/*
 * Parport GPIO control
 *
 * Copyright (c) 2009 Michael Buesch <m@bues.ch>
 *
 * Licensed under the GNU/GPL version 2 or later.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/ppdev.h>
#include <linux/parport.h>


#define ARRAY_SIZE(a)	(sizeof(a) / sizeof((a)[0]))

enum gpio_type {
	GPIO_PPDATA,
	GPIO_PPCONTROL,
	GPIO_PPSTATUS,
};

enum gpio_direction {
	GPIO_OUT,
	GPIO_IN,
};

struct gpio {
	enum gpio_type type;
	enum gpio_direction dir;
	unsigned int bit;
	int default_state;
};

/* Mask of hardware inverters. */
static const unsigned char ppcontrol_hwinvert_mask = 0x0B;
static const unsigned char ppstatus_hwinvert_mask = 0x80;

static const struct gpio gpio_table[] = {
/* Data outputs */
	{ /* GPIO 0 = Pin 2 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 0,
	},
	{ /* GPIO 1 = Pin 3 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 1,
	},
	{ /* GPIO 2 = Pin 4 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 2,
	},
	{ /* GPIO 3 = Pin 5 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 3,
	},
	{ /* GPIO 4 = Pin 6 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 4,
	},
	{ /* GPIO 5 = Pin 7 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 5,
	},
	{ /* GPIO 6 = Pin 8 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 6,
	},
	{ /* GPIO 7 = Pin 9 */
		.type		= GPIO_PPDATA,
		.dir		= GPIO_OUT,
		.bit		= 7,
	},
/* Control outputs */
	{ /* GPIO 8 = Pin 1 */
		.type		= GPIO_PPCONTROL,
		.dir		= GPIO_OUT,
		.bit		= 0,
	},
	{ /* GPIO 9 = Pin 14 */
		.type		= GPIO_PPCONTROL,
		.dir		= GPIO_OUT,
		.bit		= 1,
	},
	{ /* GPIO 10 = Pin 16 */
		.type		= GPIO_PPCONTROL,
		.dir		= GPIO_OUT,
		.bit		= 2,
	},
	{ /* GPIO 11 = Pin 17 */
		.type		= GPIO_PPCONTROL,
		.dir		= GPIO_OUT,
		.bit		= 3,
	},
/* Inputs */
	{ /* GPIO 12 = Pin 15 */
		.type		= GPIO_PPSTATUS,
		.dir		= GPIO_IN,
		.bit		= 3,
	},
	{ /* GPIO 13 = Pin 13 */
		.type		= GPIO_PPSTATUS,
		.dir		= GPIO_IN,
		.bit		= 4,
	},
	{ /* GPIO 14 = Pin 12 */
		.type		= GPIO_PPSTATUS,
		.dir		= GPIO_IN,
		.bit		= 5,
	},
	{ /* GPIO 15 = Pin 10 */
		.type		= GPIO_PPSTATUS,
		.dir		= GPIO_IN,
		.bit		= 6,
	},
	{ /* GPIO 16 = Pin 11 */
		.type		= GPIO_PPSTATUS,
		.dir		= GPIO_IN,
		.bit		= 7,
	},
};

static int gpio_set(int fd, const struct gpio *gpio, int state)
{
	unsigned char data;
	int err;
	struct ppdev_frob_struct control_frob;

	if (gpio->dir != GPIO_OUT) {
		fprintf(stderr, "GPIO is not an output pin\n");
		return -1;
	}

	switch (gpio->type) {
	case GPIO_PPDATA:
		err = ioctl(fd, PPRDATA, &data);
		if (err) {
			fprintf(stderr, "Failed to read parport DATA: %s\n",
				strerror(errno));
			return -1;
		}

		data &= ~(1 << gpio->bit);
		if (state)
			data |= (1 << gpio->bit);

		err = ioctl(fd, PPWDATA, &data);
		if (err) {
			fprintf(stderr, "Failed to write parport DATA: %s\n",
				strerror(errno));
			return -1;
		}
		break;
	case GPIO_PPCONTROL:
		control_frob.mask = (1 << gpio->bit);
		control_frob.val = 0;
		if (state)
			control_frob.val = (1 << gpio->bit);

		control_frob.val ^= ppcontrol_hwinvert_mask;
		control_frob.val &= control_frob.mask;

		err = ioctl(fd, PPFCONTROL, &control_frob);
		if (err) {
			fprintf(stderr, "Failed to frob parport CONTROL: %s\n",
				strerror(errno));
			return -1;
		}
		break;
	case GPIO_PPSTATUS:
		fprintf(stderr, "gpio_set: Cannot write status port.\n");
		return -1;
	}

	return 0;
}

static int gpio_get(int fd, const struct gpio *gpio)
{
	int err;
	unsigned char d;

	switch (gpio->type) {
	case GPIO_PPDATA:
		err = ioctl(fd, PPRDATA, &d);
		if (err) {
			fprintf(stderr, "Failed to read parport DATA: %s\n",
				strerror(errno));
			return -1;
		}
		break;
	case GPIO_PPCONTROL:
		err = ioctl(fd, PPRCONTROL, &d);
		if (err) {
			fprintf(stderr, "Failed to read parport CONTROL: %s\n",
				strerror(errno));
			return -1;
		}
		d ^= ppcontrol_hwinvert_mask;
		break;
	case GPIO_PPSTATUS:
		err = ioctl(fd, PPRSTATUS, &d);
		if (err) {
			fprintf(stderr, "Failed to read parport STATUS: %s\n",
				strerror(errno));
			return -1;
		}
		d ^= ppstatus_hwinvert_mask;
		break;
	}

	return !!(d & (1 << gpio->bit));
}

static int do_setup(int fd)
{
	const struct gpio *gpio;
	int dir, mode, err;
	unsigned int i;

	err = ioctl(fd, PPCLAIM);
	if (err) {
		fprintf(stderr, "Failed to claim parport device: %s\n",
			strerror(errno));
		return -1;
	}

	mode = IEEE1284_MODE_COMPAT;
	err = ioctl(fd, PPSETMODE, &mode);
	if (err) {
		fprintf(stderr, "Failed to set parport mode: %s\n",
			strerror(errno));
		goto out;
	}

	dir = 0;
	err = ioctl(fd, PPDATADIR, &dir);
	if (err) {
		fprintf(stderr, "Failed to turn on DATA output: %s\n",
			strerror(errno));
		goto out;
	}

	err = 0;
	for (i = 0; i < ARRAY_SIZE(gpio_table); i++) {
		gpio = &(gpio_table[i]);
		if (gpio->dir == GPIO_OUT) {
			err = gpio_set(fd, gpio, gpio->default_state);
			if (err)
				break;
		}
	}
out:
	ioctl(fd, PPRELEASE);

	return err;
}

static int do_change_gpio_state(int fd, unsigned int gpionr, int newstate)
{
	const struct gpio *gpio;
	int err;

	if (gpionr >= ARRAY_SIZE(gpio_table)) {
		fprintf(stderr, "GPIO number is too big\n");
		return -1;
	}
	gpio = &(gpio_table[gpionr]);

	err = ioctl(fd, PPCLAIM);
	if (err) {
		fprintf(stderr, "Failed to claim parport device: %s\n",
			strerror(errno));
		return -1;
	}
	err = gpio_set(fd, gpio, newstate);
	ioctl(fd, PPRELEASE);

	return err;
}

static int do_get_gpio_state(int fd, unsigned int gpionr)
{
	const struct gpio *gpio;
	int err, res;

	if (gpionr >= ARRAY_SIZE(gpio_table)) {
		fprintf(stderr, "GPIO number is too big\n");
		return -1;
	}
	gpio = &(gpio_table[gpionr]);

	err = ioctl(fd, PPCLAIM);
	if (err) {
		fprintf(stderr, "Failed to claim parport device: %s\n",
			strerror(errno));
		return -1;
	}
	res = gpio_get(fd, gpio);
	ioctl(fd, PPRELEASE);

	return res;
}

static int str2bool(const char *str)
{
	int res = -1;

	if ((strcasecmp(str, "1") == 0) ||
	    (strcasecmp(str, "on") == 0) ||
	    (strcasecmp(str, "yes") == 0) ||
	    (strcasecmp(str, "true") == 0))
		res = 1;
	else if ((strcasecmp(str, "0") == 0) ||
		 (strcasecmp(str, "off") == 0) ||
		 (strcasecmp(str, "no") == 0) ||
		 (strcasecmp(str, "false") == 0))
		res = 0;

	return res;
}

static void usage(int argc, char **argv)
{
	printf("Usage: %s /dev/parport0 GPIONR on/off\n", argv[0]);
	printf("       %s /dev/parport0 GPIONR get\n", argv[0]);
	printf("       %s /dev/parport0 --setup\n", argv[0]);
}

#define ERRCODE_FAIL	0xFF

int main(int argc, char **argv)
{
	const char *ppdev, *gpiostr, *statestr;
	unsigned int gpionr;
	int err, res, state = 0, fd;
	int setup = 0, get = 0;

	if ((argc != 4) && (argc != 3)) {
		usage(argc, argv);
		return ERRCODE_FAIL;
	}
	if (argc == 4) {
		ppdev = argv[1];
		gpiostr = argv[2];
		statestr = argv[3];

		if (sscanf(gpiostr, "%u", &gpionr) != 1) {
			fprintf(stderr, "Invalid GPIO number.\n");
			return ERRCODE_FAIL;
		}
		if (strcasecmp(statestr, "get") == 0) {
			get = 1;
		} else {
			state = str2bool(statestr);
			if (state == -1) {
				fprintf(stderr, "Invalid boolean state value.\n");
				return ERRCODE_FAIL;
			}
		}
	} else {
		ppdev = argv[1];
		if (strcasecmp(argv[2], "--setup") != 0) {
			usage(argc, argv);
			return ERRCODE_FAIL;
		}
		setup = 1;
	}

	fd = open(ppdev, O_RDWR);
	if (fd == -1) {
		fprintf(stderr, "Failed to open %s: %s\n",
			ppdev, strerror(errno));
		return ERRCODE_FAIL;
	}

	res = 0;
	err = 0;
	if (setup) {
		err = do_setup(fd);
	} else {
		if (get) {
			res = do_get_gpio_state(fd, gpionr);
			if (res < 0)
				err = -1;
			else
				printf("%d\n", res);
		} else
			err = do_change_gpio_state(fd, gpionr, state);
	}
	close(fd);

	return err ? ERRCODE_FAIL : res;
}