The UART divider should be calculated based on the base frequency

and baudrate, not hardcoded in addition to that.

Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Acked-by: Peter Stuge <peter@stuge.se>



git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6538 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

src/console/uart8250_console.c

@@ -25,7 +25,13 @@ static void ttyS0_init(void)
 {
 	static const unsigned char div[8] = { 1, 2, 3, 6, 12, 24, 48, 96 };
 	int b_index = 0;
-	unsigned int divisor = CONFIG_TTYS0_DIV;
+	/* TODO the divisor calculation is hard coded to standard UARTs. Some
+	 * UARTs won't work with these values. This should be a property of the
+	 * UART used, worst case a Kconfig variable. For now live with hard
+	 * codes as the only devices that might be different are the iWave
+	 * iRainbowG6 and the OXPCIe952 card (and the latter is memory mapped)
+	 */
+	unsigned int divisor = 115200 / CONFIG_TTYS0_BAUD;
 
 	if (get_option(&b_index, "baud_rate") == 0) {
 		divisor = div[b_index];

src/include/uart8250.h

@@ -28,13 +28,9 @@
 #ifndef CONFIG_TTYS0_BAUD
 #define CONFIG_TTYS0_BAUD 115200
 #endif
-
-#ifndef CONFIG_TTYS0_DIV
 #if ((115200%CONFIG_TTYS0_BAUD) != 0)
 #error Bad ttys0 baud rate
 #endif
-#define CONFIG_TTYS0_DIV	(115200/CONFIG_TTYS0_BAUD)
-#endif
 
 /* Line Control Settings */
 #ifndef CONFIG_TTYS0_LCS

src/lib/uart8250.c

@@ -88,6 +88,12 @@ void uart8250_init(unsigned base_port, unsigned divisor)
 #if defined(__PRE_RAM__) || defined(__SMM__)
 void uart_init(void)
 {
+	/* TODO the divisor calculation is hard coded to standard UARTs. Some
+	 * UARTs won't work with these values. This should be a property of the
+	 * UART used, worst case a Kconfig variable. For now live with hard
+	 * codes as the only devices that might be different are the iWave
+	 * iRainbowG6 and the OXPCIe952 card (and the latter is memory mapped)
+	 */
 #if CONFIG_USE_OPTION_TABLE && !defined(__SMM__)
         static const unsigned char divisor[] = { 1, 2, 3, 6, 12, 24, 48, 96 };
         unsigned ttys0_div, ttys0_index;
@@ -97,7 +103,7 @@ void uart_init(void)
 
 	uart8250_init(CONFIG_TTYS0_BASE, ttys0_div);
 #else
-	uart8250_init(CONFIG_TTYS0_BASE, CONFIG_TTYS0_DIV);
+	uart8250_init(CONFIG_TTYS0_BASE, (115200 / CONFIG_TTYS0_BAUD));
 #endif
 }
 #endif

src/mainboard/iwave/iWRainbowG6/Kconfig

@@ -37,9 +37,7 @@ config IRQ_SLOT_COUNT
 	int
 	default 10
 
-# WTF, is this 19200?
+# This mainboard might have a higher clocked UART or might not be able to run
-config TTYS0_DIV
+# serial output at 115200 baud
-	int
-	default 6
 
 endif