1 files changed, 196 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/arm/stm32f4/console/usart.c b/c/src/lib/libbsp/arm/stm32f4/console/usart.c
new file mode 100644
index 0000000000..539423faa2
--- /dev/null
+++ b/c/src/lib/libbsp/arm/stm32f4/console/usart.c
@@ -0,0 +1,196 @@
+/*
+ * Copyright (c) 2012 Sebastian Huber.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Obere Lagerstr. 30
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.com/license/LICENSE.
+ */
+
+#include <libchip/sersupp.h>
+
+#include <bsp.h>
+#include <bsp/irq.h>
+#include <bsp/usart.h>
+#include <bsp/stm32f4.h>
+
+static volatile stm32f4_usart *usart_get_regs(const console_tbl *ct)
+{
+  return (stm32f4_usart *) ct->ulCtrlPort1;
+}
+
+#if 0
+static rtems_vector_number usart_get_irq_number(const console_tbl *ct)
+{
+  return ct->ulIntVector;
+}
+#endif
+
+static const uint8_t usart_pclk_index [] = { 1, 0, 0, 0, 0, 1 };
+
+static const uint32_t usart_pclk_by_index [] = {
+  STM32F4_PCLK1,
+  STM32F4_PCLK2
+};
+
+static uint32_t usart_get_pclk(const console_tbl *ct)
+{
+  return usart_pclk_by_index [usart_pclk_index [ct->ulCtrlPort2]];
+}
+
+static uint32_t usart_get_baud(const console_tbl *ct)
+{
+  return ct->ulClock;
+}
+
+/*
+ * a = 8 * (2 - CR1[OVER8])
+ *
+ * usartdiv = div_mantissa + div_fraction / a
+ *
+ * baud = pclk / (a * usartdiv)
+ *
+ * usartdiv = pclk / (a * baud)
+ *
+ * Calculation in integer arithmetic:
+ *
+ * 1. div_mantissa = pclk / (a * baud)
+ *
+ * 2. div_fraction = pclk / (baud - a * div_mantissa)
+ */
+static uint32_t usart_get_bbr(
+  volatile stm32f4_usart *usart,
+  uint32_t pclk,
+  uint32_t baud
+)
+{
+  uint32_t a = 8 * (2 - ((usart->cr1 & STM32F4_USART_CR1_OVER8) != 0));
+  uint32_t div_mantissa_low = pclk / (a * baud);
+  uint32_t div_fraction_low = pclk / (baud - a * div_mantissa_low);
+  uint32_t div_mantissa_high;
+  uint32_t div_fraction_high;
+  uint32_t high_err;
+  uint32_t low_err;
+  uint32_t div_mantissa;
+  uint32_t div_fraction;
+
+  if (div_fraction_low < a - 1) {
+    div_mantissa_high = div_fraction_low;
+    div_fraction_high = div_fraction_low + 1;
+  } else {
+    div_mantissa_high = div_fraction_low + 1;
+    div_fraction_high = 0;
+  }
+
+  high_err = pclk - baud * (a * div_mantissa_high + div_fraction_high);
+  low_err = baud * (a * div_mantissa_low + div_fraction_low) - pclk;
+
+  if (low_err < high_err) {
+    div_mantissa = div_mantissa_low;
+    div_fraction = div_fraction_low;
+  } else {
+    div_mantissa = div_mantissa_high;
+    div_fraction = div_fraction_high;
+  }
+
+  return STM32F4_USART_BBR_DIV_MANTISSA(div_mantissa)
+    | STM32F4_USART_BBR_DIV_FRACTION(div_fraction);
+}
+
+static void usart_initialize(int minor)
+{
+  const console_tbl *ct = Console_Port_Tbl [minor];
+  volatile stm32f4_usart *usart = usart_get_regs(ct);
+  uint32_t pclk = usart_get_pclk(ct);
+  uint32_t baud = usart_get_baud(ct);
+  volatile stm32f4_rcc *rcc = &STM32F4_RCC;
+
+  rcc->apb2enr |= STM32F4_RCC_APB2ENR_USART1_EN;
+
+  usart->cr1 = 0;
+  usart->cr2 = 0;
+  usart->cr3 = 0;
+  usart->bbr = usart_get_bbr(usart, pclk, baud);
+  usart->cr1 = STM32F4_USART_CR1_UE
+    | STM32F4_USART_CR1_TE
+    | STM32F4_USART_CR1_RE;
+}
+
+static int usart_first_open(int major, int minor, void *arg)
+{
+  rtems_libio_open_close_args_t *oc = (rtems_libio_open_close_args_t *) arg;
+  struct rtems_termios_tty *tty = (struct rtems_termios_tty *) oc->iop->data1;
+  const console_tbl *ct = Console_Port_Tbl [minor];
+  console_data *cd = &Console_Port_Data [minor];
+
+  cd->termios_data = tty;
+  rtems_termios_set_initial_baud(tty, ct->ulClock);
+
+  return 0;
+}
+
+static int usart_last_close(int major, int minor, void *arg)
+{
+  return 0;
+}
+
+static int usart_read_polled(int minor)
+{
+  const console_tbl *ct = Console_Port_Tbl [minor];
+  volatile stm32f4_usart *usart = usart_get_regs(ct);
+
+  if ((usart->sr & STM32F4_USART_SR_RXNE) != 0) {
+    return STM32F4_USART_DR_GET(usart->dr);
+  } else {
+    return -1;
+  }
+}
+
+static void usart_write_polled(int minor, char c)
+{
+  const console_tbl *ct = Console_Port_Tbl [minor];
+  volatile stm32f4_usart *usart = usart_get_regs(ct);
+
+  while ((usart->sr & STM32F4_USART_SR_TXE) == 0) {
+    /* Wait */
+  }
+
+  usart->dr = STM32F4_USART_DR(c);
+}
+
+static ssize_t usart_write_support_polled(
+  int minor,
+  const char *s,
+  size_t n
+)
+{
+  ssize_t i = 0;
+
+  for (i = 0; i < n; ++i) {
+    usart_write_polled(minor, s [i]);
+  }
+
+  return n;
+}
+
+static int usart_set_attributes(int minor, const struct termios *term)
+{
+  return -1;
+}
+
+console_fns stm32f4_usart_fns = {
+  .deviceProbe = libchip_serial_default_probe,
+  .deviceFirstOpen = usart_first_open,
+  .deviceLastClose = usart_last_close,
+  .deviceRead = usart_read_polled,
+  .deviceWrite = usart_write_support_polled,
+  .deviceInitialize = usart_initialize,
+  .deviceWritePolled = usart_write_polled,
+  .deviceSetAttributes = usart_set_attributes,
+  .deviceOutputUsesInterrupts = false
+};