kernel/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/pm.h>
  46 #include <linux/slab.h>
  47
  48 #define PCA954X_MAX_NCHANS 8
  49
  50 enum pca_type {
  51         pca_9540,
  52         pca_9542,
  53         pca_9543,
  54         pca_9544,
  55         pca_9545,
  56         pca_9546,
  57         pca_9547,
  58         pca_9548,
  59 };
  60
  61 struct pca954x {
  62         enum pca_type type;
  63         struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
  64
  65         u8 last_chan;           /* last register value */
  66 };
  67
  68 struct chip_desc {
  69         u8 nchans;
  70         u8 enable;      /* used for muxes only */
  71         enum muxtype {
  72                 pca954x_ismux = 0,
  73                 pca954x_isswi
  74         } muxtype;
  75 };
  76
  77 /* Provide specs for the PCA954x types we know about */
  78 static const struct chip_desc chips[] = {
  79         [pca_9540] = {
  80                 .nchans = 2,
  81                 .enable = 0x4,
  82                 .muxtype = pca954x_ismux,
  83         },
  84         [pca_9543] = {
  85                 .nchans = 2,
  86                 .muxtype = pca954x_isswi,
  87         },
  88         [pca_9544] = {
  89                 .nchans = 4,
  90                 .enable = 0x4,
  91                 .muxtype = pca954x_ismux,
  92         },
  93         [pca_9545] = {
  94                 .nchans = 4,
  95                 .muxtype = pca954x_isswi,
  96         },
  97         [pca_9547] = {
  98                 .nchans = 8,
  99                 .enable = 0x8,
 100                 .muxtype = pca954x_ismux,
 101         },
 102         [pca_9548] = {
 103                 .nchans = 8,
 104                 .muxtype = pca954x_isswi,
 105         },
 106 };
 107
 108 static const struct i2c_device_id pca954x_id[] = {
 109         { "pca9540", pca_9540 },
 110         { "pca9542", pca_9540 },
 111         { "pca9543", pca_9543 },
 112         { "pca9544", pca_9544 },
 113         { "pca9545", pca_9545 },
 114         { "pca9546", pca_9545 },
 115         { "pca9547", pca_9547 },
 116         { "pca9548", pca_9548 },
 117         { }
 118 };
 119 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 120
 121 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
 122    for this as they will try to lock adapter a second time */
 123 static int pca954x_reg_write(struct i2c_adapter *adap,
 124                              struct i2c_client *client, u8 val)
 125 {
 126         int ret = -ENODEV;
 127
 128         if (adap->algo->master_xfer) {
 129                 struct i2c_msg msg;
 130                 char buf[1];
 131
 132                 msg.addr = client->addr;
 133                 msg.flags = 0;
 134                 msg.len = 1;
 135                 buf[0] = val;
 136                 msg.buf = buf;
 137                 ret = adap->algo->master_xfer(adap, &msg, 1);
 138         } else {
 139                 union i2c_smbus_data data;
 140                 ret = adap->algo->smbus_xfer(adap, client->addr,
 141                                              client->flags,
 142                                              I2C_SMBUS_WRITE,
 143                                              val, I2C_SMBUS_BYTE, &data);
 144         }
 145
 146         return ret;
 147 }
 148
 149 static int pca954x_select_chan(struct i2c_adapter *adap,
 150                                void *client, u32 chan)
 151 {
 152         struct pca954x *data = i2c_get_clientdata(client);
 153         const struct chip_desc *chip = &chips[data->type];
 154         u8 regval;
 155         int ret = 0;
 156
 157         /* we make switches look like muxes, not sure how to be smarter */
 158         if (chip->muxtype == pca954x_ismux)
 159                 regval = chan | chip->enable;
 160         else
 161                 regval = 1 << chan;
 162
 163         /* Only select the channel if its different from the last channel */
 164         if (data->last_chan != regval) {
 165                 ret = pca954x_reg_write(adap, client, regval);
 166                 data->last_chan = regval;
 167         }
 168
 169         return ret;
 170 }
 171
 172 static int pca954x_deselect_mux(struct i2c_adapter *adap,
 173                                 void *client, u32 chan)
 174 {
 175         struct pca954x *data = i2c_get_clientdata(client);
 176
 177         /* Deselect active channel */
 178         data->last_chan = 0;
 179         return pca954x_reg_write(adap, client, data->last_chan);
 180 }
 181
 182 /*
 183  * I2C init/probing/exit functions
 184  */
 185 static int pca954x_probe(struct i2c_client *client,
 186                          const struct i2c_device_id *id)
 187 {
 188         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 189         struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
 190         struct device_node *of_node = client->dev.of_node;
 191         bool idle_disconnect_dt;
 192         struct gpio_desc *gpio;
 193         int num, force, class;
 194         struct pca954x *data;
 195         int ret;
 196
 197         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
 198                 return -ENODEV;
 199
 200         data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL);
 201         if (!data)
 202                 return -ENOMEM;
 203
 204         i2c_set_clientdata(client, data);
 205
 206         /* Get the mux out of reset if a reset GPIO is specified. */
 207         gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
 208         if (IS_ERR(gpio))
 209                 return PTR_ERR(gpio);
 210
 211         /* Write the mux register at addr to verify
 212          * that the mux is in fact present. This also
 213          * initializes the mux to disconnected state.
 214          */
 215         if (i2c_smbus_write_byte(client, 0) < 0) {
 216                 dev_warn(&client->dev, "probe failed\n");
 217                 return -ENODEV;
 218         }
 219
 220         data->type = id->driver_data;
 221         data->last_chan = 0;               /* force the first selection */
 222
 223         idle_disconnect_dt = of_node &&
 224                 of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
 225
 226         /* Now create an adapter for each channel */
 227         for (num = 0; num < chips[data->type].nchans; num++) {
 228                 bool idle_disconnect_pd = false;
 229
 230                 force = 0;                        /* dynamic adap number */
 231                 class = 0;                        /* no class by default */
 232                 if (pdata) {
 233                         if (num < pdata->num_modes) {
 234                                 /* force static number */
 235                                 force = pdata->modes[num].adap_id;
 236                                 class = pdata->modes[num].class;
 237                         } else
 238                                 /* discard unconfigured channels */
 239                                 break;
 240                         idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
 241                 }
 242
 243                 data->virt_adaps[num] =
 244                         i2c_add_mux_adapter(adap, &client->dev, client,
 245                                 force, num, class, pca954x_select_chan,
 246                                 (idle_disconnect_pd || idle_disconnect_dt)
 247                                         ? pca954x_deselect_mux : NULL);
 248
 249                 if (data->virt_adaps[num] == NULL) {
 250                         ret = -ENODEV;
 251                         dev_err(&client->dev,
 252                                 "failed to register multiplexed adapter"
 253                                 " %d as bus %d\n", num, force);
 254                         goto virt_reg_failed;
 255                 }
 256         }
 257
 258         dev_info(&client->dev,
 259                  "registered %d multiplexed busses for I2C %s %s\n",
 260                  num, chips[data->type].muxtype == pca954x_ismux
 261                                 ? "mux" : "switch", client->name);
 262
 263         return 0;
 264
 265 virt_reg_failed:
 266         for (num--; num >= 0; num--)
 267                 i2c_del_mux_adapter(data->virt_adaps[num]);
 268         return ret;
 269 }
 270
 271 static int pca954x_remove(struct i2c_client *client)
 272 {
 273         struct pca954x *data = i2c_get_clientdata(client);
 274         const struct chip_desc *chip = &chips[data->type];
 275         int i;
 276
 277         for (i = 0; i < chip->nchans; ++i)
 278                 if (data->virt_adaps[i]) {
 279                         i2c_del_mux_adapter(data->virt_adaps[i]);
 280                         data->virt_adaps[i] = NULL;
 281                 }
 282
 283         return 0;
 284 }
 285
 286 #ifdef CONFIG_PM_SLEEP
 287 static int pca954x_resume(struct device *dev)
 288 {
 289         struct i2c_client *client = to_i2c_client(dev);
 290         struct pca954x *data = i2c_get_clientdata(client);
 291
 292         data->last_chan = 0;
 293         return i2c_smbus_write_byte(client, 0);
 294 }
 295 #endif
 296
 297 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);
 298
 299 static struct i2c_driver pca954x_driver = {
 300         .driver         = {
 301                 .name   = "pca954x",
 302                 .pm     = &pca954x_pm,
 303                 .owner  = THIS_MODULE,
 304         },
 305         .probe          = pca954x_probe,
 306         .remove         = pca954x_remove,
 307         .id_table       = pca954x_id,
 308 };
 309
 310 module_i2c_driver(pca954x_driver);
 311
 312 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 313 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 314 MODULE_LICENSE("GPL v2");