/*
 * JR-IDE Project
 * - (c) 2017 Alan Hightower
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "netpi.h"


#include <sys/ioctl.h>
#include <linux/spi/spidev.h>

static int spi_fd = -1;
static uint32_t spi_bitrate = 0;


int spi_init (int cs, uint32_t rate)
{
	if (spi_fd < 0)
		spi_term ();

	char *path;

	if (cs == 0)
		path = "/dev/spidev0.0";
	else if (cs == 1)
		path = "/dev/spidev0.1";
	else
		return -1;

	if ((spi_fd = open (path, O_RDWR)) < 0)
	{
		LOGERR("Unable to open SPI device '%s' - %s",
		       path, strerror (errno));

		return -1;
	}

	// Rest of settings are non-fatal

	uint8_t mode = 0;

	ioctl (spi_fd, SPI_IOC_RD_MODE, &mode);
	ioctl (spi_fd, SPI_IOC_WR_MODE, &mode);
  
	uint8_t bpw = 8;

	ioctl (spi_fd, SPI_IOC_RD_BITS_PER_WORD, &bpw);
	ioctl (spi_fd, SPI_IOC_WR_BITS_PER_WORD, &bpw);

	spi_bitrate = rate;

	ioctl (spi_fd, SPI_IOC_RD_MAX_SPEED_HZ, &rate);
	ioctl (spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &rate);

	LOGDBG("Opened SPI:%d interface @ %.2f MHz\n", cs, spi_bitrate / 1000000.0);

	return 0;
}


int spi_xfer (void *buf, int len)
{
	struct spi_ioc_transfer spi;

	memset (&spi, 0, sizeof (spi));

	spi.tx_buf        = (unsigned long) buf;
	spi.rx_buf        = (unsigned long) buf;
	spi.len           = len;
	spi.delay_usecs   = 0;
	spi.speed_hz      = spi_bitrate;
	spi.bits_per_word = 8;

	return (ioctl (spi_fd, SPI_IOC_MESSAGE(1), &spi) == len) ? len : -1;
}


void spi_term (void)
{
	if (spi_fd >= 0)
	{
		close (spi_fd);

		LOGDBG("Closed SPI interface\n");
	}

	spi_fd = -1;

	return;
}