source: rtems/c/src/lib/libbsp/arm/raspberrypi/console/usart.c @ c32b1ef

/*
 * Copyright (c) 2013 Alan Cudmore
 *
 *  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/raspberrypi.h>

static void usart_delay(uint32_t n)
{
   volatile uint32_t i = 0;
   for(i = 0; i < n; i++);
}

static rtems_vector_number usart_get_irq_number(const console_tbl *ct)
{
   return ct->ulIntVector;
}

static uint32_t usart_get_baud(const console_tbl *ct)
{
   return ct->ulClock;
}

static void usart_set_baud(int minor, int baud)
{
   /*
   ** Nothing for now
   */
   return;
}

static void usart_initialize(int minor)
{
   unsigned int gpio_reg;

   /*
   ** Program GPIO pins for UART 0
   */
   gpio_reg = BCM2835_REG(BCM2835_GPIO_GPFSEL1);
   gpio_reg &= ~(7<<12);    /* gpio14 */
   gpio_reg |=  (4<<12);    /* alt0   */
   gpio_reg &= ~(7<<15);    /* gpio15 */
   gpio_reg |=  (4<<15);    /* alt0   */
   BCM2835_REG(BCM2835_GPIO_GPFSEL1) = gpio_reg;

   BCM2835_REG(BCM2835_GPIO_GPPUD) = 0;
   usart_delay(150);
   BCM2835_REG(BCM2835_GPIO_GPPUDCLK0) = (1<<14)|(1<<15);
   usart_delay(150);
   BCM2835_REG(BCM2835_GPIO_GPPUDCLK0) = 0;

   /*
   ** Init the PL011 UART
   */
   BCM2835_REG(BCM2835_UART0_CR)   = 0;
   BCM2835_REG(BCM2835_UART0_ICR)  = 0x7FF;
   BCM2835_REG(BCM2835_UART0_IMSC) = 0;
   BCM2835_REG(BCM2835_UART0_IBRD) = 1;
   BCM2835_REG(BCM2835_UART0_FBRD) = 40;
   BCM2835_REG(BCM2835_UART0_LCRH) = 0x70;
   BCM2835_REG(BCM2835_UART0_RSRECR) =  0;

   BCM2835_REG(BCM2835_UART0_CR)   = 0x301;

   BCM2835_REG(BCM2835_UART0_IMSC) = BCM2835_UART0_IMSC_RX;

   usart_set_baud(minor, 115000);

}

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)
{
   if (minor == 0)
   {
      if(((BCM2835_REG(BCM2835_UART0_FR)) & BCM2835_UART0_FR_RXFE) == 0)
      {
         return((BCM2835_REG(BCM2835_UART0_DR)) & 0xFF );
      }
      else
      {
         return -1;
      }
   }
   else
   {
      printk("Unknown console minor number: %d\n", minor);
      return -1;
   }

}

static void usart_write_polled(int minor, char c)
{
   while (1)
   {
      if ((BCM2835_REG(BCM2835_UART0_FR) & BCM2835_UART0_FR_TXFF) == 0) break;
   }
   BCM2835_REG(BCM2835_UART0_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;
}

const console_fns bcm2835_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
};