/* $NetBSD: fixedfactorclock.c,v 1.4 2021/01/27 03:10:21 thorpej Exp $ */

/*-
* Copyright (c) 2017 Jared McNeill <[email protected]>
* 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: fixedfactorclock.c,v 1.4 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      fixedfactorclock_match(device_t, cfdata_t, void *);
static void     fixedfactorclock_attach(device_t, device_t, void *);

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

static const struct fdtbus_clock_controller_func fixedfactorclock_fdt_funcs = {
       .decode = fixedfactorclock_decode
};

static struct clk *fixedfactorclock_get(void *, const char *);
static void     fixedfactorclock_put(void *, struct clk *);
static u_int    fixedfactorclock_get_rate(void *, struct clk *);

static const struct clk_funcs fixedfactorclock_clk_funcs = {
       .get = fixedfactorclock_get,
       .put = fixedfactorclock_put,
       .get_rate = fixedfactorclock_get_rate,
};

struct fixedfactorclock_clk {
       struct clk      base;

       u_int           div;
       u_int           mult;
};

struct fixedfactorclock_softc {
       device_t        sc_dev;
       int             sc_phandle;

       struct clk_domain sc_clkdom;
       struct fixedfactorclock_clk sc_clk;
};

CFATTACH_DECL_NEW(ffclock, sizeof(struct fixedfactorclock_softc),
   fixedfactorclock_match, fixedfactorclock_attach, NULL, NULL);

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

static int
fixedfactorclock_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
fixedfactorclock_attach(device_t parent, device_t self, void *aux)
{
       struct fixedfactorclock_softc * const sc = device_private(self);
       const struct fdt_attach_args *faa = aux;
       const int phandle = faa->faa_phandle;
       const char *name;

       sc->sc_dev = self;
       sc->sc_phandle = phandle;
       sc->sc_clkdom.name = device_xname(self);
       sc->sc_clkdom.funcs = &fixedfactorclock_clk_funcs;
       sc->sc_clkdom.priv = sc;

       of_getprop_uint32(phandle, "clock-div", &sc->sc_clk.div);
       of_getprop_uint32(phandle, "clock-mult", &sc->sc_clk.mult);

       if (sc->sc_clk.div == 0 || sc->sc_clk.mult == 0) {
               aprint_error(": invalid properties\n");
               return;
       }

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

       sc->sc_clk.base.domain = &sc->sc_clkdom;
       sc->sc_clk.base.name = name;
       clk_attach(&sc->sc_clk.base);

       aprint_naive("\n");
       aprint_normal(": x%u /%u fixed-factor clock\n",
           sc->sc_clk.mult, sc->sc_clk.div);

       fdtbus_register_clock_controller(self, phandle,
           &fixedfactorclock_fdt_funcs);
}

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

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

       return &sc->sc_clk.base;
}

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

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

       return &sc->sc_clk.base;
}

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

static u_int
fixedfactorclock_get_rate(void *priv, struct clk *clk)
{
       struct fixedfactorclock_softc * const sc = priv;
       struct fixedfactorclock_clk *fclk = (struct fixedfactorclock_clk *)clk;
       struct clk *clkp_parent;

       clkp_parent = fdtbus_clock_get_index(sc->sc_phandle, 0);
       if (clkp_parent == NULL)
               return 0;

       return (clk_get_rate(clkp_parent) * fclk->mult) / fclk->div;
}

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