FreeBSD/Linux Kernel Cross Reference
sys/dev/gpio/gpiobacklight.c

     /*-
      * Copyright (c) 2015-2016 Oleksandr Tymoshenko <gonzo@freebsd.org>
      * 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 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 AUTHOR 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>
    __FBSDID("$FreeBSD$");
    
    #include "opt_platform.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/gpio.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/mutex.h>
    #include <sys/sysctl.h>
    
    #include <dev/fdt/fdt_common.h>
    #include <dev/ofw/ofw_bus.h>
    
    #include <dev/gpio/gpiobusvar.h>
    
    struct gpiobacklight_softc 
    {
            gpio_pin_t              sc_pin;
            struct sysctl_oid       *sc_oid;
            bool                    sc_brightness;
    };
    
    static int gpiobacklight_sysctl(SYSCTL_HANDLER_ARGS);
    static void gpiobacklight_update_brightness(struct gpiobacklight_softc *);
    static int gpiobacklight_probe(device_t);
    static int gpiobacklight_attach(device_t);
    static int gpiobacklight_detach(device_t);
    
    static void 
    gpiobacklight_update_brightness(struct gpiobacklight_softc *sc)
    {
    
            if (sc->sc_pin)
                    gpio_pin_set_active(sc->sc_pin, sc->sc_brightness);
    }
    
    static int
    gpiobacklight_sysctl(SYSCTL_HANDLER_ARGS)
    {
            struct gpiobacklight_softc *sc;
            int error;
            int brightness;
    
            sc = (struct gpiobacklight_softc*)arg1;
    
            brightness = sc->sc_brightness;
            error = sysctl_handle_int(oidp, &brightness, 0, req);
    
            if (error != 0 || req->newptr == NULL)
                    return (error);
    
            sc->sc_brightness = (brightness > 0);
            gpiobacklight_update_brightness(sc);
    
            return (0);
    }
    
    static int
    gpiobacklight_probe(device_t dev)
    {
    
            if (!ofw_bus_is_compatible(dev, "gpio-backlight"))
                    return (ENXIO);
    
            device_set_desc(dev, "GPIO backlight");
    
            return (0);
   }
   
   static int
   gpiobacklight_attach(device_t dev)
   {
           struct gpiobacklight_softc *sc;
           struct sysctl_ctx_list *ctx;
           struct sysctl_oid *tree;
           phandle_t node;
   
           sc = device_get_softc(dev);
   
           if ((node = ofw_bus_get_node(dev)) == -1)
                   return (ENXIO);
   
           if (OF_hasprop(node, "default-on"))
                   sc->sc_brightness = true;
           else
                   sc->sc_brightness = false;
   
           gpio_pin_get_by_ofw_idx(dev, node, 0, &sc->sc_pin);
           if (sc->sc_pin == NULL) {
                   device_printf(dev, "failed to map GPIO pin\n");
                   return (ENXIO);
           }
   
           gpio_pin_setflags(sc->sc_pin, GPIO_PIN_OUTPUT);
   
           gpiobacklight_update_brightness(sc);
   
           /* Init backlight interface */
           ctx = device_get_sysctl_ctx(dev);
           tree = device_get_sysctl_tree(dev);
           sc->sc_oid = SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
               "brightness", CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, sc, 0,
               gpiobacklight_sysctl, "I", "backlight brightness");
   
           return (0);
   }
   
   static int
   gpiobacklight_detach(device_t dev)
   {
           struct gpiobacklight_softc *sc;
   
           sc = device_get_softc(dev);
   
           if (sc->sc_pin)
                   gpio_pin_release(sc->sc_pin);
   
           return (0);
   }
   
   static device_method_t gpiobacklight_methods[] = {
           /* Device interface */
           DEVMETHOD(device_probe,         gpiobacklight_probe),
           DEVMETHOD(device_attach,        gpiobacklight_attach),
           DEVMETHOD(device_detach,        gpiobacklight_detach),
   
           DEVMETHOD_END
   };
   
   static driver_t gpiobacklight_driver = {
           "gpiobacklight",
           gpiobacklight_methods,
           sizeof(struct gpiobacklight_softc),
   };
   
   DRIVER_MODULE(gpiobacklight, simplebus, gpiobacklight_driver, 0, 0);
   MODULE_DEPEND(gpiobacklight, gpiobus, 1, 1, 1);

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