resource.c 1.5 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. #include <linux/ioport.h>
  3. #include <linux/printk.h>
  4. #include <asm/e820/api.h>
  5. #include <asm/pci_x86.h>
  6. static void resource_clip(struct resource *res, resource_size_t start,
  7. resource_size_t end)
  8. {
  9. resource_size_t low = 0, high = 0;
  10. if (res->end < start || res->start > end)
  11. return; /* no conflict */
  12. if (res->start < start)
  13. low = start - res->start;
  14. if (res->end > end)
  15. high = res->end - end;
  16. /* Keep the area above or below the conflict, whichever is larger */
  17. if (low > high)
  18. res->end = start - 1;
  19. else
  20. res->start = end + 1;
  21. }
  22. static void remove_e820_regions(struct resource *avail)
  23. {
  24. int i;
  25. struct e820_entry *entry;
  26. u64 e820_start, e820_end;
  27. struct resource orig = *avail;
  28. if (!pci_use_e820)
  29. return;
  30. for (i = 0; i < e820_table->nr_entries; i++) {
  31. entry = &e820_table->entries[i];
  32. e820_start = entry->addr;
  33. e820_end = entry->addr + entry->size - 1;
  34. resource_clip(avail, e820_start, e820_end);
  35. if (orig.start != avail->start || orig.end != avail->end) {
  36. pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n",
  37. &orig, avail, e820_start, e820_end);
  38. orig = *avail;
  39. }
  40. }
  41. }
  42. void arch_remove_reservations(struct resource *avail)
  43. {
  44. /*
  45. * Trim out BIOS area (high 2MB) and E820 regions. We do not remove
  46. * the low 1MB unconditionally, as this area is needed for some ISA
  47. * cards requiring a memory range, e.g. the i82365 PCMCIA controller.
  48. */
  49. if (avail->flags & IORESOURCE_MEM) {
  50. resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END);
  51. remove_e820_regions(avail);
  52. }
  53. }