device->con->write = efi_earlycon_write;
 272         earlycon_console = device->con;
 273         return 0;
 274 }
 275 EARLYCON_DECLARE(efifb, efi_earlycon_setup);