FreeBSD/Linux Kernel Cross Reference
sys/dev/iicbus/mux/ltc430x.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause
      *
      * 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/bus.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/systm.h>
    
    #include <dev/iicbus/iicbus.h>
    #include <dev/iicbus/iiconf.h>
    #include "iicbus_if.h"
    #include "iicmux_if.h"
    
    static struct chip_info {
            const char      *partname;
            const char      *description;
            int             numchannels;
    } chip_infos[] = {
            {"ltc4305", "LTC4305 I2C Mux", 2},
            {"ltc4306", "LTC4306 I2C Mux", 4},
    };
    #define CHIP_NONE       (-1)
    #define CHIP_LTC4305    0
    #define CHIP_LTC4306    1
    
    #ifdef FDT
    #include <dev/ofw/ofw_bus.h>
    #include <dev/ofw/ofw_bus_subr.h>
    #include <dev/ofw/openfirm.h>
    
    static struct ofw_compat_data compat_data[] = {
            {"lltc,ltc4305",  CHIP_LTC4305},
            {"lltc,ltc4306",  CHIP_LTC4306},
            {NULL,            CHIP_NONE}
    };
    IICBUS_FDT_PNP_INFO(compat_data);
    #endif
    
    #include <dev/iicbus/mux/iicmux.h>
    
    struct ltc430x_softc {
            struct iicmux_softc mux;
            bool idle_disconnect;
    };
    
    /*
     * The datasheet doesn't name the registers, it calls them control register 0-3.
     */
    #define LTC430X_CTLREG_0        0
    #define LTC430X_CTLREG_1        1
    #define LTC430X_CTLREG_2        2
    #define   LTC430X_CR2_ENABLE_MW   (1u << 3) /* Enable mass write address. */
    #define LTC430X_CTLREG_3        3
    
    static int
    ltc430x_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd)
    {
            struct ltc430x_softc *sc = device_get_softc(dev);
            uint8_t busbits;
    
            /*
             * The iicmux caller ensures busidx is between 0 and the number of buses
             * we passed to iicmux_init_softc(), no need for validation here.  If
             * the fdt data has the idle_disconnect property we idle the bus by
             * selecting no downstream buses, otherwise we just leave the current
             * bus active.  The upper bits of control register 3 activate the
             * downstream buses; bit 7 is the first bus, bit 6 the second, etc.
             */
            if (busidx == IICMUX_SELECT_IDLE) {
                   if (sc->idle_disconnect)
                           busbits = 0;
                   else
                           return (0);
           } else {
                   busbits = 1u << (7 - busidx);
           }
   
           /*
            * We have to add the IIC_RECURSIVE flag because the iicmux core has
            * already reserved the bus for us, and iicdev_writeto() is going to try
            * to reserve it again, which is allowed with the recursive flag.
            */
           return (iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
               rd->flags | IIC_RECURSIVE));
   }
   
   static int
   ltc430x_find_chiptype(device_t dev)
   {
   #ifdef FDT
           return (ofw_bus_search_compatible(dev, compat_data)->ocd_data);
   #else
           const char *type;
           int i;
   
           if (resource_string_value(device_get_name(dev), device_get_unit(dev),
               "chip_type", &type) == 0) {
                   for (i = 0; i < nitems(chip_infos); ++i) {
                           if (strcasecmp(type, chip_infos[i].partname) == 0) {
                                   return (i);
                           }
                   }
           }
           return (CHIP_NONE);
   #endif
   }
   
   static int
   ltc430x_probe(device_t dev)
   {
           int type;
   
   #ifdef FDT
           if (!ofw_bus_status_okay(dev))
                   return (ENXIO);
   #endif
   
           type = ltc430x_find_chiptype(dev);
           if (type == CHIP_NONE)
                   return (ENXIO);
   
           device_set_desc(dev, chip_infos[type].description);
   
           return (BUS_PROBE_DEFAULT);
   }
   
   static int
   ltc430x_attach(device_t dev)
   {
           struct ltc430x_softc *sc __unused;
           int chip, err, numchan, val;
           uint8_t busbits, ctlreg2;
   
           sc = device_get_softc(dev);
   
           busbits = 0;
           ctlreg2 = LTC430X_CR2_ENABLE_MW;
   
           /*
            * Check for the idle-disconnect and ctlreg2 options, first in FDT data,
            * then allow them to be overridden by hints data.
            */
   #ifdef FDT
           phandle_t node;
   
           node = ofw_bus_get_node(dev);
           sc->idle_disconnect = OF_hasprop(node, "i2c-mux-idle-disconnect");
   
           if (OF_getprop(node, "freebsd,ctlreg2", &val, sizeof(val)) > 0) {
                   ctlreg2 = val;
           }
   #endif
   
           if (resource_int_value(device_get_name(dev), device_get_unit(dev),
               "idle_disconnect", &val) == 0) {
                   sc->idle_disconnect = val;
           }
   
           if (resource_int_value(device_get_name(dev), device_get_unit(dev),
               "ctlreg2", &val) == 0) {
                   ctlreg2 = val;
           }
   
           /* We found the chip type when probing, so now it "can't fail". */
           if ((chip = ltc430x_find_chiptype(dev)) == CHIP_NONE) {
                   device_printf(dev, "impossible: can't identify chip type\n");
                   return (ENXIO);
           }
           numchan = chip_infos[chip].numchannels;
   
           /* Set control reg 2 with configured (or default) values. */
           iicdev_writeto(dev, LTC430X_CTLREG_2, &ctlreg2, sizeof(ctlreg2),
               IIC_WAIT);
   
           /* If configured for idle-disconnect, ensure we start disconnected. */
           if (sc->idle_disconnect) {
                   iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
                       IIC_WAIT);
           }
   
           /*
            * Invoke the iicmux framework's attach code, and if it succeeds, invoke
            * the probe and attach code of any child iicbus instances it added.
            */
           if ((err = iicmux_attach(dev, device_get_parent(dev), numchan)) == 0)
                   bus_generic_attach(dev);
   
           return (err);
   }
   
   static int
   ltc430x_detach(device_t dev)
   {
           int err;
   
           if ((err = iicmux_detach(dev)) != 0)
                   return (err);
   
           return (0);
   }
   
   static device_method_t ltc430x_methods[] = {
           /* device methods */
           DEVMETHOD(device_probe,                 ltc430x_probe),
           DEVMETHOD(device_attach,                ltc430x_attach),
           DEVMETHOD(device_detach,                ltc430x_detach),
   
           /* iicmux methods */
           DEVMETHOD(iicmux_bus_select,            ltc430x_bus_select),
   
           DEVMETHOD_END
   };
   
   DEFINE_CLASS_1(ltc430x, ltc430x_driver, ltc430x_methods,
       sizeof(struct ltc430x_softc), iicmux_driver);
   DRIVER_MODULE(ltc430x, iicbus, ltc430x_driver, 0, 0);
   
   #ifdef FDT
   DRIVER_MODULE(ofw_iicbus, ltc430x, ofw_iicbus_driver, 0, 0);
   #else
   DRIVER_MODULE(iicbus, ltc430x, iicbus_driver, 0, 0);
   #endif
   
   MODULE_DEPEND(ltc430x, iicmux, 1, 1, 1);
   MODULE_DEPEND(ltc430x, iicbus, 1, 1, 1);
   

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