/*      $NetBSD: sun4i_spi.c,v 1.11 2025/09/10 04:17:19 thorpej Exp $   */

/*
 * Copyright (c) 2019 Tobias Nygren
 * Copyright (c) 2018 Jonathan A. Kollasch
 * 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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: sun4i_spi.c,v 1.11 2025/09/10 04:17:19 thorpej Exp $");

#include <sys/param.h>
#include <sys/device.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/intr.h>
#include <sys/kernel.h>
#include <sys/bitops.h>
#include <dev/spi/spivar.h>
#include <arm/sunxi/sun4i_spireg.h>
#include <dev/fdt/fdtvar.h>

static const struct device_compatible_entry compat_data[] = {
        { .compat = "allwinner,sun4i-a10-spi" },
        DEVICE_COMPAT_EOL
};

struct sun4ispi_softc {
        device_t                sc_dev;
        bus_space_tag_t         sc_bst;
        bus_space_handle_t      sc_bsh;
        void                    *sc_intrh;
        struct spi_controller   sc_spi;
        SIMPLEQ_HEAD(,spi_transfer) sc_q;
        struct spi_transfer     *sc_transfer;
        struct spi_chunk        *sc_rchunk, *sc_wchunk;
        uint32_t                sc_CTL;
        u_int                   sc_modclkrate;
        volatile bool           sc_running;
};

#define SPIREG_READ(sc, reg) \
    bus_space_read_4((sc)->sc_bst, (sc)->sc_bsh, (reg))
#define SPIREG_WRITE(sc, reg, val) \
    bus_space_write_4((sc)->sc_bst, (sc)->sc_bsh, (reg), (val))

static int sun4ispi_match(device_t, cfdata_t, void *);
static void sun4ispi_attach(device_t, device_t, void *);

static int sun4ispi_configure(void *, int, int, int);
static int sun4ispi_transfer(void *, struct spi_transfer *);

static void sun4ispi_txfifo_fill(struct sun4ispi_softc * const, size_t);
static void sun4ispi_rxfifo_drain(struct sun4ispi_softc * const, size_t);
static void sun4ispi_rxtx(struct sun4ispi_softc * const);
static void sun4ispi_set_interrupt_mask(struct sun4ispi_softc * const);
static void sun4ispi_start(struct sun4ispi_softc * const);
static int sun4ispi_intr(void *);

CFATTACH_DECL_NEW(sun4i_spi, sizeof(struct sun4ispi_softc),
    sun4ispi_match, sun4ispi_attach, NULL, NULL);

static int
sun4ispi_match(device_t parent, cfdata_t cf, void *aux)
{
        struct fdt_attach_args * const faa = aux;

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

static void
sun4ispi_attach(device_t parent, device_t self, void *aux)
{
        struct sun4ispi_softc * const sc = device_private(self);
        struct fdt_attach_args * const faa = aux;
        const int phandle = faa->faa_phandle;
        bus_addr_t addr;
        bus_size_t size;
        struct clk *clk, *modclk;
        char intrstr[128];

        sc->sc_dev = self;
        sc->sc_bst = faa->faa_bst;
        SIMPLEQ_INIT(&sc->sc_q);

        if ((clk = fdtbus_clock_get_index(phandle, 0)) == NULL
            || clk_enable(clk) != 0) {
                aprint_error(": couldn't enable clock\n");
                return;
        }

        if ((modclk = fdtbus_clock_get(phandle, "mod")) == NULL
            || clk_set_rate(modclk, clk_get_rate(clk)) != 0
            || clk_enable(modclk) != 0) {
                aprint_error(": couldn't enable module clock\n");
                return;
        }
        sc->sc_modclkrate = clk_get_rate(modclk);

        if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0
            || bus_space_map(sc->sc_bst, addr, size, 0, &sc->sc_bsh) != 0) {
                aprint_error(": couldn't map registers\n");
                return;
        }

        SPIREG_WRITE(sc, SPI_CTL, SPI_CTL_SSPOL | SPI_CTL_RF_RST
            | SPI_CTL_TF_RST | SPI_CTL_MODE);
        SPIREG_WRITE(sc, SPI_DMACTL, 0);
        SPIREG_WRITE(sc, SPI_WAIT, 0);
        SPIREG_WRITE(sc, SPI_INTCTL, 0);
        SPIREG_WRITE(sc, SPI_INT_STA, ~0);

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

        sc->sc_intrh = fdtbus_intr_establish_xname(phandle, 0, IPL_VM, 0,
            sun4ispi_intr, sc, device_xname(self));
        if (sc->sc_intrh == NULL) {
                aprint_error(": unable to establish interrupt\n");
                return;
        }

        aprint_naive("\n");
        aprint_normal(": SPI\n");
        aprint_normal_dev(self, "interrupting on %s\n", intrstr);

        sc->sc_spi.sct_cookie = sc;
        sc->sc_spi.sct_configure = sun4ispi_configure;
        sc->sc_spi.sct_transfer = sun4ispi_transfer;
        (void) of_getprop_uint32(phandle, "num-cs", &sc->sc_spi.sct_nslaves);

        spibus_attach(self, &sc->sc_spi);
}

static int
sun4ispi_configure(void *cookie, int slave, int mode, int speed)
{
        struct sun4ispi_softc * const sc = cookie;
        uint32_t ctl, cctl;
        uint32_t minfreq, maxfreq;

        minfreq = sc->sc_modclkrate >> 16;
        maxfreq = sc->sc_modclkrate >> 1;

        if (speed <= 0 || speed < minfreq || speed > maxfreq)
                return EINVAL;

        if (slave >= sc->sc_spi.sct_nslaves)
                return EINVAL;

        ctl = SPI_CTL_SDM | SPI_CTL_TP_EN | SPI_CTL_SSPOL | SPI_CTL_MODE | SPI_CTL_EN;

        switch (mode) {
        case SPI_MODE_0:
                ctl |= 0;
                break;
        case SPI_MODE_1:
                ctl |= SPI_CTL_PHA;
                break;
        case SPI_MODE_2:
                ctl |= SPI_CTL_POL;
                break;
        case SPI_MODE_3:
                ctl |= SPI_CTL_PHA | SPI_CTL_POL;
                break;
        default:
                return EINVAL;
        }

        if (speed < sc->sc_modclkrate / 512) {
                for (cctl = 0; cctl <= __SHIFTOUT_MASK(SPI_CCTL_CDR1); cctl++) {
                        if ((sc->sc_modclkrate / (1 << cctl)) <= speed)
                                goto cdr1_found;
                }
                return EINVAL;
cdr1_found:
                cctl = __SHIFTIN(cctl, SPI_CCTL_CDR1);
        } else {
                cctl = howmany(sc->sc_modclkrate, 2 * speed) - 1;
                cctl = SPI_CCTL_DRS|__SHIFTIN(cctl, SPI_CCTL_CDR2);
        }

        device_printf(sc->sc_dev, "ctl 0x%x, cctl 0x%x, CLK %uHz, SCLK %uHz\n",
            ctl, cctl, sc->sc_modclkrate,
            (cctl & SPI_CCTL_DRS)
            ? (sc->sc_modclkrate / (u_int)(2 * (__SHIFTOUT(cctl, SPI_CCTL_CDR2) + 1)))
            : (sc->sc_modclkrate >> (__SHIFTOUT(cctl, SPI_CCTL_CDR1) + 1))
        );

        sc->sc_CTL = ctl;
        SPIREG_WRITE(sc, SPI_CTL, (ctl | SPI_CTL_RF_RST | SPI_CTL_TF_RST) & ~SPI_CTL_EN);
        SPIREG_WRITE(sc, SPI_CCTL, cctl);
        SPIREG_WRITE(sc, SPI_CTL, ctl);

        return 0;
}

static int
sun4ispi_transfer(void *cookie, struct spi_transfer *st)
{
        struct sun4ispi_softc * const sc = cookie;
        int s;

        s = splbio();
        spi_transq_enqueue(&sc->sc_q, st);
        if (sc->sc_running == false) {
                sun4ispi_start(sc);
        }
        splx(s);

        return 0;
}

static void
sun4ispi_txfifo_fill(struct sun4ispi_softc * const sc, size_t maxlen)
{
        struct spi_chunk *chunk = sc->sc_wchunk;
        size_t len;
        uint8_t b;

        if (chunk == NULL)
                return;

        len = MIN(maxlen, chunk->chunk_wresid);
        chunk->chunk_wresid -= len;
        while (len--) {
                if (chunk->chunk_wptr) {
                        b = *chunk->chunk_wptr++;
                } else {
                        b = 0;
                }
                bus_space_write_1(sc->sc_bst, sc->sc_bsh, SPI_TXDATA, b);
        }
        if (sc->sc_wchunk->chunk_wresid == 0) {
                sc->sc_wchunk = sc->sc_wchunk->chunk_next;
        }
}

static void
sun4ispi_rxfifo_drain(struct sun4ispi_softc * const sc, size_t maxlen)
{
        struct spi_chunk *chunk = sc->sc_rchunk;
        size_t len;
        uint8_t b;

        if (chunk == NULL)
                return;

        len = MIN(maxlen, chunk->chunk_rresid);
        chunk->chunk_rresid -= len;

        while (len--) {
                b = bus_space_read_1(sc->sc_bst, sc->sc_bsh, SPI_RXDATA);
                if (chunk->chunk_rptr) {
                        *chunk->chunk_rptr++ = b;
                }
        }
        if (sc->sc_rchunk->chunk_rresid == 0) {
                sc->sc_rchunk = sc->sc_rchunk->chunk_next;
        }
}

static void
sun4ispi_rxtx(struct sun4ispi_softc * const sc)
{
        bool again;
        size_t rxavail, txavail;
        uint32_t fsr;

        /* service both FIFOs until no more progress can be made */
        again = true;
        while (again) {
                again = false;
                fsr = SPIREG_READ(sc, SPI_FIFO_STA);
                rxavail = __SHIFTOUT(fsr, SPI_FIFO_STA_RF_CNT);
                txavail = 64 - __SHIFTOUT(fsr, SPI_FIFO_STA_TF_CNT);
                if (rxavail > 0) {
                        KASSERT(sc->sc_rchunk != NULL);
                        sun4ispi_rxfifo_drain(sc, rxavail);
                        again = true;
                }
                if (txavail > 0 && sc->sc_wchunk != NULL) {
                        sun4ispi_txfifo_fill(sc, txavail);
                        again = true;
                }
        }
}

static void
sun4ispi_set_interrupt_mask(struct sun4ispi_softc * const sc)
{
        uint32_t intctl;

        intctl = SPI_INTCTL_TX_INT_EN;
        intctl |= SPI_INTCTL_RF_OF_INT_EN;
        intctl |= SPI_INTCTL_TF_UR_INT_EN;

        if (sc->sc_rchunk) {
                if (sc->sc_rchunk->chunk_rresid >= 32) {
                        intctl |= SPI_INTCTL_RF_HALF_FU_INT_EN;
                } else {
                        intctl |= SPI_INTCTL_RF_RDY_INT_EN;
                }
        }
        if (sc->sc_wchunk) {
                intctl |= SPI_INTCTL_TF_HALF_EMP_INT_EN;
        }
        SPIREG_WRITE(sc, SPI_INTCTL, intctl);
}

static void
sun4ispi_start(struct sun4ispi_softc * const sc)
{
        struct spi_transfer *st;
        uint32_t ctl;
        struct spi_chunk *chunk;
        size_t burstcount;

        while ((st = spi_transq_first(&sc->sc_q)) != NULL) {

                spi_transq_dequeue(&sc->sc_q);

                KASSERT(sc->sc_transfer == NULL);
                sc->sc_transfer = st;
                sc->sc_rchunk = sc->sc_wchunk = st->st_chunks;
                sc->sc_running = true;

                burstcount = 0;
                for (chunk = st->st_chunks; chunk; chunk = chunk->chunk_next) {
                        burstcount += chunk->chunk_count;
                }
                KASSERT(burstcount <= SPI_BC_BC);
                SPIREG_WRITE(sc, SPI_BC, __SHIFTIN(burstcount, SPI_BC_BC));
                SPIREG_WRITE(sc, SPI_TC, __SHIFTIN(burstcount, SPI_TC_WTC));

                sun4ispi_rxtx(sc);
                sun4ispi_set_interrupt_mask(sc);

                KASSERT(st->st_slave < sc->sc_spi.sct_nslaves);
                ctl = sc->sc_CTL | __SHIFTIN(st->st_slave, SPI_CTL_SS) | SPI_CTL_XCH;
                SPIREG_WRITE(sc, SPI_CTL, ctl);

                if (!cold)
                        return;

                for (;;) {
                        (void) sun4ispi_intr(sc);
                        if (ISSET(st->st_flags, SPI_F_DONE))
                                break;
                }
        }
        sc->sc_running = false;
}

static int
sun4ispi_intr(void *cookie)
{
        struct sun4ispi_softc * const sc = cookie;
        struct spi_transfer *st;
        uint32_t isr;

        isr = SPIREG_READ(sc, SPI_INT_STA);
        if (!isr)
                return 0;

        if (ISSET(isr, SPI_INT_STA_RO)) {
                device_printf(sc->sc_dev, "RXFIFO overflow\n");
        }
        if (ISSET(isr, SPI_INT_STA_TU)) {
                device_printf(sc->sc_dev, "TXFIFO underrun\n");
        }

        sun4ispi_rxtx(sc);

        if (ISSET(isr, SPI_INT_STA_TC)) {
                SPIREG_WRITE(sc, SPI_INTCTL, 0);
                KASSERT(sc->sc_rchunk == NULL);
                KASSERT(sc->sc_wchunk == NULL);
                st = sc->sc_transfer;
                sc->sc_transfer = NULL;
                KASSERT(st != NULL);
                spi_done(st, 0);
                sc->sc_running = false;
        } else {
                sun4ispi_set_interrupt_mask(sc);
        }
        SPIREG_WRITE(sc, SPI_INT_STA, isr);

        return 1;
}