1 files changed, 228 insertions, 0 deletions
diff --git a/bsps/aarch64/xilinx-versal/dev/serial/versal-uart-polled.c b/bsps/aarch64/xilinx-versal/dev/serial/versal-uart-polled.c
new file mode 100644
index 0000000000..be46c99efd
--- /dev/null
+++ b/bsps/aarch64/xilinx-versal/dev/serial/versal-uart-polled.c
@@ -0,0 +1,228 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/*
+ * Copyright (C) 2021 Gedare Bloom <gedare@rtems.org> 
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <dev/serial/versal-uart.h>
+#include <dev/serial/versal-uart-regs.h>
+
+#include <bspopts.h>
+
+static inline volatile versal_uart *versal_uart_get_regs(
+  rtems_termios_device_context *base
+)
+{
+  versal_uart_context *ctx = (versal_uart_context *) base;
+  return ctx->regs;
+}
+
+/*
+ * Make weak and let the user override.
+ */
+uint32_t versal_uart_input_clock(void) __attribute__ ((weak));
+
+uint32_t versal_uart_input_clock(void)
+{
+  return VERSAL_CLOCK_UART;
+}
+
+int32_t versal_cal_baud_rate(
+  uint32_t baudrate,
+  uint32_t maxerror,
+  uint32_t *ibdiv,
+  uint32_t *fbdiv
+)
+{
+  uint32_t calcbaudrate;
+  uint32_t bauderror;
+  uint32_t percenterror;
+  uint32_t fbdivrnd;
+  uint32_t inputclk = versal_uart_input_clock();
+
+  /*
+   * The baud rate cannot be larger than the UART clock / 16.
+   */
+  if ((baudrate * 16) > inputclk) {
+    return -1;
+  }
+
+  /* 
+   * The UART clock cannot be larger than 16*65535*baudrate.
+   * Could maybe use an estimate (inputclk / 2**16) to save a division.
+   * This invariant gets checked below, by ensuring ibdiv < 2**16.
+   */
+
+  /*
+   * The UART clock cannot be more than 5/3 times faster than the LPD_LSBUS_CLK
+   *  - TODO?
+   */
+  
+  /*
+   * The baud rate divisor is a 16-bit integer and 6-bit fractional part.
+   * It is equal to the UART clock / (16 * baudrate).
+   */
+  *ibdiv = inputclk / 16 / baudrate;
+  if ( *ibdiv > 1<<16 ) {
+    return -1;
+  }
+
+  /*
+   * Find the fractional part. This can overflow with 32-bit arithmetic if
+   * inputclk > 536870911, so use 64-bit. Unfortunately, this means we have
+   * two 64-bit divisions here.
+   */
+  fbdivrnd = ((((uint64_t)inputclk / 16) << 7) / baudrate) & 0x1;
+  *fbdiv = (((((uint64_t)inputclk / 16) << 6) / baudrate) & 0x3F) + fbdivrnd;
+
+  /*
+   * calculate the baudrate and check if the error is too large.
+   */
+  calcbaudrate = (((uint64_t)inputclk / 16) << 6) / ((*ibdiv << 6) | *fbdiv);
+
+  if (baudrate > calcbaudrate) {
+    bauderror = baudrate - calcbaudrate;
+  } else {
+    bauderror = calcbaudrate - baudrate;
+  }
+
+  percenterror = (bauderror * 100) / baudrate;
+
+  if (maxerror < percenterror) {
+    return -1;
+  }
+
+  return 0;
+}
+
+int versal_uart_initialize(rtems_termios_device_context *base)
+{
+  volatile versal_uart *regs = versal_uart_get_regs(base);
+  uint32_t maxerr = 3;
+  uint32_t ibauddiv = 0;
+  uint32_t fbauddiv = 0;
+  int rv;
+
+  versal_uart_reset_tx_flush(base);
+
+  rv = versal_cal_baud_rate(
+      VERSAL_UART_DEFAULT_BAUD,
+      maxerr,
+      &ibauddiv,
+      &fbauddiv
+  );
+
+  if ( rv < 0 ) {
+    return rv;
+  }
+
+  /* Line control: 8-bit word length, no parity, no FIFO, 1 stop bit */
+  regs->uartlcr_h = VERSAL_UARTLCR_H_WLEN( VERSAL_UARTLCR_H_WLEN_8 );
+
+  /* Control: receive, transmit, uart enable, no CTS, no RTS, no loopback */
+  regs->uartcr = VERSAL_UARTCR_RXE
+    | VERSAL_UARTCR_TXE
+    | VERSAL_UARTCR_UARTEN;
+
+  regs->uartibrd = VERSAL_UARTIBRD_BAUD_DIVINT(ibauddiv);
+  regs->uartfbrd = VERSAL_UARTFBRD_BAUD_DIVFRAC(fbauddiv);
+
+  return 0;
+}
+
+static bool versal_uart_first_open(
+  struct rtems_termios_tty *tty,
+  rtems_termios_device_context *base,
+  struct termios *term,
+  rtems_libio_open_close_args_t *args
+)
+{
+  int rc = versal_uart_initialize(base);
+  if ( rc < 0 ) {
+    return false;
+  }
+
+  rtems_termios_set_initial_baud(tty, VERSAL_UART_DEFAULT_BAUD);
+
+  return true;
+}
+
+int versal_uart_read_polled(rtems_termios_device_context *base)
+{
+  volatile versal_uart *regs = versal_uart_get_regs(base);
+
+  if ((regs->uartfr & VERSAL_UARTFR_RXFE) != 0) {
+    return -1;
+  } else {
+    return VERSAL_UARTDR_DATA_GET(regs->uartdr);
+  }
+}
+
+void versal_uart_write_polled(
+  rtems_termios_device_context *base,
+  char c
+)
+{
+  volatile versal_uart *regs = versal_uart_get_regs(base);
+
+  while ((regs->uartfr & VERSAL_UARTFR_TXFF) != 0) {
+    /* Wait while full */
+  }
+
+  regs->uartdr = VERSAL_UARTDR_DATA(c);
+}
+
+void versal_uart_reset_tx_flush(rtems_termios_device_context *base)
+{
+  volatile versal_uart *regs = versal_uart_get_regs(base);
+  int c = 4;
+
+  while (c-- > 0)
+    versal_uart_write_polled(base, '\r');
+
+  while ((regs->uartfr & VERSAL_UARTFR_TXFE) == 0) {
+    /* Wait for empty */
+  }
+}
+
+static void versal_uart_write_support(
+  rtems_termios_device_context *base,
+  const char *s,
+  size_t n
+)
+{
+  size_t i;
+
+  for (i = 0; i < n; i++) {
+    versal_uart_write_polled(base, s[i]);
+  }
+}
+
+const rtems_termios_device_handler versal_uart_handler = {
+  .first_open = versal_uart_first_open,
+  .write = versal_uart_write_support,
+  .poll_read = versal_uart_read_polled,
+  .mode = TERMIOS_POLLED
+};
+