text: /****************************************************************************
   * arch/risc-v/src/k210/k210_serial.c
   *
   *   Copyright (C) 2019 Masayuki Ishikawa. All rights reserved.
   *   Author: Masayuki Ishikawa <masayuki.ishikawa@gmail.com>
   *
   * 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.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * 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.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <stdbool.h>
  #include <unistd.h>
  #include <string.h>
  #include <errno.h>
  #include <debug.h>
  
  #include <nuttx/irq.h>
  #include <nuttx/arch.h>
  #include <nuttx/serial/serial.h>
  
  #include <arch/board/board.h>
  
  #include "riscv_arch.h"
  #include "riscv_internal.h"
  
  #include "k210_config.h"
  #include "chip.h"
  #include "k210.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 TTYS0_DEV       g_uart0port     /* UART0 is ttyS0 */
  #    undef  TTYS1_DEV                       /* No ttyS1 */
  #    define SERIAL_CONSOLE  1
  #  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
  #  if defined(CONFIG_K210_UART0)
  #    define TTYS0_DEV       g_uart0port     /* UART0 is ttyS0 */
  #    undef  TTYS1_DEV                       /* No ttyS1 */
  #    define SERIAL_CONSOLE  1
  #  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 up_earlyserialinit(), up_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 */
    uint8_t   irq;      /* IRQ associated with this UART */
    uint8_t   im;       /* Interrupt mask state */
  };
  
  /****************************************************************************
   * Private Function Prototypes
   ****************************************************************************/
  
  /* Low-level helpers */
  
  static uint32_t up_serialin(struct up_dev_s *priv, int offset);
  static void up_serialout(struct up_dev_s *priv, int offset, uint32_t value);
  static void up_restoreuartint(struct up_dev_s *priv, uint8_t im);
  static void up_disableuartint(struct up_dev_s *priv, uint8_t *im);
  
  /* Serial driver methods */
  
  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  up_interrupt(int irq, void *context, FAR void *arg);
  static int  up_ioctl(struct file *filep, int cmd, unsigned long arg);
  static int  up_receive(struct uart_dev_s *dev, uint32_t *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_K210_UART0
  static char g_uart0rxbuffer[CONFIG_UART0_RXBUFSIZE];
  static char g_uart0txbuffer[CONFIG_UART0_TXBUFSIZE];
  static uint32_t g_rxdata;
  #endif
  
  #ifdef CONFIG_K210_UART0
  static struct up_dev_s g_uart0priv =
  {
    .uartbase  = K210_UART0_BASE,
    .baud      = CONFIG_UART0_BAUD,
    .irq       = K210_IRQ_UART0,
  };
  
  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
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: up_serialin
   ****************************************************************************/
  
  static uint32_t up_serialin(struct up_dev_s *priv, int offset)
  {
    return getreg32(priv->uartbase + offset);
  }
  
  /****************************************************************************
   * Name: up_serialout
   ****************************************************************************/
  
  static void up_serialout(struct up_dev_s *priv, int offset, uint32_t value)
  {
    putreg32(value, priv->uartbase + offset);
  }
  
  /****************************************************************************
   * Name: up_restoreuartint
   ****************************************************************************/
  
  static void up_restoreuartint(struct up_dev_s *priv, uint8_t im)
  {
    irqstate_t flags = enter_critical_section();
  
    priv->im = im;
    up_serialout(priv, UART_IE_OFFSET, im);
  
    leave_critical_section(flags);
  }
  
  /****************************************************************************
   * Name: up_disableuartint
   ****************************************************************************/
  
  static void up_disableuartint(struct up_dev_s *priv, uint8_t *im)
  {
    irqstate_t flags = enter_critical_section();
  
    /* Return the current interrupt mask value */
  
    if (im)
      {
       *im = priv->im;
      }
  
    /* Disable all interrupts */
  
    priv->im = 0;
    up_serialout(priv, UART_IE_OFFSET, 0);
    leave_critical_section(flags);
  }
  
  /****************************************************************************
   * 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)
  {
    struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  
  #if 0 /* TODO: Setup divisor */
  #endif
  
    /* Enable RX */
  
    up_serialout(priv, UART_RXCTL_OFFSET, 1);
  
    /* Set TX watermark level to 1 and enable TX */
  
    up_serialout(priv, UART_TXCTL_OFFSET, 1 << 16 | 1);
  
    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);
  }
  
  /****************************************************************************
   * 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;
  
    /* Initialize interrupt generation on the peripheral */
  
    up_serialout(priv, UART_IE_OFFSET, UART_IE_TXWM | UART_IE_RXWM);
  
    ret = irq_attach(priv->irq, up_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 received on the 'irq'  It should call uart_transmitchars or
   *   uart_receivechar to perform the appropriate data transfers.  The
   *   interrupt handling logic must be able to map the 'irq' number into the
   *   appropriate uart_dev_s structure in order to call these functions.
   *
   ****************************************************************************/
  
  static int up_interrupt(int irq, void *context, FAR 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++)
      {
        /* Retrieve interrupt pending status */
  
        status = up_serialin(priv, UART_IP_OFFSET);
  
        if (status == 0)
          {
            break;
          }
  
        if (status & UART_IP_RXWM)
          {
            /* Process incoming bytes */
  
            uart_recvchars(dev);
          }
  
        if (status & UART_IP_TXWM)
          {
            /* Process outgoing bytes */
  
            uart_xmitchars(dev);
          }
      }
  
    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)
  {
    return -ENOTTY;
  }
  
  /****************************************************************************
   * 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)
  {
    /* Return status information */
  
    if (status)
      {
        *status = 0; /* We are not yet tracking serial errors */
      }
  
    /* Return cached data */
  
    return g_rxdata;
  }
  
  /****************************************************************************
   * 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;
    irqstate_t flags = enter_critical_section();
  
    if (enable)
      {
  #ifndef CONFIG_SUPPRESS_SERIAL_INTS
        priv->im |= UART_IE_RXWM;
  #endif
      }
    else
      {
        priv->im &= ~UART_IE_RXWM;
      }
  
    up_serialout(priv, UART_IE_OFFSET, priv->im);
    leave_critical_section(flags);
  }
  
  /****************************************************************************
   * Name: up_rxavailable
   *
   * Description:
   *   Return true if the receive register is not empty
   *
   ****************************************************************************/
  
  static bool up_rxavailable(struct uart_dev_s *dev)
  {
    struct up_dev_s *priv = (struct up_dev_s *)dev->priv;
  
    /* Return true is data is available in the receive data buffer */
  
    uint32_t rxdata = up_serialin(priv, UART_RXDATA_OFFSET);
  
    /* NOTE: In K210, actual data is also retrieved */
  
    g_rxdata = rxdata & 0xff;
  
    return (rxdata & UART_RX_EMPTY) == 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;
    up_serialout(priv, UART_TXDATA_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)
      {
        /* Enable the TX interrupt */
  
  #ifndef CONFIG_SUPPRESS_SERIAL_INTS
        priv->im |= UART_IE_TXWM;
        up_serialout(priv, UART_IE_OFFSET, priv->im);
  
        /* Fake a TX interrupt here by just calling uart_xmitchars() with
         * interrupts disabled (note this may recurse).
         */
  
        uart_xmitchars(dev);
  #endif
      }
    else
      {
        /* Disable the TX interrupt */
  
        priv->im &= ~UART_IE_TXWM;
        up_serialout(priv, UART_IE_OFFSET, priv->im);
      }
  
    leave_critical_section(flags);
  }
  
  /****************************************************************************
   * Name: up_txready
   *
   * Description:
   *   Return true if the tranmsit 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 TRUE if the TX FIFO is not full */
  
    return (up_serialin(priv, UART_TXDATA_OFFSET) & UART_TX_FULL) == 0;
  }
  
  /****************************************************************************
   * Name: up_txempty
   *
   * Description:
   *   Return true if the tranmsit 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 TRUE if the TX wartermak is pending */
  
    return (up_serialin(priv, UART_IP_OFFSET) & UART_IP_TXWM) == 1;
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  #ifdef USE_EARLYSERIALINIT
  
  /****************************************************************************
   * Name: up_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 up_serialinit.  NOTE:  This function depends on GPIO pin
   *   configuration performed in up_consoleinit() and main clock iniialization
   *   performed in up_clkinitialize().
   *
   ****************************************************************************/
  
  void up_earlyserialinit(void)
  {
    /* Disable interrupts from all UARTS.  The console is enabled in
     * k210_consoleinit().
     */
  
    up_disableuartint(TTYS0_DEV.priv, NULL);
  #ifdef TTYS1_DEV
    up_disableuartint(TTYS1_DEV.priv, NULL);
  #endif
  
    /* Configuration whichever one is the console */
  
  #ifdef HAVE_SERIAL_CONSOLE
    CONSOLE_DEV.isconsole = true;
    up_setup(&CONSOLE_DEV);
  #endif
  }
  #endif
  
  /****************************************************************************
   * Name: up_serialinit
   *
   * Description:
   *   Register serial console and serial ports.  This assumes
   *   that up_earlyserialinit was called previously.
   *
   ****************************************************************************/
  
  void up_serialinit(void)
  {
    /* Register the console */
  
  #ifdef HAVE_SERIAL_CONSOLE
    uart_register("/dev/console", &CONSOLE_DEV);
  #endif
  
    /* Register all UARTs */
  
    uart_register("/dev/ttyS0", &TTYS0_DEV);
  #ifdef TTYS1_DEV
    uart_register("/dev/ttyS1", &TTYS1_DEV);
  #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;
    uint8_t imr;
  
    up_disableuartint(priv, &imr);
  
    /* Check for LF */
  
    if (ch == '\n')
      {
        /* Add CR */
  
        up_lowputc('\r');
      }
  
    up_lowputc(ch);
    up_restoreuartint(priv, imr);
  #endif
    return ch;
  }
  
  /****************************************************************************
   * Name: up_earlyserialinit, up_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 up_earlyserialinit(void)
  {
  }
  
  void up_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 */
  
        up_lowputc('\r');
      }
  
    up_lowputc(ch);
  #endif
    return ch;
  }
  
  #endif /* USE_SERIALDRIVER */
  