1 files changed, 79 insertions, 0 deletions
diff --git a/src/lpc176x/serial.c b/src/lpc176x/serial.c
new file mode 100644
index 00000000..7f2a0db9
--- /dev/null
+++ b/src/lpc176x/serial.c
@@ -0,0 +1,79 @@
+// lpc176x serial port
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "LPC17xx.h" // LPC_UART0
+#include "autoconf.h" // CONFIG_SERIAL_BAUD
+#include "board/irq.h" // irq_save
+#include "board/serial_irq.h" // serial_rx_data
+#include "internal.h" // gpio_peripheral
+#include "sched.h" // DECL_INIT
+
+void
+serial_init(void)
+{
+    // Setup baud
+    LPC_UART0->LCR = (1<<7); // set DLAB bit
+    LPC_SC->PCLKSEL0 = (LPC_SC->PCLKSEL0 & ~(0x3<<6)) | (0x1<<6);
+    uint32_t pclk = SystemCoreClock;
+    uint32_t div = pclk / (CONFIG_SERIAL_BAUD * 16);
+    LPC_UART0->DLL = div & 0xff;
+    LPC_UART0->DLM = (div >> 8) & 0xff;
+    LPC_UART0->LCR = 3; // 8N1 ; clear DLAB bit
+
+    // Enable fifo
+    LPC_UART0->FCR = 0x01;
+
+    // Setup pins
+    gpio_peripheral(0, 2, 1, 0);
+    gpio_peripheral(0, 3, 1, 0);
+
+    // Enable receive irq
+    NVIC_SetPriority(UART0_IRQn, 0);
+    NVIC_EnableIRQ(UART0_IRQn);
+    LPC_UART0->IER = 0x01;
+}
+DECL_INIT(serial_init);
+
+// Write tx bytes to the serial port
+static void
+kick_tx(void)
+{
+    for (;;) {
+        if (!(LPC_UART0->LSR & (1<<5))) {
+            // Output fifo full - enable tx irq
+            LPC_UART0->IER = 0x03;
+            break;
+        }
+        uint8_t data;
+        int ret = serial_get_tx_byte(&data);
+        if (ret) {
+            // No more data to send - disable tx irq
+            LPC_UART0->IER = 0x01;
+            break;
+        }
+        LPC_UART0->THR = data;
+    }
+}
+
+void __visible
+UART0_IRQHandler(void)
+{
+    uint32_t iir = LPC_UART0->IIR, status = iir & 0x0f;
+    if (status == 0x04)
+        serial_rx_byte(LPC_UART0->RBR);
+    else if (status == 0x02)
+        kick_tx();
+}
+
+void
+serial_enable_tx_irq(void)
+{
+    if (LPC_UART0->LSR & (1<<5)) {
+        irqstatus_t flag = irq_save();
+        kick_tx();
+        irq_restore(flag);
+    }
+}