| /* |
| * (C) Copyright 2002 |
| * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| */ |
| |
| #include <common.h> |
| #include <asm/io.h> |
| #include <asm/i8254.h> |
| |
| #define TIMER1_VALUE 18 /* 15.6us */ |
| #define TIMER2_VALUE 0x0a8e /* 440Hz */ |
| |
| int i8254_init(void) |
| { |
| /* |
| * Initialize counter 1, used to refresh request signal. |
| * This is required for legacy purpose as some codes like |
| * vgabios utilizes counter 1 to provide delay functionality. |
| */ |
| outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2, |
| PIT_BASE + PIT_COMMAND); |
| outb(TIMER1_VALUE, PIT_BASE + PIT_T1); |
| |
| /* |
| * Initialize counter 2, used to drive the speaker. |
| * To start a beep, set both bit0 and bit1 of port 0x61. |
| * To stop it, clear both bit0 and bit1 of port 0x61. |
| */ |
| outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3, |
| PIT_BASE + PIT_COMMAND); |
| outb(TIMER2_VALUE & 0xff, PIT_BASE + PIT_T2); |
| outb(TIMER2_VALUE >> 8, PIT_BASE + PIT_T2); |
| |
| return 0; |
| } |