Fixed MTP to work with TWRP

arch/x86/boot/edd.c

@@ -0,0 +1,182 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright (C) 1991, 1992 Linus Torvalds
+ *   Copyright 2007 rPath, Inc. - All Rights Reserved
+ *   Copyright 2009 Intel Corporation; author H. Peter Anvin
+ *
+ *   This file is part of the Linux kernel, and is made available under
+ *   the terms of the GNU General Public License version 2.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * Get EDD BIOS disk information
+ */
+
+#include "boot.h"
+#include <linux/edd.h>
+#include "string.h"
+
+#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
+
+/*
+ * Read the MBR (first sector) from a specific device.
+ */
+static int read_mbr(u8 devno, void *buf)
+{
+	struct biosregs ireg, oreg;
+
+	initregs(&ireg);
+	ireg.ax = 0x0201;		/* Legacy Read, one sector */
+	ireg.cx = 0x0001;		/* Sector 0-0-1 */
+	ireg.dl = devno;
+	ireg.bx = (size_t)buf;
+
+	intcall(0x13, &ireg, &oreg);
+
+	return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */
+}
+
+static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
+{
+	int sector_size;
+	char *mbrbuf_ptr, *mbrbuf_end;
+	u32 buf_base, mbr_base;
+	extern char _end[];
+	u16 mbr_magic;
+
+	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 -1;
+	if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)
+		return -1;
+
+	memset(mbrbuf_ptr, 0, sector_size);
+	if (read_mbr(devno, mbrbuf_ptr))
+		return -1;
+
+	*mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
+	mbr_magic = *(u16 *)&mbrbuf_ptr[510];
+
+	/* check for valid MBR magic */
+	return mbr_magic == 0xAA55 ? 0 : -1;
+}
+
+static int get_edd_info(u8 devno, struct edd_info *ei)
+{
+	struct biosregs ireg, oreg;
+
+	memset(ei, 0, sizeof *ei);
+
+	/* Check Extensions Present */
+
+	initregs(&ireg);
+	ireg.ah = 0x41;
+	ireg.bx = EDDMAGIC1;
+	ireg.dl = devno;
+	intcall(0x13, &ireg, &oreg);
+
+	if (oreg.eflags & X86_EFLAGS_CF)
+		return -1;	/* No extended information */
+
+	if (oreg.bx != EDDMAGIC2)
+		return -1;
+
+	ei->device  = devno;
+	ei->version = oreg.ah;		 /* EDD version number */
+	ei->interface_support = oreg.cx; /* EDD functionality subsets */
+
+	/* Extended Get Device Parameters */
+
+	ei->params.length = sizeof(ei->params);
+	ireg.ah = 0x48;
+	ireg.si = (size_t)&ei->params;
+	intcall(0x13, &ireg, &oreg);
+
+	/* Get legacy CHS parameters */
+
+	/* Ralf Brown recommends setting ES:DI to 0:0 */
+	ireg.ah = 0x08;
+	ireg.es = 0;
+	intcall(0x13, &ireg, &oreg);
+
+	if (!(oreg.eflags & X86_EFLAGS_CF)) {
+		ei->legacy_max_cylinder = oreg.ch + ((oreg.cl & 0xc0) << 2);
+		ei->legacy_max_head = oreg.dh;
+		ei->legacy_sectors_per_track = oreg.cl & 0x3f;
+	}
+
+	return 0;
+}
+
+void query_edd(void)
+{
+	char eddarg[8];
+	int do_mbr = 1;
+#ifdef CONFIG_EDD_OFF
+	int do_edd = 0;
+#else
+	int do_edd = 1;
+#endif
+	int be_quiet;
+	int devno;
+	struct edd_info ei, *edp;
+	u32 *mbrptr;
+
+	if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) {
+		if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) {
+			do_edd = 1;
+			do_mbr = 0;
+		}
+		else if (!strcmp(eddarg, "off"))
+			do_edd = 0;
+		else if (!strcmp(eddarg, "on"))
+			do_edd = 1;
+	}
+
+	be_quiet = cmdline_find_option_bool("quiet");
+
+	edp    = boot_params.eddbuf;
+	mbrptr = boot_params.edd_mbr_sig_buffer;
+
+	if (!do_edd)
+		return;
+
+	/* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe,
+	 * so give a hint if this happens.
+	 */
+
+	if (!be_quiet)
+		printf("Probing EDD (edd=off to disable)... ");
+
+	for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) {
+		/*
+		 * Scan the BIOS-supported hard disks and query EDD
+		 * information...
+		 */
+		if (!get_edd_info(devno, &ei)
+		    && boot_params.eddbuf_entries < EDDMAXNR) {
+			memcpy(edp, &ei, sizeof ei);
+			edp++;
+			boot_params.eddbuf_entries++;
+		}
+
+		if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++))
+			boot_params.edd_mbr_sig_buf_entries = devno-0x80+1;
+	}
+
+	if (!be_quiet)
+		printf("ok\n");
+}
+
+#endif