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 series of I2C multiplexer/switch chips
   8  * made by Philips Semiconductors.
   9  * This includes the:
  10  *       PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
  11  *       and PCA9548.
  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/i2c/pca954x.h>
  43 #include <linux/interrupt.h>
  44 #include <linux/irq.h>
  45 #include <linux/module.h>
  46 #include <linux/of.h>
  47 #include <linux/of_device.h>
  48 #include <linux/of_irq.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 };
  67
  68 struct chip_desc {
  69         u8 nchans;
  70         u8 enable;      /* used for muxes only */
  71         u8 has_irq;
  72         enum muxtype {
  73                 pca954x_ismux = 0,
  74                 pca954x_isswi
  75         } muxtype;
  76 };
  77
  78 struct pca954x {
  79         const struct chip_desc *chip;
  80
  81         u8 last_chan;           /* last register value */
  82         u8 deselect;
  83         struct i2c_client *client;
  84
  85         struct irq_domain *irq;
  86         unsigned int irq_mask;
  87         spinlock_t lock;
  88 };
  89
  90 /* Provide specs for the PCA954x types we know about */
  91 static const struct chip_desc chips[] = {
  92         [pca_9540] = {
  93                 .nchans = 2,
  94                 .enable = 0x4,
  95                 .muxtype = pca954x_ismux,
  96         },
  97         [pca_9542] = {
  98                 .nchans = 2,
  99                 .enable = 0x4,
 100                 .has_irq = 1,
 101                 .muxtype = pca954x_ismux,
 102         },
 103         [pca_9543] = {
 104                 .nchans = 2,
 105                 .has_irq = 1,
 106                 .muxtype = pca954x_isswi,
 107         },
 108         [pca_9544] = {
 109                 .nchans = 4,
 110                 .enable = 0x4,
 111                 .has_irq = 1,
 112                 .muxtype = pca954x_ismux,
 113         },
 114         [pca_9545] = {
 115                 .nchans = 4,
 116                 .has_irq = 1,
 117                 .muxtype = pca954x_isswi,
 118         },
 119         [pca_9546] = {
 120                 .nchans = 4,
 121                 .muxtype = pca954x_isswi,
 122         },
 123         [pca_9547] = {
 124                 .nchans = 8,
 125                 .enable = 0x8,
 126                 .muxtype = pca954x_ismux,
 127         },
 128         [pca_9548] = {
 129                 .nchans = 8,
 130                 .muxtype = pca954x_isswi,
 131         },
 132 };
 133
 134 static const struct i2c_device_id pca954x_id[] = {
 135         { "pca9540", pca_9540 },
 136         { "pca9542", pca_9542 },
 137         { "pca9543", pca_9543 },
 138         { "pca9544", pca_9544 },
 139         { "pca9545", pca_9545 },
 140         { "pca9546", pca_9546 },
 141         { "pca9547", pca_9547 },
 142         { "pca9548", pca_9548 },
 143         { }
 144 };
 145 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 146
 147 #ifdef CONFIG_OF
 148 static const struct of_device_id pca954x_of_match[] = {
 149         { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
 150         { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
 151         { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
 152         { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
 153         { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
 154         { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
 155         { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
 156         { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
 157         {}
 158 };
 159 MODULE_DEVICE_TABLE(of, pca954x_of_match);
 160 #endif
 161
 162 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
 163    for this as they will try to lock adapter a second time */
 164 static int pca954x_reg_write(struct i2c_adapter *adap,
 165                              struct i2c_client *client, u8 val)
 166 {
 167         int ret = -ENODEV;
 168
 169         if (adap->algo->master_xfer) {
 170                 struct i2c_msg msg;
 171                 char buf[1];
 172
 173                 msg.addr = client->addr;
 174                 msg.flags = 0;
 175                 msg.len = 1;
 176                 buf[0] = val;
 177                 msg.buf = buf;
 178                 ret = __i2c_transfer(adap, &msg, 1);
 179
 180                 if (ret >= 0 && ret != 1)
 181                         ret = -EREMOTEIO;
 182         } else {
 183                 union i2c_smbus_data data;
 184                 ret = adap->algo->smbus_xfer(adap, client->addr,
 185                                              client->flags,
 186                                              I2C_SMBUS_WRITE,
 187                                              val, I2C_SMBUS_BYTE, &data);
 188         }
 189
 190         return ret;
 191 }
 192
 193 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
 194 {
 195         struct pca954x *data = i2c_mux_priv(muxc);
 196         struct i2c_client *client = data->client;
 197         const struct chip_desc *chip = data->chip;
 198         u8 regval;
 199         int ret = 0;
 200
 201         /* we make switches look like muxes, not sure how to be smarter */
 202         if (chip->muxtype == pca954x_ismux)
 203                 regval = chan | chip->enable;
 204         else
 205                 regval = 1 << chan;
 206
 207         /* Only select the channel if its different from the last channel */
 208         if (data->last_chan != regval) {
 209                 ret = pca954x_reg_write(muxc->parent, client, regval);
 210                 data->last_chan = ret < 0 ? 0 : regval;
 211         }
 212
 213         return ret;
 214 }
 215
 216 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
 217 {
 218         struct pca954x *data = i2c_mux_priv(muxc);
 219         struct i2c_client *client = data->client;
 220
 221         if (!(data->deselect & (1 << chan)))
 222                 return 0;
 223
 224         /* Deselect active channel */
 225         data->last_chan = 0;
 226         return pca954x_reg_write(muxc->parent, client, data->last_chan);
 227 }
 228
 229 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
 230 {
 231         struct pca954x *data = dev_id;
 232         unsigned int child_irq;
 233         int ret, i, handled = 0;
 234
 235         ret = i2c_smbus_read_byte(data->client);
 236         if (ret < 0)
 237                 return IRQ_NONE;
 238
 239         for (i = 0; i < data->chip->nchans; i++) {
 240                 if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
 241                         child_irq = irq_linear_revmap(data->irq, i);
 242                         handle_nested_irq(child_irq);
 243                         handled++;
 244                 }
 245         }
 246         return handled ? IRQ_HANDLED : IRQ_NONE;
 247 }
 248
 249 static void pca954x_irq_mask(struct irq_data *idata)
 250 {
 251         struct pca954x *data = irq_data_get_irq_chip_data(idata);
 252         unsigned int pos = idata->hwirq;
 253         unsigned long flags;
 254
 255         spin_lock_irqsave(&data->lock, flags);
 256
 257         data->irq_mask &= ~BIT(pos);
 258         if (!data->irq_mask)
 259                 disable_irq(data->client->irq);
 260
 261         spin_unlock_irqrestore(&data->lock, flags);
 262 }
 263
 264 static void pca954x_irq_unmask(struct irq_data *idata)
 265 {
 266         struct pca954x *data = irq_data_get_irq_chip_data(idata);
 267         unsigned int pos = idata->hwirq;
 268         unsigned long flags;
 269
 270         spin_lock_irqsave(&data->lock, flags);
 271
 272         if (!data->irq_mask)
 273                 enable_irq(data->client->irq);
 274         data->irq_mask |= BIT(pos);
 275
 276         spin_unlock_irqrestore(&data->lock, flags);
 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_mask = pca954x_irq_mask,
 289         .irq_unmask = pca954x_irq_unmask,
 290         .irq_set_type = pca954x_irq_set_type,
 291 };
 292
 293 static int pca954x_irq_setup(struct i2c_mux_core *muxc)
 294 {
 295         struct pca954x *data = i2c_mux_priv(muxc);
 296         struct i2c_client *client = data->client;
 297         int c, err, irq;
 298
 299         if (!data->chip->has_irq || client->irq <= 0)
 300                 return 0;
 301
 302         spin_lock_init(&data->lock);
 303
 304         data->irq = irq_domain_add_linear(client->dev.of_node,
 305                                           data->chip->nchans,
 306                                           &irq_domain_simple_ops, data);
 307         if (!data->irq)
 308                 return -ENODEV;
 309
 310         for (c = 0; c < data->chip->nchans; c++) {
 311                 irq = irq_create_mapping(data->irq, c);
 312                 irq_set_chip_data(irq, data);
 313                 irq_set_chip_and_handler(irq, &pca954x_irq_chip,
 314                         handle_simple_irq);
 315         }
 316
 317         err = devm_request_threaded_irq(&client->dev, data->client->irq, NULL,
 318                                         pca954x_irq_handler,
 319                                         IRQF_ONESHOT | IRQF_SHARED,
 320                                         "pca954x", data);
 321         if (err)
 322                 goto err_req_irq;
 323
 324         disable_irq(data->client->irq);
 325
 326         return 0;
 327 err_req_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         return err;
 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_del_adapters;
 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
 417                 if (ret) {
 418                         dev_err(&client->dev,
 419                                 "failed to register multiplexed adapter"
 420                                 " %d as bus %d\n", num, force);
 421                         goto fail_del_adapters;
 422                 }
 423         }
 424
 425         dev_info(&client->dev,
 426                  "registered %d multiplexed busses for I2C %s %s\n",
 427                  num, data->chip->muxtype == pca954x_ismux
 428                                 ? "mux" : "switch", client->name);
 429
 430         return 0;
 431
 432 fail_del_adapters:
 433         i2c_mux_del_adapters(muxc);
 434         return ret;
 435 }
 436
 437 static int pca954x_remove(struct i2c_client *client)
 438 {
 439         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 440         struct pca954x *data = i2c_mux_priv(muxc);
 441         int c, irq;
 442
 443         if (data->irq) {
 444                 for (c = 0; c < data->chip->nchans; c++) {
 445                         irq = irq_find_mapping(data->irq, c);
 446                         irq_dispose_mapping(irq);
 447                 }
 448                 irq_domain_remove(data->irq);
 449         }
 450
 451         i2c_mux_del_adapters(muxc);
 452         return 0;
 453 }
 454
 455 #ifdef CONFIG_PM_SLEEP
 456 static int pca954x_resume(struct device *dev)
 457 {
 458         struct i2c_client *client = to_i2c_client(dev);
 459         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 460         struct pca954x *data = i2c_mux_priv(muxc);
 461
 462         data->last_chan = 0;
 463         return i2c_smbus_write_byte(client, 0);
 464 }
 465 #endif
 466
 467 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
 468
 469 static struct i2c_driver pca954x_driver = {
 470         .driver         = {
 471                 .name   = "pca954x",
 472                 .pm     = &pca954x_pm,
 473                 .of_match_table = of_match_ptr(pca954x_of_match),
 474         },
 475         .probe          = pca954x_probe,
 476         .remove         = pca954x_remove,
 477         .id_table       = pca954x_id,
 478 };
 479
 480 module_i2c_driver(pca954x_driver);
 481
 482 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 483 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 484 MODULE_LICENSE("GPL v2");