i2cmux.c revision 1.2
1 /* $NetBSD: i2cmux.c,v 1.2 2021/01/24 19:35:21 jmcneill Exp $ */ 2 3 /*- 4 * Copyright (c) 2020 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __KERNEL_RCSID(0, "$NetBSD: i2cmux.c,v 1.2 2021/01/24 19:35:21 jmcneill Exp $"); 34 35 #include <sys/types.h> 36 #include <sys/device.h> 37 #include <sys/kernel.h> 38 #include <sys/kmem.h> 39 40 #include <dev/fdt/fdtvar.h> 41 #include <dev/i2c/i2cvar.h> 42 #include <dev/i2c/i2cmuxvar.h> 43 44 /* 45 * i2c mux 46 * 47 * This works by interposing a set of virtual controllers behind the real 48 * i2c controller. We provide our own acquire and release functions that 49 * perform the following tasks: 50 * 51 * acquire -> acquire parent controller, program mux 52 * 53 * release -> idle mux, release parent controller 54 * 55 * All of the actual I/O operations are transparently passed through. 56 * 57 * N.B. the locking order; the generic I2C layer has already acquired 58 * our virtual controller's mutex before calling our acquire function, 59 * and we will then acquire the real controller's mutex when we acquire 60 * the bus, so the order is: 61 * 62 * mux virtual controller -> parent controller 63 * 64 * These are common routines used by various i2c mux controller 65 * implementations (gpio, pin mux, i2c device, etc.). 66 */ 67 68 /*****************************************************************************/ 69 70 static int 71 iicmux_acquire_bus(void * const v, int const flags) 72 { 73 struct iicmux_bus * const bus = v; 74 struct iicmux_softc * const sc = bus->mux; 75 int error; 76 77 error = iic_acquire_bus(sc->sc_i2c_parent, flags); 78 if (error) { 79 return error; 80 } 81 82 error = sc->sc_config->acquire_bus(bus, flags); 83 if (error) { 84 iic_release_bus(sc->sc_i2c_parent, flags); 85 } 86 87 return error; 88 } 89 90 static void 91 iicmux_release_bus(void * const v, int const flags) 92 { 93 struct iicmux_bus * const bus = v; 94 struct iicmux_softc * const sc = bus->mux; 95 96 sc->sc_config->release_bus(bus, flags); 97 iic_release_bus(sc->sc_i2c_parent, flags); 98 } 99 100 static int 101 iicmux_exec(void * const v, i2c_op_t const op, i2c_addr_t const addr, 102 const void * const cmdbuf, size_t const cmdlen, void * const databuf, 103 size_t const datalen, int const flags) 104 { 105 struct iicmux_bus * const bus = v; 106 struct iicmux_softc * const sc = bus->mux; 107 108 return iic_exec(sc->sc_i2c_parent, op, addr, cmdbuf, cmdlen, 109 databuf, datalen, flags); 110 } 111 112 /*****************************************************************************/ 113 114 static int 115 iicmux_count_children(struct iicmux_softc * const sc) 116 { 117 char name[32]; 118 int child, count; 119 120 restart: 121 for (child = OF_child(sc->sc_i2c_mux_phandle), count = 0; child; 122 child = OF_peer(child)) { 123 if (OF_getprop(child, "name", name, sizeof(name)) <= 0) { 124 continue; 125 } 126 if (strcmp(name, "i2c-mux") == 0) { 127 /* 128 * The node we encountered is the acutal parent 129 * of the i2c bus children. Stash its phandle 130 * and restart the enumeration. 131 */ 132 sc->sc_i2c_mux_phandle = child; 133 goto restart; 134 } 135 count++; 136 } 137 138 return count; 139 } 140 141 /* XXX iicbus_print() should be able to do this. */ 142 static int 143 iicmux_print(void * const aux, const char * const pnp) 144 { 145 i2c_tag_t const tag = aux; 146 struct iicmux_bus * const bus = tag->ic_cookie; 147 int rv; 148 149 rv = iicbus_print(aux, pnp); 150 aprint_normal(" bus %d", bus->busidx); 151 152 return rv; 153 } 154 155 static void 156 iicmux_attach_bus(struct iicmux_softc * const sc, 157 int const phandle, int const busidx) 158 { 159 struct iicmux_bus * const bus = &sc->sc_busses[busidx]; 160 161 bus->mux = sc; 162 bus->busidx = busidx; 163 bus->phandle = phandle; 164 165 bus->bus_data = sc->sc_config->get_bus_info(bus); 166 if (bus->bus_data == NULL) { 167 aprint_error_dev(sc->sc_dev, 168 "unable to get info for bus %d\n", busidx); 169 return; 170 } 171 172 iic_tag_init(&bus->controller); 173 bus->controller.ic_cookie = bus; 174 bus->controller.ic_acquire_bus = iicmux_acquire_bus; 175 bus->controller.ic_release_bus = iicmux_release_bus; 176 bus->controller.ic_exec = iicmux_exec; 177 178 fdtbus_register_i2c_controller(&bus->controller, bus->phandle); 179 180 fdtbus_attach_i2cbus(sc->sc_dev, bus->phandle, &bus->controller, 181 iicmux_print); 182 } 183 184 void 185 iicmux_attach(struct iicmux_softc * const sc) 186 { 187 188 /* 189 * We expect sc->sc_phandle, sc->sc_config, and sc->sc_i2c_parent 190 * to be initialized by the front-end. 191 */ 192 KASSERT(sc->sc_phandle > 0); 193 KASSERT(sc->sc_config != NULL); 194 KASSERT(sc->sc_i2c_parent != NULL); 195 196 /* 197 * We start out assuming that the i2c bus nodes are children of 198 * our own node. We'll adjust later if we encounter an "i2c-mux" 199 * node when counting our children. If we encounter such a node, 200 * then it's that node that is the parent of the i2c bus children. 201 */ 202 sc->sc_i2c_mux_phandle = sc->sc_phandle; 203 204 /* 205 * Gather up all of the various bits of information needed 206 * for this particular type of i2c mux. 207 */ 208 sc->sc_mux_data = sc->sc_config->get_mux_info(sc); 209 if (sc->sc_mux_data == NULL) { 210 aprint_error_dev(sc->sc_dev, "unable to get info for mux\n"); 211 return; 212 } 213 214 sc->sc_nbusses = iicmux_count_children(sc); 215 if (sc->sc_nbusses == 0) { 216 return; 217 } 218 219 sc->sc_busses = kmem_zalloc(sizeof(*sc->sc_busses) * sc->sc_nbusses, 220 KM_SLEEP); 221 222 int child, idx; 223 for (child = OF_child(sc->sc_i2c_mux_phandle), idx = 0; child; 224 child = OF_peer(child), idx++) { 225 KASSERT(idx < sc->sc_nbusses); 226 iicmux_attach_bus(sc, child, idx); 227 } 228 } 229
Indexes created Thu Oct 02 01:09:59 GMT 2025