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Fix libpayload speaker driver 

The frequency for the PC speaker has to be specified as
1193180 / frequency according to http://wiki.osdev.org/PC_Speaker

Change-Id: Iaca9d45807e080efe834611e719b350680b5fb90
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/337
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
This commit is contained in:
Stefan Reinauer 2011-10-25 14:15:57 -07:00 committed by Patrick Georgi
parent 6eb8bef25e
commit bbfc9c449f
1 changed files with 4 additions and 2 deletions
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6
payloads/libpayload/drivers/speaker.c
View File

@ -60,13 +60,15 @@
*/ */
void speaker_enable(u16 freq) void speaker_enable(u16 freq)
{ {
u16 reg16 = 1193180 / freq;
/* Select counter 2. Read/write LSB first, then MSB. Use mode 3 /* Select counter 2. Read/write LSB first, then MSB. Use mode 3
(square wave generator). Use a 16bit binary counter. */ (square wave generator). Use a 16bit binary counter. */
outb(0xb6, I82C54_CONTROL_WORD_REGISTER); outb(0xb6, I82C54_CONTROL_WORD_REGISTER);
/* Set the desired tone frequency. */ /* Set the desired tone frequency. */
outb((u8)(freq & 0x00ff), I82C54_COUNTER2); /* LSB. */ outb((u8)(reg16 & 0x00ff), I82C54_COUNTER2); /* LSB. */
outb((u8)(freq >> 8), I82C54_COUNTER2); /* MSB. */ outb((u8)(reg16 >> 8), I82C54_COUNTER2); /* MSB. */
/* Enable the PC speaker (set bits 0 and 1). */ /* Enable the PC speaker (set bits 0 and 1). */
outb(inb(PC_SPEAKER_PORT) | 0x03, PC_SPEAKER_PORT); outb(inb(PC_SPEAKER_PORT) | 0x03, PC_SPEAKER_PORT);