src/soc/intel/apollolake/mmap_boot.c

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 #include <boot_device.h>
   4 #include <commonlib/region.h>
   5 #include <console/console.h>
   6 #include <fmap.h>
   7 #include <intelblocks/fast_spi.h>
   8 #include <spi_flash.h>
   9
  10 /*
  11  * BIOS region on the flash is mapped right below 4GiB in the address
  12  * space. However, 256KiB right below 4GiB is decoded by read-only SRAM and not
  13  * boot media.
  14  *
  15  *                                                +-----------+ 0
  16  *                                                |           |
  17  *                                                |           |
  18  *                                                |           |
  19  *                                                |           |
  20  *                                                |           |
  21  *                                                |           |
  22  *                                                |           |
  23  *                                                |           |
  24  *                  +--------+                    |           |
  25  *                  |  IFD   |                    |           |
  26  * bios_start +---> +--------+------------------> +-----------+ 4GiB - bios_size
  27  *     ^            |        |          ^         |           |
  28  *     |            |        |          |         |           |
  29  *     |            |        |  bios_mapped_size  |    BIOS   |
  30  *     |            |  BIOS  |          |         |           |
  31  * bios_size        |        |          |         |           |
  32  *     |            |        |          v         |           |
  33  *     |            |        +------------------> +-----------+ 4GiB - 256KiB
  34  *     |            |        |                    | Read only |
  35  *     v            |        |                    |    SRAM   |
  36  * bios_end   +---> +--------+                    +-----------+ 4GiB
  37  *                  | Device |
  38  *                  |   ext  |
  39  *                  +--------+
  40  *
  41  */
  42
  43 static size_t bios_size;
  44
  45 static struct region_device shadow_dev;
  46 static struct xlate_region_device real_dev;
  47 static struct xlate_window real_dev_window;
  48
  49 static void bios_mmap_init(void)
  50 {
  51         size_t size, start, bios_mapped_size;
  52         uintptr_t base;
  53
  54         size = bios_size;
  55
  56         /* If bios_size is initialized, then bail out. */
  57         if (size != 0)
  58                 return;
  59         start = fast_spi_get_bios_region(&size);
  60
  61         /* BIOS region is mapped right below 4G. */
  62         base = 4ULL * GiB - size;
  63
  64         /*
  65          * The 256 KiB right below 4G are decoded by readonly SRAM,
  66          * not boot media.
  67          */
  68         bios_mapped_size = size - 256 * KiB;
  69
  70         rdev_chain_mem(&shadow_dev, (void *)base, bios_mapped_size);
  71
  72         xlate_window_init(&real_dev_window, &shadow_dev, start, bios_mapped_size);
  73         xlate_region_device_ro_init(&real_dev, 1, &real_dev_window, CONFIG_ROM_SIZE);
  74
  75         bios_size = size;
  76
  77         /* Check that the CBFS lies within the memory mapped area. It's too
  78            easy to forget the SRAM mapping when crafting an FMAP file. */
  79         struct region cbfs_region;
  80         if (!fmap_locate_area("COREBOOT", &cbfs_region) &&
  81             !region_is_subregion(&real_dev_window.sub_region, &cbfs_region))
  82                 printk(BIOS_CRIT,
  83                        "ERROR: CBFS @ %zx size %zx exceeds mem-mapped area @ %zx size %zx\n",
  84                        region_offset(&cbfs_region), region_sz(&cbfs_region),
  85                        start, bios_mapped_size);
  86 }
  87
  88 const struct region_device *boot_device_ro(void)
  89 {
  90         bios_mmap_init();
  91
  92         return &real_dev.rdev;
  93 }
  94
  95 uint32_t spi_flash_get_mmap_windows(struct flash_mmap_window *table)
  96 {
  97         bios_mmap_init();
  98
  99         table->flash_base = region_offset(&real_dev_window.sub_region);
 100         table->host_base = (uintptr_t)rdev_mmap_full(&shadow_dev);
 101         table->size = region_sz(&real_dev_window.sub_region);
 102
 103         return 1;
 104 }