1 files changed, 147 insertions, 0 deletions
diff --git a/02-usart/src/arch/stm32l4xxx/peripherals/usart.c b/02-usart/src/arch/stm32l4xxx/peripherals/usart.c
new file mode 100644
index 0000000..d37eee2
--- /dev/null
+++ b/02-usart/src/arch/stm32l4xxx/peripherals/usart.c
@@ -0,0 +1,147 @@
+#include "arch/stm32l4xxx/peripherals/usart.h"
+#include "kern/delay.h"
+#include "kern/lib.h"
+#include <stdarg.h>
+
+void set_usart1_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src)
+{
+  rcc->ccip_r = (rcc->ccip_r & (~0x03)) | usart_clk_src;
+}
+
+void set_usart2_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src)
+{
+  rcc->ccip_r = (rcc->ccip_r & ~(0x03 << 2)) | (usart_clk_src << 2);
+}
+
+void set_usart2_clock_enabled(__IO rcc_t* rcc, bool enable)
+{
+  if (enable) {
+    rcc->apb1en1_r |= BIT(17);
+  } else {
+    rcc->apb1en1_r &= ~BIT(17);
+  }
+}
+
+void set_usart1_clock_enabled(__IO rcc_t* rcc, bool enable)
+{
+  if (enable) {
+    rcc->apb2en_r |= BIT(14);
+  } else {
+    rcc->apb2en_r &= ~BIT(14);
+  }
+}
+
+void usart_set_parity(__IO usart_t* usart, usart_parity_t parity)
+{
+  uint32_t c_r1 = usart->c_r1;
+  c_r1 &= ~(0x3 << 9);
+  c_r1 |= parity;
+  usart->c_r1 = c_r1;
+}
+
+void usart_set_enabled(__IO usart_t* usart, usart_enable_t enabled)
+{
+  if (!enabled) {
+    regset(usart->c_r1, usart_ue, 0);
+  } else {
+    /* Set the rx enabled. */
+    regset(usart->c_r1, usart_re, !!(enabled & USART_ENABLE_RX));
+    regset(usart->c_r1, usart_te, !!(enabled & USART_ENABLE_TX));
+    regset(usart->c_r1, usart_ue, 1);
+  }
+}
+
+void usart_transmit_byte_sync(__IO usart_t* usart, uint8_t byte)
+{
+  usart->td_r = byte;
+  /* Per the manual, when bit 7 of the IS register is set, then the usart
+   * data has been sent to the shift register.
+   *
+   * This bit is cleared by writing to the TD register. */
+  while (!(usart->is_r & BIT(7)))
+    ;
+}
+
+void usart_transmit_bytes_sync(__IO usart_t* usart, const uint8_t* bytes, uint32_t n)
+{
+  while (n --) {
+    usart_transmit_byte_sync(usart, *(bytes ++));
+  }
+}
+
+void usart_transmit_str_sync(__IO usart_t* usart, const char* str)
+{
+  while (*str) {
+    if (*str == '\n') {
+      usart_transmit_byte_sync(usart, '\r');
+    }
+    usart_transmit_byte_sync(usart, *(str ++));
+  }
+}
+
+void usart_enable_dma(__IO usart_t* usart, usart_enable_t enabled)
+{
+  switch(enabled) {
+    case USART_ENABLE_DISABLED:
+      regset(usart->c_r3, usart_dmar, 0);
+      regset(usart->c_r3, usart_dmat, 0);
+      break;
+
+    case USART_ENABLE_TX:
+      regset(usart->c_r3, usart_dmat, 1);
+      break;
+
+    case USART_ENABLE_RX:
+      regset(usart->c_r3, usart_dmar, 1);
+      break;
+  };
+}
+
+void usart_printf(__IO usart_t* usart, const char* fmt, ...)
+{
+  va_list l;
+  union {
+    void* ptr;
+    char* str;
+    int i;
+  } b;
+  char buf[128];
+
+  va_start(l, fmt);
+
+  while (*fmt != 0) {
+    if (*fmt == '%') {
+      switch (*(++fmt)) {
+        case 0:
+          goto end;
+        case '%':
+          usart_transmit_byte_sync(usart, '%');
+          break;
+        case 'p':
+          b.ptr = va_arg(l, void*);
+          hexify(ptr2reg(b.ptr), buf);
+          usart_transmit_str_sync(usart, "0x");
+          usart_transmit_str_sync(usart, buf);
+          break;
+        case 'd':
+        case 'i':
+          b.i = va_arg(l, int);
+          decimalify(b.i, buf);
+          usart_transmit_str_sync(usart, buf);
+          break;
+        case 's':
+          b.str = va_arg(l, char*);
+          usart_transmit_str_sync(usart, b.str);
+      }
+      ++ fmt;
+    } else {
+      if (*fmt == '\n') {
+        usart_transmit_byte_sync(usart, '\r');
+      }
+      usart_transmit_byte_sync(usart, *(fmt ++));
+    }
+  }
+
+end:
+  va_end(l);
+}