/*      $NetBSD: i2cmux.c,v 1.7 2021/11/10 15:39:03 msaitoh Exp $       */

/*-
* Copyright (c) 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/

#if defined(__i386__) || defined(__amd64__) || defined(__aarch64__)
#include "acpica.h"
#endif

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: i2cmux.c,v 1.7 2021/11/10 15:39:03 msaitoh Exp $");

#include <sys/types.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/kmem.h>

#include <dev/fdt/fdtvar.h>
#include <dev/i2c/i2cvar.h>
#include <dev/i2c/i2cmuxvar.h>

#if NACPICA > 0
#include <dev/acpi/acpivar.h>
#include <dev/acpi/acpi_i2c.h>
#endif

/*
* i2c mux
*
* This works by interposing a set of virtual controllers behind the real
* i2c controller.  We provide our own acquire and release functions that
* perform the following tasks:
*
*      acquire -> acquire parent controller, program mux
*
*      release -> idle mux, release parent controller
*
* All of the actual I/O operations are transparently passed through.
*
* N.B. the locking order; the generic I2C layer has already acquired
* our virtual controller's mutex before calling our acquire function,
* and we will then acquire the real controller's mutex when we acquire
* the bus, so the order is:
*
*      mux virtual controller -> parent controller
*
* These are common routines used by various i2c mux controller
* implementations (gpio, pin mux, i2c device, etc.).
*/

/*****************************************************************************/

static int
iicmux_acquire_bus(void * const v, int const flags)
{
       struct iicmux_bus * const bus = v;
       struct iicmux_softc * const sc = bus->mux;
       int error;

       error = iic_acquire_bus(sc->sc_i2c_parent, flags);
       if (error) {
               return error;
       }

       error = sc->sc_config->acquire_bus(bus, flags);
       if (error) {
               iic_release_bus(sc->sc_i2c_parent, flags);
       }

       return error;
}

static void
iicmux_release_bus(void * const v, int const flags)
{
       struct iicmux_bus * const bus = v;
       struct iicmux_softc * const sc = bus->mux;

       sc->sc_config->release_bus(bus, flags);
       iic_release_bus(sc->sc_i2c_parent, flags);
}

static int
iicmux_exec(void * const v, i2c_op_t const op, i2c_addr_t const addr,
   const void * const cmdbuf, size_t const cmdlen, void * const databuf,
   size_t const datalen, int const flags)
{
       struct iicmux_bus * const bus = v;
       struct iicmux_softc * const sc = bus->mux;

       return iic_exec(sc->sc_i2c_parent, op, addr, cmdbuf, cmdlen,
                       databuf, datalen, flags);
}

/*****************************************************************************/

static int
iicmux_count_children(struct iicmux_softc * const sc)
{
       char name[32];
       int child, count;

restart:
       for (child = OF_child(sc->sc_i2c_mux_phandle), count = 0; child;
            child = OF_peer(child)) {
               if (OF_getprop(child, "name", name, sizeof(name)) <= 0) {
                       continue;
               }
               if (strcmp(name, "i2c-mux") == 0) {
                       /*
                        * The node we encountered is the actual parent
                        * of the i2c bus children.  Stash its phandle
                        * and restart the enumeration.
                        */
                       sc->sc_i2c_mux_phandle = child;
                       goto restart;
               }
               count++;
       }

       return count;
}

/* XXX iicbus_print() should be able to do this. */
static int
iicmux_print(void * const aux, const char * const pnp)
{
       i2c_tag_t const tag = aux;
       struct iicmux_bus * const bus = tag->ic_cookie;
       int rv;

       rv = iicbus_print(aux, pnp);
       aprint_normal(" bus %d", bus->busidx);

       return rv;
}

static void
iicmux_attach_bus(struct iicmux_softc * const sc,
   uintptr_t const handle, enum i2c_cookie_type handletype, int const busidx)
{
       struct iicmux_bus * const bus = &sc->sc_busses[busidx];

       bus->mux = sc;
       bus->busidx = busidx;
       bus->handle = handle;
       bus->handletype = handletype;

       bus->bus_data = sc->sc_config->get_bus_info(bus);
       if (bus->bus_data == NULL) {
               aprint_error_dev(sc->sc_dev,
                   "unable to get info for bus %d\n", busidx);
               return;
       }

       iic_tag_init(&bus->controller);
       bus->controller.ic_cookie = bus;
       bus->controller.ic_acquire_bus = iicmux_acquire_bus;
       bus->controller.ic_release_bus = iicmux_release_bus;
       bus->controller.ic_exec = iicmux_exec;

       switch (handletype) {
       case I2C_COOKIE_OF:
               fdtbus_register_i2c_controller(&bus->controller,
                   (int)bus->handle);

               fdtbus_attach_i2cbus(sc->sc_dev, (int)bus->handle,
                   &bus->controller, iicmux_print);
               break;
#if NACPICA > 0
       case I2C_COOKIE_ACPI: {
               struct acpi_devnode *ad = acpi_match_node((ACPI_HANDLE)handle);
               KASSERT(ad != NULL);
               struct i2cbus_attach_args iba = {
                       .iba_tag = &bus->controller,
                       .iba_child_devices = acpi_enter_i2c_devs(NULL, ad)
               };
               config_found(sc->sc_dev, &iba, iicbus_print, CFARGS_NONE);
       }       break;
#endif
       default:
               aprint_error_dev(sc->sc_dev, "unknown handle type\n");
               break;
       }
}

static void
iicmux_attach_fdt(struct iicmux_softc * const sc)
{
       /*
        * We start out assuming that the i2c bus nodes are children of
        * our own node.  We'll adjust later if we encounter an "i2c-mux"
        * node when counting our children.  If we encounter such a node,
        * then it's that node that is the parent of the i2c bus children.
        */
       sc->sc_i2c_mux_phandle = (int)sc->sc_handle;

       sc->sc_nbusses = iicmux_count_children(sc);
       if (sc->sc_nbusses == 0) {
               return;
       }

       sc->sc_busses = kmem_zalloc(sizeof(*sc->sc_busses) * sc->sc_nbusses,
           KM_SLEEP);

       int child, idx;
       for (child = OF_child(sc->sc_i2c_mux_phandle), idx = 0; child;
            child = OF_peer(child), idx++) {
               KASSERT(idx < sc->sc_nbusses);
               iicmux_attach_bus(sc, child, I2C_COOKIE_OF, idx);
       }
}

#if NACPICA > 0
static void
iicmux_attach_acpi(struct iicmux_softc * const sc)
{
       ACPI_HANDLE hdl = (ACPI_HANDLE)sc->sc_handle;
       struct acpi_devnode *devnode, *ad;
       int idx;

       devnode = acpi_match_node(hdl);
       KASSERT(devnode != NULL);

       /* Count child busses */
       sc->sc_nbusses = 0;
       SIMPLEQ_FOREACH(ad, &devnode->ad_child_head, ad_child_list) {
               if (ad->ad_devinfo->Type != ACPI_TYPE_DEVICE ||
                   !acpi_device_present(ad->ad_handle)) {
                       continue;
               }
               sc->sc_nbusses++;
       }

       sc->sc_busses = kmem_zalloc(sizeof(*sc->sc_busses) * sc->sc_nbusses,
           KM_SLEEP);

       /* Attach child busses */
       idx = 0;
       SIMPLEQ_FOREACH(ad, &devnode->ad_child_head, ad_child_list) {
               if (ad->ad_devinfo->Type != ACPI_TYPE_DEVICE ||
                   !acpi_device_present(ad->ad_handle)) {
                       continue;
               }
               iicmux_attach_bus(sc, (uintptr_t)ad->ad_handle,
                   I2C_COOKIE_ACPI, idx);
               idx++;
       }
}
#endif

void
iicmux_attach(struct iicmux_softc * const sc)
{
       /*
        * We expect sc->sc_handle, sc->sc_config, and sc->sc_i2c_parent
        * to be initialized by the front-end.
        */
       KASSERT(sc->sc_handle > 0);
       KASSERT(sc->sc_config != NULL);
       KASSERT(sc->sc_i2c_parent != NULL);

       /*
        * Gather up all of the various bits of information needed
        * for this particular type of i2c mux.
        */
       sc->sc_mux_data = sc->sc_config->get_mux_info(sc);
       if (sc->sc_mux_data == NULL) {
               aprint_error_dev(sc->sc_dev, "unable to get info for mux\n");
               return;
       }

       /*
        * Do configuration method (OF, ACPI) specific setup.
        */
       switch (sc->sc_handletype) {
       case I2C_COOKIE_OF:
               iicmux_attach_fdt(sc);
               break;
#if NACPICA > 0
       case I2C_COOKIE_ACPI:
               iicmux_attach_acpi(sc);
               break;
#endif
       default:
               aprint_error_dev(sc->sc_dev, "could not configure mux: "
                   "handle type %u not supported\n", sc->sc_handletype);
               break;
       }
}

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