/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2019 Ian Lepore * * 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. */ /* * Driver for i2c bus muxes controlled by one or more gpio pins. * * This driver has #ifdef FDT sections in it, as if it supports both fdt and * hinted attachment, but there is currently no support for hinted attachment. */ #include #include "opt_platform.h" #include #include #include #include #include #include #include #include #include #ifdef FDT #include #include #include static struct ofw_compat_data compat_data[] = { {"i2c-mux-gpio", true}, {NULL, false} }; OFWBUS_PNP_INFO(compat_data); SIMPLEBUS_PNP_INFO(compat_data); #endif /* FDT */ #include #include "iicmux.h" #include "iicmux_if.h" struct gpiomux_softc { struct iicmux_softc mux; int idleidx; int numpins; gpio_pin_t pins[IICMUX_MAX_BUSES]; }; #define IDLE_NOOP (-1) /* When asked to idle the bus, do nothing. */ static int gpiomux_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd) { struct gpiomux_softc *sc = device_get_softc(dev); int i; /* * The iicmux caller ensures busidx is between 0 and the number of buses * we passed to iicmux_init_softc(), no need for validation here. The * bits in the index number are transcribed to the state of the pins, * except when we're asked to idle the bus. In that case, we transcribe * sc->idleidx to the pins, unless that is IDLE_NOOP (leave the current * bus selected), in which case we just bail. */ if (busidx == IICMUX_SELECT_IDLE) { if (sc->idleidx == IDLE_NOOP) return (0); busidx = sc->idleidx; } for (i = 0; i < sc->numpins; ++i) gpio_pin_set_active(sc->pins[i], busidx & (1u << i)); return (0); } static int gpiomux_probe(device_t dev) { int rv; rv = ENXIO; #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, "I2C GPIO Mux"); return (rv); } static void gpiomux_release_pins(struct gpiomux_softc *sc) { int i; for (i = 0; i < sc->numpins; ++i) gpio_pin_release(sc->pins[i]); } static int gpiomux_attach(device_t dev) { struct gpiomux_softc *sc = device_get_softc(dev); ssize_t len; device_t busdev; int err, i, idlebits, numchannels; pcell_t propval; phandle_t node; node = ofw_bus_get_node(dev); /* * Locate the gpio pin(s) that control the mux hardware. There can be * multiple pins, but there must be at least one. */ for (i = 0; ; ++i) { err = gpio_pin_get_by_ofw_propidx(dev, node, "mux-gpios", i, &sc->pins[i]); if (err != 0) { break; } } sc->numpins = i; if (sc->numpins == 0) { device_printf(dev, "cannot acquire pins listed in mux-gpios\n"); if (err == 0) err = ENXIO; goto errexit; } numchannels = 1u << sc->numpins; if (numchannels > IICMUX_MAX_BUSES) { device_printf(dev, "too many mux-gpios pins for max %d buses\n", IICMUX_MAX_BUSES); err = EINVAL; goto errexit; } /* * We don't have a parent/child relationship to the upstream bus, we * have to locate it via the i2c-parent property. Explicitly tell the * user which upstream we're associated with, since the normal attach * message is going to mention only our actual parent. */ len = OF_getencprop(node, "i2c-parent", &propval, sizeof(propval)); if (len != sizeof(propval)) { device_printf(dev, "cannot obtain i2c-parent property\n"); err = ENXIO; goto errexit; } busdev = OF_device_from_xref((phandle_t)propval); if (busdev == NULL) { device_printf(dev, "cannot find device referenced by i2c-parent property\n"); err = ENXIO; goto errexit; } device_printf(dev, "upstream bus is %s\n", device_get_nameunit(busdev)); /* * If there is an idle-state property, that is the value we set the pins * to when the bus is idle, otherwise idling the bus is a no-op * (whichever bus was last accessed remains active). */ len = OF_getencprop(node, "idle-state", &propval, sizeof(propval)); if (len == sizeof(propval)) { if ((int)propval >= numchannels) { device_printf(dev, "idle-state property %d exceeds channel count\n", propval); } sc->idleidx = (int)propval; idlebits = sc->idleidx; } else { sc->idleidx = IDLE_NOOP; idlebits = 0; } /* Preset the mux to the idle state to get things started. */ for (i = 0; i < sc->numpins; ++i) { gpio_pin_setflags(sc->pins[i], GPIO_PIN_OUTPUT); gpio_pin_set_active(sc->pins[i], idlebits & (1u << i)); } /* Init the core driver, have it add our child downstream buses. */ if ((err = iicmux_attach(dev, busdev, numchannels)) == 0) bus_generic_attach(dev); errexit: if (err != 0) gpiomux_release_pins(sc); return (err); } static int gpiomux_detach(device_t dev) { struct gpiomux_softc *sc = device_get_softc(dev); int err; if ((err = iicmux_detach(dev)) != 0) return (err); gpiomux_release_pins(sc); return (0); } static device_method_t gpiomux_methods[] = { /* device methods */ DEVMETHOD(device_probe, gpiomux_probe), DEVMETHOD(device_attach, gpiomux_attach), DEVMETHOD(device_detach, gpiomux_detach), /* iicmux methods */ DEVMETHOD(iicmux_bus_select, gpiomux_bus_select), DEVMETHOD_END }; static devclass_t gpiomux_devclass; DEFINE_CLASS_1(iic_gpiomux, iic_gpiomux_driver, gpiomux_methods, sizeof(struct gpiomux_softc), iicmux_driver); DRIVER_MODULE(iic_gpiomux, simplebus, iic_gpiomux_driver, gpiomux_devclass, 0, 0); DRIVER_MODULE(iic_gpiomux, ofw_simplebus, iic_gpiomux_driver, gpiomux_devclass, 0, 0); #ifdef FDT DRIVER_MODULE(ofw_iicbus, iic_gpiomux, ofw_iicbus_driver, ofw_iicbus_devclass, 0, 0); #else DRIVER_MODULE(iicbus, iic_gpiomux, iicbus_driver, iicbus_devclass, 0, 0); #endif MODULE_DEPEND(iic_gpiomux, iicmux, 1, 1, 1); MODULE_DEPEND(iic_gpiomux, iicbus, 1, 1, 1);