[platform][lpc43xx] hook up debug uart

For the moment, just a trivial implementation in debug.c.
To be replaced with a standard lk uart "driver" later on.

platform/lpc43xx/debug.c

@@ -24,8 +24,31 @@
 #include <debug.h>
 #include <reg.h>
 
+#include <platform/lpc43xx-uart.h>
+
+#if TARGET_DEBUG_UART == 1
+#define UART_BASE UART0_BASE
+#elif TARGET_DEBUG_UART == 2
+#define UART_BASE UART1_BASE
+#elif TARGET_DEBUG_UART == 3
+#define UART_BASE UART2_BASE
+#elif TARGET_DEBUG_UART == 4
+#define UART_BASE UART3_BASE
+#else
+#warning TARGET_DEBUG_UART unspecified
+#endif
+
 void lpc43xx_debug_early_init(void)
 {
+#ifdef UART_BASE
+	// config for 115200-n-8-1 from 12MHz clock
+	writel(LCR_DLAB, UART_BASE + REG_LCR);
+	writel(4, UART_BASE + REG_DLL);
+	writel(0, UART_BASE + REG_DLM);
+	writel(FDR_DIVADDVAL(5) | FDR_MULVAL(8), UART_BASE + REG_FDR);
+	writel(LCR_WLS_8 | LCR_SBS_1, UART_BASE + REG_LCR);
+	writel(FCR_FIFOEN | FCR_RX_TRIG_1, UART_BASE + REG_FCR);
+#endif
 }
 
 void lpc43xx_debug_init(void)
@@ -34,13 +57,28 @@ void lpc43xx_debug_init(void)
 
 void platform_dputc(char c)
 {
+#ifdef UART_BASE
+	while (!(readl(UART_BASE + REG_LSR) & LSR_THRE)) ;
+	writel(c, UART_BASE + REG_THR);
+#endif
 }
 
 int platform_dgetc(char *c, bool wait)
 {
+#ifdef UART_BASE
+	while (!(readl(UART_BASE + REG_LSR) & LSR_RDR)) {
+		if (!wait) {
+			return -1;
+		}
+	}
+
+	*c = readl(UART_BASE + REG_RBR);
+	return 0;
+#else
 	if (wait) {
 		for (;;) ;
 	}
 	return -1;
+#endif
 }
 

platform/lpc43xx/init.c

@@ -24,8 +24,11 @@
 #include <debug.h>
 #include <arch/arm/cm.h>
 
+void lpc43xx_debug_early_init(void);
+
 void platform_early_init(void)
 {
+	lpc43xx_debug_early_init();
 	arm_cm_systick_init(96000000);
 }
 

target/lpc43xx-generic/init.c

@@ -21,10 +21,16 @@
  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <reg.h>
 #include <debug.h>
 
+#include <platform/lpc43xx-gpio.h>
+
 void target_early_init(void)
 {
+	// UART2 on P1.15 (TX) and P1.16 (RX)
+	writel(PIN_MODE(1) | PIN_PLAIN, PIN_CFG(1, 15));
+	writel(PIN_MODE(1) | PIN_PLAIN | PIN_INPUT, PIN_CFG(1, 16));
 }
 
 void target_init(void)

target/lpc43xx-generic/rules.mk

@@ -5,7 +5,8 @@ MODULE := $(LOCAL_DIR)
 PLATFORM := lpc43xx
 
 GLOBAL_DEFINES += \
-	CRYSTAL_FREQ=12000000
+	CRYSTAL_FREQ=12000000 \
+	TARGET_DEBUG_UART=3
 
 GLOBAL_INCLUDES += \
 	$(LOCAL_DIR)/include