New patch to review for coreboot: 4466cc9 ti/am335x: Fix baudrate calculation

[Kyösti Mälkki]

Kyösti Mälkki ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/5290

-gerrit

commit 4466cc98e31aff9800041fbab5ece91d876732e2
Author: Kyösti Mälkki 
Date:   Wed Feb 19 08:58:12 2014 +0200

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 
---
 src/cpu/ti/am335x/uart.c | 38 +++++++++++++++++---------------------
 1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/src/cpu/ti/am335x/uart.c b/src/cpu/ti/am335x/uart.c
index bd2ff44..719215e 100644
--- a/src/cpu/ti/am335x/uart.c
+++ b/src/cpu/ti/am335x/uart.c
@@ -35,10 +35,10 @@
 #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.
  */
-static void am335x_uart_init_dev(void)
+static void am335x_uart_init(uint16_t div)
 {
    struct am335x_uart *uart = (struct am335x_uart *)
    				CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
@@ -107,24 +107,8 @@ static void am335x_uart_init_dev(void)
    write16(0xbf, &uart->lcr);

/* 7. Set dll and dlh to the desired values (table 19-25) */
-	if (CONFIG_CONSOLE_SERIAL_9600) {
-		write16(0x01, &uart->dlh);
-		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? */
-	}
+	write16((div >> 8), &uart->dlh);
+	write16((div & 0xff), &uart->dll);

/* 8. Switch to operational mode to access ier */
    write16(0x0, &uart->lcr);
@@ -173,12 +157,24 @@ static void am335x_uart_tx_byte(unsigned char data)
    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)
 {
    return CONFIG_CONSOLE_SERIAL_UART_ADDRESS;
 }

-#if !defined(__PRE_RAM__)
 static const struct console_driver exynos5_uart_console __console = {
    .init     = am335x_uart_init_dev,
    .tx_byte  = am335x_uart_tx_byte,