/*-
 * Copyright (c) 2011, Aleksandr Rybalko <ray@dlink.ua>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_gpio.h"

#include <sys/param.h>
#include <sys/systm.h>

#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/rman.h>
#include <sys/sysctl.h>

#include <sys/gpio.h>
#include "gpiobus_if.h"

#include <dev/gpio/gpiobusvar.h>

#include <dev/spibus/spi.h>
#include <dev/spibus/spibusvar.h>
#include "spibus_if.h"

#ifdef	GPIO_SPI_DEBUG
#define	dprintf printf
#else
#define	dprintf(x, arg...)
#endif	/* GPIO_SPI_DEBUG */

struct gpio_spi_softc {
	device_t	sc_dev;
	device_t	sc_busdev;
	int		sc_freq;
	uint8_t		sc_sclk;
	uint8_t		sc_miso;
	uint8_t		sc_mosi;
	uint8_t		sc_cs0;
	uint8_t		sc_cs1;
	uint8_t		sc_cs2;
	uint8_t		sc_cs3;
};

static void gpio_spi_chip_activate(struct gpio_spi_softc *, int);
static void gpio_spi_chip_deactivate(struct gpio_spi_softc *, int);

static int
gpio_spi_probe(device_t dev)
{
	device_set_desc(dev, "GPIO SPI bit-banging driver");
	return (0);
}

static void
gpio_delay(struct gpio_spi_softc *sc)
{
	int d;

	d = sc->sc_freq / 1000000;
	if (d == 0)
		d = 1;

	DELAY(d);
}

static int
gpio_spi_attach(device_t dev)
{
	uint32_t value;
	struct gpio_spi_softc *sc;

	sc = device_get_softc(dev);
	sc->sc_dev = dev;
	sc->sc_busdev = device_get_parent(dev);

	/* Required variables */
	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "sclk", &value))
		 return (ENXIO);
	sc->sc_sclk = value & 0xff;

	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "mosi", &value))
		 return (ENXIO);
	sc->sc_mosi = value & 0xff;

	/* Handle no miso; we just never read back from the device */
	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "miso", &value))
		 value = 0xff;
	sc->sc_miso = value & 0xff;

	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "cs0", &value))
		 return (ENXIO);
	sc->sc_cs0 = value & 0xff;

	/* Optional variables */
	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "cs1", &value))
		value = 0xff;
	sc->sc_cs1 = value & 0xff;

	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "cs2", &value))
		value = 0xff;
	sc->sc_cs2 = value & 0xff;

	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "cs3", &value))
		value = 0xff;
	sc->sc_cs3 = value & 0xff;

	/* Default to 100KHz */
	if (resource_int_value(device_get_name(dev),
	    device_get_unit(dev), "freq", &value)) {
		value = 100000;
	}
	sc->sc_freq = value;

	if (bootverbose) {
		device_printf(dev, "frequency: %d Hz\n",
		    sc->sc_freq);
		device_printf(dev,
		    "Use GPIO pins: sclk=%d, mosi=%d, miso=%d, "
		    "cs0=%d, cs1=%d, cs2=%d, cs3=%d\n",
		    sc->sc_sclk, sc->sc_mosi, sc->sc_miso,
		    sc->sc_cs0, sc->sc_cs1, sc->sc_cs2, sc->sc_cs3);
	}

	/* Set directions */
	GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_sclk,
	    GPIO_PIN_OUTPUT|GPIO_PIN_PULLDOWN);
	GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_mosi,
	    GPIO_PIN_OUTPUT|GPIO_PIN_PULLDOWN);
	if (sc->sc_miso != 0xff) {
		GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_miso,
		    GPIO_PIN_INPUT|GPIO_PIN_PULLDOWN);
	}

	GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_cs0,
	    GPIO_PIN_OUTPUT|GPIO_PIN_PULLUP);

	if (sc->sc_cs1 != 0xff)
		GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_cs1,
		    GPIO_PIN_OUTPUT|GPIO_PIN_PULLUP);
	if (sc->sc_cs2 != 0xff)
		GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_cs2,
		    GPIO_PIN_OUTPUT|GPIO_PIN_PULLUP);
	if (sc->sc_cs3 != 0xff)
		GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, sc->sc_cs3,
		    GPIO_PIN_OUTPUT|GPIO_PIN_PULLUP);

	gpio_spi_chip_deactivate(sc, -1);

	device_add_child(dev, "spibus", -1);
	return (bus_generic_attach(dev));
}

static int
gpio_spi_detach(device_t dev)
{

	return (0);
}

static void
gpio_spi_chip_activate(struct gpio_spi_softc *sc, int cs)
{

	/* called with locked gpiobus */
	switch (cs) {
	case 0:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs0, 0);
		break;
	case 1:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs1, 0);
		break;
	case 2:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs2, 0);
		break;
	case 3:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs3, 0);
		break;
	default:
		device_printf(sc->sc_dev, "don't have CS%d\n", cs);
	}

	gpio_delay(sc);
}

static void
gpio_spi_chip_deactivate(struct gpio_spi_softc *sc, int cs)
{

	/* called wth locked gpiobus */
	/*
	 * Put CSx to high
	 */
	switch (cs) {
	case -1:
		/* All CS */
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs0, 1);
		if (sc->sc_cs1 == 0xff) break;
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs1, 1);
		if (sc->sc_cs2 == 0xff) break;
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs2, 1);
		if (sc->sc_cs3 == 0xff) break;
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs3, 1);
		break;
	case 0:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs0, 1);
		break;
	case 1:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs1, 1);
		break;
	case 2:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs2, 1);
		break;
	case 3:
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_cs3, 1);
		break;
	default:
		device_printf(sc->sc_dev, "don't have CS%d\n", cs);
	}
}

static uint8_t
gpio_spi_txrx(struct gpio_spi_softc *sc, int cs, int mode, uint8_t data)
{
	uint32_t mask, out = 0;
	unsigned int bit;


	/* called with locked gpiobus */

	for (mask = 0x80; mask > 0; mask >>= 1) {
		if ((mode == SPIBUS_MODE_CPOL) ||
		    (mode == SPIBUS_MODE_CPHA)) {
			/* If mode 1 or 2 */

			/* first step */
			GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
			    sc->sc_mosi, (data & mask)?1:0);
			GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
			    sc->sc_sclk, 0);
			gpio_delay(sc);
			/* second step */
			if (sc->sc_miso != 0xff) {
				GPIOBUS_PIN_GET(sc->sc_busdev, sc->sc_dev,
				    sc->sc_miso, &bit);
				out |= bit?mask:0;
			}
			/* Data captured */
			gpio_delay(sc);
			GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
			    sc->sc_sclk, 1);
			gpio_delay(sc);
		} else {
			/* If mode 0 or 3 */

			/* first step */
			GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
			    sc->sc_mosi, (data & mask)?1:0);
			GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
			    sc->sc_sclk, 1);
			gpio_delay(sc);
			/* second step */
			if (sc->sc_miso != 0xff) {
				GPIOBUS_PIN_GET(sc->sc_busdev, sc->sc_dev,
				    sc->sc_miso, &bit);
				out |= bit?mask:0;
			}
			 /* Data captured */
			gpio_delay(sc);
			GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
			    sc->sc_sclk, 0);
			gpio_delay(sc);
		}
	}

	return (out & 0xff);
}

static int
gpio_spi_transfer(device_t dev, device_t child, struct spi_command *cmd)
{
	struct gpio_spi_softc *sc;
	uint8_t *buf_in, *buf_out;
	struct spibus_ivar *devi = SPIBUS_IVAR(child);
	int i;

	sc = device_get_softc(dev);

	KASSERT(cmd->tx_cmd_sz == cmd->rx_cmd_sz, 
	    ("TX/RX command sizes should be equal"));
	KASSERT(cmd->tx_data_sz == cmd->rx_data_sz, 
	    ("TX/RX data sizes should be equal"));

	gpio_spi_chip_activate(sc, devi->cs);

	/* Preset pins */
	if ((devi->mode == SPIBUS_MODE_CPOL) ||
	    (devi->mode == SPIBUS_MODE_CPHA)) {
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_sclk, 1);
	} else {
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_sclk, 0);
	}

	/*
	 * Transfer command
	 */
	buf_out = (uint8_t *)cmd->tx_cmd;
	buf_in = (uint8_t *)cmd->rx_cmd;

	for (i = 0; i < cmd->tx_cmd_sz; i++)
		buf_in[i] = gpio_spi_txrx(sc, devi->cs, devi->mode, buf_out[i]);

	/*
	 * Receive/transmit data (depends on command)
	 */
	buf_out = (uint8_t *)cmd->tx_data;
	buf_in = (uint8_t *)cmd->rx_data;
	for (i = 0; i < cmd->tx_data_sz; i++)
		buf_in[i] = gpio_spi_txrx(sc, devi->cs, devi->mode, buf_out[i]);

	/* Return pins to mode default */
	if ((devi->mode == SPIBUS_MODE_CPOL) ||
	    (devi->mode == SPIBUS_MODE_CPHA)) {
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_sclk, 1);
	} else {
		GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev,
		    sc->sc_sclk, 0);
	}

	gpio_spi_chip_deactivate(sc, devi->cs);

	return (0);
}

static device_method_t gpio_spi_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe,		gpio_spi_probe),
	DEVMETHOD(device_attach,	gpio_spi_attach),
	DEVMETHOD(device_detach,	gpio_spi_detach),

	DEVMETHOD(spibus_transfer,	gpio_spi_transfer),

	{0, 0}
};

static driver_t gpio_spi_driver = {
	"gpiospi",
	gpio_spi_methods,
	sizeof(struct gpio_spi_softc),
};

DRIVER_MODULE(gpiospi, gpiobus, gpio_spi_driver, 0, 0);
DRIVER_MODULE(spibus, gpiospi, spibus_driver, 0, 0);
MODULE_DEPEND(spi, gpiospi, 1, 1, 1);
MODULE_DEPEND(gpiobus, gpiospi, 1, 1, 1);