/*
 * Copyright © 2012 Keith Packard <keithp@keithp.com>
 *
 * 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; version 2 of the License.
 *
 * 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, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 */

#include <ao.h>
#include <ao_hmc5883.h>
#include <ao_exti.h>

static uint8_t	ao_hmc5883_configured;

static void
ao_hmc5883_reg_write(uint8_t addr, uint8_t data)
{
	uint8_t	d[2];

	d[0] = addr;
	d[1] = data;
	ao_i2c_get(AO_HMC5883_I2C_INDEX);
	ao_i2c_start(AO_HMC5883_I2C_INDEX, HMC5883_ADDR_WRITE);
	ao_i2c_send(d, 2, AO_HMC5883_I2C_INDEX, TRUE);
	ao_i2c_put(AO_HMC5883_I2C_INDEX);
}

static void
ao_hmc5883_read(uint8_t addr, uint8_t *data, uint8_t len)
{
	ao_i2c_get(AO_HMC5883_I2C_INDEX);
	ao_i2c_start(AO_HMC5883_I2C_INDEX, HMC5883_ADDR_WRITE);
	ao_i2c_send(&addr, 1, AO_HMC5883_I2C_INDEX, FALSE);
	ao_i2c_start(AO_HMC5883_I2C_INDEX, HMC5883_ADDR_READ);
	ao_i2c_recv(data, len, AO_HMC5883_I2C_INDEX, TRUE);
	ao_i2c_put(AO_HMC5883_I2C_INDEX);
}

static uint8_t ao_hmc5883_done;

static void
ao_hmc5883_isr(void)
{
	ao_exti_disable(&AO_HMC5883_INT_PORT, AO_HMC5883_INT_PIN);
	ao_hmc5883_done = 1;
	ao_wakeup(&ao_hmc5883_done);
}

void
ao_hmc5883_sample(struct ao_hmc5883_sample *sample)
{
	uint16_t	*d = (uint16_t *) sample;
	int		i = sizeof (*sample) / 2;
	uint8_t		single = HMC5883_MODE_SINGLE;

	ao_hmc5883_done = 0;
	ao_exti_enable(&AO_HMC5883_INT_PORT, AO_HMC5883_INT_PIN);
	ao_hmc5883_reg_write(HMC5883_MODE, HMC5883_MODE_SINGLE);
	cli();
	while (!ao_hmc5883_done)
		ao_sleep(&ao_hmc5883_done);
	sei();
	ao_hmc5883_read(HMC5883_X_MSB, (uint8_t *) sample, sizeof (struct ao_hmc5883_sample));
#if __BYTE_ORDER == __LITTLE_ENDIAN
	/* byte swap */
	while (i--) {
		uint16_t	t = *d;
		*d++ = (t >> 8) | (t << 8);
	}
#endif
}

static uint8_t
ao_hmc5883_setup(void)
{
	uint8_t	present;
	if (ao_hmc5883_configured)
		return 1;

	/* Enable the EXTI interrupt for the appropriate pin */
	ao_enable_port(AO_HMC5883_INT_PORT);
	ao_exti_setup(&AO_HMC5883_INT_PORT, AO_HMC5883_INT_PIN,
		      AO_EXTI_MODE_FALLING, ao_hmc5883_isr);

	ao_i2c_get(AO_HMC5883_I2C_INDEX);
	present = ao_i2c_start(AO_HMC5883_I2C_INDEX, HMC5883_ADDR_READ);
	ao_i2c_recv(NULL, 0, AO_HMC5883_I2C_INDEX, TRUE);
	ao_i2c_put(AO_HMC5883_I2C_INDEX);
	if (!present)
		return 0;
	ao_hmc5883_configured = 1;
	return 1;
}

static void
ao_hmc5883_show(void)
{
	uint8_t	addr, data;
	struct ao_hmc5883_sample sample;

	if (!ao_hmc5883_setup()) {
		printf("hmc5883 not present\n");
		return;
	}
#if 0
	for (addr = 0; addr <= 12; addr++) {
		ao_hmc5883_read(addr, &data, 1);
		printf ("hmc5883 register %2d: %02x\n",
			addr, data);
	}
#endif
	ao_hmc5883_sample(&sample);
	printf ("X: %d Y: %d Z: %d\n", sample.x, sample.y, sample.z);
}

static const struct ao_cmds ao_hmc5883_cmds[] = {
	{ ao_hmc5883_show,	"M\0Show HMC5883 status" },
	{ 0, NULL }
};

void
ao_hmc5883_init(void)
{
	ao_hmc5883_configured = 0;

	ao_exti_setup(&AO_HMC5883_INT_PORT,
		      AO_HMC5883_INT_PIN,
		      AO_EXTI_MODE_FALLING,
		      ao_hmc5883_isr);

	ao_cmd_register(&ao_hmc5883_cmds[0]);
}