path: root/c/src/lib/libbsp/sparc/shared/can/grcan.c

/*
 *  GRCAN driver
 *
 *  COPYRIGHT (c) 2007.
 *  Gaisler Research.
 *
 *  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.
 *
 *
 *  2007-06-13, Daniel Hellstrom <daniel@gaisler.com>
 *    New driver in sparc shared directory. Parts taken
 *    from rasta grhcan driver.
 *
 */

#include <bsp.h>
#include <rtems/libio.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>
#include <rtems/bspIo.h>

#include <grcan.h>
#include <ambapp.h>
#include <grlib.h>

#define WRAP_AROUND_TX_MSGS 1
#define WRAP_AROUND_RX_MSGS 2
#define GRCAN_MSG_SIZE sizeof(struct grcan_msg)
#define BLOCK_SIZE (16*4)

/* Default Maximium buffer size for statically allocated buffers */
#ifndef TX_BUF_SIZE
#define TX_BUF_SIZE (BLOCK_SIZE*16)
#endif

/* Make receiver buffers bigger than transmitt */
#ifndef RX_BUF_SIZE
#define RX_BUF_SIZE ((3*BLOCK_SIZE)*16)
#endif

#ifndef IRQ_GLOBAL_PREPARE
 #define IRQ_GLOBAL_PREPARE(level) rtems_interrupt_level level
#endif

#ifndef IRQ_GLOBAL_DISABLE
 #define IRQ_GLOBAL_DISABLE(level) rtems_interrupt_disable(level)
#endif

#ifndef IRQ_GLOBAL_ENABLE
 #define IRQ_GLOBAL_ENABLE(level) rtems_interrupt_enable(level)
#endif

#ifndef IRQ_CLEAR_PENDING
 #define IRQ_CLEAR_PENDING(irqno)
#endif

#ifndef IRQ_UNMASK
 #define IRQ_UNMASK(irqno)
#endif

#ifndef IRQ_MASK
 #define IRQ_MASK(irqno)
#endif

#ifndef GRCAN_PREFIX
 #define GRCAN_PREFIX(name) grcan##name
#endif

#ifndef MEMAREA_TO_HW
  #define MEMAREA_TO_HW(x) (x)
#endif

/* default name to /dev/grcan0 */
#if !defined(GRCAN_DEVNAME) || !defined(GRCAN_DEVNAME_NO)
 #undef GRCAN_DEVNAME
 #undef GRCAN_DEVNAME_NO
 #define GRCAN_DEVNAME "/dev/grcan0"
 #define GRCAN_DEVNAME_NO(devstr,no) ((devstr)[10]='0'+(no))
#endif

#ifndef GRCAN_REG_INT
 #define GRCAN_REG_INT(handler,irqno,arg) set_vector(handler,irqno+0x10,1)
 #undef  GRCAN_DEFINE_INTHANDLER
 #define GRCAN_DEFINE_INTHANDLER
#endif

#ifndef GRCAN_DEFAULT_BAUD
  /* default to 500kbits/s */
  #define GRCAN_DEFAULT_BAUD 500000
#endif

#ifndef GRCAN_SAMPLING_POINT
#define GRCAN_SAMPLING_POINT 80
#endif

/* Uncomment for debug output */
/****************** DEBUG Definitions ********************/
#define DBG_IOCTRL 1
#define DBG_TX 2
#define DBG_RX 4

#define DEBUG_FLAGS (DBG_IOCTRL | DBG_RX | DBG_TX )
/*
#define DEBUG
#define DEBUGFUNCS
*/
#include <debug_defs.h>

/*********************************************************/

/* grcan needs to have it buffers aligned to 1k boundaries */
#define BUFFER_ALIGNMENT_NEEDS 1024

#ifdef STATICALLY_ALLOCATED_TX_BUFFER
static unsigned int tx_circbuf[GRCAN_MAX_CORES][TX_BUF_SIZE]
	__attribute__ ((aligned(BUFFER_ALIGNMENT_NEEDS)));
#define STATIC_TX_BUF_SIZE TX_BUF_SIZE
#define STATIC_TX_BUF_ADDR(core) (&tx_circbuf[(core)][0])
#endif

#ifdef STATICALLY_ALLOCATED_RX_BUFFER
static unsigned int rx_circbuf[GRCAN_MAX_CORES][RX_BUF_SIZE]
	__attribute__ ((aligned(BUFFER_ALIGNMENT_NEEDS)));
#define STATIC_RX_BUF_SIZE RX_BUF_SIZE
#define STATIC_RX_BUF_ADDR(core) (&rx_circbuf[(core)][0])
#endif

/*
 * If USE_AT697_RAM is defined the RAM on the AT697 board will be used for DMA buffers (but rx message queue is always in AT697 ram).
 * USE_AT697_DMA specifies whether the messages will be fetched using DMA or PIO.
 *
 * RASTA_PCI_BASE is the base address of the GRPCI AHB slave
 *
 * GRCAN_BUF_SIZE must be set to the size (in bytes) of the GRCAN DMA buffers.
 *
 * RX_QUEUE_SIZE defines the number of messages that fits in the  RX message queue. On RX interrupts the messages in the DMA buffer
 * are copied into the message queue (using dma if the rx buf is not in the AT697 ram).
 */

/*#define USE_AT697_RAM              1      */
#define USE_AT697_DMA              1
#define RASTA_PCI_BASE             0xe0000000
#define GRCAN_BUF_SIZE            4096
#define RX_QUEUE_SIZE              1024

#define INDEX(x) ( x&(RX_QUEUE_SIZE-1) )

/* pa(x)
 *
 * x: address in AT697 address space
 *
 * returns the address in the RASTA address space that can be used to access x with dma.
 *
*/
#ifdef USE_AT697_RAM
static inline unsigned int pa(unsigned int addr) {
    return ((addr & 0x0fffffff) | RASTA_PCI_BASE);
}
#else
static inline unsigned int pa(unsigned int addr) {
    return ((addr & 0x0fffffff) | 0x40000000);
}
#endif

struct grcan_msg {
    unsigned int head[2];
    unsigned char data[8];
};

struct grcan_config {
	struct grcan_timing timing;
	struct grcan_selection selection;
	int abort;
	int silent;
};

struct grcan_priv {
  unsigned int baseaddr, ram_base;
  struct grcan_regs *regs;
  int irq;
  int minor;
  int open;
  int started;
  unsigned int channel;
  int flushing;
  unsigned int corefreq_hz;

  /* Circular DMA buffers */
  void *_rx;
  void *_tx;
  struct grcan_msg *rx;
  struct grcan_msg *tx;
  unsigned int rxbuf_size;    /* requested RX buf size in bytes */
  unsigned int txbuf_size;    /* requested TX buf size in bytes */

  int txblock, rxblock;
  int txcomplete, rxcomplete;
  int txerror, rxerror;

  struct grcan_filter sfilter;
  struct grcan_filter afilter;
  int config_changed; /* 0=no changes, 1=changes ==> a Core reset is needed */
  struct grcan_config config;
  struct grcan_stats stats;

  rtems_id rx_sem, tx_sem, txempty_sem, dev_sem;
};

static int grcan_core_cnt;
struct grcan_priv *grcans;
static struct ambapp_bus *amba_bus;
struct grcan_device_info *grcan_cores;
static int grcan_core_cnt;

static rtems_device_driver grcan_initialize(rtems_device_major_number  major, rtems_device_minor_number  minor, void *arg);
static rtems_device_driver grcan_open(rtems_device_major_number major, rtems_device_minor_number minor, void *arg);
static rtems_device_driver grcan_close(rtems_device_major_number major, rtems_device_minor_number minor, void *arg);
static rtems_device_driver grcan_read(rtems_device_major_number major, rtems_device_minor_number minor, void *arg);
static rtems_device_driver grcan_write(rtems_device_major_number major, rtems_device_minor_number minor, void *arg);
static rtems_device_driver grcan_ioctl(rtems_device_major_number major, rtems_device_minor_number minor, void *arg);

#define GRCAN_DRIVER_TABLE_ENTRY { grcan_initialize, grcan_open, grcan_close, grcan_read, grcan_write, grcan_ioctl }

static unsigned int grcan_hw_read_try(
  struct grcan_priv *pDev,
  struct grcan_regs *regs,
  CANMsg *buffer,
  int max);

static unsigned int grcan_hw_write_try(
  struct grcan_priv *pDev,
  struct grcan_regs *regs,
  CANMsg *buffer,
  int count);

static void grcan_hw_config(
  struct grcan_regs *regs,
  struct grcan_config *conf);

static void grcan_hw_accept(
  struct grcan_regs *regs,
  struct grcan_filter *afilter);

static void grcan_hw_sync(
  struct grcan_regs *regs,
  struct grcan_filter *sfilter);

#ifndef GRCAN_DONT_DECLARE_IRQ_HANDLER
static rtems_isr grcan_interrupt_handler(rtems_vector_number v);
#endif

static void grcan_interrupt(struct grcan_priv *pDev);

#ifdef GRCAN_REG_BYPASS_CACHE
#define READ_REG(address) _grcan_read_nocache((unsigned int)(address))
#else
#define READ_REG(address) (*(volatile unsigned int *)(address))
#endif

#ifdef GRCAN_DMA_BYPASS_CACHE
#define READ_DMA_WORD(address) _grcan_read_nocache((unsigned int)(address))
#define READ_DMA_BYTE(address) _grcan_read_nocache_byte((unsigned int)(address))
static unsigned char __inline__ _grcan_read_nocache_byte(unsigned int address)
{
  unsigned char tmp;
  __asm__ (" lduba [%1]1, %0 "
    : "=r"(tmp)
    : "r"(address)
  );
  return tmp;
}
#else
#define READ_DMA_WORD(address) (*(volatile unsigned int *)(address))
#define READ_DMA_BYTE(address) (*(volatile unsigned char *)(address))
#endif

#if defined(GRCAN_REG_BYPASS_CACHE) || defined(GRCAN_DMA_BYPASS_CACHE)
static unsigned int __inline__ _grcan_read_nocache(unsigned int address)
{
  unsigned int tmp;
  __asm__ (" lda [%1]1, %0 "
    : "=r"(tmp)
    : "r"(address)
  );
  return tmp;
}
#endif


static rtems_driver_address_table grcan_driver = GRCAN_DRIVER_TABLE_ENTRY;

static void __inline__ grcan_hw_reset(struct grcan_regs *regs)
{
	regs->ctrl = GRCAN_CTRL_RESET;
}

static rtems_device_driver grcan_start(struct grcan_priv *pDev)
{
  /*
   * tmp is set but never used. GCC gives a warning for this
   * and we need to tell GCC not to complain.
   */
  unsigned int tmp RTEMS_COMPILER_UNUSED_ATTRIBUTE;

  IRQ_GLOBAL_PREPARE(oldLevel);

  FUNCDBG();

  /* Check that memory has been allocated successfully */
  if ( !pDev->tx || !pDev->rx )
    return RTEMS_NO_MEMORY;

  /* Configure FIFO configuration register
   * and Setup timing
   */
  if ( pDev->config_changed ){
    grcan_hw_config(pDev->regs,&pDev->config);
    pDev->config_changed = 0;
  }

  /* Setup receiver */
  pDev->regs->rx0addr = MEMAREA_TO_HW((unsigned int)pDev->rx);
  pDev->regs->rx0size = pDev->rxbuf_size;

  /* Setup Transmitter */
  pDev->regs->tx0addr = MEMAREA_TO_HW((unsigned int)pDev->tx);
  pDev->regs->tx0size = pDev->txbuf_size;

  /* Setup acceptance filters */
  grcan_hw_accept(pDev->regs,&pDev->afilter);

  /* Sync filters */
  grcan_hw_sync(pDev->regs,&pDev->sfilter);

  /* Clear status bits */
  tmp = READ_REG(&pDev->regs->stat);
  pDev->regs->stat = 0;

  /* Setup IRQ handling */

  /* Clear all IRQs */
  tmp = READ_REG(&pDev->regs->pir);
  pDev->regs->picr = 0x1ffff;

  /* unmask TxLoss|TxErrCntr|RxErrCntr|TxAHBErr|RxAHBErr|OR|OFF|PASS */
  pDev->regs->imr = 0x1601f;

  /* Enable routing of the IRQs */
  IRQ_GLOBAL_DISABLE(oldLevel);
  IRQ_UNMASK(pDev->irq+GRCAN_IRQ_TXSYNC);
  IRQ_UNMASK(pDev->irq+GRCAN_IRQ_RXSYNC);
  IRQ_UNMASK(pDev->irq+GRCAN_IRQ_IRQ);
  IRQ_GLOBAL_ENABLE(oldLevel);

  /* Reset some software data */
  /*pDev->txerror = 0;
  pDev->rxerror = 0;*/

  /* Enable receiver/transmitter */
  pDev->regs->rx0ctrl = GRCAN_RXCTRL_ENABLE;
  pDev->regs->tx0ctrl = GRCAN_TXCTRL_ENABLE;

  /* Enable HurriCANe core */
  pDev->regs->ctrl = GRCAN_CTRL_ENABLE;

  /* Leave transmitter disabled, it is enabled when
   * trying to send something.
   */
  return RTEMS_SUCCESSFUL;
}

static void grcan_stop(struct grcan_priv *pDev)
{
  FUNCDBG();

  /* Mask all IRQs */
  pDev->regs->imr = 0;
  IRQ_MASK(pDev->irq+GRCAN_IRQ_TXSYNC);
  IRQ_MASK(pDev->irq+GRCAN_IRQ_RXSYNC);
  IRQ_MASK(pDev->irq+GRCAN_IRQ_IRQ);

  /* Disable receiver & transmitter */
  pDev->regs->rx0ctrl = 0;
  pDev->regs->tx0ctrl = 0;

  /* Reset semaphores to the initial state and wakeing
   * all threads waiting for an IRQ. The threads that
   * get woken up must check for RTEMS_UNSATISFIED in
   * order to determine that they should return to
   * user space with error status.
   */
  rtems_semaphore_flush(pDev->rx_sem);
  rtems_semaphore_flush(pDev->tx_sem);
  rtems_semaphore_flush(pDev->txempty_sem);
}

static void grcan_hw_config(
  struct grcan_regs *regs,
  struct grcan_config *conf
  )
{
  unsigned int config=0;

  /* Reset HurriCANe Core */
  regs->ctrl = 0;

  if ( conf->silent )
    config |= GRCAN_CFG_SILENT;

  if ( conf->abort )
    config |= GRCAN_CFG_ABORT;

  if ( conf->selection.selection )
    config |= GRCAN_CFG_SELECTION;

  if ( conf->selection.enable0 )
    config |= GRCAN_CFG_ENABLE0;

  if ( conf->selection.enable1 )
    config |= GRCAN_CFG_ENABLE1;

  /* Timing */
  config |= (conf->timing.bpr<<GRCAN_CFG_BPR_BIT) & GRCAN_CFG_BPR;
  config |= (conf->timing.rsj<<GRCAN_CFG_RSJ_BIT) & GRCAN_CFG_RSJ;
  config |= (conf->timing.ps1<<GRCAN_CFG_PS1_BIT) & GRCAN_CFG_PS1;
  config |= (conf->timing.ps2<<GRCAN_CFG_PS2_BIT) & GRCAN_CFG_PS2;
  config |= (conf->timing.scaler<<GRCAN_CFG_SCALER_BIT) & GRCAN_CFG_SCALER;

  /* Write configuration */
  regs->conf = config;

  /* Enable HurriCANe Core */
  regs->ctrl = GRCAN_CTRL_ENABLE;
}

static void grcan_hw_accept(
  struct grcan_regs *regs,
  struct grcan_filter *afilter
  )
{
  /* Disable Sync mask totaly (if we change scode or smask
   * in an unfortunate way we may trigger a sync match)
   */
  regs->rx0mask = 0xffffffff;

  /* Set Sync Filter in a controlled way */
  regs->rx0code = afilter->code;
  regs->rx0mask = afilter->mask;
}

static void grcan_hw_sync(
  struct grcan_regs *regs,
  struct grcan_filter *sfilter
  )
{
  /* Disable Sync mask totaly (if we change scode or smask
   * in an unfortunate way we may trigger a sync match)
   */
  regs->smask = 0xffffffff;

  /* Set Sync Filter in a controlled way */
  regs->scode = sfilter->code;
  regs->smask = sfilter->mask;
}

static unsigned int grcan_hw_rxavail(
  unsigned int rp,
  unsigned int wp,
  unsigned int size
  )
{
  if ( rp == wp ) {
    /* read pointer and write pointer is equal only
     * when RX buffer is empty.
     */
    return 0;
  }

  if ( wp > rp ) {
    return (wp-rp)/GRCAN_MSG_SIZE;
  }else{
    return (size-(rp-wp))/GRCAN_MSG_SIZE;
  }
}

static unsigned int grcan_hw_txspace(
  unsigned int rp,
  unsigned int wp,
  unsigned int size
  )
{
  unsigned int left;

  if ( rp == wp ) {
    /* read pointer and write pointer is equal only
     * when TX buffer is empty.
     */
    return size/GRCAN_MSG_SIZE-WRAP_AROUND_TX_MSGS;
  }

  /* size - 4 - abs(read-write) */
  if ( wp > rp ) {
    left = size-(wp-rp);
  }else{
    left = rp-wp;
  }

  return left/GRCAN_MSG_SIZE-WRAP_AROUND_TX_MSGS;
}

static int grcan_hw_rx_ongoing(struct grcan_regs *regs)
{
  return READ_REG(&regs->rx0ctrl) & GRCAN_RXCTRL_ONGOING;
};

static int grcan_hw_tx_ongoing(struct grcan_regs *regs)
{
  return READ_REG(&regs->tx0ctrl) & GRCAN_TXCTRL_ONGOING;
};


#define MIN_TSEG1 1
#define MIN_TSEG2 2
#define MAX_TSEG1 14
#define MAX_TSEG2 8

static int grcan_calc_timing(
  unsigned int baud,          /* The requested BAUD to calculate timing for */
  unsigned int core_hz,       /* Frequency in Hz of GRCAN Core */
  unsigned int sampl_pt,
  struct grcan_timing *timing /* result is placed here */
  )
{
	int best_error = 1000000000;
	int error;
	int best_tseg=0, best_brp=0, brp=0;
	int tseg=0, tseg1=0, tseg2=0;
	int sjw = 1;

  /* Default to 90% */
  if ( (sampl_pt < 50) || (sampl_pt>99) ){
    sampl_pt = GRCAN_SAMPLING_POINT;
  }

	if ( (baud<5000) || (baud>1000000) ){
		/* invalid speed mode */
		return -1;
	}

	/* find best match, return -2 if no good reg
	 * combination is available for this frequency
   */

	/* some heuristic specials */
	if (baud > ((1000000 + 500000) / 2))
		sampl_pt = 75;

	if (baud < ((12500 + 10000) / 2))
		sampl_pt = 75;

	/* tseg even = round down, odd = round up */
	for (tseg = (MIN_TSEG1 + MIN_TSEG2 + 2) * 2;
	     tseg <= (MAX_TSEG2 + MAX_TSEG1 + 2) * 2 + 1;
	     tseg++)
	{
		brp = core_hz / ((1 + tseg / 2) * baud) + tseg % 2;
		if ((brp <= 0) ||
        ( (brp > 256*1) && (brp <= 256*2) && (brp&0x1) ) ||
        ( (brp > 256*2) && (brp <= 256*4) && (brp&0x3) ) ||
        ( (brp > 256*4) && (brp <= 256*8) && (brp&0x7) ) ||
        (brp > 256*8)
        )
			continue;

		error = baud - core_hz / (brp * (1 + tseg / 2));
		if (error < 0)
		{
			error = -error;
		}

		if (error <= best_error)
		{
			best_error = error;
			best_tseg = tseg/2;
			best_brp = brp-1;
		}
	}

	if (best_error && (baud / best_error < 10))
	{
		return -2;
	}else if ( !timing )
		return 0; /* nothing to store result in, but a valid bitrate can be calculated */

	tseg2 = best_tseg - (sampl_pt * (best_tseg + 1)) / 100;

	if (tseg2 < MIN_TSEG2)
	{
		tseg2 = MIN_TSEG2;
	}

	if (tseg2 > MAX_TSEG2)
	{
		tseg2 = MAX_TSEG2;
	}

	tseg1 = best_tseg - tseg2 - 2;

	if (tseg1 > MAX_TSEG1)
	{
		tseg1 = MAX_TSEG1;
		tseg2 = best_tseg - tseg1 - 2;
	}

  /* Get scaler and BRP from pseudo BRP */
  if ( best_brp <= 256 ){
    timing->scaler = best_brp;
    timing->bpr = 0;
  }else if ( best_brp <= 256*2 ){
    timing->scaler = ((best_brp+1)>>1) -1;
    timing->bpr = 1;
  }else if ( best_brp <= 256*4 ){
    timing->scaler = ((best_brp+1)>>2) -1;
    timing->bpr = 2;
  }else{
    timing->scaler = ((best_brp+1)>>3) -1;
    timing->bpr = 3;
  }

	timing->ps1    = tseg1+1;
	timing->ps2    = tseg2;
	timing->rsj    = sjw;

	return 0;
}

static unsigned int grcan_hw_read_try(
  struct grcan_priv *pDev,
  struct grcan_regs *regs,
  CANMsg *buffer,
  int max
  )
{
  int i,j;
  CANMsg *dest;
  struct grcan_msg *source,tmp;
  unsigned int wp,rp,size,rxmax,addr,trunk_msg_cnt;

  FUNCDBG();

  wp = READ_REG(&regs->rx0wr);
  rp = READ_REG(&regs->rx0rd);

  /*
   * Due to hardware wrap around simplification write pointer will
   * never reach the read pointer, at least a gap of 8 bytes.
   * The only time they are equal is when the read pointer has
   * reached the write pointer (empty buffer)
   *
   */
  if ( wp != rp ){
    /* Not empty, we have received chars...
     * Read as much as possible from DMA buffer
     */
    size = READ_REG(&regs->rx0size);

    /* Get number of bytes available in RX buffer */
    trunk_msg_cnt = grcan_hw_rxavail(rp,wp,size);

    /* truncate size if user space buffer hasn't room for
     * all received chars.
     */
    if ( trunk_msg_cnt > max )
      trunk_msg_cnt = max;

    /* Read until i is 0 */
    i=trunk_msg_cnt;

    addr = (unsigned int)pDev->rx;
    source = (struct grcan_msg *)(addr + rp);
    dest = buffer;
    rxmax = addr + (size-GRCAN_MSG_SIZE);

    /* Read as many can messages as possible */
    while(i>0){
      /* Read CAN message from DMA buffer */
      tmp.head[0] = READ_DMA_WORD(&source->head[0]);
      tmp.head[1] = READ_DMA_WORD(&source->head[1]);
      /* Convert one grcan CAN message to one "software" CAN message */
      dest->extended = tmp.head[0]>>31;
      dest->rtr = (tmp.head[0] >>30) & 0x1;
      if ( dest->extended ){
        dest->id = tmp.head[0] & 0x3fffffff;
      }else{
        dest->id = (tmp.head[0] >>18) & 0xfff;
      }
      dest->len = tmp.head[1] >> 28;
      for(j=0; j<dest->len; j++)
        dest->data[j] = READ_DMA_BYTE(&source->data[j]);

      /* wrap around if neccessary */
      source = ( (unsigned int)source >= rxmax ) ? (struct grcan_msg *)addr : source+1;
      dest++; /* straight user buffer */
      i--;
    }
    /* Increment Hardware READ pointer (mark read byte as read)
     * ! wait for registers to be safely re-configurable
     */
    regs->rx0ctrl = 0; /* DISABLE RX CHANNEL */
    i=0;
    while( grcan_hw_rx_ongoing(regs) && (i<1000) ){
      i++;
    }
    regs->rx0rd = (unsigned int)source-addr;
    regs->rx0ctrl = GRCAN_RXCTRL_ENABLE; /* ENABLE_RX_CHANNEL */
    return trunk_msg_cnt;
  }
  return 0;
}

static unsigned int grcan_hw_write_try(
  struct grcan_priv *pDev,
  struct grcan_regs *regs,
  CANMsg *buffer,
  int count
  )
{
  unsigned int rp, wp, size, txmax, addr, ret;
  struct grcan_msg *dest;
  CANMsg *source;
  int space_left;
  unsigned int tmp;
  int i;

  DBGC(DBG_TX,"\n");
  /*FUNCDBG();*/

  rp = READ_REG(&regs->tx0rd);
  wp = READ_REG(&regs->tx0wr);
  size = READ_REG(&regs->tx0size);

  space_left = grcan_hw_txspace(rp,wp,size);

  /* is circular fifo full? */
  if ( space_left < 1 )
    return 0;

  /* Truncate size */
  if ( space_left > count )
    space_left = count;
  ret = space_left;

  addr = (unsigned int)pDev->tx;

  dest = (struct grcan_msg *)(addr + wp);
  source = (CANMsg *)buffer;
  txmax = addr + (size-GRCAN_MSG_SIZE);

  while ( space_left>0 ) {
    /* Convert and write CAN message to DMA buffer */
    if ( source->extended ){
      tmp = (1<<31) | (source->id & 0x3fffffff);
    }else{
      tmp = (source->id&0xfff)<<18;
    }
    if ( source->rtr )
      tmp|=(1<<30);
    dest->head[0] = tmp;
    dest->head[1] = source->len<<28;
    for ( i=0; i<source->len; i++)
      dest->data[i] = source->data[i];
    source++; /* straight user buffer */
    dest = ((unsigned int)dest >= txmax) ? (struct grcan_msg *)addr : dest+1;
    space_left--;
  }

  /* Update write pointer
   * ! wait for registers to be safely re-configurable
   */
  regs->tx0ctrl = 0; /* DISABLE TX CHANNEL */
  i=0;
  while( (grcan_hw_tx_ongoing(regs)) && i<1000 ){
    i++;
  }
  regs->tx0wr = (unsigned int)dest - addr; /* Update write pointer */
  regs->tx0ctrl = GRCAN_TXCTRL_ENABLE; /* ENABLE_TX_CHANNEL */
  return ret;
}

static int grcan_wait_rxdata(
  struct grcan_priv *pDev,
  int min
  )
{
  unsigned int wp, rp, size, irq;
  unsigned int irq_trunk, dataavail;
  int wait;
  IRQ_GLOBAL_PREPARE(oldLevel);

  FUNCDBG();

  /*** block until receive IRQ received
   * Set up a valid IRQ point so that an IRQ is received
   * when one or more messages are received
   */
  IRQ_GLOBAL_DISABLE(oldLevel);

  size = READ_REG(&pDev->regs->rx0size);
  rp = READ_REG(&pDev->regs->rx0rd);
  wp = READ_REG(&pDev->regs->rx0wr);

  /**** Calculate IRQ Pointer ****/
  irq = wp + min*GRCAN_MSG_SIZE;
  /* wrap irq around */
  if ( irq >= size ){
    irq_trunk = irq-size;
  }else
    irq_trunk = irq;

  /* init IRQ HW */
  pDev->regs->rx0irq = irq_trunk;

  /* Clear pending Rx IRQ */
  pDev->regs->picr = GRCAN_RXIRQ_IRQ;

  wp = READ_REG(&pDev->regs->rx0wr);

  /* Calculate messages available */
  dataavail = grcan_hw_rxavail(rp,wp,size);

  if ( dataavail < min ){
    /* Still empty, proceed with sleep - Turn on IRQ (unmask irq) */
    pDev->regs->imr = READ_REG(&pDev->regs->imr) | GRCAN_RXIRQ_IRQ;
    wait=1;
  }else{
    /* enough message has been received, abort sleep - don't unmask interrupt */
    wait=0;
  }
  IRQ_GLOBAL_ENABLE(oldLevel);

    /* Wait for IRQ to fire only if has been triggered */
  if ( wait ){
    if ( rtems_semaphore_obtain(pDev->rx_sem, RTEMS_WAIT, RTEMS_NO_TIMEOUT) == RTEMS_UNSATISFIED )
      return -1; /* Device driver has been closed or stopped, return with error status */
  }

  return 0;
}

/* Wait until min bytes available in TX circular buffer.
 * The IRQ RxIrq is used to pin point the location of
 *
 * min must be at least WRAP_AROUND_TX_BYTES bytes less
 * than max buffer for this algo to work.
 *
 */
static int grcan_wait_txspace(
  struct grcan_priv *pDev,
  int min
  )
{
  int wait;
  unsigned int irq, rp, wp, size, space_left;
  unsigned int irq_trunk;
  IRQ_GLOBAL_PREPARE(oldLevel);

  DBGC(DBG_TX,"\n");
  /*FUNCDBG();*/

  IRQ_GLOBAL_DISABLE(oldLevel);

  /*pDev->regs->tx0ctrl = GRCAN_TXCTRL_ENABLE;*/

  size = READ_REG(&pDev->regs->tx0size);
  wp = READ_REG(&pDev->regs->tx0wr);

  rp = READ_REG(&pDev->regs->tx0rd);

  /**** Calculate IRQ Pointer ****/
  irq = rp + min*GRCAN_MSG_SIZE;
  /* wrap irq around */
  if ( irq >= size ){
    irq_trunk = irq - size;
  }else
    irq_trunk = irq;

  /* trigger HW to do a IRQ when enough room in buffer */
  pDev->regs->tx0irq = irq_trunk;

  /* Clear pending Tx IRQ */
  pDev->regs->picr = GRCAN_TXIRQ_IRQ;

  /* One problem, if HW already gone past IRQ place the IRQ will
   * never be received resulting in a thread hang. We check if so
   * before proceeding.
   *
   * has the HW already gone past the IRQ generation place?
   *  == does min fit info tx buffer?
   */
  rp = READ_REG(&pDev->regs->tx0rd);

  space_left = grcan_hw_txspace(rp,wp,size);

  if ( space_left < min ){
    /* Still too full, proceed with sleep - Turn on IRQ (unmask irq) */
    pDev->regs->imr = READ_REG(&pDev->regs->imr) | GRCAN_TXIRQ_IRQ;
    wait=1;
  }else{
    /* There are enough room in buffer, abort wait - don't unmask interrupt */
    wait=0;
  }
  IRQ_GLOBAL_ENABLE(oldLevel);

  /* Wait for IRQ to fire only if it has been triggered */
  if ( wait ){
    if ( rtems_semaphore_obtain(pDev->tx_sem, RTEMS_WAIT, 100) ==
         RTEMS_UNSATISFIED ){
      /* Device driver has flushed us, this may be due to another thread has
       * closed the device, this is to avoid deadlock */
      return -1;
    }
  }

  /* At this point the TxIRQ has been masked, we ned not to mask it */
  return 0;
}

static int grcan_tx_flush(struct grcan_priv *pDev)
{
  int wait;
  unsigned int rp, wp;
  IRQ_GLOBAL_PREPARE(oldLevel);
  FUNCDBG();

  /* loop until all data in circular buffer has been read by hw.
   * (write pointer != read pointer )
   *
   * Hardware doesn't update write pointer - we do
   */
  while ( (wp=READ_REG(&pDev->regs->tx0wr)) != (rp=READ_REG(&pDev->regs->tx0rd)) ) {
    /* Wait for TX empty IRQ */
    IRQ_GLOBAL_DISABLE(oldLevel);
    /* Clear pending TXEmpty IRQ */
    pDev->regs->picr = GRCAN_TXEMPTY_IRQ;

    if ( wp != READ_REG(&pDev->regs->tx0rd) ) {
      /* Still not empty, proceed with sleep - Turn on IRQ (unmask irq) */
      pDev->regs->imr = READ_REG(&pDev->regs->imr) | GRCAN_TXEMPTY_IRQ;
      wait = 1;
    }else{
      /* TX fifo is empty */
      wait = 0;
    }
    IRQ_GLOBAL_ENABLE(oldLevel);
    if ( !wait )
      break;

    /* Wait for IRQ to wake us */
    if ( rtems_semaphore_obtain(pDev->txempty_sem, RTEMS_WAIT, RTEMS_NO_TIMEOUT) ==
         RTEMS_UNSATISFIED ) {
      return -1;
    }
  }
  return 0;
}

static int grcan_alloc_buffers(struct grcan_priv *pDev, int rx, int tx)
{
  FUNCDBG();

  if ( tx ) {
#ifdef STATIC_TX_BUF_ADDR
    pDev->_tx = STATIC_TX_BUF_ADDR(pDev->minor);
    if ( pDev->txbuf_size > STATIC_TX_BUF_SIZE ){
      pDev->txbuf_size = STATIC_TX_BUF_SIZE;
      return -1;
    }
    /* Assume aligned buffer */
    pDev->tx = (struct grcan_msg *)pDev->_tx;
#else
    pDev->_tx = malloc(pDev->txbuf_size + BUFFER_ALIGNMENT_NEEDS);
    if ( !pDev->_tx )
      return -1;

    /* Align TX buffer */
    pDev->tx = (struct grcan_msg *)
               (((unsigned int)pDev->_tx + (BUFFER_ALIGNMENT_NEEDS-1)) &
               ~(BUFFER_ALIGNMENT_NEEDS-1));
#endif
  }

  if ( rx ) {
#ifdef STATIC_RX_BUF_ADDR
    pDev->_rx = STATIC_RX_BUF_ADDR(pDev->minor);
    if ( pDev->rxbuf_size > STATIC_RX_BUF_SIZE ){
      pDev->rxbuf_size = STATIC_RX_BUF_SIZE;
      return -1;
    }
    /* Assume aligned buffer */
    pDev->rx = (struct grcan_msg *)pDev->_rx;
#else
    pDev->_rx = malloc(pDev->rxbuf_size + BUFFER_ALIGNMENT_NEEDS);
    if ( !pDev->_rx )
      return -1;

    /* Align TX buffer */
    pDev->rx = (struct grcan_msg *)
               (((unsigned int)pDev->_rx + (BUFFER_ALIGNMENT_NEEDS-1)) &
               ~(BUFFER_ALIGNMENT_NEEDS-1));
#endif
  }
  return 0;
}

static void grcan_free_buffers(struct grcan_priv *pDev, int rx, int tx)
{
  FUNCDBG();

#ifndef STATIC_TX_BUF_ADDR
  if ( tx && pDev->_tx ){
    free(pDev->_tx);
    pDev->_tx = NULL;
    pDev->tx = NULL;
  }
#endif
#ifndef STATIC_RX_BUF_ADDR
  if ( rx && pDev->_rx ){
    free(pDev->_rx);
    pDev->_rx = NULL;
    pDev->rx = NULL;
  }
#endif
}

#if 0
static char *almalloc(int sz)
{
  char *tmp;
  tmp = calloc(1,2*sz);
  tmp = (char *) (((int)tmp+sz) & ~(sz -1));
  return(tmp);
}
#endif

static rtems_device_driver grcan_initialize(
  rtems_device_major_number major,
  rtems_device_minor_number unused,
  void *arg
  )
{
  int minor;
  struct grcan_priv *pDev;
  struct ambapp_apb_info dev;
  rtems_status_code status;
  char fs_name[20];
  unsigned int sys_freq_hz;
  unsigned int deviceid = GAISLER_GRHCAN;

  printk("grcan_initialize()\n\r");

  FUNCDBG();

  /* find GRCAN cores */
  if ( !grcan_cores ) {
    grcan_core_cnt = ambapp_get_number_apbslv_devices(amba_bus, VENDOR_GAISLER,
                                                      deviceid);
    if ( grcan_core_cnt < 1 ){
      deviceid = GAISLER_GRCAN;
      grcan_core_cnt = ambapp_get_number_apbslv_devices(amba_bus, VENDOR_GAISLER,
                                                        deviceid);
      if ( grcan_core_cnt < 1 ) {
        DBG("GRCAN: Using AMBA Plug&Play, found %d cores\n",grcan_core_cnt);
        return RTEMS_UNSATISFIED;
      }
    }
    DBG("GRCAN: Using AMBA Plug&Play, found %d cores\n",grcan_core_cnt);
  }

#ifdef GRCAN_MAX_CORENR
  /* limit number of cores */
  if ( grcan_core_cnt > GRCAN_MAX_CORENR )
    grcan_core_cnt = GRCAN_MAX_CORENR;
#endif

  /* Allocate memory for cores */
  grcans = malloc(grcan_core_cnt * sizeof(struct grcan_priv));
  if ( !grcans )
    return RTEMS_NO_MEMORY;
  memset(grcans,0,grcan_core_cnt * sizeof(struct grcan_priv));

  /* make a local copy of device name */
  strcpy(fs_name,GRCAN_DEVNAME);

  /* Detect System Frequency from initialized timer */
#ifndef SYS_FREQ_HZ
#if defined(LEON3)
  /* LEON3: find timer address via AMBA Plug&Play info */
  {
    struct ambapp_apb_info gptimer;
    struct gptimer_regs *tregs;

    if (ambapp_find_apbslv (&ambapp_plb, VENDOR_GAISLER, GAISLER_GPTIMER, &gptimer)
        == 1) {
      tregs = (struct gptimer_regs *) gptimer.start;
      sys_freq_hz = (tregs->scaler_reload + 1) * 1000 * 1000;
      DBG("GRCAN: detected %dHZ system frequency\n\r", sys_freq_hz);
    } else {
      sys_freq_hz = 40000000;   /* Default to 40MHz */
      printk("GRCAN: Failed to detect system frequency\n\r");
    }
  }
#elif defined(LEON2)
  /* LEON2: use hardcoded address to get to timer */
  {
    LEON_Register_Map *regs = (LEON_Register_Map *) 0x80000000;

    sys_freq_hz = (regs->Scaler_Reload + 1) * 1000 * 1000;
  }
#else
#error CPU not supported by driver
#endif
#else
  /* Use hardcoded frequency */
  sys_freq_hz = SYS_FREQ_HZ;
#endif

  for(minor=0; minor<grcan_core_cnt; minor++){

    pDev = &grcans[minor];
    pDev->minor = minor;
    pDev->open = 0;
    pDev->corefreq_hz = sys_freq_hz;
    GRCAN_DEVNAME_NO(fs_name,minor);

    /* Find core address & IRQ */
    if ( !grcan_cores ) {
      ambapp_find_apbslv_next(amba_bus, VENDOR_GAISLER, deviceid, &dev, minor);
      pDev->irq = dev.irq;
      pDev->regs = (struct grcan_regs *)dev.start;
    }else{
      pDev->irq = grcan_cores[minor].irq;
      pDev->regs = (struct grcan_regs *)grcan_cores[minor].base_address;
    }

    printk("Registering GRCAN core at [0x%x] irq %d, minor %d as %s\n\r",pDev->regs,pDev->irq,minor,fs_name);

    status = rtems_io_register_name(fs_name, major, 0);
    if (status != RTEMS_SUCCESSFUL)
      rtems_fatal_error_occurred(status);

		/* Reset Hardware before attaching IRQ handler */
    grcan_hw_reset(pDev->regs);

    /* Register interrupt handler */
    GRCAN_REG_INT(GRCAN_PREFIX(_interrupt_handler), pDev->irq+GRCAN_IRQ_IRQ, pDev);
    /*
    GRCAN_REG_INT(grcan_interrupt_handler, pDev->irq+GRCAN_IRQ_TXSYNC, pDev);
    GRCAN_REG_INT(grcan_interrupt_handler, pDev->irq+GRCAN_IRQ_RXSYNC, pDev);
    */

    /* RX Semaphore created with count = 0 */
    if ( rtems_semaphore_create(rtems_build_name('G', 'C', 'R', '0'+minor),
        0,
        RTEMS_FIFO|RTEMS_SIMPLE_BINARY_SEMAPHORE|RTEMS_NO_INHERIT_PRIORITY|\
        RTEMS_LOCAL|RTEMS_NO_PRIORITY_CEILING,
        0,
        &pDev->rx_sem) != RTEMS_SUCCESSFUL )
      return RTEMS_INTERNAL_ERROR;

    /* TX Semaphore created with count = 0 */
    if ( rtems_semaphore_create(rtems_build_name('G', 'C', 'T', '0'+minor),
        0,
        RTEMS_FIFO|RTEMS_SIMPLE_BINARY_SEMAPHORE|RTEMS_NO_INHERIT_PRIORITY|\
        RTEMS_LOCAL|RTEMS_NO_PRIORITY_CEILING,
        0,
        &pDev->tx_sem) != RTEMS_SUCCESSFUL )
      return RTEMS_INTERNAL_ERROR;

    /* TX Empty Semaphore created with count = 0 */
    if ( rtems_semaphore_create(rtems_build_name('G', 'C', 'E', '0'+minor),
        0,
        RTEMS_FIFO|RTEMS_SIMPLE_BINARY_SEMAPHORE|RTEMS_NO_INHERIT_PRIORITY|\
        RTEMS_LOCAL|RTEMS_NO_PRIORITY_CEILING,
        0,
        &pDev->txempty_sem) != RTEMS_SUCCESSFUL )
      return RTEMS_INTERNAL_ERROR;

    /* Device Semaphore created with count = 1 */
    if ( rtems_semaphore_create(rtems_build_name('G', 'C', 'A', '0'+minor),
        1,
        RTEMS_FIFO|RTEMS_SIMPLE_BINARY_SEMAPHORE|RTEMS_NO_INHERIT_PRIORITY|\
        RTEMS_LOCAL|RTEMS_NO_PRIORITY_CEILING,
        0,
        &pDev->dev_sem) != RTEMS_SUCCESSFUL )
      return RTEMS_INTERNAL_ERROR;
  }

  return RTEMS_SUCCESSFUL;
}

static rtems_device_driver grcan_open(rtems_device_major_number major, rtems_device_minor_number minor, void *arg) {
  struct grcan_priv *pDev;
  rtems_device_driver ret;

  FUNCDBG();

  if ( (minor < 0) || (minor>=grcan_core_cnt) ) {
    DBG("Wrong minor %d\n", minor);
    return RTEMS_INVALID_NUMBER;
  }

  pDev = &grcans[minor];

  /* Wait until we get semaphore */
  if ( rtems_semaphore_obtain(pDev->dev_sem, RTEMS_WAIT, RTEMS_NO_TIMEOUT) !=
       RTEMS_SUCCESSFUL ){
    return RTEMS_INTERNAL_ERROR;
  }

  /* is device busy/taken? */
  if  ( pDev->open ) {
    ret=RTEMS_RESOURCE_IN_USE;
    goto out;
  }

  /* Mark device taken */
  pDev->open = 1;

  pDev->txblock = pDev->rxblock = 1;
  pDev->txcomplete = pDev->rxcomplete = 0;
  pDev->started = 0;
  pDev->config_changed = 1;
  pDev->config.silent = 0;
  pDev->config.abort = 0;
  pDev->config.selection.selection = 0;
  pDev->config.selection.enable0 = 0;
  pDev->config.selection.enable1 = 1;
  pDev->flushing = 0;
  pDev->rx = pDev->_rx = NULL;
  pDev->tx = pDev->_tx = NULL;
  pDev->txbuf_size = TX_BUF_SIZE;
  pDev->rxbuf_size = RX_BUF_SIZE;
  printk("Defaulting to rxbufsize: %d, txbufsize: %d\n",RX_BUF_SIZE,TX_BUF_SIZE);

  /* Default to accept all messages */
  pDev->afilter.mask = 0x00000000;
  pDev->afilter.code = 0x00000000;

  /* Default to disable sync messages (only trigger when id is set to all ones) */
  pDev->sfilter.mask = 0xffffffff;
  pDev->sfilter.code = 0x00000000;

  /* Calculate default timing register values */
  grcan_calc_timing(GRCAN_DEFAULT_BAUD,pDev->corefreq_hz,GRCAN_SAMPLING_POINT,&pDev->config.timing);

  if ( grcan_alloc_buffers(pDev,1,1) ) {
    ret=RTEMS_NO_MEMORY;
    goto out;
  }

  /* Clear statistics */
  memset(&pDev->stats,0,sizeof(struct grcan_stats));

  ret = RTEMS_SUCCESSFUL;
out:
  rtems_semaphore_release(pDev->dev_sem);
  return ret;
}

static rtems_device_driver grcan_close(rtems_device_major_number major, rtems_device_minor_number minor, void *arg)
{
  struct grcan_priv *pDev = &grcans[minor];

  FUNCDBG();

  if ( pDev->started )
    grcan_stop(pDev);

  grcan_hw_reset(pDev->regs);

  grcan_free_buffers(pDev,1,1);

  /* Mark Device as closed */
  pDev->open = 0;

  return RTEMS_SUCCESSFUL;
}

static rtems_device_driver grcan_read(rtems_device_major_number major, rtems_device_minor_number minor, void *arg)
{
  struct grcan_priv *pDev = &grcans[minor];
  rtems_libio_rw_args_t *rw_args;
  CANMsg *dest;
  unsigned int count, left;
  int req_cnt;

  rw_args = (rtems_libio_rw_args_t *) arg;
  dest = (CANMsg *) rw_args->buffer;
  req_cnt = rw_args->count / sizeof(CANMsg);

  FUNCDBG();

  if ( (!dest) || (req_cnt<1) )
    return RTEMS_INVALID_NAME;

  if ( !pDev->started )
    return RTEMS_RESOURCE_IN_USE;

/*  FUNCDBG("grcan_read [%i,%i]: buf: 0x%x len: %i\n",major, minor, (unsigned int)rw_args->buffer,rw_args->count);*/

  count = grcan_hw_read_try(pDev,pDev->regs,dest,req_cnt);
  if ( !( pDev->rxblock && pDev->rxcomplete && (count!=req_cnt) ) ){
    if ( count > 0 ) {
      /* Successfully received messages (at least one) */
      rw_args->bytes_moved = count * sizeof(CANMsg);
      return RTEMS_SUCCESSFUL;
    }

    /* nothing read, shall we block? */
    if ( !pDev->rxblock ) {
      /* non-blocking mode */
      rw_args->bytes_moved = 0;
      return RTEMS_TIMEOUT;
    }
  }

  while(count == 0 || (pDev->rxcomplete && (count!=req_cnt)) ){

    if ( !pDev->rxcomplete ){
      left = 1; /* return as soon as there is one message available */
    }else{
      left = req_cnt - count;     /* return as soon as all data are available */

      /* never wait for more than the half the maximum size of the receive buffer
       * Why? We need some time to copy buffer before to catch up with hw, otherwise
       * we would have to copy everything when the data has been received.
       */
      if ( left > ((pDev->rxbuf_size/GRCAN_MSG_SIZE)/2) ){
        left = (pDev->rxbuf_size/GRCAN_MSG_SIZE)/2;
      }
    }

    if ( grcan_wait_rxdata(pDev,left) ) {
      /* The wait has been aborted, probably due to
       * the device driver has been closed by another
       * thread.
       */
      rw_args->bytes_moved = count * sizeof(CANMsg);
      return RTEMS_UNSATISFIED;
    }

    /* Try read bytes from circular buffer */
    count += grcan_hw_read_try(
      pDev,
      pDev->regs,
      dest+count,
      req_cnt-count);
  }
  /* no need to unmask IRQ as IRQ Handler do that for us. */
  rw_args->bytes_moved = count * sizeof(CANMsg);
  return RTEMS_SUCCESSFUL;
}

static rtems_device_driver grcan_write(rtems_device_major_number major, rtems_device_minor_number minor, void *arg)
{
  struct grcan_priv *pDev = &grcans[minor];
  rtems_libio_rw_args_t *rw_args;
  CANMsg *source;
  unsigned int count, left;
  int req_cnt;

  DBGC(DBG_TX,"\n");
  /*FUNCDBG();*/

  if ( !pDev->started || pDev->config.silent || pDev->flushing )
    return RTEMS_RESOURCE_IN_USE;

  rw_args = (rtems_libio_rw_args_t *) arg;
  req_cnt = rw_args->count / sizeof(CANMsg);
  source = (CANMsg *) rw_args->buffer;

  /* check proper length and buffer pointer */
  if (( req_cnt < 1) || (source == NULL) ){
    return RTEMS_INVALID_NAME;
  }

  count = grcan_hw_write_try(pDev,pDev->regs,source,req_cnt);
  if ( !(pDev->txblock && pDev->txcomplete && (count!=req_cnt)) ) {
    if ( count > 0 ) {
      /* Successfully transmitted chars (at least one char) */
      rw_args->bytes_moved = count * sizeof(CANMsg);
      return RTEMS_SUCCESSFUL;
    }

    /* nothing written, shall we block? */
    if ( !pDev->txblock ) {
      /* non-blocking mode */
      rw_args->bytes_moved = 0;
      return RTEMS_TIMEOUT;
    }
  }

  /* if in txcomplete mode we need to transmit all chars */
  while((count == 0) || (pDev->txcomplete && (count!=req_cnt)) ){
    /*** block until room to fit all or as much of transmit buffer as possible IRQ comes
     * Set up a valid IRQ point so that an IRQ is received
     * when we can put a chunk of data into transmit fifo
     */
    if ( !pDev->txcomplete ){
      left = 1; /* wait for anything to fit buffer */
    }else{
      left = req_cnt - count; /* wait for all data to fit in buffer */

      /* never wait for more than the half the maximum size of the transmitt buffer
       * Why? We need some time to fill buffer before hw catches up.
       */
      if ( left > ((pDev->txbuf_size/GRCAN_MSG_SIZE)/2) ){
        left = (pDev->txbuf_size/GRCAN_MSG_SIZE)/2;
      }
    }

    /* Wait until more room in transmit buffer */
    if ( grcan_wait_txspace(pDev,left) ){
      /* The wait has been aborted, probably due to
       * the device driver has been closed by another
       * thread. To avoid deadlock we return directly
       * with error status.
       */
      rw_args->bytes_moved = count * sizeof(CANMsg);
      return RTEMS_UNSATISFIED;
    }

    if ( pDev->txerror ){
      /* Return number of bytes sent, compare write pointers */
      pDev->txerror = 0;
#if 0
#error HANDLE AMBA error
#endif
    }

    /* Try read bytes from circular buffer */
    count += grcan_hw_write_try(
      pDev,
      pDev->regs,
      source+count,
      req_cnt-count);
  }
  /* no need to unmask IRQ as IRQ Handler do that for us. */

  rw_args->bytes_moved = count * sizeof(CANMsg);
  return RTEMS_SUCCESSFUL;
}

static rtems_device_driver grcan_ioctl(rtems_device_major_number major, rtems_device_minor_number minor, void *arg)
{
  struct grcan_priv *pDev = &grcans[minor];
  rtems_libio_ioctl_args_t *ioarg = (rtems_libio_ioctl_args_t *)arg;
  unsigned int *data = ioarg->buffer;
  struct grcan_timing timing;
  unsigned int speed;
  struct grcan_selection *selection;
  int tmp,ret;
  rtems_device_driver status;
  struct grcan_stats *stats;
  struct grcan_filter *filter;
  IRQ_GLOBAL_PREPARE(oldLevel);

  FUNCDBG();

  if (!ioarg)
    return RTEMS_INVALID_NAME;

  ioarg->ioctl_return = 0;
  switch(ioarg->command) {
    case GRCAN_IOC_START:
      if ( pDev->started )
        return RTEMS_RESOURCE_IN_USE; /* EBUSY */

      if ( (status=grcan_start(pDev)) != RTEMS_SUCCESSFUL ){
        return status;
      }
      /* Read and write are now open... */
      pDev->started = 1;
      break;

    case GRCAN_IOC_STOP:
      if ( !pDev->started )
        return RTEMS_RESOURCE_IN_USE;

      grcan_stop(pDev);
      pDev->started = 0;
      break;

    case GRCAN_IOC_ISSTARTED:
      if ( !pDev->started )
        return RTEMS_RESOURCE_IN_USE;
      break;

    case GRCAN_IOC_FLUSH:
      if ( !pDev->started || pDev->flushing || pDev->config.silent )
        return RTEMS_RESOURCE_IN_USE;

      pDev->flushing = 1;
      tmp = grcan_tx_flush(pDev);
      pDev->flushing = 0;
      if ( tmp ) {
        /* The wait has been aborted, probably due to
         * the device driver has been closed by another
         * thread.
         */
         return RTEMS_UNSATISFIED;
      }
      break;

#if 0
    /* Set physical link */
		case GRCAN_IOC_SET_LINK:
#ifdef REDUNDANT_CHANNELS
			if ( pDev->started )
				return RTEMS_RESOURCE_IN_USE; /* EBUSY */

			/* switch HW channel */
			pDev->channel = (unsigned int)ioargs->buffer;
#else
			return RTEMS_NOT_IMPLEMENTED;
#endif
			break;
#endif

    case GRCAN_IOC_SET_SILENT:
      if ( pDev->started )
        return RTEMS_RESOURCE_IN_USE;
      pDev->config.silent = (int)ioarg->buffer;
      pDev->config_changed = 1;
      break;

    case GRCAN_IOC_SET_ABORT:
      if ( pDev->started )
        return RTEMS_RESOURCE_IN_USE;
      pDev->config.abort = (int)ioarg->buffer;
      /* This Configuration parameter doesn't need HurriCANe reset
       * ==> no pDev->config_changed = 1;
       */
      break;

    case GRCAN_IOC_SET_SELECTION:
      if ( pDev->started )
        return RTEMS_RESOURCE_IN_USE;

      selection = (struct grcan_selection *)ioarg->buffer;
      if ( !selection )
        return RTEMS_INVALID_NAME;

      pDev->config.selection = *selection;
      pDev->config_changed = 1;
      break;

    case GRCAN_IOC_SET_RXBLOCK:
      pDev->rxblock = (int)ioarg->buffer;
      break;

    case GRCAN_IOC_SET_TXBLOCK:
      pDev->txblock = (int)ioarg->buffer;
      break;

    case GRCAN_IOC_SET_TXCOMPLETE:
      pDev->txcomplete = (int)ioarg->buffer;
      break;

    case GRCAN_IOC_SET_RXCOMPLETE:
      pDev->rxcomplete = (int)ioarg->buffer;
      break;

    case GRCAN_IOC_GET_STATS:
      stats = (struct grcan_stats *)ioarg->buffer;
      if ( !stats )
        return RTEMS_INVALID_NAME;
      *stats = pDev->stats;
      break;

    case GRCAN_IOC_CLR_STATS:
      IRQ_GLOBAL_DISABLE(oldLevel);
      memset(&pDev->stats,0,sizeof(struct grcan_stats));
      IRQ_GLOBAL_ENABLE(oldLevel);
      break;

		case GRCAN_IOC_SET_SPEED:

			/* cannot change speed during run mode */
			if ( pDev->started )
				return RTEMS_RESOURCE_IN_USE; /* EBUSY */

			/* get speed rate from argument */
			speed = (unsigned int)ioarg->buffer;
			ret = grcan_calc_timing(speed,pDev->corefreq_hz,GRCAN_SAMPLING_POINT,&timing);
			if ( ret )
				return  RTEMS_INVALID_NAME; /* EINVAL */

			/* save timing/speed */
			pDev->config.timing = timing;
      pDev->config_changed = 1;
			break;

    case GRCAN_IOC_SET_BTRS:
			/* Set BTR registers manually
			 * Read GRCAN/HurriCANe Manual.
			 */
			if ( pDev->started )
				return RTEMS_RESOURCE_IN_USE; /* EBUSY */

			if ( !ioarg->buffer )
        return RTEMS_INVALID_NAME;

			pDev->config.timing = *(struct grcan_timing *)ioarg->buffer;
      pDev->config_changed = 1;
			break;

    case GRCAN_IOC_SET_AFILTER:
      filter = (struct grcan_filter *)ioarg->buffer;
      if ( !filter ){
        /* Disable filtering - let all messages pass */
        pDev->afilter.mask = 0x0;
        pDev->afilter.code = 0x0;
      }else{
        /* Save filter */
        pDev->afilter = *filter;
      }
      /* Set hardware acceptance filter */
      grcan_hw_accept(pDev->regs,&pDev->afilter);
      break;

    case GRCAN_IOC_SET_SFILTER:
      filter = (struct grcan_filter *)ioarg->buffer;
      if ( !filter ){
        /* disable TX/RX SYNC filtering */
        pDev->sfilter.mask = 0xffffffff;
        pDev->sfilter.mask = 0;

        /* disable Sync interrupt */
        pDev->regs->imr = READ_REG(&pDev->regs->imr) & ~(GRCAN_RXSYNC_IRQ|GRCAN_TXSYNC_IRQ);
      }else{
        /* Save filter */
        pDev->sfilter = *filter;

        /* Enable Sync interrupt */
        pDev->regs->imr = READ_REG(&pDev->regs->imr) | (GRCAN_RXSYNC_IRQ|GRCAN_TXSYNC_IRQ);
      }
      /* Set Sync RX/TX filter */
      grcan_hw_sync(pDev->regs,&pDev->sfilter);
      break;

    case GRCAN_IOC_GET_STATUS:
      if ( !data )
        return RTEMS_INVALID_NAME;
      /* Read out the statsu register from the GRCAN core */
      data[0] = READ_REG(&pDev->regs->stat);
      break;

    default:
      return RTEMS_NOT_DEFINED;
  }
  return RTEMS_SUCCESSFUL;
}

#ifndef GRCAN_DONT_DECLARE_IRQ_HANDLER
/* Find what device caused the IRQ */
static rtems_isr grcan_interrupt_handler(rtems_vector_number v)
{
  int minor=0;
  while ( minor < grcan_core_cnt ){
    if ( (grcans[minor].irq+0x10) == v ){
      grcan_interrupt(&grcans[minor]);
      break;
    }
  }
}
#endif

/* Handle the IRQ */
static void grcan_interrupt(struct grcan_priv *pDev)
{
  unsigned int status = READ_REG(&pDev->regs->pimsr);
  unsigned int canstat = READ_REG(&pDev->regs->stat);

  /* Spurious IRQ call? */
  if ( !status && !canstat )
    return;

  FUNCDBG();

  /* Increment number of interrupts counter */
  pDev->stats.ints++;

  if ( (status & GRCAN_ERR_IRQ) || (canstat & GRCAN_STAT_PASS) ){
    /* Error-Passive interrupt */
    pDev->stats.passive_cnt++;
  }

  if ( (status & GRCAN_OFF_IRQ) || (canstat & GRCAN_STAT_OFF) ){
    /* Bus-off condition interrupt
     * The link is brought down by hardware, we wake all threads
     * that is blocked in read/write calls and stop futher calls
     * to read/write until user has called ioctl(fd,START,0).
     */
     pDev->started = 0;
     grcan_stop(pDev); /* this mask all IRQ sources */
     status=0x1ffff; /* clear all interrupts */
     goto out;
  }

  if ( (status & GRCAN_OR_IRQ) || (canstat & GRCAN_STAT_OR) ){
    /* Over-run during reception interrupt */
    pDev->stats.overrun_cnt++;
  }

  if ( (status & GRCAN_RXAHBERR_IRQ) ||
       (status & GRCAN_TXAHBERR_IRQ) ||
       (canstat & GRCAN_STAT_AHBERR) ){
    /* RX or Tx AHB Error interrupt */
    printk("AHBERROR: status: 0x%x, canstat: 0x%x\n",status,canstat);
    pDev->stats.ahberr_cnt++;
  }

  if ( status & GRCAN_TXLOSS_IRQ ) {
    pDev->stats.txloss_cnt++;
  }

  if ( status & GRCAN_RXIRQ_IRQ ){
    /* RX IRQ pointer interrupt */
    /*printk("RxIrq 0x%x\n",status);*/
    pDev->regs->imr = READ_REG(&pDev->regs->imr) & ~GRCAN_RXIRQ_IRQ;
    rtems_semaphore_release(pDev->rx_sem);
  }

  if ( status & GRCAN_TXIRQ_IRQ ){
    /* TX IRQ pointer interrupt */
    pDev->regs->imr = READ_REG(&pDev->regs->imr) & ~GRCAN_TXIRQ_IRQ;
    rtems_semaphore_release(pDev->tx_sem);
  }

  if ( status & GRCAN_TXSYNC_IRQ ){
    /* TxSync message transmitted interrupt */
    pDev->stats.txsync_cnt++;
  }

  if ( status & GRCAN_RXSYNC_IRQ ){
    /* RxSync message received interrupt */
    pDev->stats.rxsync_cnt++;
  }

  if ( status & GRCAN_TXEMPTY_IRQ ){
    pDev->regs->imr = READ_REG(&pDev->regs->imr) & ~GRCAN_TXEMPTY_IRQ;
    rtems_semaphore_release(pDev->txempty_sem);
  }

out:
  /* Clear IRQs */
  pDev->regs->picr = status;
}

static int grcan_register_internal(void)
{
  rtems_status_code r;
  rtems_device_major_number m;

  if ((r = rtems_io_register_driver(0, &grcan_driver, &m)) !=
       RTEMS_SUCCESSFUL) {
    switch(r) {
      case RTEMS_TOO_MANY:
        DBG2("failed RTEMS_TOO_MANY\n");
        break;
      case RTEMS_INVALID_NUMBER:
        DBG2("failed RTEMS_INVALID_NUMBER\n");
        break;
      case RTEMS_RESOURCE_IN_USE:
        DBG2("failed RTEMS_RESOURCE_IN_USE\n");
        break;
      default:
        DBG("failed %i\n",r);
        break;
    }
    return 1;
  }
  DBG("Registered GRCAN on major %d\n",m);
  return 0;
}


/* Use custom addresses and IRQs to find hardware */
int GRCAN_PREFIX(_register_abs)(struct grcan_device_info *devices, int dev_cnt)
{
  FUNCDBG();

  if ( !devices || (dev_cnt<0) )
    return 1;
  grcan_cores = devices;
  grcan_core_cnt = dev_cnt;

  amba_bus = NULL;
	return grcan_register_internal();
}

/* Use prescanned AMBA Plug&Play information to find all GRCAN cores */
int GRCAN_PREFIX(_register)(struct ambapp_bus *abus)
{
  FUNCDBG();

  if ( !abus )
    return 1;
  amba_bus = abus;
  grcan_cores = NULL;
  grcan_core_cnt = 0;
  return grcan_register_internal();
}