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