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Date: Mon, 9 Jul 2007 19:52:02 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
andi@...stfloor.org, akpm@...ux-foundation.org
Cc: "H. Peter Anvin" <hpa@...or.com>
Subject: [x86 setup 23/33] EDD probing code for the new x86 setup code
From: H. Peter Anvin <hpa@...or.com>
Probe EDD and MBR signatures, in order to make it easier to map
physical hard drives to BIOS drives.
Signed-off-by: H. Peter Anvin <hpa@...or.com>
---
arch/i386/boot/edd.c | 196 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 196 insertions(+), 0 deletions(-)
create mode 100644 arch/i386/boot/edd.c
diff --git a/arch/i386/boot/edd.c b/arch/i386/boot/edd.c
new file mode 100644
index 0000000..25a2824
--- /dev/null
+++ b/arch/i386/boot/edd.c
@@ -0,0 +1,196 @@
+/* -*- 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[];
+ static char mbr_buf[1024];
+
+ sector_size = ei->params.bytes_per_sector;
+ if (!sector_size)
+ sector_size = 512; /* Best available guess */
+
+ buf_base = (ds() << 4) + (u32)&_end;
+ mbr_base = (buf_base+sector_size-1) & ~(sector_size-1);
+ mbrbuf_ptr = mbr_buf + (mbr_base-buf_base);
+ mbrbuf_end = mbrbuf_ptr + sector_size;
+
+ 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
--
1.5.2.2
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