initial commit

lib/uart.c

@@ -0,0 +1,103 @@
+#include <uart.h>
+#include <gpio.h>
+
+/* Auxilary mini UART registers */
+#define AUX_ENABLE      ((volatile unsigned int*)(MMIO_BASE+0x00215004))
+#define AUX_MU_IO       ((volatile unsigned int*)(MMIO_BASE+0x00215040))
+#define AUX_MU_IER      ((volatile unsigned int*)(MMIO_BASE+0x00215044))
+#define AUX_MU_IIR      ((volatile unsigned int*)(MMIO_BASE+0x00215048))
+#define AUX_MU_LCR      ((volatile unsigned int*)(MMIO_BASE+0x0021504C))
+#define AUX_MU_MCR      ((volatile unsigned int*)(MMIO_BASE+0x00215050))
+#define AUX_MU_LSR      ((volatile unsigned int*)(MMIO_BASE+0x00215054))
+#define AUX_MU_MSR      ((volatile unsigned int*)(MMIO_BASE+0x00215058))
+#define AUX_MU_SCRATCH  ((volatile unsigned int*)(MMIO_BASE+0x0021505C))
+#define AUX_MU_CNTL     ((volatile unsigned int*)(MMIO_BASE+0x00215060))
+#define AUX_MU_STAT     ((volatile unsigned int*)(MMIO_BASE+0x00215064))
+#define AUX_MU_BAUD     ((volatile unsigned int*)(MMIO_BASE+0x00215068))
+
+/**
+ * Set baud rate and characteristics (115200 8N1) and map to GPIO
+ */
+void uart_init()
+{
+    register unsigned int r;
+    
+    /* initialize UART */
+    *AUX_ENABLE |=1;       // enable UART1, AUX mini uart
+    *AUX_MU_IER = 0;
+    *AUX_MU_CNTL = 0;
+    *AUX_MU_LCR = 3;       // 8 bits
+    *AUX_MU_MCR = 0;
+    *AUX_MU_IER = 0;
+    *AUX_MU_IIR = 0xc6;    // disable interrupts
+    *AUX_MU_BAUD = 270;    // 115200 baud
+    /* map UART1 to GPIO pins */
+    r=*GPFSEL1;
+    r&=~((7<<12)|(7<<15)); // gpio14, gpio15
+    r|=(2<<12)|(2<<15);    // alt5
+    *GPFSEL1 = r;
+    *GPPUD = 0;            // enable pins 14 and 15
+    r=150; while(r--) { asm volatile("nop"); }
+    *GPPUDCLK0 = (1<<14)|(1<<15);
+    r=150; while(r--) { asm volatile("nop"); }
+    *GPPUDCLK0 = 0;        // flush GPIO setup
+    *AUX_MU_CNTL = 3;      // enable Tx, Rx
+}
+
+/**
+ * Send a character
+ */
+void uart_send(unsigned int c) {
+    /* wait until we can send */
+    do{asm volatile("nop");}while(!(*AUX_MU_LSR&0x20));
+    /* write the character to the buffer */
+    *AUX_MU_IO=c;
+}
+
+byte_t uart_getb()
+{
+  byte_t r;
+  /* wait until something is in the buffer */
+  do{asm volatile("nop");}while(!(*AUX_MU_LSR&0x01));
+  /* read it and return */
+  r=(byte_t)(*AUX_MU_IO);
+
+  return r;
+}
+
+/**
+ * Receive a character
+ */
+char uart_getc() {
+  char r = (char)uart_getb();
+
+  /* convert carrige return to newline */
+  return r=='\r'?'\n':r;
+}
+
+/**
+ * Display a string
+ */
+void uart_puts(char *s) {
+    while(*s) {
+        /* convert newline to carrige return + newline */
+        if(*s=='\n')
+            uart_send('\r');
+        uart_send(*s++);
+    }
+}
+
+/**
+ * Display a binary value in hexadecimal
+ */
+void uart_hex(unsigned int d) {
+    unsigned int n;
+    int c;
+    for(c=28;c>=0;c-=4) {
+        // get highest tetrad
+        n=(d>>c)&0xF;
+        // 0-9 => '0'-'9', 10-15 => 'A'-'F'
+        n+=n>9?0x37:0x30;
+        uart_send(n);
+    }
+}