pru.h

/** \file
 * Simplified interface to the ARM PRU.
 *
 */
#ifndef _pru_h_
#define _pru_h_

#ifdef __cplusplus
extern "C" {
#endif

#include <stdio.h>
#include <inttypes.h>
#include "util.h"

/** Mapping of the PRU memory spaces.
 *
 * The PRU has a small, fast local data RAM that is mapped into ARM memory,
 * as well as slower access to the DDR RAM of the ARM.
 */
typedef struct {
  unsigned pru_num;

  void *data_ram;       // PRU data ram in ARM space
  size_t data_ram_size; // size in bytes of the PRU's data RAM

  void *ddr;          // PRU DMA address (in ARM space)
  uintptr_t ddr_addr; // PRU DMA address (in PRU space)
  size_t ddr_size;    // Size in bytes of the shared space
} pru_t;

extern pru_t *pru_init(const unsigned short pru_num);

extern void pru_exec(pru_t *const pru, const char *const program);

extern void pru_close(pru_t *const pru);

/** Configure a GPIO pin.
 *
 * Since the device tree won't do it for us, we need to do it via
 * /sys/class/gpio to set the direction and initial value for
 * all of the pins that we use.
 *
 * Direction 0 == in, 1 == out.
 */
extern int pru_gpio(unsigned gpio, unsigned pin, unsigned direction,
                    const unsigned initial_value);

#ifdef __cplusplus
}
#endif
#endif