1 /* $NetBSD: gatea20.c,v 1.10 2007/10/17 19:54:59 garbled Exp $ */ 2 3 /* extracted from freebsd:sys/i386/boot/biosboot/io.c */ 4 5 #include <sys/types.h> 6 7 #include <lib/libsa/stand.h> 8 9 #include "libi386.h" 10 #include "biosmca.h" 11 #include "cpufunc.h" 12 13 #define K_RDWR 0x60 /* keyboard data & cmds (read/write) */ 14 #define K_STATUS 0x64 /* keyboard status */ 15 #define K_CMD 0x64 /* keybd ctlr command (write-only) */ 16 17 #define K_OBUF_FUL 0x01 /* output buffer full */ 18 #define K_IBUF_FUL 0x02 /* input buffer full */ 19 20 #define KC_CMD_WIN 0xd0 /* read output port */ 21 #define KC_CMD_WOUT 0xd1 /* write output port */ 22 #define KB_A20 0x9f /* enable A20, 23 reset (!), 24 enable output buffer full interrupt 25 enable data line 26 disable clock line */ 27 28 /* 29 * Gate A20 for high memory 30 */ 31 static unsigned char x_20 = KB_A20; 32 33 void 34 gateA20(void) 35 { 36 u_long psl; 37 38 psl = x86_read_psl(); 39 x86_disable_intr(); 40 /* 41 * Not all systems enable A20 via the keyboard controller. 42 * * IBM PS/2 L40 43 * * AMD Elan SC520-based systems 44 */ 45 if ( 46 #ifdef SUPPORT_PS2 47 biosmca_ps2model == 0xf82 || 48 #endif 49 (inb(K_STATUS) == 0xff && inb(K_RDWR) == 0xff)) { 50 int data; 51 52 data = inb(0x92); 53 outb(0x92, data | 0x2); 54 } else { 55 while (inb(K_STATUS) & K_IBUF_FUL); 56 57 while (inb(K_STATUS) & K_OBUF_FUL) 58 (void)inb(K_RDWR); 59 60 outb(K_CMD, KC_CMD_WOUT); 61 62 delay(100); 63 while (inb(K_STATUS) & K_IBUF_FUL); 64 65 outb(K_RDWR, x_20); 66 67 delay(100); 68 while (inb(K_STATUS) & K_IBUF_FUL); 69 70 while (inb(K_STATUS) & K_OBUF_FUL) 71 (void)inb(K_RDWR); 72 } 73 x86_write_psl(psl); 74 } 75