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_9546] = {
 100                 .nchans = 4,
 101                 .muxtype = pca954x_isswi,
 102         },
 103         [pca_9547] = {
 104                 .nchans = 8,
 105                 .enable = 0x8,
 106                 .muxtype = pca954x_ismux,
 107         },
 108         [pca_9548] = {
 109                 .nchans = 8,
 110                 .muxtype = pca954x_isswi,
 111         },
 112 };
 113
 114 static const struct i2c_device_id pca954x_id[] = {
 115         { "pca9540", pca_9540 },
 116         { "pca9542", pca_9540 },
 117         { "pca9543", pca_9543 },
 118         { "pca9544", pca_9544 },
 119         { "pca9545", pca_9545 },
 120         { "pca9546", pca_9546 },
 121         { "pca9547", pca_9547 },
 122         { "pca9548", pca_9548 },
 123         { }
 124 };
 125 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 126
 127 #ifdef CONFIG_OF
 128 static const struct of_device_id pca954x_of_match[] = {
 129         { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
 130         { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
 131         { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
 132         { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
 133         { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
 134         { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
 135         { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
 136         { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
 137         {}
 138 };
 139 #endif
 140
 141 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
 142    for this as they will try to lock adapter a second time */
 143 static int pca954x_reg_write(struct i2c_adapter *adap,
 144                              struct i2c_client *client, u8 val)
 145 {
 146         int ret = -ENODEV;
 147
 148         if (adap->algo->master_xfer) {
 149                 struct i2c_msg msg;
 150                 char buf[1];
 151
 152                 msg.addr = client->addr;
 153                 msg.flags = 0;
 154                 msg.len = 1;
 155                 buf[0] = val;
 156                 msg.buf = buf;
 157                 ret = __i2c_transfer(adap, &msg, 1);
 158
 159                 if (ret >= 0 && ret != 1)
 160                         ret = -EREMOTEIO;
 161         } else {
 162                 union i2c_smbus_data data;
 163                 ret = adap->algo->smbus_xfer(adap, client->addr,
 164                                              client->flags,
 165                                              I2C_SMBUS_WRITE,
 166                                              val, I2C_SMBUS_BYTE, &data);
 167         }
 168
 169         return ret;
 170 }
 171
 172 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
 173 {
 174         struct pca954x *data = i2c_mux_priv(muxc);
 175         struct i2c_client *client = data->client;
 176         const struct chip_desc *chip = data->chip;
 177         u8 regval;
 178         int ret = 0;
 179
 180         /* we make switches look like muxes, not sure how to be smarter */
 181         if (chip->muxtype == pca954x_ismux)
 182                 regval = chan | chip->enable;
 183         else
 184                 regval = 1 << chan;
 185
 186         /* Only select the channel if its different from the last channel */
 187         if (data->last_chan != regval) {
 188                 ret = pca954x_reg_write(muxc->parent, client, regval);
 189                 data->last_chan = ret < 0 ? 0 : regval;
 190         }
 191
 192         return ret;
 193 }
 194
 195 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
 196 {
 197         struct pca954x *data = i2c_mux_priv(muxc);
 198         struct i2c_client *client = data->client;
 199
 200         if (!(data->deselect & (1 << chan)))
 201                 return 0;
 202
 203         /* Deselect active channel */
 204         data->last_chan = 0;
 205         return pca954x_reg_write(muxc->parent, client, data->last_chan);
 206 }
 207
 208 /*
 209  * I2C init/probing/exit functions
 210  */
 211 static int pca954x_probe(struct i2c_client *client,
 212                          const struct i2c_device_id *id)
 213 {
 214         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 215         struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
 216         struct device_node *of_node = client->dev.of_node;
 217         bool idle_disconnect_dt;
 218         struct gpio_desc *gpio;
 219         int num, force, class;
 220         struct i2c_mux_core *muxc;
 221         struct pca954x *data;
 222         const struct of_device_id *match;
 223         int ret;
 224
 225         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
 226                 return -ENODEV;
 227
 228         muxc = i2c_mux_alloc(adap, &client->dev,
 229                              PCA954X_MAX_NCHANS, sizeof(*data), 0,
 230                              pca954x_select_chan, pca954x_deselect_mux);
 231         if (!muxc)
 232                 return -ENOMEM;
 233         data = i2c_mux_priv(muxc);
 234
 235         i2c_set_clientdata(client, muxc);
 236         data->client = client;
 237
 238         /* Get the mux out of reset if a reset GPIO is specified. */
 239         gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
 240         if (IS_ERR(gpio))
 241                 return PTR_ERR(gpio);
 242
 243         /* Write the mux register at addr to verify
 244          * that the mux is in fact present. This also
 245          * initializes the mux to disconnected state.
 246          */
 247         if (i2c_smbus_write_byte(client, 0) < 0) {
 248                 dev_warn(&client->dev, "probe failed\n");
 249                 return -ENODEV;
 250         }
 251
 252         match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
 253         if (match)
 254                 data->chip = of_device_get_match_data(&client->dev);
 255         else
 256                 data->chip = &chips[id->driver_data];
 257
 258         data->last_chan = 0;               /* force the first selection */
 259
 260         idle_disconnect_dt = of_node &&
 261                 of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
 262
 263         /* Now create an adapter for each channel */
 264         for (num = 0; num < data->chip->nchans; num++) {
 265                 bool idle_disconnect_pd = false;
 266
 267                 force = 0;                        /* dynamic adap number */
 268                 class = 0;                        /* no class by default */
 269                 if (pdata) {
 270                         if (num < pdata->num_modes) {
 271                                 /* force static number */
 272                                 force = pdata->modes[num].adap_id;
 273                                 class = pdata->modes[num].class;
 274                         } else
 275                                 /* discard unconfigured channels */
 276                                 break;
 277                         idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
 278                 }
 279                 data->deselect |= (idle_disconnect_pd ||
 280                                    idle_disconnect_dt) << num;
 281
 282                 ret = i2c_mux_add_adapter(muxc, force, num, class);
 283
 284                 if (ret) {
 285                         dev_err(&client->dev,
 286                                 "failed to register multiplexed adapter"
 287                                 " %d as bus %d\n", num, force);
 288                         goto virt_reg_failed;
 289                 }
 290         }
 291
 292         dev_info(&client->dev,
 293                  "registered %d multiplexed busses for I2C %s %s\n",
 294                  num, data->chip->muxtype == pca954x_ismux
 295                                 ? "mux" : "switch", client->name);
 296
 297         return 0;
 298
 299 virt_reg_failed:
 300         i2c_mux_del_adapters(muxc);
 301         return ret;
 302 }
 303
 304 static int pca954x_remove(struct i2c_client *client)
 305 {
 306         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 307
 308         i2c_mux_del_adapters(muxc);
 309         return 0;
 310 }
 311
 312 #ifdef CONFIG_PM_SLEEP
 313 static int pca954x_resume(struct device *dev)
 314 {
 315         struct i2c_client *client = to_i2c_client(dev);
 316         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 317         struct pca954x *data = i2c_mux_priv(muxc);
 318
 319         data->last_chan = 0;
 320         return i2c_smbus_write_byte(client, 0);
 321 }
 322 #endif
 323
 324 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
 325
 326 static struct i2c_driver pca954x_driver = {
 327         .driver         = {
 328                 .name   = "pca954x",
 329                 .pm     = &pca954x_pm,
 330                 .of_match_table = of_match_ptr(pca954x_of_match),
 331         },
 332         .probe          = pca954x_probe,
 333         .remove         = pca954x_remove,
 334         .id_table       = pca954x_id,
 335 };
 336
 337 module_i2c_driver(pca954x_driver);
 338
 339 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 340 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 341 MODULE_LICENSE("GPL v2");