drivers/i2c/muxes/i2c-mux-pca954x.c

   1 /*
   2  * I2C multiplexer
   3  *
   4  * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
   5  * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
   6  *
   7  * This module supports the PCA954x and PCA954x series of I2C multiplexer/switch
   8  * chips made by NXP Semiconductors.
   9  * This includes the:
  10  *       PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547,
  11  *       PCA9548, PCA9846, PCA9847, PCA9848 and PCA9849.
  12  *
  13  * These chips are all controlled via the I2C bus itself, and all have a
  14  * single 8-bit register. The upstream "parent" bus fans out to two,
  15  * four, or eight downstream busses or channels; which of these
  16  * are selected is determined by the chip type and register contents. A
  17  * mux can select only one sub-bus at a time; a switch can select any
  18  * combination simultaneously.
  19  *
  20  * Based on:
  21  *      pca954x.c from Kumar Gala <galak@kernel.crashing.org>
  22  * Copyright (C) 2006
  23  *
  24  * Based on:
  25  *      pca954x.c from Ken Harrenstien
  26  * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
  27  *
  28  * Based on:
  29  *      i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
  30  * and
  31  *      pca9540.c from Jean Delvare <jdelvare@suse.de>.
  32  *
  33  * This file is licensed under the terms of the GNU General Public
  34  * License version 2. This program is licensed "as is" without any
  35  * warranty of any kind, whether express or implied.
  36  */
  37
  38 #include <linux/device.h>
  39 #include <linux/gpio/consumer.h>
  40 #include <linux/i2c.h>
  41 #include <linux/i2c-mux.h>
  42 #include <linux/interrupt.h>
  43 #include <linux/irq.h>
  44 #include <linux/module.h>
  45 #include <linux/of.h>
  46 #include <linux/of_device.h>
  47 #include <linux/of_irq.h>
  48 #include <linux/platform_data/pca954x.h>
  49 #include <linux/pm.h>
  50 #include <linux/slab.h>
  51 #include <linux/spinlock.h>
  52
  53 #define PCA954X_MAX_NCHANS 8
  54
  55 #define PCA954X_IRQ_OFFSET 4
  56
  57 enum pca_type {
  58         pca_9540,
  59         pca_9542,
  60         pca_9543,
  61         pca_9544,
  62         pca_9545,
  63         pca_9546,
  64         pca_9547,
  65         pca_9548,
  66         pca_9846,
  67         pca_9847,
  68         pca_9848,
  69         pca_9849,
  70 };
  71
  72 struct chip_desc {
  73         u8 nchans;
  74         u8 enable;      /* used for muxes only */
  75         u8 has_irq;
  76         enum muxtype {
  77                 pca954x_ismux = 0,
  78                 pca954x_isswi
  79         } muxtype;
  80 };
  81
  82 struct pca954x {
  83         const struct chip_desc *chip;
  84
  85         u8 last_chan;           /* last register value */
  86         u8 deselect;
  87         struct i2c_client *client;
  88
  89         struct irq_domain *irq;
  90         unsigned int irq_mask;
  91         raw_spinlock_t lock;
  92 };
  93
  94 /* Provide specs for the PCA954x types we know about */
  95 static const struct chip_desc chips[] = {
  96         [pca_9540] = {
  97                 .nchans = 2,
  98                 .enable = 0x4,
  99                 .muxtype = pca954x_ismux,
 100         },
 101         [pca_9542] = {
 102                 .nchans = 2,
 103                 .enable = 0x4,
 104                 .has_irq = 1,
 105                 .muxtype = pca954x_ismux,
 106         },
 107         [pca_9543] = {
 108                 .nchans = 2,
 109                 .has_irq = 1,
 110                 .muxtype = pca954x_isswi,
 111         },
 112         [pca_9544] = {
 113                 .nchans = 4,
 114                 .enable = 0x4,
 115                 .has_irq = 1,
 116                 .muxtype = pca954x_ismux,
 117         },
 118         [pca_9545] = {
 119                 .nchans = 4,
 120                 .has_irq = 1,
 121                 .muxtype = pca954x_isswi,
 122         },
 123         [pca_9546] = {
 124                 .nchans = 4,
 125                 .muxtype = pca954x_isswi,
 126         },
 127         [pca_9547] = {
 128                 .nchans = 8,
 129                 .enable = 0x8,
 130                 .muxtype = pca954x_ismux,
 131         },
 132         [pca_9548] = {
 133                 .nchans = 8,
 134                 .muxtype = pca954x_isswi,
 135         },
 136         [pca_9846] = {
 137                 .nchans = 4,
 138                 .muxtype = pca954x_isswi,
 139         },
 140         [pca_9847] = {
 141                 .nchans = 8,
 142                 .enable = 0x8,
 143                 .muxtype = pca954x_ismux,
 144         },
 145         [pca_9848] = {
 146                 .nchans = 8,
 147                 .muxtype = pca954x_isswi,
 148         },
 149         [pca_9849] = {
 150                 .nchans = 4,
 151                 .enable = 0x4,
 152                 .muxtype = pca954x_ismux,
 153         },
 154 };
 155
 156 static const struct i2c_device_id pca954x_id[] = {
 157         { "pca9540", pca_9540 },
 158         { "pca9542", pca_9542 },
 159         { "pca9543", pca_9543 },
 160         { "pca9544", pca_9544 },
 161         { "pca9545", pca_9545 },
 162         { "pca9546", pca_9546 },
 163         { "pca9547", pca_9547 },
 164         { "pca9548", pca_9548 },
 165         { "pca9846", pca_9846 },
 166         { "pca9847", pca_9847 },
 167         { "pca9848", pca_9848 },
 168         { "pca9849", pca_9849 },
 169         { }
 170 };
 171 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 172
 173 #ifdef CONFIG_OF
 174 static const struct of_device_id pca954x_of_match[] = {
 175         { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
 176         { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
 177         { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
 178         { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
 179         { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
 180         { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
 181         { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
 182         { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
 183         { .compatible = "nxp,pca9846", .data = &chips[pca_9846] },
 184         { .compatible = "nxp,pca9847", .data = &chips[pca_9847] },
 185         { .compatible = "nxp,pca9848", .data = &chips[pca_9848] },
 186         { .compatible = "nxp,pca9849", .data = &chips[pca_9849] },
 187         {}
 188 };
 189 MODULE_DEVICE_TABLE(of, pca954x_of_match);
 190 #endif
 191
 192 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
 193    for this as they will try to lock adapter a second time */
 194 static int pca954x_reg_write(struct i2c_adapter *adap,
 195                              struct i2c_client *client, u8 val)
 196 {
 197         int ret = -ENODEV;
 198
 199         if (adap->algo->master_xfer) {
 200                 struct i2c_msg msg;
 201                 char buf[1];
 202
 203                 msg.addr = client->addr;
 204                 msg.flags = 0;
 205                 msg.len = 1;
 206                 buf[0] = val;
 207                 msg.buf = buf;
 208                 ret = __i2c_transfer(adap, &msg, 1);
 209
 210                 if (ret >= 0 && ret != 1)
 211                         ret = -EREMOTEIO;
 212         } else {
 213                 union i2c_smbus_data data;
 214                 ret = adap->algo->smbus_xfer(adap, client->addr,
 215                                              client->flags,
 216                                              I2C_SMBUS_WRITE,
 217                                              val, I2C_SMBUS_BYTE, &data);
 218         }
 219
 220         return ret;
 221 }
 222
 223 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
 224 {
 225         struct pca954x *data = i2c_mux_priv(muxc);
 226         struct i2c_client *client = data->client;
 227         const struct chip_desc *chip = data->chip;
 228         u8 regval;
 229         int ret = 0;
 230
 231         /* we make switches look like muxes, not sure how to be smarter */
 232         if (chip->muxtype == pca954x_ismux)
 233                 regval = chan | chip->enable;
 234         else
 235                 regval = 1 << chan;
 236
 237         /* Only select the channel if its different from the last channel */
 238         if (data->last_chan != regval) {
 239                 ret = pca954x_reg_write(muxc->parent, client, regval);
 240                 data->last_chan = ret < 0 ? 0 : regval;
 241         }
 242
 243         return ret;
 244 }
 245
 246 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
 247 {
 248         struct pca954x *data = i2c_mux_priv(muxc);
 249         struct i2c_client *client = data->client;
 250
 251         if (!(data->deselect & (1 << chan)))
 252                 return 0;
 253
 254         /* Deselect active channel */
 255         data->last_chan = 0;
 256         return pca954x_reg_write(muxc->parent, client, data->last_chan);
 257 }
 258
 259 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
 260 {
 261         struct pca954x *data = dev_id;
 262         unsigned int child_irq;
 263         int ret, i, handled = 0;
 264
 265         ret = i2c_smbus_read_byte(data->client);
 266         if (ret < 0)
 267                 return IRQ_NONE;
 268
 269         for (i = 0; i < data->chip->nchans; i++) {
 270                 if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
 271                         child_irq = irq_linear_revmap(data->irq, i);
 272                         handle_nested_irq(child_irq);
 273                         handled++;
 274                 }
 275         }
 276         return handled ? IRQ_HANDLED : IRQ_NONE;
 277 }
 278
 279 static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
 280 {
 281         if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
 282                 return -EINVAL;
 283         return 0;
 284 }
 285
 286 static struct irq_chip pca954x_irq_chip = {
 287         .name = "i2c-mux-pca954x",
 288         .irq_set_type = pca954x_irq_set_type,
 289 };
 290
 291 static int pca954x_irq_setup(struct i2c_mux_core *muxc)
 292 {
 293         struct pca954x *data = i2c_mux_priv(muxc);
 294         struct i2c_client *client = data->client;
 295         int c, irq;
 296
 297         if (!data->chip->has_irq || client->irq <= 0)
 298                 return 0;
 299
 300         raw_spin_lock_init(&data->lock);
 301
 302         data->irq = irq_domain_add_linear(client->dev.of_node,
 303                                           data->chip->nchans,
 304                                           &irq_domain_simple_ops, data);
 305         if (!data->irq)
 306                 return -ENODEV;
 307
 308         for (c = 0; c < data->chip->nchans; c++) {
 309                 irq = irq_create_mapping(data->irq, c);
 310                 if (!irq) {
 311                         dev_err(&client->dev, "failed irq create map\n");
 312                         return -EINVAL;
 313                 }
 314                 irq_set_chip_data(irq, data);
 315                 irq_set_chip_and_handler(irq, &pca954x_irq_chip,
 316                         handle_simple_irq);
 317         }
 318
 319         return 0;
 320 }
 321
 322 static void pca954x_cleanup(struct i2c_mux_core *muxc)
 323 {
 324         struct pca954x *data = i2c_mux_priv(muxc);
 325         int c, irq;
 326
 327         if (data->irq) {
 328                 for (c = 0; c < data->chip->nchans; c++) {
 329                         irq = irq_find_mapping(data->irq, c);
 330                         irq_dispose_mapping(irq);
 331                 }
 332                 irq_domain_remove(data->irq);
 333         }
 334         i2c_mux_del_adapters(muxc);
 335 }
 336
 337 /*
 338  * I2C init/probing/exit functions
 339  */
 340 static int pca954x_probe(struct i2c_client *client,
 341                          const struct i2c_device_id *id)
 342 {
 343         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 344         struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
 345         struct device_node *of_node = client->dev.of_node;
 346         bool idle_disconnect_dt;
 347         struct gpio_desc *gpio;
 348         int num, force, class;
 349         struct i2c_mux_core *muxc;
 350         struct pca954x *data;
 351         const struct of_device_id *match;
 352         int ret;
 353
 354         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
 355                 return -ENODEV;
 356
 357         muxc = i2c_mux_alloc(adap, &client->dev,
 358                              PCA954X_MAX_NCHANS, sizeof(*data), 0,
 359                              pca954x_select_chan, pca954x_deselect_mux);
 360         if (!muxc)
 361                 return -ENOMEM;
 362         data = i2c_mux_priv(muxc);
 363
 364         i2c_set_clientdata(client, muxc);
 365         data->client = client;
 366
 367         /* Get the mux out of reset if a reset GPIO is specified. */
 368         gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
 369         if (IS_ERR(gpio))
 370                 return PTR_ERR(gpio);
 371
 372         /* Write the mux register at addr to verify
 373          * that the mux is in fact present. This also
 374          * initializes the mux to disconnected state.
 375          */
 376         if (i2c_smbus_write_byte(client, 0) < 0) {
 377                 dev_warn(&client->dev, "probe failed\n");
 378                 return -ENODEV;
 379         }
 380
 381         match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
 382         if (match)
 383                 data->chip = of_device_get_match_data(&client->dev);
 384         else
 385                 data->chip = &chips[id->driver_data];
 386
 387         data->last_chan = 0;               /* force the first selection */
 388
 389         idle_disconnect_dt = of_node &&
 390                 of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
 391
 392         ret = pca954x_irq_setup(muxc);
 393         if (ret)
 394                 goto fail_cleanup;
 395
 396         /* Now create an adapter for each channel */
 397         for (num = 0; num < data->chip->nchans; num++) {
 398                 bool idle_disconnect_pd = false;
 399
 400                 force = 0;                        /* dynamic adap number */
 401                 class = 0;                        /* no class by default */
 402                 if (pdata) {
 403                         if (num < pdata->num_modes) {
 404                                 /* force static number */
 405                                 force = pdata->modes[num].adap_id;
 406                                 class = pdata->modes[num].class;
 407                         } else
 408                                 /* discard unconfigured channels */
 409                                 break;
 410                         idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
 411                 }
 412                 data->deselect |= (idle_disconnect_pd ||
 413                                    idle_disconnect_dt) << num;
 414
 415                 ret = i2c_mux_add_adapter(muxc, force, num, class);
 416                 if (ret)
 417                         goto fail_cleanup;
 418         }
 419
 420         if (data->irq) {
 421                 ret = devm_request_threaded_irq(&client->dev, data->client->irq,
 422                                                 NULL, pca954x_irq_handler,
 423                                                 IRQF_ONESHOT | IRQF_SHARED,
 424                                                 "pca954x", data);
 425                 if (ret)
 426                         goto fail_cleanup;
 427         }
 428
 429         dev_info(&client->dev,
 430                  "registered %d multiplexed busses for I2C %s %s\n",
 431                  num, data->chip->muxtype == pca954x_ismux
 432                                 ? "mux" : "switch", client->name);
 433
 434         return 0;
 435
 436 fail_cleanup:
 437         pca954x_cleanup(muxc);
 438         return ret;
 439 }
 440
 441 static int pca954x_remove(struct i2c_client *client)
 442 {
 443         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 444
 445         pca954x_cleanup(muxc);
 446         return 0;
 447 }
 448
 449 #ifdef CONFIG_PM_SLEEP
 450 static int pca954x_resume(struct device *dev)
 451 {
 452         struct i2c_client *client = to_i2c_client(dev);
 453         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 454         struct pca954x *data = i2c_mux_priv(muxc);
 455
 456         data->last_chan = 0;
 457         return i2c_smbus_write_byte(client, 0);
 458 }
 459 #endif
 460
 461 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
 462
 463 static struct i2c_driver pca954x_driver = {
 464         .driver         = {
 465                 .name   = "pca954x",
 466                 .pm     = &pca954x_pm,
 467                 .of_match_table = of_match_ptr(pca954x_of_match),
 468         },
 469         .probe          = pca954x_probe,
 470         .remove         = pca954x_remove,
 471         .id_table       = pca954x_id,
 472 };
 473
 474 module_i2c_driver(pca954x_driver);
 475
 476 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 477 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 478 MODULE_LICENSE("GPL v2");