/*      $NetBSD: exynos_i2c.c,v 1.24 2025/09/16 11:55:17 thorpej Exp $ */

/*
 * Copyright (c) 2015 Jared D. 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 "opt_exynos.h"
#include "opt_arm_debug.h"

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: exynos_i2c.c,v 1.24 2025/09/16 11:55:17 thorpej Exp $");

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

#include <arm/samsung/exynos_reg.h>
#include <arm/samsung/exynos_var.h>
#include <arm/samsung/exynos_intr.h>

#include <sys/gpio.h>
#include <dev/gpio/gpiovar.h>

#include <dev/i2c/i2cvar.h>
#include <dev/i2c/i2c_bitbang.h>

#include <dev/fdt/fdtvar.h>

struct exynos_i2c_softc {
        device_t                sc_dev;
        bus_space_tag_t         sc_bst;
        bus_space_handle_t      sc_bsh;
        void *                  sc_ih;
        struct clk *            sc_clk;

        struct fdtbus_pinctrl_pin  *sc_sda;
        struct fdtbus_pinctrl_pin  *sc_scl;
        bool                    sc_sda_is_output;

        struct i2c_controller   sc_ic;
        kmutex_t                sc_intr_lock;
        kcondvar_t              sc_intr_wait;
};

static int      exynos_i2c_intr(void *);

static int      exynos_i2c_send_start(void *, int);
static int      exynos_i2c_send_stop(void *, int);
static int      exynos_i2c_initiate_xfer(void *, i2c_addr_t, int);
static int      exynos_i2c_read_byte(void *, uint8_t *, int);
static int      exynos_i2c_write_byte(void *, uint8_t , int);

static int      exynos_i2c_wait(struct exynos_i2c_softc *, int);


static int exynos_i2c_match(device_t, cfdata_t, void *);
static void exynos_i2c_attach(device_t, device_t, void *);

CFATTACH_DECL_NEW(exynos_i2c, sizeof(struct exynos_i2c_softc),
    exynos_i2c_match, exynos_i2c_attach, NULL, NULL);

#define I2C_WRITE(sc, reg, val) \
    bus_space_write_1((sc)->sc_bst, (sc)->sc_bsh, (reg), (val))
#define I2C_READ(sc, reg) \
    bus_space_read_1((sc)->sc_bst, (sc)->sc_bsh, (reg))

#define IICCON  0x00
#define IICSTAT 0x04
#define IICADD  0x08
#define IICDS   0x0C

#define ACKENABLE  (1<<7)
#define TXPRESCALE (1<<6)
#define INTENABLE  (1<<5)
#define IRQPEND    (1<<4)
#define PRESCALE   (0x0f)

#define MODESELECT  (3<<6)
#define BUSYSTART   (1<<5)
#define BUSENABLE   (1<<4)
#define ARBITRATION (1<<3)
#define SLAVESTATUS (1<<2)
#define ZEROSTATUS  (1<<1)
#define LASTBIT     (1<<0)

#define READBIT     (1<<7)

static const struct device_compatible_entry compat_data[] = {
        { .compat = "samsung,s3c2440-i2c" },
        DEVICE_COMPAT_EOL
};

static int
exynos_i2c_match(device_t self, cfdata_t cf, void *aux)
{
        struct fdt_attach_args * const faa = aux;

        return of_compatible_match(faa->faa_phandle, compat_data);
}

static void
exynos_i2c_attach(device_t parent, device_t self, void *aux)
{
        struct exynos_i2c_softc * const sc =  device_private(self);
        struct fdt_attach_args * const faa = aux;
        const int phandle = faa->faa_phandle;
        char intrstr[128];
        bus_addr_t addr;
        bus_size_t size;
        int error;

        if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
                aprint_error(": couldn't get registers\n");
                return;
        }

        sc->sc_dev  = self;
        sc->sc_bst = faa->faa_bst;
        error = bus_space_map(sc->sc_bst, addr, size, 0, &sc->sc_bsh);
        if (error) {
                aprint_error(": couldn't map %#" PRIxBUSADDR ": %d", addr,
                             error);
                return;
        }

        mutex_init(&sc->sc_intr_lock, MUTEX_DEFAULT, IPL_VM);
        cv_init(&sc->sc_intr_wait, device_xname(self));
        aprint_normal(" @ 0x%08x\n", (uint)addr);

        if (!fdtbus_intr_str(phandle, 0, intrstr, sizeof(intrstr))) {
                aprint_error_dev(self, "failed to decode interrupt\n");
                return;
        }

        sc->sc_ih = fdtbus_intr_establish_xname(phandle, 0, IPL_VM,
            FDT_INTR_MPSAFE, exynos_i2c_intr, sc, device_xname(self));
        if (sc->sc_ih == NULL) {
                aprint_error_dev(self, "couldn't establish interrupt on %s\n",
                    intrstr);
                return;
        }
        aprint_normal_dev(self, "interrupting on %s\n", intrstr);

        iic_tag_init(&sc->sc_ic);
        sc->sc_ic.ic_cookie = sc;
        sc->sc_ic.ic_send_start  = exynos_i2c_send_start;
        sc->sc_ic.ic_send_stop   = exynos_i2c_send_stop;
        sc->sc_ic.ic_initiate_xfer = exynos_i2c_initiate_xfer;
        sc->sc_ic.ic_read_byte   = exynos_i2c_read_byte;
        sc->sc_ic.ic_write_byte  = exynos_i2c_write_byte;

        iicbus_attach(self, &sc->sc_ic);
}

static int
exynos_i2c_intr(void *priv)
{
        struct exynos_i2c_softc * const sc = priv;

        uint8_t istatus = I2C_READ(sc, IICCON);
        if (!(istatus & IRQPEND))
                return 0;
        istatus &= ~IRQPEND;
        I2C_WRITE(sc, IICCON, istatus);

        mutex_enter(&sc->sc_intr_lock);
        cv_broadcast(&sc->sc_intr_wait);
        mutex_exit(&sc->sc_intr_lock);

        return 1;
}

static int
exynos_i2c_wait(struct exynos_i2c_softc *sc, int flags)
{
        int error, retry;
        uint8_t stat = 0;

        retry = (flags & I2C_F_POLL) ? 100000 : 100;

        while (--retry > 0) {
                if ((flags & I2C_F_POLL) == 0) {
                        error = cv_timedwait_sig(&sc->sc_intr_wait,
                                                 &sc->sc_intr_lock,
                                                 uimax(mstohz(10), 1));
                        if (error) {
                                return error;
                        }
                }
                stat = I2C_READ(sc, IICSTAT);
                if (!(stat & BUSYSTART)) {
                        break;
                }
                if (flags & I2C_F_POLL) {
                        delay(10);
                }
        }
        if (retry == 0) {
                stat = I2C_READ(sc, IICSTAT);
                device_printf(sc->sc_dev, "timed out, status = %#x\n", stat);
                return ETIMEDOUT;
        }

        return 0;
}


static int
exynos_i2c_send_start_locked(struct exynos_i2c_softc *sc, int flags)
{
        I2C_WRITE(sc, IICSTAT, 0xF0);
        return 0;
}

static int
exynos_i2c_send_stop_locked(struct exynos_i2c_softc *sc, int flags)
{
        I2C_WRITE(sc, IICSTAT, 0xD0);
        return 0;
}

static int
exynos_i2c_write_byte_locked(struct exynos_i2c_softc *sc, uint8_t byte,
    int flags)
{
        int error = exynos_i2c_wait(sc, flags);
        if (error) {
                return error;
        }
        I2C_WRITE(sc, IICDS, byte);
        return 0;
}

static int
exynos_i2c_send_start(void *cookie, int flags)
{
        struct exynos_i2c_softc *sc = cookie;

        mutex_enter(&sc->sc_intr_lock);
        int error = exynos_i2c_send_start_locked(sc, flags);
        mutex_exit(&sc->sc_intr_lock);
        return error;
}

static int
exynos_i2c_send_stop(void *cookie, int flags)
{
        struct exynos_i2c_softc *sc = cookie;

        mutex_enter(&sc->sc_intr_lock);
        int error = exynos_i2c_send_stop_locked(sc, flags);
        mutex_exit(&sc->sc_intr_lock);
        return error;
}

static int
exynos_i2c_initiate_xfer(void *cookie, i2c_addr_t addr, int flags)
{
        struct exynos_i2c_softc *sc = cookie;
        uint8_t byte = addr & 0x7f;
        int error;

        if (flags & I2C_F_READ)
                byte |= READBIT;
        else
                byte &= ~READBIT;

        mutex_enter(&sc->sc_intr_lock);
        I2C_WRITE(sc, IICADD, addr);
        exynos_i2c_send_start_locked(sc, flags);
        exynos_i2c_write_byte_locked(sc, byte, flags);
        error = exynos_i2c_wait(cookie, flags);
        mutex_exit(&sc->sc_intr_lock);

        return error;
}

static int
exynos_i2c_read_byte(void *cookie, uint8_t *bytep, int flags)
{
        struct exynos_i2c_softc *sc = cookie;

        mutex_enter(&sc->sc_intr_lock);
        int error = exynos_i2c_wait(sc, flags);
        if (error) {
                mutex_exit(&sc->sc_intr_lock);
                return error;
        }
        *bytep = I2C_READ(sc, IICDS) & 0xff;
        if (flags & I2C_F_STOP)
                exynos_i2c_send_stop_locked(sc, flags);
        mutex_exit(&sc->sc_intr_lock);
        return 0;
}

static int
exynos_i2c_write_byte(void *cookie, uint8_t byte, int flags)
{
        struct exynos_i2c_softc *sc = cookie;

        mutex_enter(&sc->sc_intr_lock);
        int error = exynos_i2c_write_byte_locked(sc, byte, flags);
        mutex_exit(&sc->sc_intr_lock);
        return error;
}