/*      $NetBSD: bcm2835_pwm.c,v 1.4 2021/01/27 03:10:19 thorpej Exp $ */

/*-
 * Copyright (c) 2015 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Michael van Elst
 *
 * 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.
 */

/*
 * Driver for BCM2835 Pulse Width Modulator
 *
 * Each channel can be allocated and used individually, but
 * for FIFO usage, both channels must to be requested.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bcm2835_pwm.c,v 1.4 2021/01/27 03:10:19 thorpej Exp $");

#include "bcmdmac.h"

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

#include <arm/broadcom/bcm2835reg.h>

#include <arm/broadcom/bcm2835_pwm.h>

#include <dev/fdt/fdtvar.h>

struct bcm_pwm_channel {
        struct bcm2835pwm_softc *sc;
        uint32_t ctlmask, stamask, gapomask;
        int rng, dat;
        bool inuse;
        uint32_t ctlsave, rngsave, datsave;
};

struct bcm2835pwm_softc {
        device_t                sc_dev;

        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;
        bus_addr_t              sc_iob;

        struct clk              *sc_clk;
        int                     sc_clockrate;
        struct bcm_pwm_channel  sc_channels[2];
        kmutex_t                sc_lock;
};

#define PWM_WRITE(sc, reg, val) \
        bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
#define PWM_READ(sc, reg) \
        bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg))

static int bcmpwm_match(device_t, cfdata_t, void *);
static void bcmpwm_attach(device_t, device_t, void *);
static int bcmpwm_wait(struct bcm2835pwm_softc *);

CFATTACH_DECL_NEW(bcmpwm, sizeof(struct bcm2835pwm_softc),
    bcmpwm_match, bcmpwm_attach, NULL, NULL);

static const struct device_compatible_entry compat_data[] = {
        { .compat = "brcm,bcm2835-pwm" },
        DEVICE_COMPAT_EOL
};

/* ARGSUSED */
static int
bcmpwm_match(device_t parent, cfdata_t match, void *aux)
{
        struct fdt_attach_args * const faa = aux;

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

static void
bcmpwm_attach(device_t parent, device_t self, void *aux)
{
        struct bcm2835pwm_softc *sc = device_private(self);
        struct fdt_attach_args * const faa = aux;
        const int phandle = faa->faa_phandle;
        bus_size_t size;

        sc->sc_dev = self;
        sc->sc_iot = faa->faa_bst;

        int error = fdtbus_get_reg(phandle, 0, &sc->sc_iob, &size);
        if (error) {
                aprint_error(": failed to get registers\n");
                return;
        }

        if (bus_space_map(sc->sc_iot, sc->sc_iob, size, 0,
            &sc->sc_ioh)) {
                aprint_error_dev(sc->sc_dev, "unable to map device\n");
                return;
        }

        sc->sc_clk = fdtbus_clock_get_index(phandle, 0);
        if (sc->sc_clk == NULL) {
                aprint_error(": couldn't get clk\n");
                return;
        }

        error = clk_enable(sc->sc_clk);
        if (error != 0) {
                aprint_error(": couldn't enable clk\n");
                return;
        }

        aprint_naive("\n");
        aprint_normal(": Pulse Width Modulator\n");

        sc->sc_clockrate = clk_get_rate(sc->sc_clk);

        sc->sc_channels[0].sc = sc;
        sc->sc_channels[0].ctlmask = PWM_CTL_MSEN1 | PWM_CTL_USEF1 |
                                     PWM_CTL_POLA1 | PWM_CTL_SBIT1 |
                                     PWM_CTL_RPTL1 | PWM_CTL_MODE1 |
                                     PWM_CTL_PWEN1;
        sc->sc_channels[0].stamask = PWM_STA_STA1;
        sc->sc_channels[0].gapomask = PWM_STA_GAPO1;
        sc->sc_channels[0].rng = PWM_RNG1;
        sc->sc_channels[0].dat = PWM_DAT1;

        sc->sc_channels[1].sc = sc;
        sc->sc_channels[1].ctlmask = PWM_CTL_MSEN2 | PWM_CTL_USEF2 |
                                     PWM_CTL_POLA2 | PWM_CTL_SBIT2 |
                                     PWM_CTL_RPTL2 | PWM_CTL_MODE2 |
                                     PWM_CTL_PWEN2;
        sc->sc_channels[1].stamask = PWM_STA_STA2;
        sc->sc_channels[1].gapomask = PWM_STA_GAPO2;
        sc->sc_channels[1].rng = PWM_RNG2;
        sc->sc_channels[1].dat = PWM_DAT2;

        /* The PWM hardware can be used by vcaudio if the
         * analog output is selected
         */
        sc->sc_channels[0].inuse = false;
        sc->sc_channels[1].inuse = false;

        mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE);

        /* Success!  */

        return;
}

struct bcm_pwm_channel *
bcm_pwm_alloc(int num)
{
        struct bcm2835pwm_softc *sc;
        device_t dev;
        struct bcm_pwm_channel *pwm;

        dev = device_find_by_driver_unit("bcmpwm", 0);
        if (dev == NULL)
                return NULL;
        sc = device_private(dev);

        if (num < 0 || num >= __arraycount(sc->sc_channels))
                return NULL;

        pwm = &sc->sc_channels[num];

        mutex_enter(&sc->sc_lock);
        if (pwm->inuse)
                pwm = NULL;
        else
                pwm->inuse = true;
        mutex_exit(&sc->sc_lock);

        if (pwm) {
                pwm->datsave = PWM_READ(pwm->sc, pwm->dat);
                pwm->ctlsave = PWM_READ(pwm->sc, PWM_CTL);
                pwm->rngsave = PWM_READ(pwm->sc, pwm->rng);
        }

        return pwm;
}

void
bcm_pwm_free(struct bcm_pwm_channel *pwm)
{
        struct bcm2835pwm_softc *sc = pwm->sc;

        KASSERT(pwm->inuse);

        PWM_WRITE(pwm->sc, pwm->rng, pwm->rngsave);
        PWM_WRITE(pwm->sc, PWM_CTL, pwm->ctlsave & ~PWM_CTL_WRITEZERO);
        PWM_WRITE(pwm->sc, pwm->dat, pwm->datsave);

        mutex_enter(&sc->sc_lock);
        pwm->inuse = false;
        mutex_exit(&sc->sc_lock);
}

void
bcm_pwm_control(struct bcm_pwm_channel *pwm, uint32_t ctl, uint32_t rng)
{
        struct bcm2835pwm_softc *sc = pwm->sc;
        uint32_t w;

        KASSERT(pwm->inuse);

        /* set control bits like for channel 0
         * there are generic bit definitions that the caller can use.
         */
        w = PWM_READ(pwm->sc, PWM_CTL);
        ctl = (w & ~pwm->ctlmask) | __SHIFTIN(ctl, pwm->ctlmask);

        /* when FIFO usage gets enabled but wasn't clear the FIFO */
        if ((w & (PWM_CTL_USEF1|PWM_CTL_USEF2)) == 0 &&
            (ctl & (PWM_CTL_USEF1|PWM_CTL_USEF2)) != 0)
                ctl |= PWM_CTL_CLRF1;

        PWM_WRITE(sc, pwm->rng, rng);
        PWM_WRITE(sc, PWM_CTL, ctl & ~PWM_CTL_WRITEZERO);
}

uint32_t
bcm_pwm_status(struct bcm_pwm_channel *pwm)
{
        uint32_t w;
        uint32_t common = PWM_STA_BERR | PWM_STA_RERR1 |
                          PWM_STA_WERR1 | PWM_STA_EMPT1 | PWM_STA_FULL1;

        /* return status bits like for channel 0
         * there are generic bit definitions that the caller can use.
         *
         * The BERR bit is returned for both channels.
         */
        w = PWM_READ(pwm->sc, PWM_STA);
        PWM_WRITE(pwm->sc, PWM_STA, w &
                (pwm->stamask | pwm->gapomask | common));

        w = __SHIFTIN(__SHIFTOUT(w, pwm->stamask), PWM_STA_STA)
          | __SHIFTIN(__SHIFTOUT(w, pwm->gapomask), PWM_STA_GAPO)
          | (w & common);

        return w;
}

static int
bcmpwm_wait(struct bcm2835pwm_softc *sc)
{
        int i;
        uint32_t s;

        for (i=0; i<1000; ++i) {
                s = PWM_READ(sc, PWM_STA);
                if ((s & PWM_STA_FULL1) == 0)
                        break;
                delay(1);
        }
        if (i >= 1000)
                return -1;

        return 0;
}

int
bcm_pwm_write(struct bcm_pwm_channel *pwm, uint32_t *data1, uint32_t *data2,
    int len)
{
        struct bcm2835pwm_softc *sc = pwm->sc;
        int n;
        uint32_t r;
        bool even = false;

        KASSERT(pwm->inuse);

        n = len;
        while (n > 0) {
                if (bcmpwm_wait(sc))
                        break;
                r = even ? *data2++ : *data1++;
                PWM_WRITE(sc, PWM_FIFO, r);
                if (data2 != NULL)
                        even = !even;
                --n;
        }

        return len - n;
}

void
bcm_pwm_set(struct bcm_pwm_channel *pwm, uint32_t w)
{
        struct bcm2835pwm_softc *sc = pwm->sc;

        PWM_WRITE(sc, pwm->dat, w);
}

int
bcm_pwm_flush(struct bcm_pwm_channel *pwm)
{
        struct bcm2835pwm_softc *sc = pwm->sc;

        return bcmpwm_wait(sc) ? EIO : 0;
}

void
bcm_pwm_dma_enable(struct bcm_pwm_channel *pwm, bool enable)
{
        struct bcm2835pwm_softc *sc = pwm->sc;
        uint32_t w;

#if 0
        w = PWM_READ(sc, PWM_DMAC);
        if (enable)
                w |= PWM_DMAC_ENAB;
        else
                w &= ~PWM_DMAC_ENAB;
#else
        w = (enable ? PWM_DMAC_ENAB : 0)
          | __SHIFTIN(7, PWM_DMAC_PANIC)
          | __SHIFTIN(7, PWM_DMAC_DREQ);
#endif
        PWM_WRITE(sc, PWM_DMAC, w & ~PWM_DMAC_WRITEZERO);
}

uint32_t
bcm_pwm_dma_address(struct bcm_pwm_channel *pwm)
{
        struct bcm2835pwm_softc *sc = pwm->sc;

        return sc->sc_iob + PWM_FIFO;
}