/* $NetBSD: tcagpio.c,v 1.9 2025/09/17 13:42:43 thorpej Exp $ */

/*-
 * Copyright (c) 2017 Jared McNeill <jmcneill@invisible.ca>
 * 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, 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__KERNEL_RCSID(0, "$NetBSD: tcagpio.c,v 1.9 2025/09/17 13:42:43 thorpej Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/conf.h>
#include <sys/bus.h>
#include <sys/kmem.h>
#include <sys/gpio.h>

#include <dev/i2c/i2cvar.h>

#include <dev/fdt/fdtvar.h>

#define PORT_BANK(pin)          (pin / 8)
#define PORT_BIT(pin)           __BIT(pin % 8)

#define PORT_IN(pin)            (0x00 + PORT_BANK(pin))
#define PORT_OUT(pin)           (0x02 + PORT_BANK(pin))
#define PORT_POLARITY(pin)      (0x04 + PORT_BANK(pin))
#define PORT_CFG(pin)           (0x06 + PORT_BANK(pin))

#define TCA_PIN_COUNT           16

struct tcagpio_softc {
        device_t        sc_dev;
        i2c_tag_t       sc_i2c;
        i2c_addr_t      sc_addr;
        int             sc_phandle;

        int             sc_npins;
};

struct tcagpio_pin {
        struct tcagpio_softc    *pin_sc;
        int                     pin_num;
        int                     pin_flags;
        bool                    pin_actlo;
};

static const struct device_compatible_entry compat_data[] = {
        { .compat = "ti,tca9539" },
        DEVICE_COMPAT_EOL
};

static uint8_t
tcagpio_read(struct tcagpio_softc *sc, uint8_t reg, int flags)
{
        uint8_t val = 0;
        int error;

        error = iic_exec(sc->sc_i2c, I2C_OP_READ_WITH_STOP, sc->sc_addr,
            &reg, 1, &val, 1, flags);
        if (error != 0)
                aprint_error_dev(sc->sc_dev, "error reading reg %#x: %d\n", reg, error);

        return val;
}

static void
tcagpio_write(struct tcagpio_softc *sc, uint8_t reg, uint8_t val, int flags)
{
        uint8_t buf[2];
        int error;

        buf[0] = reg;
        buf[1] = val;

        error = iic_exec(sc->sc_i2c, I2C_OP_WRITE_WITH_STOP, sc->sc_addr,
            NULL, 0, buf, 2, flags);
        if (error != 0)
                aprint_error_dev(sc->sc_dev, "error writing reg %#x: %d\n", reg, error);
}

#define I2C_READ(sc, reg)       tcagpio_read((sc), (reg), 0)
#define I2C_WRITE(sc, reg, val) tcagpio_write((sc), (reg), (val), 0)
#define I2C_LOCK(sc)            iic_acquire_bus((sc)->sc_i2c, 0)
#define I2C_UNLOCK(sc)          iic_release_bus((sc)->sc_i2c, 0)

static int
tcagpio_gpio_config(struct tcagpio_softc *sc, int pin, int flags)
{
        uint16_t gpio;

        KASSERT(pin >= 0 && pin < sc->sc_npins);

        gpio = I2C_READ(sc, PORT_CFG(pin));

        switch (flags & (GPIO_PIN_INPUT|GPIO_PIN_OUTPUT)) {
        case GPIO_PIN_INPUT:
                gpio |= PORT_BIT(pin);
                break;
        case GPIO_PIN_OUTPUT:
                gpio &= ~PORT_BIT(pin);
                break;
        default:
                return EINVAL;
        }

        I2C_WRITE(sc, PORT_CFG(pin), gpio);

        return 0;
}

static void *
tcagpio_gpio_acquire(device_t dev, const void *data, size_t len, int flags)
{
        struct tcagpio_softc * const sc = device_private(dev);
        struct tcagpio_pin *gpin;
        const u_int *gpio = data;
        int error;

        if (len != 12)
                return NULL;

        const uint8_t pin = be32toh(gpio[1]) & 0xff;
        const bool actlo = (be32toh(gpio[2]) & __BIT(0)) != 0;
        
        if (pin >= sc->sc_npins)
                return NULL;

        I2C_LOCK(sc);
        error = tcagpio_gpio_config(sc, pin, flags);
        I2C_UNLOCK(sc);

        if (error != 0) {
                device_printf(dev, "bad pin %d config %#x\n", pin, flags);
                return NULL;
        }

        gpin = kmem_zalloc(sizeof(*gpin), KM_SLEEP);
        gpin->pin_sc = sc;
        gpin->pin_num = pin;
        gpin->pin_flags = flags;
        gpin->pin_actlo = actlo;

        return gpin;
}

static void
tcagpio_gpio_release(device_t dev, void *priv)
{
        struct tcagpio_softc * const sc = device_private(dev);
        struct tcagpio_pin *gpin = priv;

        I2C_LOCK(sc);
        tcagpio_gpio_config(sc, gpin->pin_num, GPIO_PIN_INPUT);
        I2C_UNLOCK(sc);

        kmem_free(gpin, sizeof(*gpin));
}

static int
tcagpio_gpio_read(device_t dev, void *priv, bool raw)
{
        struct tcagpio_softc * const sc = device_private(dev);
        struct tcagpio_pin *gpin = priv;
        uint8_t gpio;
        int val;

        I2C_LOCK(sc);
        gpio = I2C_READ(sc, PORT_IN(gpin->pin_num));
        I2C_UNLOCK(sc);

        val = __SHIFTOUT(gpio, PORT_BIT(gpin->pin_num));
        if (!raw && gpin->pin_actlo)
                val = !val;

#ifdef TCAGPIO_DEBUG
        device_printf(sc->sc_dev, "GPIO%d rd %02x (%d %d)\n",
            gpin->pin_num, gpio,
            (int)__SHIFTOUT(gpio, PORT_BIT(gpin->pin_num)), val);
#endif

        return val;
}

static void
tcagpio_gpio_write(device_t dev, void *priv, int val, bool raw)
{
        struct tcagpio_softc * const sc = device_private(dev);
        struct tcagpio_pin *gpin = priv;
        uint8_t gpio;

        if (!raw && gpin->pin_actlo)
                val = !val;

        I2C_LOCK(sc);
        gpio = I2C_READ(sc, PORT_OUT(gpin->pin_num));
        gpio &= ~PORT_BIT(gpin->pin_num);
        gpio |= __SHIFTIN(val, PORT_BIT(gpin->pin_num));
#ifdef TCAGPIO_DEBUG
        device_printf(sc->sc_dev, "GPIO%d wr %02x -> %02x\n",
            gpin->pin_num,
            I2C_READ(sc, PORT_OUT(gpin->pin_num)), gpio);
#endif
        I2C_WRITE(sc, PORT_OUT(gpin->pin_num), gpio);
        I2C_UNLOCK(sc);
}

static struct fdtbus_gpio_controller_func tcagpio_gpio_funcs = {
        .acquire = tcagpio_gpio_acquire,
        .release = tcagpio_gpio_release,
        .read = tcagpio_gpio_read,
        .write = tcagpio_gpio_write,
};

static void
tcagpio_gpio_attach(struct tcagpio_softc *sc)
{
        fdtbus_register_gpio_controller(sc->sc_dev, sc->sc_phandle,
            &tcagpio_gpio_funcs);
}

static int
tcagpio_match(device_t parent, cfdata_t match, void *aux)
{
        struct i2c_attach_args *ia = aux;
        int match_result;

        if (iic_use_direct_match(ia, match, compat_data, &match_result))
                return match_result;

        return 0;
}

static void
tcagpio_attach(device_t parent, device_t self, void *aux)
{
        struct tcagpio_softc * const sc = device_private(self);
        struct i2c_attach_args *ia = aux;

        sc->sc_dev = self;
        sc->sc_i2c = ia->ia_tag;
        sc->sc_addr = ia->ia_addr;
        sc->sc_phandle = devhandle_to_of(device_handle(self));
        sc->sc_npins = TCA_PIN_COUNT;

        aprint_naive("\n");
        aprint_normal(": I2C/SMBus I/O Expander\n");

        tcagpio_gpio_attach(sc);
}

CFATTACH_DECL_NEW(tcagpio, sizeof(struct tcagpio_softc),
    tcagpio_match, tcagpio_attach, NULL, NULL);