/* $NetBSD: fixedclock.c,v 1.6 2021/01/27 03:10:21 thorpej Exp $ */

/*-
 * Copyright (c) 2017 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 AUTHOR ``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 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: fixedclock.c,v 1.6 2021/01/27 03:10:21 thorpej Exp $");

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

#include <dev/clk/clk_backend.h>

#include <dev/fdt/fdtvar.h>

static int      fixedclock_match(device_t, cfdata_t, void *);
static void     fixedclock_attach(device_t, device_t, void *);

static struct clk *fixedclock_decode(device_t, int, const void *, size_t);

static const struct fdtbus_clock_controller_func fixedclock_fdt_funcs = {
        .decode = fixedclock_decode
};

static struct clk *fixedclock_get(void *, const char *);
static void     fixedclock_put(void *, struct clk *);
static u_int    fixedclock_get_rate(void *, struct clk *);

static const struct clk_funcs fixedclock_clk_funcs = {
        .get = fixedclock_get,
        .put = fixedclock_put,
        .get_rate = fixedclock_get_rate,
};

struct fixedclock_clk {
        struct clk      base;
        u_int           rate;
};

struct fixedclock_softc {
        device_t        sc_dev;
        int             sc_phandle;

        struct clk_domain sc_clkdom;
        struct fixedclock_clk sc_clk;
};

CFATTACH_DECL_NEW(fclock, sizeof(struct fixedclock_softc),
    fixedclock_match, fixedclock_attach, NULL, NULL);

static const struct device_compatible_entry compat_data[] = {
        { .compat = "fixed-clock" },
        DEVICE_COMPAT_EOL
};

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

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

static void
fixedclock_attach(device_t parent, device_t self, void *aux)
{
        struct fixedclock_softc * const sc = device_private(self);
        const struct fdt_attach_args *faa = aux;
        const int phandle = faa->faa_phandle;
        const char *clkname;

        clkname = fdtbus_get_string(phandle, "clock-output-names");
        if (!clkname)
                clkname = faa->faa_name;

        sc->sc_dev = self;
        sc->sc_phandle = phandle;
        sc->sc_clkdom.name = device_xname(self);
        sc->sc_clkdom.funcs = &fixedclock_clk_funcs;
        sc->sc_clkdom.priv = sc;
        if (of_getprop_uint32(phandle, "clock-frequency",
            &sc->sc_clk.rate) != 0) {
                aprint_error(": couldn't determine frequency\n");
                return;
        }
        sc->sc_clk.base.domain = &sc->sc_clkdom;
        sc->sc_clk.base.name = kmem_asprintf("%s", clkname);
        clk_attach(&sc->sc_clk.base);

        aprint_naive("\n");
        aprint_normal(": %u Hz fixed clock (%s)\n", sc->sc_clk.rate, clkname);

        fdtbus_register_clock_controller(self, phandle, &fixedclock_fdt_funcs);
}

static struct clk *
fixedclock_decode(device_t dev, int cc_phandle, const void *data, size_t len)
{
        struct fixedclock_softc * const sc = device_private(dev);

        /* #clock-cells for a fixed clock is always 0 */
        if (len != 0)
                return NULL;

        return &sc->sc_clk.base;
}

static struct clk *
fixedclock_get(void *priv, const char *name)
{
        struct fixedclock_softc * const sc = priv;

        if (strcmp(name, sc->sc_clk.base.name) != 0)
                return NULL;

        return &sc->sc_clk.base;
}

static void
fixedclock_put(void *priv, struct clk *clk)
{
}

static u_int
fixedclock_get_rate(void *priv, struct clk *clk)
{
        struct fixedclock_clk *fclk = (struct fixedclock_clk *)clk;

        return fclk->rate;
}