source: rtems/bsps/arm/csb337/console/usart.c

/*
 *  Driver for AT91RM9200 USART ports
 */

/*
 * COPYRIGHT (c) 2006-2009.
 * NCB - Sistemas Embarcados Ltda. (Brazil)
 * Fernando Nicodemos <fgnicodemos@terra.com.br>
 *
 * and
 *
 * COPYRIGHT (c) 1989-2009.
 * On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.org/license/LICENSE.
*/

#include <bsp.h>
#include <rtems/libio.h>
#include <termios.h>

#include <at91rm9200.h>
#include <at91rm9200_usart.h>
#include <at91rm9200_pmc.h>
#include <rtems/bspIo.h>
#include <libchip/serial.h>
#include <libchip/sersupp.h>

/* static function prototypes */
static int     usart_first_open(int major, int minor, void *arg);
static int     usart_last_close(int major, int minor, void *arg);
static int     usart_read_polled(int minor);
static ssize_t usart_write_polled_support(int minor, const char *buf, size_t len);
static void    usart_init(int minor);
static void    usart_write_polled(int minor, char c);
static int     usart_set_attributes(int minor, const struct termios *t);
at91rm9200_usart_regs_t *usart_get_base(int minor);

/* Pointers to functions for handling the UART polled. */
const console_fns usart_polling_fns = {
  libchip_serial_default_probe,       /* deviceProbe */
  usart_first_open,                   /* deviceFirstOpen */
  usart_last_close,                   /* deviceLastClose */
  usart_read_polled,                  /* deviceRead */
  usart_write_polled_support,         /* deviceWrite */
  usart_init,                         /* deviceInitialize */
  usart_write_polled,                 /* deviceWritePolled */
  usart_set_attributes,               /* deviceSetAttributes */
  FALSE                 /* TRUE if interrupt driven, FALSE if not. */
};

at91rm9200_usart_regs_t *usart_get_base(int minor)
{
  console_tbl *console_entry;
  at91rm9200_usart_regs_t *port;

  console_entry = BSP_get_uart_from_minor(minor);

  if (console_entry == NULL)
    return 0;

  port = (at91rm9200_usart_regs_t *) console_entry->ulCtrlPort1;
  //printk( "minor=%d entry=%p port=%p\n", minor, console_entry, port );

  return port;
}

/*
 * Functions called via callbacks (i.e. the ones in uart_fns
 */

/*
 * This is called the first time each device is opened. Since
 * the driver is polled, we don't have to do anything. If the driver
 * were interrupt driven, we'd enable interrupts here.
 */
static int usart_first_open(int major, int minor, void *arg)
{
  at91rm9200_usart_regs_t *usart;

  usart = usart_get_base(minor);
  if ( !usart )
    return -1;

  /* XXX port isn't being initialized or enabled */

  /* XXX I hope this is enough */
  usart->cr = (US_CR_RXEN | US_CR_TXEN);
  return 0;
}

/*
 * This is called the last time each device is closed.  Since
 * the driver is polled, we don't have to do anything. If the driver
 * were interrupt driven, we'd disable interrupts here.
 */
static int usart_last_close(int major, int minor, void *arg)
{
  at91rm9200_usart_regs_t *usart;

  usart = usart_get_base(minor);
  if ( !usart )
    return -1;

  return 0;
}

/*
 * Read one character from UART.
 *
 * return -1 if there's no data, otherwise return
 * the character in lowest 8 bits of returned int.
 */
static int usart_read_polled(int minor)
{
  at91rm9200_usart_regs_t *usart;

  usart = usart_get_base(minor);
  if ( !usart )
    return -1;

  /* if nothing ready return -1 */
  if ( (usart->sr & US_IER_RXRDY) == 0 )
    return -1;

  return usart->rhr;
}


/*
 *  Write character out
 */
static void usart_write_polled(int minor, char c)
{
  at91rm9200_usart_regs_t *usart;

  usart = usart_get_base(minor);
  if ( !usart )
    return;

  /* delay until TX empty */
  while ( (usart->sr & US_IER_TXEMPTY) == 0 )
    ;

  usart->thr = c;
}

/*
 * Write buffer to UART
 *
 * return 1 on success, -1 on error
 */
static ssize_t usart_write_polled_support(int minor, const char *buf, size_t len)
{
  at91rm9200_usart_regs_t *usart;
  int nwrite=0;

  /*
   *  Verify the minor number
   */
  usart = usart_get_base(minor);
  if ( !usart )
    return -1;

  /*
   * poll each byte in the string out of the port.
   */
  while (nwrite < len) {
    usart_write_polled(minor, *buf++);
    nwrite++;
  }

  /*
   * return the number of bytes written.
   */
  return nwrite;

  return 1;
}


/* Set up the UART. */
static void usart_init(int minor)
{
  at91rm9200_usart_regs_t *usart;

  usart = usart_get_base(minor);
  if ( !usart )
    return;

}


/* This is for setting baud rate, bits, etc. */
static int usart_set_attributes(int minor, const struct termios *t)
{
  uint32_t      brgr;
  uint32_t      mode, baud, baud_requested;
  at91rm9200_usart_regs_t *usart;

  usart = usart_get_base(minor);
  if ( !usart )
    return -1;

  /* Get current mode register */
  mode = usart->mr & ~(US_MR_USMODE | US_MR_USCLKS | US_MR_CHRL
                        | US_MR_PAR | US_MR_NBSTOP);

  /* Byte size */
  switch (t->c_cflag & CSIZE){
  case CS5:
    mode |= US_MR_CHRL_5;
    break;
  case CS6:
    mode |= US_MR_CHRL_6;
    break;
  case CS7:
    mode |= US_MR_CHRL_7;
    break;
  default:
    mode |= US_MR_CHRL_8;
    break;
  }

  /* Stop bits */
  if (t->c_cflag & CSTOPB){
        mode |= US_MR_NBSTOP_2; /* 2 stop bits */
  } else
    mode |= US_MR_NBSTOP_1;     /* 1 stop bits */

  /* Parity */
  if (t->c_cflag & PARENB){
      /* Mark or Space parity */
      if (t->c_cflag & PARODD){
        mode |= US_MR_PAR_ODD;
      } else
        mode |= US_MR_PAR_EVEN;
   } else
        mode |= US_MR_PAR_NONE;

  baud_requested = t->c_ospeed;

  /* If not, set the dbgu console baud as USART baud default */
  if (!baud_requested)
    baud_requested = BSP_get_baud();

  baud = rtems_termios_baud_to_number(baud_requested);

  brgr = (at91rm9200_get_mck() / 16) / baud;

        if (brgr > 65535){    /* BRGR is 16-bit, so switch to slower clock */
                brgr /= 8;
                mode |= US_MR_USCLKS_MCK_DIV8;
        }

  usart->mr = mode;
  usart->brgr = brgr;
  return 0;
}