| /* -*- linux-c -*- ------------------------------------------------------- * |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * Copyright 2007 rPath, Inc. - All Rights Reserved |
| * |
| * This file is part of the Linux kernel, and is made available under |
| * the terms of the GNU General Public License version 2. |
| * |
| * ----------------------------------------------------------------------- */ |
| |
| /* |
| * arch/i386/boot/edd.c |
| * |
| * Get EDD BIOS disk information |
| */ |
| |
| #include "boot.h" |
| #include <linux/edd.h> |
| |
| #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) |
| |
| struct edd_dapa { |
| u8 pkt_size; |
| u8 rsvd; |
| u16 sector_cnt; |
| u16 buf_off, buf_seg; |
| u64 lba; |
| u64 buf_lin_addr; |
| }; |
| |
| /* |
| * Read the MBR (first sector) from a specific device. |
| */ |
| static int read_mbr(u8 devno, void *buf) |
| { |
| struct edd_dapa dapa; |
| u16 ax, bx, cx, dx, si; |
| |
| memset(&dapa, 0, sizeof dapa); |
| dapa.pkt_size = sizeof(dapa); |
| dapa.sector_cnt = 1; |
| dapa.buf_off = (size_t)buf; |
| dapa.buf_seg = ds(); |
| /* dapa.lba = 0; */ |
| |
| ax = 0x4200; /* Extended Read */ |
| si = (size_t)&dapa; |
| dx = devno; |
| asm("pushfl; stc; int $0x13; setc %%al; popfl" |
| : "+a" (ax), "+S" (si), "+d" (dx) |
| : "m" (dapa) |
| : "ebx", "ecx", "edi", "memory"); |
| |
| if (!(u8)ax) |
| return 0; /* OK */ |
| |
| ax = 0x0201; /* Legacy Read, one sector */ |
| cx = 0x0001; /* Sector 0-0-1 */ |
| dx = devno; |
| bx = (size_t)buf; |
| asm("pushfl; stc; int $0x13; setc %%al; popfl" |
| : "+a" (ax), "+c" (cx), "+d" (dx), "+b" (bx) |
| : : "esi", "edi", "memory"); |
| |
| return -(u8)ax; /* 0 or -1 */ |
| } |
| |
| static u32 read_mbr_sig(u8 devno, struct edd_info *ei) |
| { |
| int sector_size; |
| char *mbrbuf_ptr, *mbrbuf_end; |
| u32 mbrsig; |
| u32 buf_base, mbr_base; |
| extern char _end[]; |
| |
| sector_size = ei->params.bytes_per_sector; |
| if (!sector_size) |
| sector_size = 512; /* Best available guess */ |
| |
| /* Produce a naturally aligned buffer on the heap */ |
| buf_base = (ds() << 4) + (u32)&_end; |
| mbr_base = (buf_base+sector_size-1) & ~(sector_size-1); |
| mbrbuf_ptr = _end + (mbr_base-buf_base); |
| mbrbuf_end = mbrbuf_ptr + sector_size; |
| |
| /* Make sure we actually have space on the heap... */ |
| if (!(boot_params.hdr.loadflags & CAN_USE_HEAP)) |
| return 0; |
| if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr) |
| return 0; |
| |
| if (read_mbr(devno, mbrbuf_ptr)) |
| return 0; |
| |
| mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET]; |
| return mbrsig; |
| } |
| |
| static int get_edd_info(u8 devno, struct edd_info *ei) |
| { |
| u16 ax, bx, cx, dx, di; |
| |
| memset(ei, 0, sizeof *ei); |
| |
| /* Check Extensions Present */ |
| |
| ax = 0x4100; |
| bx = EDDMAGIC1; |
| dx = devno; |
| asm("pushfl; stc; int $0x13; setc %%al; popfl" |
| : "+a" (ax), "+b" (bx), "=c" (cx), "+d" (dx) |
| : : "esi", "edi"); |
| |
| if ((u8)ax) |
| return -1; /* No extended information */ |
| |
| if (bx != EDDMAGIC2) |
| return -1; |
| |
| ei->device = devno; |
| ei->version = ax >> 8; /* EDD version number */ |
| ei->interface_support = cx; /* EDD functionality subsets */ |
| |
| /* Extended Get Device Parameters */ |
| |
| ei->params.length = sizeof(ei->params); |
| ax = 0x4800; |
| dx = devno; |
| asm("pushfl; int $0x13; popfl" |
| : "+a" (ax), "+d" (dx) |
| : "S" (&ei->params) |
| : "ebx", "ecx", "edi"); |
| |
| /* Get legacy CHS parameters */ |
| |
| /* Ralf Brown recommends setting ES:DI to 0:0 */ |
| ax = 0x0800; |
| dx = devno; |
| di = 0; |
| asm("pushw %%es; " |
| "movw %%di,%%es; " |
| "pushfl; stc; int $0x13; setc %%al; popfl; " |
| "popw %%es" |
| : "+a" (ax), "=b" (bx), "=c" (cx), "+d" (dx), "+D" (di) |
| : : "esi"); |
| |
| if ((u8)ax == 0) { |
| ei->legacy_max_cylinder = (cx >> 8) + ((cx & 0xc0) << 2); |
| ei->legacy_max_head = dx >> 8; |
| ei->legacy_sectors_per_track = cx & 0x3f; |
| } |
| |
| return 0; |
| } |
| |
| void query_edd(void) |
| { |
| char eddarg[8]; |
| int do_mbr = 1; |
| int do_edd = 1; |
| int devno; |
| struct edd_info ei, *edp; |
| |
| if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) { |
| if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) |
| do_mbr = 0; |
| else if (!strcmp(eddarg, "off")) |
| do_edd = 0; |
| } |
| |
| edp = (struct edd_info *)boot_params.eddbuf; |
| |
| if (!do_edd) |
| return; |
| |
| for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) { |
| /* |
| * Scan the BIOS-supported hard disks and query EDD |
| * information... |
| */ |
| get_edd_info(devno, &ei); |
| |
| if (boot_params.eddbuf_entries < EDDMAXNR) { |
| memcpy(edp, &ei, sizeof ei); |
| edp++; |
| boot_params.eddbuf_entries++; |
| } |
| |
| if (do_mbr) { |
| u32 mbr_sig; |
| mbr_sig = read_mbr_sig(devno, &ei); |
| boot_params.edd_mbr_sig_buffer[devno-0x80] = mbr_sig; |
| } |
| } |
| } |
| |
| #endif |