From 835aa6b59948817f094c7e55e530a7e426c79161 Mon Sep 17 00:00:00 2001
From: Juergen Beisert <jbe@pengutronix.de>
Date: Tue, 12 Jan 2010 11:15:46 +0100
Subject: Add a low level disk drive access driver

This is a low level disk drive communication driver. It uses the real mode
BIOS found on most x86 platforms, to read and write sectors. Used by the
generic disk driver.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 arch/x86/lib/Makefile    |  1 +
 arch/x86/lib/bios_disk.S | 77 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)
 create mode 100644 arch/x86/lib/bios_disk.S

(limited to 'arch/x86')

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 5d813933dd..013d369eaa 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -5,3 +5,4 @@ obj-y += gdt.o
 # needed, when running via a 16 bit BIOS
 obj-$(CONFIG_X86_BIOS_BRINGUP) += memory16.o
 obj-$(CONFIG_X86_BIOS_BRINGUP) += traveler.o
+obj-$(CONFIG_X86_BIOS_BRINGUP) += bios_disk.o
diff --git a/arch/x86/lib/bios_disk.S b/arch/x86/lib/bios_disk.S
new file mode 100644
index 0000000000..3acd66047d
--- /dev/null
+++ b/arch/x86/lib/bios_disk.S
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2009 Juergen Beisert, Pengutronix
+ *
+ * Mostly stolen from the GRUB2 project
+ *  Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2006,2007,2008  Free Software Foundation, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ */
+
+/**
+ * @file
+ * @brief Do BIOS calls to load or save data from disks
+ *
+ * @note These functions are running in flat and real mode. Due to some
+ * other restrictions these routines must running from an address
+ * space below 0x10000
+ */
+
+#ifndef DOXYGEN_SHOULD_SKIP_THIS
+/*
+ *   int bios_disk_rw_int13_extensions (int ah, int drive, void *dap)
+ *
+ *   Call IBM/MS INT13 Extensions (int 13 %ah=AH) for DRIVE. DAP
+ *   is passed for disk address packet. If an error occurs, return
+ *   non-zero, otherwise zero.
+ */
+	.section .boot.text.bios_disk_rw_int13_extensions, "ax"
+	.code32
+	.globl bios_disk_rw_int13_extensions
+	.type bios_disk_rw_int13_extensions, @function
+
+	.extern prot_to_real
+	.extern real_to_prot
+
+bios_disk_rw_int13_extensions:
+	pushl %ebp
+	pushl %esi
+
+	/* compute the address of disk_address_packet */
+	movw %cx, %si
+	xorw %cx, %cx
+	shrl $4, %ecx	/* save the segment to cx */
+
+	movb %al, %dh
+	call prot_to_real	/* enter real mode right now */
+
+	.code16
+	movb %dh, %ah
+	movw %cx, %ds
+	int $0x13		/* do the operation */
+	movb %ah, %dl		/* save return value */
+	/* back to protected mode */
+	DATA32 call real_to_prot
+
+	.code32
+	movb %dl, %al	/* return value in %eax */
+
+	popl %esi
+	popl %ebp
+
+	ret
+
+#endif
-- 
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