APM probing code

APM probing code for the new x86 setup code.  This implements the
same functionality as the assembly version.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 97 insertions, 0 deletions

diff --git a/arch/i386/boot/apm.c b/arch/i386/boot/apm.c
new file mode 100644
index 000000000000..a34087c370c0
--- /dev/null
+++ b/arch/i386/boot/apm.c
@@ -0,0 +1,97 @@
+/* -*- linux-c -*- ------------------------------------------------------- *
+ *
+ *   Copyright (C) 1991, 1992 Linus Torvalds
+ *   Copyright 2007 rPath, Inc. - All Rights Reserved
+ *
+ *   Original APM BIOS checking by Stephen Rothwell, May 1994
+ *   (sfr@canb.auug.org.au)
+ *
+ *   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/apm.c
+ *
+ * Get APM BIOS information
+ */
+
+#include "boot.h"
+
+#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
+
+int query_apm_bios(void)
+{
+        u16 ax, bx, cx, dx, di;
+        u32 ebx, esi;
+        u8 err;
+
+        /* APM BIOS installation check */
+        ax = 0x5300;
+        bx = cx = 0;
+        asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %0"
+                     : "=d" (err), "+a" (ax), "+b" (bx), "+c" (cx)
+                     : : "esi", "edi");
+
+        if (err)
+                return -1;              /* No APM BIOS */
+
+        if (bx != 0x504d)       /* "PM" signature */
+                return -1;
+
+        if (cx & 0x02)          /* 32 bits supported? */
+                return -1;
+
+        /* Disconnect first, just in case */
+        ax = 0x5304;
+        asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp"
+                     : "+a" (ax)
+                     : : "ebx", "ecx", "edx", "esi", "edi");
+
+        /* Paranoia */
+        ebx = esi = 0;
+        cx = dx = di = 0;
+
+        /* 32-bit connect */
+        asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %6"
+                     : "=a" (ax), "+b" (ebx), "+c" (cx), "+d" (dx),
+                       "+S" (esi), "+D" (di), "=m" (err)
+                     : "a" (0x5303));
+
+        boot_params.apm_bios_info.cseg = ax;
+        boot_params.apm_bios_info.offset = ebx;
+        boot_params.apm_bios_info.cseg_16 = cx;
+        boot_params.apm_bios_info.dseg = dx;
+        boot_params.apm_bios_info.cseg_len = (u16)esi;
+        boot_params.apm_bios_info.cseg_16_len = esi >> 16;
+        boot_params.apm_bios_info.dseg_len = di;
+
+        if (err)
+                return -1;
+
+        /* Redo the installation check as the 32-bit connect;
+           some BIOSes return different flags this way... */
+
+        ax = 0x5300;
+        bx = cx = 0;
+        asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %0"
+                     : "=d" (err), "+a" (ax), "+b" (bx), "+c" (cx)
+                     : : "esi", "edi");
+
+        if (err || bx != 0x504d) {
+                /* Failure with 32-bit connect, try to disconect and ignore */
+                ax = 0x5304;
+                bx = 0;
+                asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp"
+                             : "+a" (ax), "+b" (bx)
+                             : : "ecx", "edx", "esi", "edi");
+                return -1;
+        }
+
+        boot_params.apm_bios_info.version = ax;
+        boot_params.apm_bios_info.flags = cx;
+        return 0;
+}
+
+#endif