diff options
Diffstat (limited to 'arch/x86/lib/i8254.c')
-rw-r--r-- | arch/x86/lib/i8254.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/x86/lib/i8254.c b/arch/x86/lib/i8254.c new file mode 100644 index 0000000000..46a4245289 --- /dev/null +++ b/arch/x86/lib/i8254.c @@ -0,0 +1,37 @@ +/* + * (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; +} |