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>

diff --git a/payloads/libpayload/drivers/speaker.c b/payloads/libpayload/drivers/speaker.c
index 3b3a750318c5df33557bdbaccec1e3882a966e79..3a561bcbface72155dde6d2db0cbe51de675c1bf 100644 (file)
--- a/payloads/libpayload/drivers/speaker.c
+++ b/payloads/libpayload/drivers/speaker.c
@@ -60,13 +60,15 @@
  */
 void speaker_enable(u16 freq)
 {
+       u16 reg16 = 1193180 / freq;
+
        /* Select counter 2. Read/write LSB first, then MSB. Use mode 3
           (square wave generator). Use a 16bit binary counter. */
        outb(0xb6, I82C54_CONTROL_WORD_REGISTER);
 
        /* Set the desired tone frequency. */
-       outb((u8)(freq & 0x00ff), I82C54_COUNTER2);     /* LSB. */
-       outb((u8)(freq >> 8), I82C54_COUNTER2);         /* MSB. */
+       outb((u8)(reg16 & 0x00ff), I82C54_COUNTER2);    /* LSB. */
+       outb((u8)(reg16 >> 8), I82C54_COUNTER2);        /* MSB. */
 
        /* Enable the PC speaker (set bits 0 and 1). */
        outb(inb(PC_SPEAKER_PORT) | 0x03, PC_SPEAKER_PORT);