/* Tool to control ZX76-31R5-SP-S+ digital attenuators on LTHW Main unit */

/* (C) 2016 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
 * All Rights Reserved
 *
 * Author: Philipp Maier
 *
 * 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 2 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 <stdio.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <libgen.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/utils.h>
#include "gpio.h"

/* GPIO pin assignment */
#define GPIO_LE_1 13
#define GPIO_LE_2 7
#define GPIO_LE_3 5
#define GPIO_LE_4 11
#define GPIO_DATA 15
#define GPIO_CLK 17

/* Internal GPIO alias */
#define LE_1 0
#define LE_2 1
#define LE_3 2
#define LE_4 3
#define DATA 4
#define CLK 5

/* ZX76-31R5-SP-S+ properties */
#define DB_MAX 31.5

/* Generate a clock or latch enable pulse */
static inline void gpio_pulse(struct gpio_descr *gd, unsigned int gpio)
{
	gpio_set(gd, gpio, 1);
	gpio_set(gd, gpio, 0);
}

/* Write control word to Attenuator */
void att_write(struct gpio_descr *gd, uint8_t cw, unsigned int le)
{
	int i;
	unsigned int bit;

	/* Write control word (val) to Attenuator */
	for (i = 5; i >= 0; i--) {
		bit = ((cw >> i) & 1);
		gpio_set(gd, DATA, bit);
		gpio_pulse(gd, CLK);
	}

	/* Generate latch enable pulse */
	gpio_pulse(gd, le);
}

/* Initalize attenuators */
struct gpio_descr *att_init(void)
{
	unsigned int gpios[6];
	struct gpio_descr *gd;

	/* GPIO pin mapping */
	gpios[LE_1] = GPIO_LE_1;
	gpios[LE_2] = GPIO_LE_2;
	gpios[LE_3] = GPIO_LE_3;
	gpios[LE_4] = GPIO_LE_4;
	gpios[DATA] = GPIO_DATA;
	gpios[CLK] = GPIO_CLK;

	/* Open GPIO */
	gd = gpio_open(NULL, gpios, 6);
	if (!gd) {
		printf("Error: Unable to open GPIO\n");
		exit(1);
	}

	/* Initalize GPIOs to low level */
	gpio_set(gd, LE_1, 0);
	gpio_set(gd, LE_2, 0);
	gpio_set(gd, LE_3, 0);
	gpio_set(gd, LE_4, 0);
	gpio_set(gd, DATA, 0);
	gpio_set(gd, CLK, 0);

	return gd;
}

/* Set attenuator value */
void att_set(struct gpio_descr *gd, double val, unsigned int le)
{
	uint8_t cw;

	if (val > DB_MAX || val < 0) {
		printf("Error: Invalid attenuation value!\n");
		return;
	}

	printf("Setting attenuator #%d to value %.1lf...\n", le + 1, val);
	cw = (uint8_t) (val * 2);
	att_write(gd, cw, le);
}

/* Print online help */
void print_help(char *progname)
{
	printf("Usage: %s -i ID -a ATT\n", progname);
	printf("Attenuation (ATT) in 0.5db steps, range 0-31.5\n");
	printf("\n");
	exit(0);
}

int main(int argc, char *argv[])
{
	struct gpio_descr *gd;
	int option;
	double getopt_att = -1;
	int getopt_id = -1;

	/* Parse options */
	while ((option = getopt(argc, argv, "hi:a:")) != -1) {
		switch (option) {
		case 'h':
			print_help(basename(argv[0]));
			break;
		case 'a':
			getopt_att = atof(optarg);
			break;
		case 'i':
			getopt_id = atoi(optarg) - 1;
			break;
		}
	}

	/* Check options */
	if (getopt_att < 0) {
		printf("Error: No attenuation value specified!\n");
		exit(1);
	}

	if (getopt_id < 0) {
		printf("Error: No attenuator id specified!\n");
		exit(1);
	}

	if (getopt_id > 3) {
		printf("Error: Invalid attenuator id specified!\n");
		exit(1);
	}

	/* Set attenuation */
	gd = att_init();
	att_set(gd, getopt_att, getopt_id);
	gpio_close(gd);

	return 0;
}