/* $NetBSD: pwm_backlight.c,v 1.10 2021/11/07 17:14:09 jmcneill Exp $ */

/*-
 * Copyright (c) 2018 Jared 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: pwm_backlight.c,v 1.10 2021/11/07 17:14:09 jmcneill Exp $");

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

#include <dev/pwm/pwmvar.h>

#include <dev/fdt/fdtvar.h>

struct pwm_backlight_softc {
        device_t                sc_dev;
        pwm_tag_t               sc_pwm;
        struct fdtbus_gpio_pin *sc_pin;

        u_int                   *sc_levels;
        u_int                   sc_nlevels;
        u_int                   sc_curlevel;

        char                    *sc_levelstr;

        bool                    sc_lid_state;
};

static int      pwm_backlight_match(device_t, cfdata_t, void *);
static void     pwm_backlight_attach(device_t, device_t, void *);

static void     pwm_backlight_sysctl_init(struct pwm_backlight_softc *);
static void     pwm_backlight_pmf_init(struct pwm_backlight_softc *);
static void     pwm_backlight_set(struct pwm_backlight_softc *, u_int, bool);
static u_int    pwm_backlight_get(struct pwm_backlight_softc *);

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

CFATTACH_DECL_NEW(pwmbacklight, sizeof(struct pwm_backlight_softc),
        pwm_backlight_match, pwm_backlight_attach, NULL, NULL);

static int
pwm_backlight_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
pwm_backlight_attach(device_t parent, device_t self, void *aux)
{
        struct pwm_backlight_softc * const sc = device_private(self);
        struct fdt_attach_args * const faa = aux;
        const int phandle = faa->faa_phandle;
        const u_int *levels;
        u_int default_level = 0;
        u_int n;
        int len;

        sc->sc_dev = self;
        sc->sc_pwm = fdtbus_pwm_acquire(phandle, "pwms");
        if (sc->sc_pwm == NULL) {
                aprint_error(": couldn't acquire pwm\n");
                return;
        }
        if (of_hasprop(phandle, "enable-gpios")) {
                sc->sc_pin = fdtbus_gpio_acquire(phandle, "enable-gpios",
                    GPIO_PIN_OUTPUT);
                if (!sc->sc_pin) {
                        aprint_error(": couldn't acquire enable gpio\n");
                        return;
                }
                fdtbus_gpio_write(sc->sc_pin, 1);
        }

        levels = fdtbus_get_prop(phandle, "brightness-levels", &len);
        if (levels != NULL) {
                sc->sc_nlevels = len / 4;
                sc->sc_levels = kmem_alloc(len, KM_SLEEP);
                for (n = 0; n < sc->sc_nlevels; n++)
                        sc->sc_levels[n] = be32toh(levels[n]);
        } else {
                sc->sc_nlevels = 256;
                sc->sc_levels = kmem_alloc(sc->sc_nlevels * 4, KM_SLEEP);
                for (n = 0; n < sc->sc_nlevels; n++)
                        sc->sc_levels[n] = n;
                default_level = 200;
        }

        aprint_naive("\n");
        aprint_normal(": PWM Backlight");
        if (sc->sc_nlevels > 1) {
                aprint_normal(", %u-%u (%u steps)",
                    sc->sc_levels[0], sc->sc_levels[sc->sc_nlevels - 1],
                    sc->sc_nlevels);
        }
        aprint_normal("\n");

        sc->sc_lid_state = true;

        of_getprop_uint32(phandle, "default-brightness-level", &default_level);
        if (default_level != 0) {
                /* set the default level now */
                pwm_backlight_set(sc, default_level, true);
        }

        sc->sc_curlevel = pwm_backlight_get(sc);

        pwm_backlight_sysctl_init(sc);
        pwm_backlight_pmf_init(sc);
}

static void
pwm_backlight_set(struct pwm_backlight_softc *sc, u_int index, bool set_cur)
{
        struct pwm_config conf;

        if (index >= sc->sc_nlevels)
                return;

        KASSERT(sc->sc_levels[sc->sc_nlevels - 1] != 0);
        aprint_debug_dev(sc->sc_dev, "set duty cycle to %u%%\n",
            (100 * sc->sc_levels[index]) / sc->sc_levels[sc->sc_nlevels - 1]);

        pwm_disable(sc->sc_pwm);
        pwm_get_config(sc->sc_pwm, &conf);
        conf.duty_cycle = (conf.period * sc->sc_levels[index]) / sc->sc_levels[sc->sc_nlevels - 1];
        pwm_set_config(sc->sc_pwm, &conf);
        pwm_enable(sc->sc_pwm);

        if (set_cur)
                sc->sc_curlevel = index;
}

static u_int
pwm_backlight_get(struct pwm_backlight_softc *sc)
{
        struct pwm_config conf;
        u_int raw_val, n;

        pwm_get_config(sc->sc_pwm, &conf);

        raw_val = (conf.duty_cycle * sc->sc_levels[sc->sc_nlevels - 1]) / conf.period;

        /* Return the closest setting to the raw value */
        for (n = 0; n < sc->sc_nlevels; n++) {
                if (raw_val <= sc->sc_levels[n])
                        break;
        }
        return n;
}

static int
pwm_backlight_sysctl_helper(SYSCTLFN_ARGS)
{
        struct pwm_backlight_softc * const sc = rnode->sysctl_data;
        struct sysctlnode node;
        int error;
        u_int level, n;

        node = *rnode;
        node.sysctl_data = &level;

        n = pwm_backlight_get(sc);
        level = sc->sc_levels[n];

        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return error;

        for (n = 0; n < sc->sc_nlevels; n++) {
                if (sc->sc_levels[n] == level) {
                        pwm_backlight_set(sc, n, true);
                        return 0;
                }
        }

        return EINVAL;
}

static void
pwm_backlight_sysctl_init(struct pwm_backlight_softc *sc)
{
        const struct sysctlnode *node, *pwmnode;
        struct sysctllog *log = NULL;
        int error;
        u_int n;

        sc->sc_levelstr = kmem_zalloc(strlen("XXXXX ") * sc->sc_nlevels, KM_SLEEP);
        for (n = 0; n < sc->sc_nlevels; n++) {
                char buf[7];
                snprintf(buf, sizeof(buf), n ? " %u" : "%u", sc->sc_levels[n]);
                strcat(sc->sc_levelstr, buf);
        }

        error = sysctl_createv(&log, 0, NULL, &node,
            CTLFLAG_PERMANENT, CTLTYPE_NODE, "hw", NULL,
            NULL, 0, NULL, 0, CTL_HW, CTL_EOL);
        if (error)
                goto failed;

        error = sysctl_createv(&log, 0, &node, &pwmnode,
            0, CTLTYPE_NODE, device_xname(sc->sc_dev), NULL,
            NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL);
        if (error)
                goto failed;

        error = sysctl_createv(&log, 0, &pwmnode, NULL,
            0, CTLTYPE_STRING, "levels", NULL,
            NULL, 0, sc->sc_levelstr, 0,
            CTL_CREATE, CTL_EOL);
        if (error)
                goto failed;

        error = sysctl_createv(&log, 0, &pwmnode, NULL,
            CTLFLAG_READWRITE, CTLTYPE_INT, "level", NULL,
            pwm_backlight_sysctl_helper, 0, (void *)sc, 0,
            CTL_CREATE, CTL_EOL);
        if (error)
                goto failed;

        return;

failed:
        aprint_error_dev(sc->sc_dev, "couldn't create sysctl nodes: %d\n", error);
        sysctl_teardown(&log);
}

static void
pwm_backlight_enable(struct pwm_backlight_softc *sc, int enable)
{
        if (sc->sc_pin)
                fdtbus_gpio_write(sc->sc_pin, enable);
        else
                pwm_backlight_set(sc, enable ? sc->sc_curlevel : 0, false);
}

static void
pwm_backlight_display_on(device_t dev)
{
        struct pwm_backlight_softc * const sc = device_private(dev);

        if (sc->sc_lid_state)
                pwm_backlight_enable(sc, 1);
}

static void
pwm_backlight_display_off(device_t dev)
{
        struct pwm_backlight_softc * const sc = device_private(dev);

        pwm_backlight_enable(sc, 0);
}

static void
pwm_backlight_chassis_lid_open(device_t dev)
{
        struct pwm_backlight_softc * const sc = device_private(dev);

        sc->sc_lid_state = true;

        pwm_backlight_enable(sc, 1);
}

static void
pwm_backlight_chassis_lid_close(device_t dev)
{
        struct pwm_backlight_softc * const sc = device_private(dev);

        sc->sc_lid_state = false;

        pwm_backlight_enable(sc, 0);
}

static void
pwm_backlight_display_brightness_up(device_t dev)
{
        struct pwm_backlight_softc * const sc = device_private(dev);
        u_int n;

        n = pwm_backlight_get(sc);
        if (n < sc->sc_nlevels - 1)
                pwm_backlight_set(sc, n + 1, true);
}

static void
pwm_backlight_display_brightness_down(device_t dev)
{
        struct pwm_backlight_softc * const sc = device_private(dev);
        u_int n;

        n = pwm_backlight_get(sc);
        if (n > 0)
                pwm_backlight_set(sc, n - 1, true);
}

static void
pwm_backlight_pmf_init(struct pwm_backlight_softc *sc)
{
        pmf_event_register(sc->sc_dev, PMFE_DISPLAY_ON,
            pwm_backlight_display_on, true);
        pmf_event_register(sc->sc_dev, PMFE_DISPLAY_OFF,
            pwm_backlight_display_off, true);
        pmf_event_register(sc->sc_dev, PMFE_CHASSIS_LID_OPEN,
            pwm_backlight_chassis_lid_open, true);
        pmf_event_register(sc->sc_dev, PMFE_CHASSIS_LID_CLOSE,
            pwm_backlight_chassis_lid_close, true);
        pmf_event_register(sc->sc_dev, PMFE_DISPLAY_BRIGHTNESS_UP,
            pwm_backlight_display_brightness_up, true);
        pmf_event_register(sc->sc_dev, PMFE_DISPLAY_BRIGHTNESS_DOWN,
            pwm_backlight_display_brightness_down, true);
}