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

     /*-
      * SPDX-License-Identifier: BSD-2-Clause
      *
      * Copyright (c) 2009 Oleksandr Tymoshenko <gonzo@freebsd.org>
      * Copyright (c) 2010 Luiz Otavio O Souza
      * Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
      *
      * 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/module.h>
    
    #include <dev/gpio/gpiobusvar.h>
    #include <dev/iicbus/iiconf.h>
    
    #include "gpiobus_if.h"
    #include "iicbb_if.h"
    
    #define GPIOIIC_SCL_DFLT        0
    #define GPIOIIC_SDA_DFLT        1
    #define GPIOIIC_MIN_PINS        2
    
    struct gpioiic_softc 
    {
            device_t        dev;
            gpio_pin_t      sclpin;
            gpio_pin_t      sdapin;
    };
    
    #ifdef FDT
    
    #include <dev/ofw/ofw_bus.h>
    
    static struct ofw_compat_data compat_data[] = {
            {"i2c-gpio",  true}, /* Standard devicetree compat string */
            {"gpioiic",   true}, /* Deprecated old freebsd compat string */
            {NULL,        false}
    };
    OFWBUS_PNP_INFO(compat_data);
    SIMPLEBUS_PNP_INFO(compat_data);
    
    static phandle_t
    gpioiic_get_node(device_t bus, device_t dev)
    {
    
            /* Share our fdt node with iicbus so it can find its child nodes. */
            return (ofw_bus_get_node(bus));
    }
    
    static int
    gpioiic_setup_fdt_pins(struct gpioiic_softc *sc)
    {
            phandle_t node;
            int err;
    
            node = ofw_bus_get_node(sc->dev);
    
            /*
             * Historically, we used the first two array elements of the gpios
             * property.  The modern bindings specify separate scl-gpios and
             * sda-gpios properties.  We cope with whichever is present.
             */
            if (OF_hasprop(node, "gpios")) {
                    if ((err = gpio_pin_get_by_ofw_idx(sc->dev, node,
                        GPIOIIC_SCL_DFLT, &sc->sclpin)) != 0) {
                            device_printf(sc->dev, "invalid gpios property\n");
                            return (err);
                    }
                    if ((err = gpio_pin_get_by_ofw_idx(sc->dev, node,
                        GPIOIIC_SDA_DFLT, &sc->sdapin)) != 0) {
                           device_printf(sc->dev, "ivalid gpios property\n");
                           return (err);
                   }
           } else {
                   if ((err = gpio_pin_get_by_ofw_property(sc->dev, node,
                       "scl-gpios", &sc->sclpin)) != 0) {
                           device_printf(sc->dev, "missing scl-gpios property\n");
                           return (err);
                   }
                   if ((err = gpio_pin_get_by_ofw_property(sc->dev, node,
                       "sda-gpios", &sc->sdapin)) != 0) {
                           device_printf(sc->dev, "missing sda-gpios property\n");
                           return (err);
                   }
           }
           return (0);
   }
   #endif /* FDT */
   
   static int
   gpioiic_setup_hinted_pins(struct gpioiic_softc *sc)
   {
           device_t busdev;
           const char *busname, *devname;
           int err, numpins, sclnum, sdanum, unit;
   
           devname = device_get_name(sc->dev);
           unit = device_get_unit(sc->dev);
           busdev = device_get_parent(sc->dev);
   
           /*
            * If there is not an "at" hint naming our actual parent, then we
            * weren't instantiated as a child of gpiobus via hints, and we thus
            * can't access ivars that only exist for such children.
            */
           if (resource_string_value(devname, unit, "at", &busname) != 0 ||
               (strcmp(busname, device_get_nameunit(busdev)) != 0 &&
                strcmp(busname, device_get_name(busdev)) != 0)) {
                   return (ENOENT);
           }
   
           /* Make sure there were hints for at least two pins. */
           numpins = gpiobus_get_npins(sc->dev);
           if (numpins < GPIOIIC_MIN_PINS) {
   #ifdef FDT
                   /*
                    * Be silent when there are no hints on FDT systems; the FDT
                    * data will provide the pin config (we'll whine if it doesn't).
                    */
                   if (numpins == 0) {
                           return (ENOENT);
                   }
   #endif
                   device_printf(sc->dev, 
                       "invalid pins hint; it must contain at least %d pins\n",
                       GPIOIIC_MIN_PINS);
                   return (EINVAL);
           }
   
           /*
            * Our parent bus has already parsed the pins hint and it will use that
            * info when we call gpio_pin_get_by_child_index().  But we have to
            * handle the scl/sda index hints that tell us which of the two pins is
            * the clock and which is the data.  They're optional, but if present
            * they must be a valid index (0 <= index < numpins).
            */
           if ((err = resource_int_value(devname, unit, "scl", &sclnum)) != 0)
                   sclnum = GPIOIIC_SCL_DFLT;
           else if (sclnum < 0 || sclnum >= numpins) {
                   device_printf(sc->dev, "invalid scl hint %d\n", sclnum);
                   return (EINVAL);
           }
           if ((err = resource_int_value(devname, unit, "sda", &sdanum)) != 0)
                   sdanum = GPIOIIC_SDA_DFLT;
           else if (sdanum < 0 || sdanum >= numpins) {
                   device_printf(sc->dev, "invalid sda hint %d\n", sdanum);
                   return (EINVAL);
           }
   
           /* Allocate gpiobus_pin structs for the pins we found above. */
           if ((err = gpio_pin_get_by_child_index(sc->dev, sclnum,
               &sc->sclpin)) != 0)
                   return (err);
           if ((err = gpio_pin_get_by_child_index(sc->dev, sdanum,
               &sc->sdapin)) != 0)
                   return (err);
   
           return (0);
   }
   
   static void
   gpioiic_setsda(device_t dev, int val)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
   
           if (val) {
                   gpio_pin_setflags(sc->sdapin, GPIO_PIN_INPUT);
           } else {
                   gpio_pin_setflags(sc->sdapin,
                       GPIO_PIN_OUTPUT | GPIO_PIN_OPENDRAIN);
                   gpio_pin_set_active(sc->sdapin, 0);
           }
   }
   
   static void
   gpioiic_setscl(device_t dev, int val)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
   
           if (val) {
                   gpio_pin_setflags(sc->sclpin, GPIO_PIN_INPUT);
           } else {
                   gpio_pin_setflags(sc->sclpin,
                       GPIO_PIN_OUTPUT | GPIO_PIN_OPENDRAIN);
                   gpio_pin_set_active(sc->sclpin, 0);
           }
   }
   
   static int
   gpioiic_getscl(device_t dev)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
           bool val;
   
           gpio_pin_setflags(sc->sclpin, GPIO_PIN_INPUT);
           gpio_pin_is_active(sc->sclpin, &val);
           return (val);
   }
   
   static int
   gpioiic_getsda(device_t dev)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
           bool val;
   
           gpio_pin_setflags(sc->sdapin, GPIO_PIN_INPUT);
           gpio_pin_is_active(sc->sdapin, &val);
           return (val);
   }
   
   static int
   gpioiic_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
   
           /* Stop driving the bus pins. */
           gpio_pin_setflags(sc->sdapin, GPIO_PIN_INPUT);
           gpio_pin_setflags(sc->sclpin, GPIO_PIN_INPUT);
   
           /* Indicate that we have no slave address (master mode). */
           return (IIC_ENOADDR);
   }
   
   static void
   gpioiic_cleanup(struct gpioiic_softc *sc)
   {
   
           device_delete_children(sc->dev);
   
           if (sc->sclpin != NULL)
                   gpio_pin_release(sc->sclpin);
   
           if (sc->sdapin != NULL)
                   gpio_pin_release(sc->sdapin);
   }
   
   static int
   gpioiic_probe(device_t dev)
   {
           int rv;
   
           /*
            * By default we only bid to attach if specifically added by our parent
            * (usually via hint.gpioiic.#.at=busname).  On FDT systems we bid as
            * the default driver based on being configured in the FDT data.
            */
           rv = BUS_PROBE_NOWILDCARD;
   
   #ifdef FDT
           if (ofw_bus_status_okay(dev) &&
               ofw_bus_search_compatible(dev, compat_data)->ocd_data)
                   rv = BUS_PROBE_DEFAULT;
   #endif
   
           device_set_desc(dev, "GPIO I2C");
   
           return (rv);
   }
   
   static int
   gpioiic_attach(device_t dev)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
           int err;
   
           sc->dev = dev;
   
           /* Acquire our gpio pins. */
           err = gpioiic_setup_hinted_pins(sc);
   #ifdef FDT
           if (err != 0)
                   err = gpioiic_setup_fdt_pins(sc);
   #endif
           if (err != 0) {
                   device_printf(sc->dev, "no pins configured\n");
                   gpioiic_cleanup(sc);
                   return (ENXIO);
           }
   
           /*
            * Say what we came up with for pin config.
            * NB: in the !FDT case the controller driver might not be set up enough
            * for GPIO_GET_BUS() to work.  Also, our parent is the only gpiobus
            * that can provide our pins.
            */
           device_printf(dev, "SCL pin: %s:%d, SDA pin: %s:%d\n",
   #ifdef FDT
               device_get_nameunit(GPIO_GET_BUS(sc->sclpin->dev)), sc->sclpin->pin,
               device_get_nameunit(GPIO_GET_BUS(sc->sdapin->dev)), sc->sdapin->pin);
   #else
               device_get_nameunit(device_get_parent(dev)), sc->sclpin->pin,
               device_get_nameunit(device_get_parent(dev)), sc->sdapin->pin);
   #endif
   
           /* Add the bitbang driver as our only child; it will add iicbus. */
           device_add_child(sc->dev, "iicbb", -1);
           return (bus_generic_attach(dev));
   }
   
   static int
   gpioiic_detach(device_t dev)
   {
           struct gpioiic_softc *sc = device_get_softc(dev);
           int err;
   
           if ((err = bus_generic_detach(dev)) != 0)
                   return (err);
   
           gpioiic_cleanup(sc);
   
           return (0);
   }
   
   static devclass_t gpioiic_devclass;
   
   static device_method_t gpioiic_methods[] = {
           /* Device interface */
           DEVMETHOD(device_probe,         gpioiic_probe),
           DEVMETHOD(device_attach,        gpioiic_attach),
           DEVMETHOD(device_detach,        gpioiic_detach),
   
           /* iicbb interface */
           DEVMETHOD(iicbb_setsda,         gpioiic_setsda),
           DEVMETHOD(iicbb_setscl,         gpioiic_setscl),
           DEVMETHOD(iicbb_getsda,         gpioiic_getsda),
           DEVMETHOD(iicbb_getscl,         gpioiic_getscl),
           DEVMETHOD(iicbb_reset,          gpioiic_reset),
   
   #ifdef FDT
           /* OFW bus interface */
           DEVMETHOD(ofw_bus_get_node,     gpioiic_get_node),
   #endif
   
           DEVMETHOD_END
   };
   
   static driver_t gpioiic_driver = {
           "gpioiic",
           gpioiic_methods,
           sizeof(struct gpioiic_softc),
   };
   
   DRIVER_MODULE(gpioiic, gpiobus, gpioiic_driver, gpioiic_devclass, 0, 0);
   DRIVER_MODULE(gpioiic, simplebus, gpioiic_driver, gpioiic_devclass, 0, 0);
   DRIVER_MODULE(iicbb, gpioiic, iicbb_driver, iicbb_devclass, 0, 0);
   MODULE_DEPEND(gpioiic, iicbb, IICBB_MINVER, IICBB_PREFVER, IICBB_MAXVER);
   MODULE_DEPEND(gpioiic, gpiobus, 1, 1, 1);

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