arch/risc-v/src/mpfs/mpfs_serial.c

/****************************************************************************
 * arch/risc-v/src/mpfs/mpfs_serial.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/fs/ioctl.h>
#include <nuttx/serial/serial.h>

#ifdef CONFIG_SERIAL_TERMIOS
#  include <termios.h>
#endif

#include <arch/board/board.h>

#include "chip.h"
#include "mpfs.h"
#include "mpfs_config.h"
#include "mpfs_clockconfig.h"
#include "riscv_internal.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* If we are not using the serial driver for the console, then we still must
 * provide some minimal implementation of up_putc.
 */

#ifdef USE_SERIALDRIVER

/* Which UART with be tty0/console and which tty1?  The console will always
 * be ttyS0.  If there is no console then will use the lowest numbered UART.
 */

#ifdef HAVE_SERIAL_CONSOLE
#  if defined(CONFIG_UART0_SERIAL_CONSOLE)
#    define CONSOLE_DEV     g_uart0port     /* UART0 is console */
#    define SERIAL_CONSOLE  1
#  elif defined(CONFIG_UART1_SERIAL_CONSOLE)
#    define CONSOLE_DEV     g_uart1port     /* UART1 is console */
#    define SERIAL_CONSOLE  2
#  elif defined(CONFIG_UART2_SERIAL_CONSOLE)
#    define CONSOLE_DEV     g_uart2port     /* UART2 is console */
#    define SERIAL_CONSOLE  3
#  elif defined(CONFIG_UART3_SERIAL_CONSOLE)
#    define CONSOLE_DEV     g_uart3port     /* UART3 is console */
#    define SERIAL_CONSOLE  4
#  elif defined(CONFIG_UART4_SERIAL_CONSOLE)
#    define CONSOLE_DEV     g_uart4port     /* UART4 is console */
#    define SERIAL_CONSOLE  5
#  else
#    error "I'm confused... Do we have a serial console or not?"
#  endif
#else
#  undef  CONSOLE_DEV                        /* No console */
#  undef  CONFIG_UART0_SERIAL_CONSOLE
#  undef  CONFIG_UART1_SERIAL_CONSOLE
#  undef  CONFIG_UART2_SERIAL_CONSOLE
#  undef  CONFIG_UART3_SERIAL_CONSOLE
#  undef  CONFIG_UART4_SERIAL_CONSOLE
#  if defined(CONFIG_MPFS_UART0)
#    define SERIAL_CONSOLE  1
#  elif defined(CONFIG_MPFS_UART1)
#    define SERIAL_CONSOLE  2
#  elif defined(CONFIG_MPFS_UART2)
#    define SERIAL_CONSOLE  3
#  elif defined(CONFIG_MPFS_UART3)
#    define SERIAL_CONSOLE  4
#  elif defined(CONFIG_MPFS_UART4)
#    define SERIAL_CONSOLE  5
#  else
#    undef  TTYS0_DEV
#    undef  TTYS1_DEV
#  endif
#endif

/* Common initialization logic will not not know that the all of the UARTs
 * have been disabled.  So, as a result, we may still have to provide
 * stub implementations of riscv_earlyserialinit(), riscv_serialinit(), and
 * up_putc().
 */

#ifdef HAVE_UART_DEVICE

/****************************************************************************
 * Private Types
 ****************************************************************************/

struct up_dev_s
{
  uintptr_t uartbase;  /* Base address of UART registers */
  uint32_t  baud;      /* Configured baud */
  uint32_t  ier;       /* Saved IER value */
  uint8_t   irq;       /* IRQ associated with this UART */
  uint8_t   parity;    /* 0=none, 1=odd, 2=even */
  uint8_t   bits;      /* Number of bits (7 or 8) */
  bool      stopbits2; /* true: Configure with 2 stop bits instead of 1 */
};

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

static int  up_setup(struct uart_dev_s *dev);
static void up_shutdown(struct uart_dev_s *dev);
static int  up_attach(struct uart_dev_s *dev);
static void up_detach(struct uart_dev_s *dev);
static int  uart_interrupt(int irq, void *context, void *arg);
static int  up_ioctl(struct file *filep, int cmd, unsigned long arg);
static int  up_receive(struct uart_dev_s *dev, unsigned int *status);
static void up_rxint(struct uart_dev_s *dev, bool enable);
static bool up_rxavailable(struct uart_dev_s *dev);
static void up_send(struct uart_dev_s *dev, int ch);
static void up_txint(struct uart_dev_s *dev, bool enable);
static bool up_txready(struct uart_dev_s *dev);
static bool up_txempty(struct uart_dev_s *dev);

/****************************************************************************
 * Private Data
 ****************************************************************************/

static const struct uart_ops_s g_uart_ops =
{
  .setup          = up_setup,
  .shutdown       = up_shutdown,
  .attach         = up_attach,
  .detach         = up_detach,
  .ioctl          = up_ioctl,
  .receive        = up_receive,
  .rxint          = up_rxint,
  .rxavailable    = up_rxavailable,
#ifdef CONFIG_SERIAL_IFLOWCONTROL
  .rxflowcontrol  = NULL,
#endif
  .send           = up_send,
  .txint          = up_txint,
  .txready        = up_txready,
  .txempty        = up_txempty,
};

/* I/O buffers */

#ifdef CONFIG_MPFS_UART0
static char g_uart0rxbuffer[CONFIG_UART0_RXBUFSIZE];
static char g_uart0txbuffer[CONFIG_UART0_TXBUFSIZE];
#endif

#ifdef CONFIG_MPFS_UART1
static char g_uart1rxbuffer[CONFIG_UART1_RXBUFSIZE];
static char g_uart1txbuffer[CONFIG_UART1_TXBUFSIZE];
#endif

#ifdef CONFIG_MPFS_UART2
static char g_uart2rxbuffer[CONFIG_UART2_RXBUFSIZE];
static char g_uart2txbuffer[CONFIG_UART2_TXBUFSIZE];
#endif

#ifdef CONFIG_MPFS_UART3
static char g_uart3rxbuffer[CONFIG_UART3_RXBUFSIZE];
static char g_uart3txbuffer[CONFIG_UART3_TXBUFSIZE];
#endif

#ifdef CONFIG_MPFS_UART4
static char g_uart4rxbuffer[CONFIG_UART4_RXBUFSIZE];
static char g_uart4txbuffer[CONFIG_UART4_TXBUFSIZE];
#endif

#ifdef CONFIG_MPFS_UART0
static struct up_dev_s g_uart0priv =
{
  .uartbase  = MPFS_UART0_BASE,
  .baud      = CONFIG_UART0_BAUD,
  .irq       = MPFS_IRQ_MMUART0,
  .parity    = CONFIG_UART0_PARITY,
  .bits      = CONFIG_UART0_BITS,
  .stopbits2 = CONFIG_UART0_2STOP,
};

static uart_dev_t g_uart0port =
{
#if SERIAL_CONSOLE == 1
  .isconsole = 1,
#endif
  .recv      =
  {
    .size    = CONFIG_UART0_RXBUFSIZE,
    .buffer  = g_uart0rxbuffer,
  },
  .xmit      =
  {
    .size    = CONFIG_UART0_TXBUFSIZE,
    .buffer  = g_uart0txbuffer,
  },
  .ops       = &g_uart_ops,
  .priv      = &g_uart0priv,
};
#endif

#ifdef CONFIG_MPFS_UART1
static struct up_dev_s g_uart1priv =
{
  .uartbase  = MPFS_UART1_BASE,
  .baud      = CONFIG_UART1_BAUD,
  .irq       = MPFS_IRQ_MMUART1,
  .parity    = CONFIG_UART1_PARITY,
  .bits      = CONFIG_UART1_BITS,
  .stopbits2 = CONFIG_UART1_2STOP,
};

static uart_dev_t g_uart1port =
{
#if SERIAL_CONSOLE == 2
  .isconsole = 1,
#endif
  .recv      =
  {
    .size    = CONFIG_UART1_RXBUFSIZE,
    .buffer  = g_uart1rxbuffer,
  },
  .xmit      =
  {
    .size    = CONFIG_UART1_TXBUFSIZE,
    .buffer  = g_uart1txbuffer,
  },
  .ops       = &g_uart_ops,
  .priv      = &g_uart1priv,
};
#endif

#ifdef CONFIG_MPFS_UART2
static struct up_dev_s g_uart2priv =
{
  .uartbase  = MPFS_UART2_BASE,
  .baud      = CONFIG_UART2_BAUD,
  .irq       = MPFS_IRQ_MMUART2,
  .parity    = CONFIG_UART2_PARITY,
  .bits      = CONFIG_UART2_BITS,
  .stopbits2 = CONFIG_UART2_2STOP,
};

static uart_dev_t g_uart2port =
{
#if SERIAL_CONSOLE == 3
  .isconsole = 1,
#endif
  .recv      =
  {
    .size    = CONFIG_UART2_RXBUFSIZE,
    .buffer  = g_uart2rxbuffer,
  },
  .xmit      =
  {
    .size    = CONFIG_UART2_TXBUFSIZE,
    .buffer  = g_uart2txbuffer,
  },
  .ops       = &g_uart_ops,
  .priv      = &g_uart2priv,
};
#endif

#ifdef CONFIG_MPFS_UART3
static struct up_dev_s g_uart3priv =
{
  .uartbase  = MPFS_UART3_BASE,
  .baud      = CONFIG_UART3_BAUD,
  .irq       = MPFS_IRQ_MMUART3,
  .parity    = CONFIG_UART3_PARITY,
  .bits      = CONFIG_UART3_BITS,
  .stopbits2 = CONFIG_UART3_2STOP,
};

static uart_dev_t g_uart3port =
{
#if SERIAL_CONSOLE == 4
  .isconsole = 1,
#endif
  .recv      =
  {
    .size    = CONFIG_UART3_RXBUFSIZE,
    .buffer  = g_uart3rxbuffer,
  },
  .xmit      =
  {
    .size    = CONFIG_UART3_TXBUFSIZE,
    .buffer  = g_uart3txbuffer,
  },
  .ops       = &g_uart_ops,
  .priv      = &g_uart3priv,
};
#endif

#ifdef CONFIG_MPFS_UART4
static struct up_dev_s g_uart4priv =
{
  .uartbase  = MPFS_UART4_BASE,
  .baud      = CONFIG_UART4_BAUD,
  .irq       = MPFS_IRQ_MMUART4,
  .parity    = CONFIG_UART4_PARITY,
  .bits      = CONFIG_UART4_BITS,
  .stopbits2 = CONFIG_UART4_2STOP,
};

static uart_dev_t g_uart4port =
{
#if SERIAL_CONSOLE == 5
  .isconsole = 1,
#endif
  .recv      =
  {
    .size    = CONFIG_UART4_RXBUFSIZE,
    .buffer  = g_uart4rxbuffer,
  },
  .xmit      =
  {
    .size    = CONFIG_UART4_TXBUFSIZE,
    .buffer  = g_uart4txbuffer,
  },
  .ops       = &g_uart_ops,
  .priv      = &g_uart4priv,
};
#endif

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: up_serialin
 ****************************************************************************/

static inline uint32_t up_serialin(struct up_dev_s *priv, uint32_t offset)
{
  return getreg32(priv->uartbase + offset);
}

/****************************************************************************
 * Name: up_serialout
 ****************************************************************************/

static inline void up_serialout(struct up_dev_s *priv, int offset,
                                uint32_t value)
{
  putreg32(value, priv->uartbase + offset);
}

/****************************************************************************
 * Name: up_disableuartint
 ****************************************************************************/

static inline void up_disableuartint(struct up_dev_s *priv, uint32_t *ier)
{
  if (ier)
    {
      *ier = priv->ier & UART_IER_ALLIE;
    }

  priv->ier &= ~UART_IER_ALLIE;
  up_serialout(priv, MPFS_UART_IER_OFFSET, priv->ier);
}

/****************************************************************************
 * Name: up_restoreuartint
 ****************************************************************************/

static inline void up_restoreuartint(struct up_dev_s *priv, uint32_t ier)
{
  priv->ier |= ier & UART_IER_ALLIE;
  up_serialout(priv, MPFS_UART_IER_OFFSET, priv->ier);
}

/****************************************************************************
 * Name: up_enablebreaks
 ****************************************************************************/

static inline void up_enablebreaks(struct up_dev_s *priv, bool enable)
{
  uint32_t lcr = up_serialin(priv, MPFS_UART_LCR_OFFSET);

  if (enable)
    {
      lcr |= UART_LCR_BC;
    }
  else
    {
      lcr &= ~UART_LCR_BC;
    }

  up_serialout(priv, MPFS_UART_LCR_OFFSET, lcr);
}

static void up_enable_uart(struct up_dev_s *priv, bool enable)
{
  uint32_t clock_bit = 0;
  uint32_t reset_bit = 0;

  switch (priv->uartbase)
    {
    case MPFS_UART0_BASE:
      clock_bit = SYSREG_SUBBLK_CLOCK_CR_MMUART0;
      reset_bit = SYSREG_SOFT_RESET_CR_MMUART0;
      break;
    case MPFS_UART1_BASE:
      clock_bit = SYSREG_SUBBLK_CLOCK_CR_MMUART1;
      reset_bit = SYSREG_SOFT_RESET_CR_MMUART1;
      break;
    case MPFS_UART2_BASE:
      clock_bit = SYSREG_SUBBLK_CLOCK_CR_MMUART2;
      reset_bit = SYSREG_SOFT_RESET_CR_MMUART2;
      break;
    case MPFS_UART3_BASE:
      clock_bit = SYSREG_SUBBLK_CLOCK_CR_MMUART3;
      reset_bit = SYSREG_SOFT_RESET_CR_MMUART3;
      break;
    case MPFS_UART4_BASE:
      clock_bit = SYSREG_SUBBLK_CLOCK_CR_MMUART4;
      reset_bit = SYSREG_SOFT_RESET_CR_MMUART4;
      break;

    default:
      return;
    }

  /* reset on */

  modifyreg32(MPFS_SYSREG_BASE + MPFS_SYSREG_SOFT_RESET_CR_OFFSET,
              0, reset_bit);

  if (enable)
    {
      /* reset off */

      modifyreg32(MPFS_SYSREG_BASE + MPFS_SYSREG_SUBBLK_CLOCK_CR_OFFSET,
                 0, reset_bit);

      /* clock on */

      modifyreg32(MPFS_SYSREG_BASE + MPFS_SYSREG_SOFT_RESET_CR_OFFSET,
                 clock_bit, 0);
    }
  else
    {
      /* clock off */

      modifyreg32(MPFS_SYSREG_BASE + MPFS_SYSREG_SUBBLK_CLOCK_CR_OFFSET,
                 clock_bit, 0);
    }
}

/****************************************************************************
 * Name: up_config_baud_divisors
 *
 * Description:
 *   Configure the UART baudrate divisors.
 *
 ****************************************************************************/

static void up_config_baud_divisors(struct up_dev_s *priv, uint32_t baudrate)
{
  uint32_t baud_value;
  uint32_t baud_value_by_64;
  uint32_t baud_value_by_128;
  uint32_t fractional_baud_value;
  uint64_t pclk_freq;

  pclk_freq = MPFS_MSS_APB_AHB_CLK;

  /* Compute baud value based on requested baud rate and PCLK frequency.
   * The baud value is computed using the following equation:
   *   baud_value = PCLK_Frequency / (baud_rate * 16)
   */

  baud_value_by_128 = (uint32_t)((8UL * pclk_freq) / baudrate);
  baud_value_by_64 = baud_value_by_128 / 2U;
  baud_value = baud_value_by_64 / 64U;
  fractional_baud_value = baud_value_by_64 - (baud_value * 64U);
  fractional_baud_value += (baud_value_by_128 - (baud_value * 128U))
                           - (fractional_baud_value * 2U);

  if (baud_value <= (uint32_t)UINT16_MAX)
    {
      up_serialout(priv, MPFS_UART_DLH_OFFSET, baud_value >> 8);
      up_serialout(priv, MPFS_UART_DLL_OFFSET, baud_value & 0xff);

      if (baud_value > 1)
        {
          /* Enable Fractional baud rate */

          uint8_t mm0 = up_serialin(priv, MPFS_UART_MM0_OFFSET);
          mm0 |= UART_MM0_EFBR;
          up_serialout(priv, MPFS_UART_MM0_OFFSET, mm0);
          up_serialout(priv, MPFS_UART_DFR_OFFSET, fractional_baud_value);
        }
    }
}

/****************************************************************************
 * Name: up_set_format
 *
 * Description:
 *   Set the serial line format and speed.
 *
 ****************************************************************************/

#ifndef CONFIG_SUPPRESS_UART_CONFIG
static void up_set_format(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  uint32_t lcr = 0;

  /* Set up the LCR */

  switch (priv->bits)
    {
    case 5:
      lcr |= UART_LCR_DLS_5BITS;
      break;

    case 6:
      lcr |= UART_LCR_DLS_6BITS;
      break;

    case 7:
      lcr |= UART_LCR_DLS_7BITS;
      break;

    case 8:
    default:
      lcr |= UART_LCR_DLS_8BITS;
      break;
    }

  if (priv->stopbits2)
    {
      lcr |= UART_LCR_STOP;
    }

  if (priv->parity == 1)
    {
      lcr |= UART_LCR_PEN;
    }
  else if (priv->parity == 2)
    {
      lcr |= (UART_LCR_PEN | UART_LCR_EPS);
    }

  /* Enter DLAB=1 */

  up_serialout(priv, MPFS_UART_LCR_OFFSET, (lcr | UART_LCR_DLAB));

  /* Set the BAUD divisor */

  up_config_baud_divisors(priv, priv->baud);

  /* Clear DLAB */

  up_serialout(priv, MPFS_UART_LCR_OFFSET, lcr);
}
#endif

/****************************************************************************
 * Name: up_setup
 *
 * Description:
 *   Configure the UART baud, bits, parity, etc. This method is called the
 *   first time that the serial port is opened.
 *
 ****************************************************************************/

static int up_setup(struct uart_dev_s *dev)
{
#ifndef CONFIG_SUPPRESS_UART_CONFIG
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;

  /* enable clock */

  up_enable_uart(priv, true);

  /* Disable interrupts */

  priv->ier = 0;
  up_serialout(priv, MPFS_UART_IER_OFFSET, 0);
  up_serialout(priv, MPFS_UART_IEM_OFFSET, 0);

  /* Clear fifos */

  up_serialout(priv, MPFS_UART_FCR_OFFSET,
              (UART_FCR_RFIFOR | UART_FCR_XFIFOR));

  /* set filter to minimum value */

  up_serialout(priv, MPFS_UART_GFR_OFFSET, 0);

  /* set default TX time guard */

  up_serialout(priv, MPFS_UART_TTG_OFFSET, 0);

  /* Configure the UART line format and speed. */

  up_set_format(dev);

  /* Configure the FIFOs */

  up_serialout(priv, MPFS_UART_FCR_OFFSET,
               (UART_FCR_RT_HALF | UART_FCR_XFIFOR | UART_FCR_RFIFOR |
                UART_FCR_FIFOE));

  /* Enable Auto-Flow Control in the Modem Control Register */

#if defined(CONFIG_SERIAL_IFLOWCONTROL) || defined(CONFIG_SERIAL_OFLOWCONTROL)
#  warning Missing logic
#endif

#endif
  return OK;
}

/****************************************************************************
 * Name: up_shutdown
 *
 * Description:
 *   Disable the UART.  This method is called when the serial port is closed
 *
 ****************************************************************************/

static void up_shutdown(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;

  /* Disable interrupts */

  up_disableuartint(priv, NULL);

  up_enable_uart(priv, false);
}

/****************************************************************************
 * Name: up_attach
 *
 * Description:
 *   Configure the UART to operation in interrupt driven mode. This method is
 *   called when the serial port is opened.  Normally, this is just after the
 *   the setup() method is called, however, the serial console may operate in
 *   a non-interrupt driven mode during the boot phase.
 *
 *   RX and TX interrupts are not enabled by the attach method (unless the
 *   hardware supports multiple levels of interrupt enabling).  The RX and TX
 *   interrupts are not enabled until the txint() and rxint() are called.
 *
 ****************************************************************************/

static int up_attach(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  int ret;

  /* Attach and enable the IRQ */

  ret = irq_attach(priv->irq, uart_interrupt, dev);
  if (ret == OK)
    {
      /* Enable the interrupt (RX and TX interrupts are still disabled
       * in the UART
       */

      up_enable_irq(priv->irq);
    }

  return ret;
}

/****************************************************************************
 * Name: up_detach
 *
 * Description:
 *   Detach UART interrupts.  This method is called when the serial port is
 *   closed normally just before the shutdown method is called. The exception
 *   is the serial console which is never shutdown.
 *
 ****************************************************************************/

static void up_detach(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;

  /* Disable interrupts */

  up_disable_irq(priv->irq);

  /* Detach from the interrupt */

  irq_detach(priv->irq);
}

/****************************************************************************
 * Name: up_interrupt
 *
 * Description:
 *   This is the UART interrupt handler.  It will be invoked when an
 *   interrupt is received on the 'irq'.  It should call uart_xmitchars or
 *   uart_recvchars to perform the appropriate data transfers.  The
 *   interrupt handling logic must be able to map the 'arg' to the
 *   appropriate uart_dev_s structure in order to call these functions.
 *
 ****************************************************************************/

static int uart_interrupt(int irq, void *context, void *arg)
{
  struct uart_dev_s *dev = (struct uart_dev_s *)arg;
  struct up_dev_s *priv;
  uint32_t status;
  int passes;

  DEBUGASSERT(dev != NULL && dev->priv != NULL);
  priv = (struct up_dev_s *)dev->priv;

  /* Loop until there are no characters to be transferred or,
   * until we have been looping for a long time.
   */

  for (passes = 0; passes < 256; passes++)
    {
      /* Get the current UART status */

      status = up_serialin(priv, MPFS_UART_IIR_OFFSET);

      /* Handle the interrupt by its interrupt ID field */

      switch (status & UART_IIR_IID_MASK)
        {
          /* Handle incoming, receive bytes (with or without timeout) */

          case UART_IIR_IID_RECV:
          case UART_IIR_IID_TIMEOUT:
            {
              uart_recvchars(dev);
              break;
            }

          /* Handle outgoing, transmit bytes */

          case UART_IIR_IID_TXEMPTY:
            {
              uart_xmitchars(dev);
              break;
            }

          /* Just clear modem status interrupts */

          case UART_IIR_IID_MODEM:
            {
              /* Read the modem status register (MSR) to clear */

              status = up_serialin(priv, MPFS_UART_MSR_OFFSET);
              _info("MSR: %02" PRIx32 "\n", status);
              break;
            }

          /* Just clear any line status interrupts */

          case UART_IIR_IID_LINESTATUS:
            {
              /* Read the line status register (LSR) to clear */

              status = up_serialin(priv, MPFS_UART_LSR_OFFSET);
              _info("LSR: %02" PRIx32 "\n", status);
              break;
            }

          /* No further interrupts pending... return now */

          case UART_IIR_IID_NONE:
            {
              return OK;
            }

            /* Otherwise we have received an interrupt
             * that we cannot handle
             */

          default:
            {
              _err("ERROR: Unexpected IIR: %02" PRIx32 "\n", status);
              break;
            }
        }
    }

  return OK;
}

/****************************************************************************
 * Name: up_ioctl
 *
 * Description:
 *   All ioctl calls will be routed through this method
 *
 ****************************************************************************/

static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
{
#if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_SERIAL_TIOCSERGSTRUCT)
  struct inode      *inode = filep->f_inode;
  struct uart_dev_s *dev   = inode->i_private;

  struct up_dev_s   *priv  = (struct up_dev_s *)dev->priv;
#endif

  int                ret   = OK;

  switch (cmd)
    {
#ifdef CONFIG_SERIAL_TIOCSERGSTRUCT
    case TIOCSERGSTRUCT:
      {
        struct up_dev_s *user = (struct up_dev_s *)arg;
        if (!user)
          {
            ret = -EINVAL;
          }
        else
          {
            memcpy(user, dev, sizeof(struct up_dev_s));
          }
      }
      break;
#endif

#ifdef CONFIG_SERIAL_TERMIOS
    case TCGETS:
      {
        struct termios *termiosp = (struct termios *)arg;

        if (!termiosp)
          {
            ret = -EINVAL;
            break;
          }

#ifdef CONFIG_SERIAL_OFLOWCONTROL
#endif
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#endif
        termiosp->c_cflag =
          ((priv->parity != 0) ? PARENB : 0) |
          ((priv->parity == 1) ? PARODD : 0) |
          ((priv->stopbits2) ? CSTOPB : 0) |
          ((priv->bits == 5) ? CS5 : 0) |
          ((priv->bits == 6) ? CS6 : 0) |
          ((priv->bits == 7) ? CS7 : 0) |
          ((priv->bits == 8) ? CS8 : 0);

        cfsetispeed(termiosp, priv->baud);
      }
      break;

    case TCSETS:
      {
        struct termios *termiosp = (struct termios *)arg;

        if (!termiosp)
          {
            ret = -EINVAL;
            break;
          }

        if (termiosp->c_cflag & PARENB)
          {
            priv->parity = (termiosp->c_cflag & PARODD) ? 1 : 2;
          }
        else
          {
            priv->parity = 0;
          }

        priv->stopbits2 = (termiosp->c_cflag & CSTOPB) != 0;

        switch (termiosp->c_cflag & CSIZE)
          {
          case CS5:
            priv->bits = 5;
            break;

          case CS6:
            priv->bits = 6;
            break;

          case CS7:
            priv->bits = 7;
            break;

          case CS8:
            priv->bits = 8;
            break;

          default:
            priv->bits = 0;
            ret = -EINVAL;
            break;
          }

        if (ret == OK)
          {
            /* Note that only cfgetispeed is used because we have knowledge
             * that only one speed is supported.
             */

            priv->baud = cfgetispeed(termiosp);

            /* Effect the changes immediately - note that we do not implement
             * TCSADRAIN / TCSAFLUSH
             */

            up_set_format(dev);
          }
      }
      break;
#endif /* CONFIG_SERIAL_TERMIOS */

      default:
        ret = -ENOTTY;
        break;
    }

    return ret;
}

/****************************************************************************
 * Name: up_receive
 *
 * Description:
 *   Called (usually) from the interrupt level to receive one
 *   character from the UART.  Error bits associated with the
 *   receipt are provided in the return 'status'.
 *
 ****************************************************************************/

static int up_receive(struct uart_dev_s *dev, uint32_t *status)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  uint32_t rbr;

  *status = up_serialin(priv, MPFS_UART_LSR_OFFSET);
  rbr     = up_serialin(priv, MPFS_UART_RBR_OFFSET);
  return rbr;
}

/****************************************************************************
 * Name: up_rxint
 *
 * Description:
 *   Call to enable or disable RX interrupts
 *
 ****************************************************************************/

static void up_rxint(struct uart_dev_s *dev, bool enable)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  if (enable)
    {
#ifndef CONFIG_SUPPRESS_SERIAL_INTS
      priv->ier |= UART_IER_ERBFI;
#endif
    }
  else
    {
      priv->ier &= ~UART_IER_ERBFI;
    }

  up_serialout(priv, MPFS_UART_IER_OFFSET, priv->ier);
}

/****************************************************************************
 * Name: up_rxavailable
 *
 * Description:
 *   Return true if the receive fifo is not empty
 *
 ****************************************************************************/

static bool up_rxavailable(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  return ((up_serialin(priv, MPFS_UART_LSR_OFFSET) & UART_LSR_DR) != 0);
}

/****************************************************************************
 * Name: up_send
 *
 * Description:
 *   This method will send one byte on the UART.
 *
 ****************************************************************************/

static void up_send(struct uart_dev_s *dev, int ch)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;

#ifdef HAVE_SERIAL_CONSOLE
  if (dev == &CONSOLE_DEV && !dev->isconsole)
    {
      return;
    }
#endif

  while ((up_serialin(priv, MPFS_UART_LSR_OFFSET)
          & UART_LSR_THRE) == 0);

  up_serialout(priv, MPFS_UART_THR_OFFSET, (uint32_t)ch);
}

/****************************************************************************
 * Name: up_txint
 *
 * Description:
 *   Call to enable or disable TX interrupts
 *
 ****************************************************************************/

static void up_txint(struct uart_dev_s *dev, bool enable)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  irqstate_t flags;

  flags = enter_critical_section();
  if (enable)
    {
#ifndef CONFIG_SUPPRESS_SERIAL_INTS
      priv->ier |= UART_IER_ETBEI;
      up_serialout(priv, MPFS_UART_IER_OFFSET, priv->ier);

      /* Fake a TX interrupt here by just calling uart_xmitchars() with
       * interrupts disabled (note this may recurse).
       */

      uart_xmitchars(dev);
#endif
    }
  else
    {
      priv->ier &= ~UART_IER_ETBEI;
      up_serialout(priv, MPFS_UART_IER_OFFSET, priv->ier);
    }

  leave_critical_section(flags);
}

/****************************************************************************
 * Name: up_txready
 *
 * Description:
 *   Return true if the transmit data register is not full
 *
 ****************************************************************************/

static bool up_txready(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  return ((up_serialin(priv, MPFS_UART_LSR_OFFSET) & UART_LSR_THRE) != 0);
}

/****************************************************************************
 * Name: up_txempty
 *
 * Description:
 *   Return true if the transmit data register is empty
 *
 ****************************************************************************/

static bool up_txempty(struct uart_dev_s *dev)
{
  struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  return ((up_serialin(priv, MPFS_UART_LSR_OFFSET) & UART_LSR_THRE) != 0);
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

#ifdef USE_EARLYSERIALINIT

/****************************************************************************
 * Name: riscv_earlyserialinit
 *
 * Description:
 *   Performs the low level UART initialization early in debug so that the
 *   serial console will be available during bootup.  This must be called
 *   before riscv_serialinit.  NOTE:  This function depends on
 *   main clock initialization performed in up_clkinitialize().
 *
 ****************************************************************************/

void riscv_earlyserialinit(void)
{
  /* Disable interrupts from all UARTS.  The console is enabled in
   * mpfs_consoleinit().
   */

#ifdef CONFIG_MPFS_UART0
  up_disableuartint(g_uart0port.priv, NULL);
#endif

#ifdef CONFIG_MPFS_UART1
  up_disableuartint(g_uart1port.priv, NULL);
#endif

#ifdef CONFIG_MPFS_UART2
  up_disableuartint(g_uart2port.priv, NULL);
#endif

#ifdef CONFIG_MPFS_UART3
  up_disableuartint(g_uart3port.priv, NULL);
#endif

#ifdef CONFIG_MPFS_UART4
  up_disableuartint(g_uart4port.priv, NULL);
#endif

  /* Configuration whichever one is the console */

#ifdef HAVE_SERIAL_CONSOLE
  CONSOLE_DEV.isconsole = true;
  up_setup(&CONSOLE_DEV);
#endif
}
#endif

/****************************************************************************
 * Name: riscv_serialinit
 *
 * Description:
 *   Register serial console and serial ports.  This assumes
 *   that riscv_earlyserialinit was called previously.
 *
 ****************************************************************************/

void riscv_serialinit(void)
{
  /* Register the console */

#ifdef HAVE_SERIAL_CONSOLE
  uart_register("/dev/console", &CONSOLE_DEV);
#endif

  /* Register all UARTs NOTE: we don't reorganize the numbering */

#ifdef CONFIG_MPFS_UART0
  uart_register("/dev/ttyS0", &g_uart0port);
#endif
#ifdef CONFIG_MPFS_UART1
  uart_register("/dev/ttyS1", &g_uart1port);
#endif
#ifdef CONFIG_MPFS_UART2
  uart_register("/dev/ttyS2", &g_uart2port);
#endif
#ifdef CONFIG_MPFS_UART3
  uart_register("/dev/ttyS3", &g_uart3port);
#endif
#ifdef CONFIG_MPFS_UART4
  uart_register("/dev/ttyS4", &g_uart4port);
#endif
}

/****************************************************************************
 * Name: up_putc
 *
 * Description:
 *   Provide priority, low-level access to support OS debug  writes
 *
 ****************************************************************************/

int up_putc(int ch)
{
#ifdef HAVE_SERIAL_CONSOLE
  struct up_dev_s *priv = (struct up_dev_s *)CONSOLE_DEV.priv;
  uint32_t ier;

  if (!CONSOLE_DEV.isconsole)
    {
      return ch;
    }

  up_disableuartint(priv, &ier);
#endif

  /* Check for LF */

  if (ch == '\n')
    {
      /* Add CR */

      riscv_lowputc('\r');
    }

  riscv_lowputc(ch);
#ifdef HAVE_SERIAL_CONSOLE
  up_restoreuartint(priv, ier);
#endif
  return ch;
}

/****************************************************************************
 * Name: riscv_earlyserialinit, riscv_serialinit, and up_putc
 *
 * Description:
 *   stubs that may be needed.  These stubs would be used if all UARTs are
 *   disabled.  In that case, the logic in common/up_initialize() is not
 *   smart enough to know that there are not UARTs and will still expect
 *   these interfaces to be provided.
 *
 ****************************************************************************/

#else /* HAVE_UART_DEVICE */
void riscv_earlyserialinit(void)
{
}

void riscv_serialinit(void)
{
}

int up_putc(int ch)
{
  return ch;
}

#endif /* HAVE_UART_DEVICE */
#else /* USE_SERIALDRIVER */

/****************************************************************************
 * Name: up_putc
 *
 * Description:
 *   Provide priority, low-level access to support OS debug writes
 *
 ****************************************************************************/

int up_putc(int ch)
{
#ifdef HAVE_SERIAL_CONSOLE
  /* Check for LF */

  if (ch == '\n')
    {
      /* Add CR */

      riscv_lowputc('\r');
    }

  riscv_lowputc(ch);
#endif
  return ch;
}

#endif /* USE_SERIALDRIVER */