Merged mcb30-realmode-redesign back to HEAD

src/arch/i386/firmware/pcbios/gateA20.c

@@ -0,0 +1,90 @@
+#include "realmode.h"
+#include "timer.h"
+#include "latch.h"
+#include "bios.h"
+
+#define K_RDWR		0x60		/* keyboard data & cmds (read/write) */
+#define K_STATUS	0x64		/* keyboard status */
+#define K_CMD		0x64		/* keybd ctlr command (write-only) */
+
+#define K_OBUF_FUL	0x01		/* output buffer full */
+#define K_IBUF_FUL	0x02		/* input buffer full */
+
+#define KC_CMD_WIN	0xd0		/* read  output port */
+#define KC_CMD_WOUT	0xd1		/* write output port */
+#define KB_SET_A20	0xdf		/* enable A20,
+					   enable output buffer full interrupt
+					   enable data line
+					   disable clock line */
+#define KB_UNSET_A20	0xdd		/* enable A20,
+					   enable output buffer full interrupt
+					   enable data line
+					   disable clock line */
+
+enum { Disable_A20 = 0x2400, Enable_A20 = 0x2401, Query_A20_Status = 0x2402,
+	Query_A20_Support = 0x2403 };
+
+#define CF ( 1 << 0 )
+
+#ifndef IBM_L40
+static void empty_8042 ( void )
+{
+	unsigned long time;
+	char st;
+
+	time = currticks() + TICKS_PER_SEC;	/* max wait of 1 second */
+	while ((((st = inb(K_CMD)) & K_OBUF_FUL) ||
+	       (st & K_IBUF_FUL)) &&
+	       currticks() < time)
+		inb(K_RDWR);
+}
+#endif	/* IBM_L40 */
+
+/*
+ * Gate A20 for high memory
+ *
+ * Note that this function gets called as part of the return path from
+ * librm's real_call, which is used to make the int15 call if librm is
+ * being used.  To avoid an infinite recursion, we make gateA20_set
+ * return immediately if it is already part of the call stack.
+ */
+void gateA20_set ( void ) {
+	static char reentry_guard = 0;
+	uint16_t flags, status;
+
+	if ( reentry_guard )
+		return;
+	reentry_guard = 1;
+
+	REAL_EXEC ( rm_enableA20,
+		    "sti\n\t"
+		    "stc\n\t"
+		    "int $0x15\n\t"
+		    "pushfw\n\t"
+		    "popw %%bx\n\t"
+		    "cli\n\t",
+		    2,
+		    OUT_CONSTRAINTS ( "=a" ( status ), "=b" ( flags ) ),
+		    IN_CONSTRAINTS ( "a" ( Enable_A20 ) ),
+		    CLOBBER ( "ecx", "edx", "ebp", "esi", "edi" ) );
+
+	if ( ( flags & CF ) ||
+	     ( ( status >> 8 ) & 0xff ) ) {
+		/* INT 15 method failed, try alternatives */
+#ifdef	IBM_L40
+		outb(0x2, 0x92);
+#else	/* IBM_L40 */
+		empty_8042();
+		outb(KC_CMD_WOUT, K_CMD);
+		empty_8042();
+		outb(KB_SET_A20, K_RDWR);
+		empty_8042();
+#endif	/* IBM_L40 */
+	}
+	
+	reentry_guard = 0;
+}
+
+void gateA20_unset ( void ) {
+	/* Not currently implemented */
+}