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sound: x86: Add beeping support in i8254

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Adjust the code to allow beeping at different frequencies, using a
calculated value for timer 2.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Simon Glass 2019-02-16 20:24:58 -07:00 committed by Bin Meng
parent 6744c0d652
commit 79a5be820d
2 changed files with 49 additions and 4 deletions
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18
arch/x86/include/asm/i8254.h
View File

@ -35,4 +35,22 @@
/* The clock frequency of the i8253/i8254 PIT */
#define PIT_TICK_RATE 1193182
/**
* i8254_enable_beep() - Start a beep using the PCAT timer
*
* This starts beeping using the legacy i8254 timer. The beep may be silenced
* after a delay with i8254_disable_beep().
*
* @frequency_hz: Frequency of beep in Hz
* @return 0 if OK, -EINVAL if frequency_hz is 0
*/
int i8254_enable_beep(uint frequency_hz);
/**
* i8254_disable_beep() - Disable the bepper
*
* This stops any existing beep
*/
void i8254_disable_beep(void);
#endif /* _ASMI386_I8954_H_ */

35
arch/x86/lib/i8254.c
View File

@ -8,8 +8,20 @@
#include <asm/io.h>
#include <asm/i8254.h>
#define TIMER1_VALUE 18 /* 15.6us */
#define TIMER2_VALUE 0x0a8e /* 440Hz */
#define TIMER1_VALUE 18 /* 15.6us */
#define BEEP_FREQUENCY_HZ 440
#define SYSCTL_PORTB 0x61
#define PORTB_BEEP_ENABLE 0x3
static void i8254_set_beep_freq(uint frequency_hz)
{
uint countdown;
countdown = PIT_TICK_RATE / frequency_hz;
outb(countdown & 0xff, PIT_BASE + PIT_T2);
outb((countdown >> 8) & 0xff, PIT_BASE + PIT_T2);
}
int i8254_init(void)
{
@ -29,8 +41,23 @@ int i8254_init(void)
*/
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);
i8254_set_beep_freq(BEEP_FREQUENCY_HZ);
return 0;
}
int i8254_enable_beep(uint frequency_hz)
{
if (!frequency_hz)
return -EINVAL;
i8254_set_beep_freq(frequency_hz);
setio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
return 0;
}
void i8254_disable_beep(void)
{
clrio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
}