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ti/am335x: Fix baudrate calculation 

UART input clock is platform dependent. Also account for possible
use of get_option() where baudrate is not compile-time constant.

The hardware reference on BeagleBone is from a 48 MHz oscillator input.
With pre-divisor of 16 we get same register values as in table 19-25.

Change-Id: I89aee27c958f8618ce79a968ae7520a867e7e8a2
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5290
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
This commit is contained in:
Kyösti Mälkki 2014-02-19 08:58:12 +02:00
parent 65ba20e17b
commit 2cbcd2b710
1 changed files with 17 additions and 21 deletions
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38
src/cpu/ti/am335x/uart.c
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@ -35,10 +35,10 @@
#define LSR_TXFIFOE (1 << 5) #define LSR_TXFIFOE (1 << 5)
/* /*
* Initialise the serial port with the given baudrate. The settings * Initialise the serial port with the given baudrate divisor. The settings
* are always 8 data bits, no parity, 1 stop bit, no start bits. * are always 8 data bits, no parity, 1 stop bit, no start bits.
*/ */
static void am335x_uart_init_dev(void) static void am335x_uart_init(uint16_t div)
{ {
struct am335x_uart *uart = (struct am335x_uart *) struct am335x_uart *uart = (struct am335x_uart *)
CONFIG_CONSOLE_SERIAL_UART_ADDRESS; CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
@ -107,24 +107,8 @@ static void am335x_uart_init_dev(void)
write16(0xbf, &uart->lcr); write16(0xbf, &uart->lcr);
/* 7. Set dll and dlh to the desired values (table 19-25) */ /* 7. Set dll and dlh to the desired values (table 19-25) */
if (CONFIG_CONSOLE_SERIAL_9600) { write16((div >> 8), &uart->dlh);
write16(0x01, &uart->dlh); write16((div & 0xff), &uart->dll);
write16(0x38, &uart->dll);
} else if (CONFIG_CONSOLE_SERIAL_19200) {
write16(0x00, &uart->dlh);
write16(0x9c, &uart->dll);
} else if (CONFIG_CONSOLE_SERIAL_38400) {
write16(0x00, &uart->dlh);
write16(0x4e, &uart->dll);
} else if (CONFIG_CONSOLE_SERIAL_57600) {
write16(0x00, &uart->dlh);
write16(0x34, &uart->dll);
} else if (CONFIG_CONSOLE_SERIAL_115200) {
write16(0x00, &uart->dlh);
write16(0x1a, &uart->dll);
} else {
/* Unrecognized baud rate? */
}
/* 8. Switch to operational mode to access ier */ /* 8. Switch to operational mode to access ier */
write16(0x0, &uart->lcr); write16(0x0, &uart->lcr);
@ -173,12 +157,24 @@ static void am335x_uart_tx_byte(unsigned char data)
return write8(data, &uart->thr); return write8(data, &uart->thr);
} }
unsigned int uart_platform_refclk(void)
{
return 48000000;
}
static void am335x_uart_init_dev(void)
{
uint16_t div = (uint16_t) uart_baudrate_divisor(
default_baudrate(), uart_platform_refclk(), 16);
am335x_uart_init(div);
}
#if !defined(__PRE_RAM__)
uint32_t uartmem_getbaseaddr(void) uint32_t uartmem_getbaseaddr(void)
{ {
return CONFIG_CONSOLE_SERIAL_UART_ADDRESS; return CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
} }
#if !defined(__PRE_RAM__)
static const struct console_driver exynos5_uart_console __console = { static const struct console_driver exynos5_uart_console __console = {
.init = am335x_uart_init_dev, .init = am335x_uart_init_dev,
.tx_byte = am335x_uart_tx_byte, .tx_byte = am335x_uart_tx_byte,