268 lines
7.2 KiB
C
268 lines
7.2 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Driver for i2c bus muxes controlled by one or more gpio pins.
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*
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* This driver has #ifdef FDT sections in it, as if it supports both fdt and
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* hinted attachment, but there is currently no support for hinted attachment.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_platform.h"
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#include <sys/param.h>
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#include <sys/bus.h>
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#include <sys/gpio.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/systm.h>
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#include <dev/gpio/gpiobusvar.h>
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#include <dev/iicbus/iicbus.h>
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#include <dev/iicbus/mux/iicmux.h>
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#ifdef FDT
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#include <dev/ofw/ofw_bus.h>
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#include <dev/ofw/ofw_bus_subr.h>
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#include <dev/ofw/openfirm.h>
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static struct ofw_compat_data compat_data[] = {
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{"i2c-mux-gpio", true},
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{NULL, false}
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};
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OFWBUS_PNP_INFO(compat_data);
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SIMPLEBUS_PNP_INFO(compat_data);
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#endif /* FDT */
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#include <dev/iicbus/iiconf.h>
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#include "iicmux.h"
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#include "iicmux_if.h"
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struct gpiomux_softc {
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struct iicmux_softc mux;
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int idleidx;
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int numpins;
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gpio_pin_t pins[IICMUX_MAX_BUSES];
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};
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#define IDLE_NOOP (-1) /* When asked to idle the bus, do nothing. */
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static int
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gpiomux_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd)
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{
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struct gpiomux_softc *sc = device_get_softc(dev);
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int i;
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/*
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* The iicmux caller ensures busidx is between 0 and the number of buses
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* we passed to iicmux_init_softc(), no need for validation here. The
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* bits in the index number are transcribed to the state of the pins,
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* except when we're asked to idle the bus. In that case, we transcribe
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* sc->idleidx to the pins, unless that is IDLE_NOOP (leave the current
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* bus selected), in which case we just bail.
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*/
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if (busidx == IICMUX_SELECT_IDLE) {
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if (sc->idleidx == IDLE_NOOP)
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return (0);
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busidx = sc->idleidx;
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}
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for (i = 0; i < sc->numpins; ++i)
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gpio_pin_set_active(sc->pins[i], busidx & (1u << i));
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return (0);
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}
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static int
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gpiomux_probe(device_t dev)
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{
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int rv;
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rv = ENXIO;
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#ifdef FDT
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if (ofw_bus_status_okay(dev) &&
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ofw_bus_search_compatible(dev, compat_data)->ocd_data)
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rv = BUS_PROBE_DEFAULT;
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#endif
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device_set_desc(dev, "I2C GPIO Mux");
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return (rv);
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}
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static void
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gpiomux_release_pins(struct gpiomux_softc *sc)
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{
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int i;
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for (i = 0; i < sc->numpins; ++i)
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gpio_pin_release(sc->pins[i]);
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}
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static int
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gpiomux_attach(device_t dev)
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{
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struct gpiomux_softc *sc = device_get_softc(dev);
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ssize_t len;
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device_t busdev;
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int err, i, idlebits, numchannels;
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pcell_t propval;
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phandle_t node;
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node = ofw_bus_get_node(dev);
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/*
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* Locate the gpio pin(s) that control the mux hardware. There can be
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* multiple pins, but there must be at least one.
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*/
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for (i = 0; ; ++i) {
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err = gpio_pin_get_by_ofw_propidx(dev, node, "mux-gpios", i,
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&sc->pins[i]);
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if (err != 0) {
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break;
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}
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}
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sc->numpins = i;
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if (sc->numpins == 0) {
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device_printf(dev, "cannot acquire pins listed in mux-gpios\n");
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if (err == 0)
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err = ENXIO;
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goto errexit;
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}
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numchannels = 1u << sc->numpins;
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if (numchannels > IICMUX_MAX_BUSES) {
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device_printf(dev, "too many mux-gpios pins for max %d buses\n",
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IICMUX_MAX_BUSES);
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err = EINVAL;
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goto errexit;
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}
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/*
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* We don't have a parent/child relationship to the upstream bus, we
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* have to locate it via the i2c-parent property. Explicitly tell the
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* user which upstream we're associated with, since the normal attach
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* message is going to mention only our actual parent.
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*/
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len = OF_getencprop(node, "i2c-parent", &propval, sizeof(propval));
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if (len != sizeof(propval)) {
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device_printf(dev, "cannot obtain i2c-parent property\n");
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err = ENXIO;
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goto errexit;
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}
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busdev = OF_device_from_xref((phandle_t)propval);
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if (busdev == NULL) {
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device_printf(dev,
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"cannot find device referenced by i2c-parent property\n");
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err = ENXIO;
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goto errexit;
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}
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device_printf(dev, "upstream bus is %s\n", device_get_nameunit(busdev));
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/*
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* If there is an idle-state property, that is the value we set the pins
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* to when the bus is idle, otherwise idling the bus is a no-op
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* (whichever bus was last accessed remains active).
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*/
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len = OF_getencprop(node, "idle-state", &propval, sizeof(propval));
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if (len == sizeof(propval)) {
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if ((int)propval >= numchannels) {
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device_printf(dev,
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"idle-state property %d exceeds channel count\n",
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propval);
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}
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sc->idleidx = (int)propval;
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idlebits = sc->idleidx;
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} else {
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sc->idleidx = IDLE_NOOP;
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idlebits = 0;
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}
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/* Preset the mux to the idle state to get things started. */
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for (i = 0; i < sc->numpins; ++i) {
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gpio_pin_setflags(sc->pins[i], GPIO_PIN_OUTPUT);
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gpio_pin_set_active(sc->pins[i], idlebits & (1u << i));
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}
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/* Init the core driver, have it add our child downstream buses. */
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if ((err = iicmux_attach(dev, busdev, numchannels)) == 0)
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bus_generic_attach(dev);
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errexit:
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if (err != 0)
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gpiomux_release_pins(sc);
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return (err);
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}
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static int
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gpiomux_detach(device_t dev)
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{
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struct gpiomux_softc *sc = device_get_softc(dev);
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int err;
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if ((err = iicmux_detach(dev)) != 0)
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return (err);
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gpiomux_release_pins(sc);
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return (0);
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}
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static device_method_t gpiomux_methods[] = {
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/* device methods */
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DEVMETHOD(device_probe, gpiomux_probe),
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DEVMETHOD(device_attach, gpiomux_attach),
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DEVMETHOD(device_detach, gpiomux_detach),
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/* iicmux methods */
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DEVMETHOD(iicmux_bus_select, gpiomux_bus_select),
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DEVMETHOD_END
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};
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static devclass_t gpiomux_devclass;
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DEFINE_CLASS_1(iic_gpiomux, iic_gpiomux_driver, gpiomux_methods,
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sizeof(struct gpiomux_softc), iicmux_driver);
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DRIVER_MODULE(iic_gpiomux, simplebus, iic_gpiomux_driver, gpiomux_devclass, 0, 0);
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DRIVER_MODULE(iic_gpiomux, ofw_simplebus, iic_gpiomux_driver, gpiomux_devclass, 0, 0);
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#ifdef FDT
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DRIVER_MODULE(ofw_iicbus, iic_gpiomux, ofw_iicbus_driver, ofw_iicbus_devclass, 0, 0);
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#else
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DRIVER_MODULE(iicbus, iic_gpiomux, iicbus_driver, iicbus_devclass, 0, 0);
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#endif
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MODULE_DEPEND(iic_gpiomux, iicmux, 1, 1, 1);
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MODULE_DEPEND(iic_gpiomux, iicbus, 1, 1, 1);
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