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#  $Id$
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This is a port of the Winsystems Linux driver to RTEMS.

In general, the goal was to minimize changes to the user level
library and only replace Linux IO calls to the device driver
with direct access functions. 

The driver uses 4 Classic API Barriers.

--joel sherrill

Issues
======
+ The library is not reentrant. The GNU/Linux version uses global variables
  to track the state of certain variables and access to these is not protected.
  This design flaw is carried over into the RTEMS version.

+ We want to timestamp samples and the initial code did not do that.  I
  added this.

New Methods
===========
  void pcmmio_initialize(
    unsigned short _base_port,
    unsigned short _irq
  );

  void flush_buffered_ints(void);

  int wait_adc_int_with_timeout(int adc_num, int milliseconds);

  int wait_dac_int_with_timeout(int dac_num, int milliseconds);

  int wait_dio_int_with_timeout(int milliseconds);

  int wait_dio_int_with_timestamp(
    int                 milliseconds,
    unsigned long long *timestamp
  );
  int dio_get_missed_interrupts(void);

RTEMS Configuration
===================
The driver needs:

+ 3 Classic API Barriers
+ 1 Classic API Message Queue
  - 1024 buffers of sizeof(din_messsage_t) (should be 12 bytes)

The pcmmio_shell example is probably over configured but is a
working guide.

RTEMS Shell Commands
====================
The following RTEMS Shell configuration aids are defined to assist in
adding PCMMIO related commands to your shell.
  CONFIGURE_PCMMIO_ALIASES
  CONFIGURE_PCMMIO_COMMANDS

pcmmio_din - Read Discrete Inputs
    pcmmio_din [-i iterations] [-p period] [-v]
    Where: maximum iterations defaults to 1
           the period is in milliseconds and defaults to 1000

pcmmio_dout - Write a Discrete Output
    pcmmio_dout bit value
    Where: bit must be 0-47
           value must be 0 or 1

pcmmio_adc - Read Analog Inputs
    pcmmio_adc [-i iterations] [-p period] [-v]
    Where: maximum iterations defaults to 1
           the period is in milliseconds and defaults to 1000

pcmmio_dac - Write Analog Output
    pcmmio_dac dac voltage
    pcmmio_dac dac low high step time_per_step maximum_time

    Where: dac must be 0-7
           voltages and step must be -10V to +10V
           times are in milliseconds

    First form is a single write.
    Second form writes a pattern.

pcmmio_irq - Wait for PCMMIO IRQs
  pcmmio_irq [-i iterations] [-p period] [-v] [-d|-D DAC|-a ADC]

  Where: maximum iterations defaults to 1
         the period is in milliseconds and defaults to 1000
         -d enables discrete input irq monitoring
         -D DAC enables irq monitoring on the DAC channel "DAC"
         -a ADC enables irq monitoring on the ADC channel "ADC"

  You select one of the three IRQ sources to monitor.

pcmmio_benchmark - Benchmark Discrete Input Interrupt Performance

  pcmmio_benchmarks [-i interrupts] [-v]

  Where: maximum interrupts must be >= 1

Aliases
  + adc  - alias for pcmmio_adc 
  + dac  - alias for pcmmio_dac 
  + din  - alias for pcmmio_din 
  + dout - alias for pcmmio_dout