AQM1248 hadling example for Raspberry Pi via register version.fill gray all area.

aqm1248.c

// AQM1248 hadling example for Raspberry Pi
// via register version
// compile: cc aqm1248.c -o aqm1248
// execute: sudo ./aqm1248

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>

#define OFF_PRT 0x20200000 // port registers
#define AQM_CONT 0x1c // AQM1248 contrust 0-0x3f
#define AQM_RS 25 // AQM1248 register selet

uint32_t *regs_map(off_t offset){
  int fd;
  void *map;

  fd = open("/dev/mem", O_RDWR | O_SYNC);
  if(fd < 0)
    return MAP_FAILED;

  map = mmap(NULL,
    getpagesize(),
    PROT_READ | PROT_WRITE,
    MAP_SHARED,
    fd,
    offset);

  close(fd);
  return map;
}

void fnc_wr(uint32_t *regs, int port, int val){
  regs[port / 10] &=  ~(7 << ((port % 10) * 3));
  regs[port / 10] |= (val << ((port % 10) * 3));
}

void prt_wr(uint32_t *regs, int port, int val){
  if(val)
    regs[7] = (1 << port);
  else
    regs[10] = (1 << port);
}

int transfer(int fd, uint8_t value){
  int ret;
  uint8_t tx;

  struct spi_ioc_transfer tr ={
    .tx_buf = (uint32_t)&tx,
    .rx_buf = (uint32_t)NULL,
    .len = 1,
    .delay_usecs = 0,
    .speed_hz = 2000000,
    .bits_per_word = 8,
  };

  tx = value;
  ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
  if(ret < 1){
    fprintf(stderr, "can't send spi message\n");
    return -1;
  }
  return 0;
}

int main(int argc, char *argv[]){
  int i, j;
  int ret = 0;
  int fd;
  uint32_t *regs;

  regs = regs_map(OFF_PRT);
  if(regs == MAP_FAILED){
    fprintf(stderr, "fail to get registers map. %s\n", strerror(errno));
    return -1;
  }

  fnc_wr(regs, AQM_RS, 1);
  fd = open("/dev/spidev0.0", O_RDWR);

  prt_wr(regs, AQM_RS, 0);
  transfer(fd, 0xae);
  transfer(fd, 0xa0);
  transfer(fd, 0xc8);
  transfer(fd, 0xa3);
  transfer(fd, 0x2c); usleep(2000);
  transfer(fd, 0x2e); usleep(2000);
  transfer(fd, 0x2f);
  transfer(fd, 0x23);
  transfer(fd, 0x81);
  transfer(fd, AQM_CONT);
  transfer(fd, 0xa4);
  transfer(fd, 0x40);
  transfer(fd, 0xa6);
  transfer(fd, 0xaf);

  for(i = 0; i < 6; i++){
    transfer(fd, 0xb0 | i);//page
    transfer(fd, 0x10);//column 0
    transfer(fd, 0x00);

    prt_wr(regs, AQM_RS, 1);
    for(j = 0; j < 64; j++){
      transfer(fd, 0x55);
      transfer(fd, 0xaa);
    }
    prt_wr(regs, AQM_RS, 0);
  }

  munmap(regs, getpagesize());
  close(fd);
  return 0;
}