FreeBSD/Linux Kernel Cross Reference
sys/dev/sram/mmio_sram.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause
      *
      * Copyright (c) 2022 Ruslan Bukin <br@bsdpad.com>
      *
      * This work was supported by Innovate UK project 105694, "Digital Security
      * by Design (DSbD) Technology Platform Prototype".
      *
      * 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 <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/rman.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    
    #include <machine/bus.h>
    
    #include <dev/fdt/simplebus.h>
    #include <dev/fdt/fdt_common.h>
    #include <dev/ofw/ofw_bus_subr.h>
    
    #include "mmio_sram_if.h"
    
    #define dprintf(fmt, ...)
    
    static struct resource_spec mmio_sram_spec[] = {
            { SYS_RES_MEMORY,       0,      RF_ACTIVE },
            { -1, 0 }
    };
    
    struct mmio_sram_softc {
            struct simplebus_softc  simplebus_sc;
            struct resource         *res[1];
            device_t                dev;
    };
    
    static int
    mmio_sram_probe(device_t dev)
    {
    
            if (!ofw_bus_is_compatible(dev, "mmio-sram"))
                    return (ENXIO);
    
            if (!ofw_bus_status_okay(dev))
                    return (ENXIO);
    
            device_set_desc(dev, "MMIO SRAM");
    
            return (BUS_PROBE_DEFAULT);
    }
    
    static int
    mmio_sram_attach(device_t dev)
    {
            struct mmio_sram_softc *sc;
            phandle_t node;
    
            sc = device_get_softc(dev);
            sc->dev = dev;
    
            if (bus_alloc_resources(dev, mmio_sram_spec, sc->res) != 0) {
                    device_printf(dev, "Can't allocate resources for device.\n");
                    return (ENXIO);
            }
    
            node = ofw_bus_get_node(dev);
            if (node == -1)
                    return (ENXIO);
    
            simplebus_init(dev, node);
    
            /*
             * Allow devices to identify.
             */
           bus_generic_probe(dev);
   
           /*
            * Now walk the OFW tree and attach top-level devices.
            */
           for (node = OF_child(node); node > 0; node = OF_peer(node))
                   simplebus_add_device(dev, node, 0, NULL, -1, NULL);
   
           return (bus_generic_attach(dev));
   }
   
   static int
   mmio_sram_detach(device_t dev)
   {
           struct mmio_sram_softc *sc;
   
           sc = device_get_softc(dev);
   
           bus_release_resources(dev, mmio_sram_spec, sc->res);
   
           return (0);
   }
   
   static uint8_t
   mmio_sram_read_1(device_t dev, bus_size_t offset)
   {
           struct mmio_sram_softc *sc;
   
           sc = device_get_softc(dev);
   
           dprintf("%s: reading from %lx\n", __func__, offset);
   
           return (bus_read_1(sc->res[0], offset));
   }
   
   static void
   mmio_sram_write_1(device_t dev, bus_size_t offset, uint8_t val)
   {
           struct mmio_sram_softc *sc;
   
           sc = device_get_softc(dev);
   
           dprintf("%s: writing to %lx val %x\n", __func__, offset, val);
   
           bus_write_1(sc->res[0], offset, val);
   }
   
   static device_method_t mmio_sram_methods[] = {
           /* Device Interface */
           DEVMETHOD(device_probe,         mmio_sram_probe),
           DEVMETHOD(device_attach,        mmio_sram_attach),
           DEVMETHOD(device_detach,        mmio_sram_detach),
   
           /* MMIO interface */
           DEVMETHOD(mmio_sram_read_1,     mmio_sram_read_1),
           DEVMETHOD(mmio_sram_write_1,    mmio_sram_write_1),
           DEVMETHOD_END
   };
   
   DEFINE_CLASS_1(mmio_sram, mmio_sram_driver, mmio_sram_methods,
       sizeof(struct mmio_sram_softc), simplebus_driver);
   
   EARLY_DRIVER_MODULE(mmio_sram, simplebus, mmio_sram_driver, 0, 0,
       BUS_PASS_SUPPORTDEV + BUS_PASS_ORDER_MIDDLE);
   MODULE_VERSION(mmio_sram, 1);

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