| 1 | /* |
| 2 | * I2C multiplexer for PCA954x series of I2C multiplexer/switch chips. |
| 3 | * |
| 4 | * Copyright 2021 Google LLC |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it |
| 7 | * under the terms of the GNU General Public License as published by the |
| 8 | * Free Software Foundation; either version 2 of the License, or |
| 9 | * (at your option) any later version. |
| 10 | * |
| 11 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * for more details. |
| 15 | */ |
| 16 | |
| 17 | #include "qemu/osdep.h" |
| 18 | #include "qapi/error.h" |
| 19 | #include "hw/i2c/i2c.h" |
| 20 | #include "hw/i2c/i2c_mux_pca954x.h" |
| 21 | #include "hw/i2c/smbus_slave.h" |
| 22 | #include "hw/core/qdev.h" |
| 23 | #include "hw/core/qdev-properties.h" |
| 24 | #include "hw/core/sysbus.h" |
| 25 | #include "qemu/log.h" |
| 26 | #include "qemu/module.h" |
| 27 | #include "qemu/queue.h" |
| 28 | #include "qom/object.h" |
| 29 | #include "trace.h" |
| 30 | |
| 31 | #define PCA9548_CHANNEL_COUNT 8 |
| 32 | #define PCA9546_CHANNEL_COUNT 4 |
| 33 | |
| 34 | /* |
| 35 | * struct Pca954xState - The pca954x state object. |
| 36 | * @control: The value written to the mux control. |
| 37 | * @channel: The set of i2c channel buses that act as channels which own the |
| 38 | * i2c children. |
| 39 | */ |
| 40 | typedef struct Pca954xState { |
| 41 | SMBusDevice parent; |
| 42 | |
| 43 | uint8_t control; |
| 44 | |
| 45 | bool enabled[PCA9548_CHANNEL_COUNT]; |
| 46 | I2CBus *bus[PCA9548_CHANNEL_COUNT]; |
| 47 | |
| 48 | char *name; |
| 49 | } Pca954xState; |
| 50 | |
| 51 | /* |
| 52 | * struct Pca954xClass - The pca954x class object. |
| 53 | * @nchans: The number of i2c channels this device has. |
| 54 | */ |
| 55 | typedef struct Pca954xClass { |
| 56 | SMBusDeviceClass parent; |
| 57 | |
| 58 | uint8_t nchans; |
| 59 | } Pca954xClass; |
| 60 | |
| 61 | #define TYPE_PCA954X "pca954x" |
| 62 | OBJECT_DECLARE_TYPE(Pca954xState, Pca954xClass, PCA954X) |
| 63 | |
| 64 | /* |
| 65 | * For each channel, if it's enabled, recursively call match on those children. |
| 66 | */ |
| 67 | static bool pca954x_match(I2CSlave *candidate, uint8_t address, |
| 68 | bool broadcast, |
| 69 | I2CNodeList *current_devs) |
| 70 | { |
| 71 | Pca954xState *mux = PCA954X(candidate); |
| 72 | Pca954xClass *mc = PCA954X_GET_CLASS(mux); |
| 73 | int i; |
| 74 | |
| 75 | /* They are talking to the mux itself (or all devices enabled). */ |
| 76 | if ((candidate->address == address) || broadcast) { |
| 77 | I2CNode *node = g_new(struct I2CNode, 1); |
| 78 | node->elt = candidate; |
| 79 | QLIST_INSERT_HEAD(current_devs, node, next); |
| 80 | if (!broadcast) { |
| 81 | return true; |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | for (i = 0; i < mc->nchans; i++) { |
| 86 | if (!mux->enabled[i]) { |
| 87 | continue; |
| 88 | } |
| 89 | |
| 90 | if (i2c_scan_bus(mux->bus[i], address, broadcast, |
| 91 | current_devs)) { |
| 92 | if (!broadcast) { |
| 93 | return true; |
| 94 | } |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | /* If we arrived here we didn't find a match, return broadcast. */ |
| 99 | return broadcast; |
| 100 | } |
| 101 | |
| 102 | static void pca954x_enable_channel(Pca954xState *s, uint8_t enable_mask) |
| 103 | { |
| 104 | Pca954xClass *mc = PCA954X_GET_CLASS(s); |
| 105 | int i; |
| 106 | |
| 107 | /* |
| 108 | * For each channel, check if their bit is set in enable_mask and if yes, |
| 109 | * enable it, otherwise disable, hide it. |
| 110 | */ |
| 111 | for (i = 0; i < mc->nchans; i++) { |
| 112 | if (enable_mask & (1 << i)) { |
| 113 | s->enabled[i] = true; |
| 114 | } else { |
| 115 | s->enabled[i] = false; |
| 116 | } |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | static void pca954x_write(Pca954xState *s, uint8_t data) |
| 121 | { |
| 122 | s->control = data; |
| 123 | pca954x_enable_channel(s, data); |
| 124 | |
| 125 | trace_pca954x_write_bytes(data); |
| 126 | } |
| 127 | |
| 128 | static int pca954x_write_data(SMBusDevice *d, uint8_t *buf, uint8_t len) |
| 129 | { |
| 130 | Pca954xState *s = PCA954X(d); |
| 131 | |
| 132 | if (len == 0) { |
| 133 | qemu_log_mask(LOG_GUEST_ERROR, "%s: writing empty data\n", __func__); |
| 134 | return -1; |
| 135 | } |
| 136 | |
| 137 | /* |
| 138 | * len should be 1, because they write one byte to enable/disable channels. |
| 139 | */ |
| 140 | if (len > 1) { |
| 141 | qemu_log_mask(LOG_GUEST_ERROR, |
| 142 | "%s: extra data after channel selection mask\n", |
| 143 | __func__); |
| 144 | return -1; |
| 145 | } |
| 146 | |
| 147 | pca954x_write(s, buf[0]); |
| 148 | return 0; |
| 149 | } |
| 150 | |
| 151 | static uint8_t pca954x_read_byte(SMBusDevice *d) |
| 152 | { |
| 153 | Pca954xState *s = PCA954X(d); |
| 154 | uint8_t data = s->control; |
| 155 | trace_pca954x_read_data(data); |
| 156 | return data; |
| 157 | } |
| 158 | |
| 159 | static void pca954x_enter_reset(Object *obj, ResetType type) |
| 160 | { |
| 161 | Pca954xState *s = PCA954X(obj); |
| 162 | /* Reset will disable all channels. */ |
| 163 | pca954x_write(s, 0); |
| 164 | } |
| 165 | |
| 166 | I2CBus *pca954x_i2c_get_bus(I2CSlave *mux, uint8_t channel) |
| 167 | { |
| 168 | Pca954xClass *pc = PCA954X_GET_CLASS(mux); |
| 169 | Pca954xState *pca954x = PCA954X(mux); |
| 170 | |
| 171 | g_assert(channel < pc->nchans); |
| 172 | return pca954x->bus[channel]; |
| 173 | } |
| 174 | |
| 175 | static void pca9546_class_init(ObjectClass *klass, const void *data) |
| 176 | { |
| 177 | Pca954xClass *s = PCA954X_CLASS(klass); |
| 178 | s->nchans = PCA9546_CHANNEL_COUNT; |
| 179 | } |
| 180 | |
| 181 | static void pca9548_class_init(ObjectClass *klass, const void *data) |
| 182 | { |
| 183 | Pca954xClass *s = PCA954X_CLASS(klass); |
| 184 | s->nchans = PCA9548_CHANNEL_COUNT; |
| 185 | } |
| 186 | |
| 187 | static void pca954x_realize(DeviceState *dev, Error **errp) |
| 188 | { |
| 189 | Pca954xState *s = PCA954X(dev); |
| 190 | DeviceState *d = DEVICE(s); |
| 191 | if (s->name) { |
| 192 | d->id = g_strdup(s->name); |
| 193 | } else { |
| 194 | d->id = g_strdup_printf("pca954x[%x]", s->parent.i2c.address); |
| 195 | } |
| 196 | } |
| 197 | |
| 198 | static void pca954x_init(Object *obj) |
| 199 | { |
| 200 | Pca954xState *s = PCA954X(obj); |
| 201 | Pca954xClass *c = PCA954X_GET_CLASS(obj); |
| 202 | int i; |
| 203 | |
| 204 | /* SMBus modules. Cannot fail. */ |
| 205 | for (i = 0; i < c->nchans; i++) { |
| 206 | g_autofree gchar *bus_name = g_strdup_printf("i2c.%d", i); |
| 207 | |
| 208 | /* start all channels as disabled. */ |
| 209 | s->enabled[i] = false; |
| 210 | s->bus[i] = i2c_init_bus(DEVICE(s), bus_name); |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | static const Property pca954x_props[] = { |
| 215 | DEFINE_PROP_STRING("name", Pca954xState, name), |
| 216 | }; |
| 217 | |
| 218 | static void pca954x_class_init(ObjectClass *klass, const void *data) |
| 219 | { |
| 220 | I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass); |
| 221 | ResettableClass *rc = RESETTABLE_CLASS(klass); |
| 222 | DeviceClass *dc = DEVICE_CLASS(klass); |
| 223 | SMBusDeviceClass *k = SMBUS_DEVICE_CLASS(klass); |
| 224 | |
| 225 | sc->match_and_add = pca954x_match; |
| 226 | |
| 227 | rc->phases.enter = pca954x_enter_reset; |
| 228 | |
| 229 | dc->desc = "Pca954x i2c-mux"; |
| 230 | dc->realize = pca954x_realize; |
| 231 | |
| 232 | k->write_data = pca954x_write_data; |
| 233 | k->receive_byte = pca954x_read_byte; |
| 234 | |
| 235 | device_class_set_props(dc, pca954x_props); |
| 236 | } |
| 237 | |
| 238 | static const TypeInfo pca954x_info[] = { |
| 239 | { |
| 240 | .name = TYPE_PCA954X, |
| 241 | .parent = TYPE_SMBUS_DEVICE, |
| 242 | .instance_size = sizeof(Pca954xState), |
| 243 | .instance_init = pca954x_init, |
| 244 | .class_size = sizeof(Pca954xClass), |
| 245 | .class_init = pca954x_class_init, |
| 246 | .abstract = true, |
| 247 | }, |
| 248 | { |
| 249 | .name = TYPE_PCA9546, |
| 250 | .parent = TYPE_PCA954X, |
| 251 | .class_init = pca9546_class_init, |
| 252 | }, |
| 253 | { |
| 254 | .name = TYPE_PCA9548, |
| 255 | .parent = TYPE_PCA954X, |
| 256 | .class_init = pca9548_class_init, |
| 257 | }, |
| 258 | }; |
| 259 | |
| 260 | DEFINE_TYPES(pca954x_info) |