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/acpi.h>
  39 #include <linux/device.h>
  40 #include <linux/gpio/consumer.h>
  41 #include <linux/i2c.h>
  42 #include <linux/i2c-mux.h>
  43 #include <linux/i2c/pca954x.h>
  44 #include <linux/module.h>
  45 #include <linux/of.h>
  46 #include <linux/of_device.h>
  47 #include <linux/pm.h>
  48 #include <linux/slab.h>
  49
  50 #define PCA954X_MAX_NCHANS 8
  51
  52 enum pca_type {
  53         pca_9540,
  54         pca_9542,
  55         pca_9543,
  56         pca_9544,
  57         pca_9545,
  58         pca_9546,
  59         pca_9547,
  60         pca_9548,
  61 };
  62
  63 struct chip_desc {
  64         u8 nchans;
  65         u8 enable;      /* used for muxes only */
  66         enum muxtype {
  67                 pca954x_ismux = 0,
  68                 pca954x_isswi
  69         } muxtype;
  70 };
  71
  72 struct pca954x {
  73         const struct chip_desc *chip;
  74
  75         u8 last_chan;           /* last register value */
  76         u8 deselect;
  77         struct i2c_client *client;
  78 };
  79
  80 /* Provide specs for the PCA954x types we know about */
  81 static const struct chip_desc chips[] = {
  82         [pca_9540] = {
  83                 .nchans = 2,
  84                 .enable = 0x4,
  85                 .muxtype = pca954x_ismux,
  86         },
  87         [pca_9543] = {
  88                 .nchans = 2,
  89                 .muxtype = pca954x_isswi,
  90         },
  91         [pca_9544] = {
  92                 .nchans = 4,
  93                 .enable = 0x4,
  94                 .muxtype = pca954x_ismux,
  95         },
  96         [pca_9545] = {
  97                 .nchans = 4,
  98                 .muxtype = pca954x_isswi,
  99         },
 100         [pca_9547] = {
 101                 .nchans = 8,
 102                 .enable = 0x8,
 103                 .muxtype = pca954x_ismux,
 104         },
 105         [pca_9548] = {
 106                 .nchans = 8,
 107                 .muxtype = pca954x_isswi,
 108         },
 109 };
 110
 111 static const struct i2c_device_id pca954x_id[] = {
 112         { "pca9540", pca_9540 },
 113         { "pca9542", pca_9540 },
 114         { "pca9543", pca_9543 },
 115         { "pca9544", pca_9544 },
 116         { "pca9545", pca_9545 },
 117         { "pca9546", pca_9545 },
 118         { "pca9547", pca_9547 },
 119         { "pca9548", pca_9548 },
 120         { }
 121 };
 122 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 123
 124 #ifdef CONFIG_ACPI
 125 static const struct acpi_device_id pca954x_acpi_ids[] = {
 126         { .id = "PCA9540", .driver_data = pca_9540 },
 127         { .id = "PCA9542", .driver_data = pca_9540 },
 128         { .id = "PCA9543", .driver_data = pca_9543 },
 129         { .id = "PCA9544", .driver_data = pca_9544 },
 130         { .id = "PCA9545", .driver_data = pca_9545 },
 131         { .id = "PCA9546", .driver_data = pca_9545 },
 132         { .id = "PCA9547", .driver_data = pca_9547 },
 133         { .id = "PCA9548", .driver_data = pca_9548 },
 134         { }
 135 };
 136 MODULE_DEVICE_TABLE(acpi, pca954x_acpi_ids);
 137 #endif
 138
 139 #ifdef CONFIG_OF
 140 static const struct of_device_id pca954x_of_match[] = {
 141         { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
 142         { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
 143         { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
 144         { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
 145         { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
 146         { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
 147         { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
 148         { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
 149         {}
 150 };
 151 #endif
 152
 153 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
 154    for this as they will try to lock adapter a second time */
 155 static int pca954x_reg_write(struct i2c_adapter *adap,
 156                              struct i2c_client *client, u8 val)
 157 {
 158         int ret = -ENODEV;
 159
 160         if (adap->algo->master_xfer) {
 161                 struct i2c_msg msg;
 162                 char buf[1];
 163
 164                 msg.addr = client->addr;
 165                 msg.flags = 0;
 166                 msg.len = 1;
 167                 buf[0] = val;
 168                 msg.buf = buf;
 169                 ret = __i2c_transfer(adap, &msg, 1);
 170
 171                 if (ret >= 0 && ret != 1)
 172                         ret = -EREMOTEIO;
 173         } else {
 174                 union i2c_smbus_data data;
 175                 ret = adap->algo->smbus_xfer(adap, client->addr,
 176                                              client->flags,
 177                                              I2C_SMBUS_WRITE,
 178                                              val, I2C_SMBUS_BYTE, &data);
 179         }
 180
 181         return ret;
 182 }
 183
 184 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
 185 {
 186         struct pca954x *data = i2c_mux_priv(muxc);
 187         struct i2c_client *client = data->client;
 188         const struct chip_desc *chip = data->chip;
 189         u8 regval;
 190         int ret = 0;
 191
 192         /* we make switches look like muxes, not sure how to be smarter */
 193         if (chip->muxtype == pca954x_ismux)
 194                 regval = chan | chip->enable;
 195         else
 196                 regval = 1 << chan;
 197
 198         /* Only select the channel if its different from the last channel */
 199         if (data->last_chan != regval) {
 200                 ret = pca954x_reg_write(muxc->parent, client, regval);
 201                 data->last_chan = ret < 0 ? 0 : regval;
 202         }
 203
 204         return ret;
 205 }
 206
 207 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
 208 {
 209         struct pca954x *data = i2c_mux_priv(muxc);
 210         struct i2c_client *client = data->client;
 211
 212         if (!(data->deselect & (1 << chan)))
 213                 return 0;
 214
 215         /* Deselect active channel */
 216         data->last_chan = 0;
 217         return pca954x_reg_write(muxc->parent, client, data->last_chan);
 218 }
 219
 220 /*
 221  * I2C init/probing/exit functions
 222  */
 223 static int pca954x_probe(struct i2c_client *client,
 224                          const struct i2c_device_id *id)
 225 {
 226         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 227         struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
 228         struct device_node *of_node = client->dev.of_node;
 229         bool idle_disconnect_dt;
 230         struct gpio_desc *gpio;
 231         int num, force, class;
 232         struct i2c_mux_core *muxc;
 233         struct pca954x *data;
 234         const struct of_device_id *match;
 235         int ret;
 236
 237         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
 238                 return -ENODEV;
 239
 240         muxc = i2c_mux_alloc(adap, &client->dev,
 241                              PCA954X_MAX_NCHANS, sizeof(*data), 0,
 242                              pca954x_select_chan, pca954x_deselect_mux);
 243         if (!muxc)
 244                 return -ENOMEM;
 245         data = i2c_mux_priv(muxc);
 246
 247         i2c_set_clientdata(client, muxc);
 248         data->client = client;
 249
 250         /* Get the mux out of reset if a reset GPIO is specified. */
 251         gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
 252         if (IS_ERR(gpio))
 253                 return PTR_ERR(gpio);
 254
 255         /* Write the mux register at addr to verify
 256          * that the mux is in fact present. This also
 257          * initializes the mux to disconnected state.
 258          */
 259         if (i2c_smbus_write_byte(client, 0) < 0) {
 260                 dev_warn(&client->dev, "probe failed\n");
 261                 return -ENODEV;
 262         }
 263
 264         match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
 265         if (match)
 266                 data->chip = of_device_get_match_data(&client->dev);
 267         else if (id)
 268                 data->chip = &chips[id->driver_data];
 269         else {
 270                 const struct acpi_device_id *acpi_id;
 271
 272                 acpi_id = acpi_match_device(ACPI_PTR(pca954x_acpi_ids),
 273                                                 &client->dev);
 274                 if (!acpi_id)
 275                         return -ENODEV;
 276                 data->chip = &chips[acpi_id->driver_data];
 277         }
 278
 279         data->last_chan = 0;               /* force the first selection */
 280
 281         idle_disconnect_dt = of_node &&
 282                 of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
 283
 284         /* Now create an adapter for each channel */
 285         for (num = 0; num < data->chip->nchans; num++) {
 286                 bool idle_disconnect_pd = false;
 287
 288                 force = 0;                        /* dynamic adap number */
 289                 class = 0;                        /* no class by default */
 290                 if (pdata) {
 291                         if (num < pdata->num_modes) {
 292                                 /* force static number */
 293                                 force = pdata->modes[num].adap_id;
 294                                 class = pdata->modes[num].class;
 295                         } else
 296                                 /* discard unconfigured channels */
 297                                 break;
 298                         idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
 299                 }
 300                 data->deselect |= (idle_disconnect_pd ||
 301                                    idle_disconnect_dt) << num;
 302
 303                 ret = i2c_mux_add_adapter(muxc, force, num, class);
 304
 305                 if (ret) {
 306                         dev_err(&client->dev,
 307                                 "failed to register multiplexed adapter"
 308                                 " %d as bus %d\n", num, force);
 309                         goto virt_reg_failed;
 310                 }
 311         }
 312
 313         dev_info(&client->dev,
 314                  "registered %d multiplexed busses for I2C %s %s\n",
 315                  num, data->chip->muxtype == pca954x_ismux
 316                                 ? "mux" : "switch", client->name);
 317
 318         return 0;
 319
 320 virt_reg_failed:
 321         i2c_mux_del_adapters(muxc);
 322         return ret;
 323 }
 324
 325 static int pca954x_remove(struct i2c_client *client)
 326 {
 327         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 328
 329         i2c_mux_del_adapters(muxc);
 330         return 0;
 331 }
 332
 333 #ifdef CONFIG_PM_SLEEP
 334 static int pca954x_resume(struct device *dev)
 335 {
 336         struct i2c_client *client = to_i2c_client(dev);
 337         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 338         struct pca954x *data = i2c_mux_priv(muxc);
 339
 340         data->last_chan = 0;
 341         return i2c_smbus_write_byte(client, 0);
 342 }
 343 #endif
 344
 345 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
 346
 347 static struct i2c_driver pca954x_driver = {
 348         .driver         = {
 349                 .name   = "pca954x",
 350                 .pm     = &pca954x_pm,
 351                 .of_match_table = of_match_ptr(pca954x_of_match),
 352                 .acpi_match_table = ACPI_PTR(pca954x_acpi_ids),
 353         },
 354         .probe          = pca954x_probe,
 355         .remove         = pca954x_remove,
 356         .id_table       = pca954x_id,
 357 };
 358
 359 module_i2c_driver(pca954x_driver);
 360
 361 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 362 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 363 MODULE_LICENSE("GPL v2");