1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * (C) Copyright 2002 4 * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> 5 */ 6 7 #include <common.h> 8 #include <asm/io.h> 9 #include <asm/i8254.h> 10 11 #define TIMER1_VALUE 18 /* 15.6us */ 12 #define BEEP_FREQUENCY_HZ 440 13 #define SYSCTL_PORTB 0x61 14 #define PORTB_BEEP_ENABLE 0x3 15 16 static void i8254_set_beep_freq(uint frequency_hz) 17 { 18 uint countdown; 19 20 countdown = PIT_TICK_RATE / frequency_hz; 21 22 outb(countdown & 0xff, PIT_BASE + PIT_T2); 23 outb((countdown >> 8) & 0xff, PIT_BASE + PIT_T2); 24 } 25 26 int i8254_init(void) 27 { 28 /* 29 * Initialize counter 1, used to refresh request signal. 30 * This is required for legacy purpose as some codes like 31 * vgabios utilizes counter 1 to provide delay functionality. 32 */ 33 outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2, 34 PIT_BASE + PIT_COMMAND); 35 outb(TIMER1_VALUE, PIT_BASE + PIT_T1); 36 37 /* 38 * Initialize counter 2, used to drive the speaker. 39 * To start a beep, set both bit0 and bit1 of port 0x61. 40 * To stop it, clear both bit0 and bit1 of port 0x61. 41 */ 42 outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3, 43 PIT_BASE + PIT_COMMAND); 44 i8254_set_beep_freq(BEEP_FREQUENCY_HZ); 45 46 return 0; 47 } 48 49 int i8254_enable_beep(uint frequency_hz) 50 { 51 if (!frequency_hz) 52 return -EINVAL; 53 54 /* make sure i8254 is setup correctly before generating beeps */ 55 outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3, 56 PIT_BASE + PIT_COMMAND); 57 58 i8254_set_beep_freq(frequency_hz); 59 setio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE); 60 61 return 0; 62 } 63 64 void i8254_disable_beep(void) 65 { 66 clrio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE); 67 } 68