1/*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2019 Ian Lepore <ian@freebsd.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28/* 29 * Driver for i2c bus muxes controlled by one or more gpio pins. 30 * 31 * This driver has #ifdef FDT sections in it, as if it supports both fdt and 32 * hinted attachment, but there is currently no support for hinted attachment. 33 */ 34 35#include <sys/cdefs.h> 36#include "opt_platform.h" 37 38#include <sys/param.h> 39#include <sys/bus.h> 40#include <sys/gpio.h> 41#include <sys/kernel.h> 42#include <sys/module.h> 43#include <sys/systm.h> 44 45#include <dev/gpio/gpiobusvar.h> 46 47#include <dev/iicbus/iicbus.h> 48#include <dev/iicbus/mux/iicmux.h> 49 50#ifdef FDT 51#include <dev/ofw/ofw_bus.h> 52#include <dev/ofw/ofw_bus_subr.h> 53#include <dev/ofw/openfirm.h> 54 55static struct ofw_compat_data compat_data[] = { 56 {"i2c-mux-gpio", true}, 57 {NULL, false} 58}; 59OFWBUS_PNP_INFO(compat_data); 60SIMPLEBUS_PNP_INFO(compat_data); 61#endif /* FDT */ 62 63#include <dev/iicbus/iiconf.h> 64#include "iicmux.h" 65#include "iicmux_if.h" 66 67struct gpiomux_softc { 68 struct iicmux_softc mux; 69 int idleidx; 70 int numpins; 71 gpio_pin_t pins[IICMUX_MAX_BUSES]; 72}; 73 74#define IDLE_NOOP (-1) /* When asked to idle the bus, do nothing. */ 75 76static int 77gpiomux_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd) 78{ 79 struct gpiomux_softc *sc = device_get_softc(dev); 80 int i; 81 82 /* 83 * The iicmux caller ensures busidx is between 0 and the number of buses 84 * we passed to iicmux_init_softc(), no need for validation here. The 85 * bits in the index number are transcribed to the state of the pins, 86 * except when we're asked to idle the bus. In that case, we transcribe 87 * sc->idleidx to the pins, unless that is IDLE_NOOP (leave the current 88 * bus selected), in which case we just bail. 89 */ 90 if (busidx == IICMUX_SELECT_IDLE) { 91 if (sc->idleidx == IDLE_NOOP) 92 return (0); 93 busidx = sc->idleidx; 94 } 95 96 for (i = 0; i < sc->numpins; ++i) 97 gpio_pin_set_active(sc->pins[i], busidx & (1u << i)); 98 99 return (0); 100} 101 102static int 103gpiomux_probe(device_t dev) 104{ 105 int rv; 106 107 rv = ENXIO; 108 109#ifdef FDT 110 if (ofw_bus_status_okay(dev) && 111 ofw_bus_search_compatible(dev, compat_data)->ocd_data) 112 rv = BUS_PROBE_DEFAULT; 113#endif 114 115 device_set_desc(dev, "I2C GPIO Mux"); 116 117 return (rv); 118} 119 120static void 121gpiomux_release_pins(struct gpiomux_softc *sc) 122{ 123 int i; 124 125 for (i = 0; i < sc->numpins; ++i) 126 gpio_pin_release(sc->pins[i]); 127} 128 129static int 130gpiomux_attach(device_t dev) 131{ 132 struct gpiomux_softc *sc = device_get_softc(dev); 133 ssize_t len; 134 device_t busdev; 135 int err, i, idlebits, numchannels; 136 pcell_t propval; 137 phandle_t node; 138 139 node = ofw_bus_get_node(dev); 140 141 /* 142 * Locate the gpio pin(s) that control the mux hardware. There can be 143 * multiple pins, but there must be at least one. 144 */ 145 for (i = 0; ; ++i) { 146 err = gpio_pin_get_by_ofw_propidx(dev, node, "mux-gpios", i, 147 &sc->pins[i]); 148 if (err != 0) { 149 break; 150 } 151 } 152 sc->numpins = i; 153 if (sc->numpins == 0) { 154 device_printf(dev, "cannot acquire pins listed in mux-gpios\n"); 155 if (err == 0) 156 err = ENXIO; 157 goto errexit; 158 } 159 numchannels = 1u << sc->numpins; 160 if (numchannels > IICMUX_MAX_BUSES) { 161 device_printf(dev, "too many mux-gpios pins for max %d buses\n", 162 IICMUX_MAX_BUSES); 163 err = EINVAL; 164 goto errexit; 165 } 166 167 /* 168 * We don't have a parent/child relationship to the upstream bus, we 169 * have to locate it via the i2c-parent property. Explicitly tell the 170 * user which upstream we're associated with, since the normal attach 171 * message is going to mention only our actual parent. 172 */ 173 len = OF_getencprop(node, "i2c-parent", &propval, sizeof(propval)); 174 if (len != sizeof(propval)) { 175 device_printf(dev, "cannot obtain i2c-parent property\n"); 176 err = ENXIO; 177 goto errexit; 178 } 179 busdev = OF_device_from_xref((phandle_t)propval); 180 if (busdev == NULL) { 181 device_printf(dev, 182 "cannot find device referenced by i2c-parent property\n"); 183 err = ENXIO; 184 goto errexit; 185 } 186 device_printf(dev, "upstream bus is %s\n", device_get_nameunit(busdev)); 187 188 /* 189 * If there is an idle-state property, that is the value we set the pins 190 * to when the bus is idle, otherwise idling the bus is a no-op 191 * (whichever bus was last accessed remains active). 192 */ 193 len = OF_getencprop(node, "idle-state", &propval, sizeof(propval)); 194 if (len == sizeof(propval)) { 195 if ((int)propval >= numchannels) { 196 device_printf(dev, 197 "idle-state property %d exceeds channel count\n", 198 propval); 199 } 200 sc->idleidx = (int)propval; 201 idlebits = sc->idleidx; 202 } else { 203 sc->idleidx = IDLE_NOOP; 204 idlebits = 0; 205 } 206 207 /* Preset the mux to the idle state to get things started. */ 208 for (i = 0; i < sc->numpins; ++i) { 209 gpio_pin_setflags(sc->pins[i], GPIO_PIN_OUTPUT); 210 gpio_pin_set_active(sc->pins[i], idlebits & (1u << i)); 211 } 212 213 /* Init the core driver, have it add our child downstream buses. */ 214 if ((err = iicmux_attach(dev, busdev, numchannels)) == 0) 215 bus_generic_attach(dev); 216 217errexit: 218 219 if (err != 0) 220 gpiomux_release_pins(sc); 221 222 return (err); 223} 224 225static int 226gpiomux_detach(device_t dev) 227{ 228 struct gpiomux_softc *sc = device_get_softc(dev); 229 int err; 230 231 if ((err = iicmux_detach(dev)) != 0) 232 return (err); 233 234 gpiomux_release_pins(sc); 235 236 return (0); 237} 238 239static device_method_t gpiomux_methods[] = { 240 /* device methods */ 241 DEVMETHOD(device_probe, gpiomux_probe), 242 DEVMETHOD(device_attach, gpiomux_attach), 243 DEVMETHOD(device_detach, gpiomux_detach), 244 245 /* iicmux methods */ 246 DEVMETHOD(iicmux_bus_select, gpiomux_bus_select), 247 248 DEVMETHOD_END 249}; 250 251DEFINE_CLASS_1(iic_gpiomux, iic_gpiomux_driver, gpiomux_methods, 252 sizeof(struct gpiomux_softc), iicmux_driver); 253DRIVER_MODULE(iic_gpiomux, simplebus, iic_gpiomux_driver, 0, 0); 254DRIVER_MODULE(iic_gpiomux, ofw_simplebus, iic_gpiomux_driver, 0, 0); 255 256#ifdef FDT 257DRIVER_MODULE(ofw_iicbus, iic_gpiomux, ofw_iicbus_driver, 0, 0); 258#else 259DRIVER_MODULE(iicbus, iic_gpiomux, iicbus_driver, 0, 0); 260#endif 261 262MODULE_DEPEND(iic_gpiomux, iicmux, 1, 1, 1); 263MODULE_DEPEND(iic_gpiomux, iicbus, 1, 1, 1); 264