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/slab.h>
  45
  46 #define PCA954X_MAX_NCHANS 8
  47
  48 enum pca_type {
  49         pca_9540,
  50         pca_9542,
  51         pca_9543,
  52         pca_9544,
  53         pca_9545,
  54         pca_9546,
  55         pca_9547,
  56         pca_9548,
  57 };
  58
  59 struct pca954x {
  60         enum pca_type type;
  61         struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
  62
  63         u8 last_chan;           /* last register value */
  64 };
  65
  66 struct chip_desc {
  67         u8 nchans;
  68         u8 enable;      /* used for muxes only */
  69         enum muxtype {
  70                 pca954x_ismux = 0,
  71                 pca954x_isswi
  72         } muxtype;
  73 };
  74
  75 /* Provide specs for the PCA954x types we know about */
  76 static const struct chip_desc chips[] = {
  77         [pca_9540] = {
  78                 .nchans = 2,
  79                 .enable = 0x4,
  80                 .muxtype = pca954x_ismux,
  81         },
  82         [pca_9543] = {
  83                 .nchans = 2,
  84                 .muxtype = pca954x_isswi,
  85         },
  86         [pca_9544] = {
  87                 .nchans = 4,
  88                 .enable = 0x4,
  89                 .muxtype = pca954x_ismux,
  90         },
  91         [pca_9545] = {
  92                 .nchans = 4,
  93                 .muxtype = pca954x_isswi,
  94         },
  95         [pca_9547] = {
  96                 .nchans = 8,
  97                 .enable = 0x8,
  98                 .muxtype = pca954x_ismux,
  99         },
 100         [pca_9548] = {
 101                 .nchans = 8,
 102                 .muxtype = pca954x_isswi,
 103         },
 104 };
 105
 106 static const struct i2c_device_id pca954x_id[] = {
 107         { "pca9540", pca_9540 },
 108         { "pca9542", pca_9540 },
 109         { "pca9543", pca_9543 },
 110         { "pca9544", pca_9544 },
 111         { "pca9545", pca_9545 },
 112         { "pca9546", pca_9545 },
 113         { "pca9547", pca_9547 },
 114         { "pca9548", pca_9548 },
 115         { }
 116 };
 117 MODULE_DEVICE_TABLE(i2c, pca954x_id);
 118
 119 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
 120    for this as they will try to lock adapter a second time */
 121 static int pca954x_reg_write(struct i2c_adapter *adap,
 122                              struct i2c_client *client, u8 val)
 123 {
 124         int ret = -ENODEV;
 125
 126         if (adap->algo->master_xfer) {
 127                 struct i2c_msg msg;
 128                 char buf[1];
 129
 130                 msg.addr = client->addr;
 131                 msg.flags = 0;
 132                 msg.len = 1;
 133                 buf[0] = val;
 134                 msg.buf = buf;
 135                 ret = adap->algo->master_xfer(adap, &msg, 1);
 136         } else {
 137                 union i2c_smbus_data data;
 138                 ret = adap->algo->smbus_xfer(adap, client->addr,
 139                                              client->flags,
 140                                              I2C_SMBUS_WRITE,
 141                                              val, I2C_SMBUS_BYTE, &data);
 142         }
 143
 144         return ret;
 145 }
 146
 147 static int pca954x_select_chan(struct i2c_adapter *adap,
 148                                void *client, u32 chan)
 149 {
 150         struct pca954x *data = i2c_get_clientdata(client);
 151         const struct chip_desc *chip = &chips[data->type];
 152         u8 regval;
 153         int ret = 0;
 154
 155         /* we make switches look like muxes, not sure how to be smarter */
 156         if (chip->muxtype == pca954x_ismux)
 157                 regval = chan | chip->enable;
 158         else
 159                 regval = 1 << chan;
 160
 161         /* Only select the channel if its different from the last channel */
 162         if (data->last_chan != regval) {
 163                 ret = pca954x_reg_write(adap, client, regval);
 164                 data->last_chan = regval;
 165         }
 166
 167         return ret;
 168 }
 169
 170 static int pca954x_deselect_mux(struct i2c_adapter *adap,
 171                                 void *client, u32 chan)
 172 {
 173         struct pca954x *data = i2c_get_clientdata(client);
 174
 175         /* Deselect active channel */
 176         data->last_chan = 0;
 177         return pca954x_reg_write(adap, client, data->last_chan);
 178 }
 179
 180 /*
 181  * I2C init/probing/exit functions
 182  */
 183 static int pca954x_probe(struct i2c_client *client,
 184                          const struct i2c_device_id *id)
 185 {
 186         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 187         struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
 188         struct gpio_desc *gpio;
 189         int num, force, class;
 190         struct pca954x *data;
 191         int ret;
 192
 193         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
 194                 return -ENODEV;
 195
 196         data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL);
 197         if (!data)
 198                 return -ENOMEM;
 199
 200         i2c_set_clientdata(client, data);
 201
 202         /* Get the mux out of reset if a reset GPIO is specified. */
 203         gpio = devm_gpiod_get(&client->dev, "reset");
 204         if (!IS_ERR(gpio))
 205                 gpiod_direction_output(gpio, 0);
 206
 207         /* Write the mux register at addr to verify
 208          * that the mux is in fact present. This also
 209          * initializes the mux to disconnected state.
 210          */
 211         if (i2c_smbus_write_byte(client, 0) < 0) {
 212                 dev_warn(&client->dev, "probe failed\n");
 213                 return -ENODEV;
 214         }
 215
 216         data->type = id->driver_data;
 217         data->last_chan = 0;               /* force the first selection */
 218
 219         /* Now create an adapter for each channel */
 220         for (num = 0; num < chips[data->type].nchans; num++) {
 221                 force = 0;                        /* dynamic adap number */
 222                 class = 0;                        /* no class by default */
 223                 if (pdata) {
 224                         if (num < pdata->num_modes) {
 225                                 /* force static number */
 226                                 force = pdata->modes[num].adap_id;
 227                                 class = pdata->modes[num].class;
 228                         } else
 229                                 /* discard unconfigured channels */
 230                                 break;
 231                 }
 232
 233                 data->virt_adaps[num] =
 234                         i2c_add_mux_adapter(adap, &client->dev, client,
 235                                 force, num, class, pca954x_select_chan,
 236                                 (pdata && pdata->modes[num].deselect_on_exit)
 237                                         ? pca954x_deselect_mux : NULL);
 238
 239                 if (data->virt_adaps[num] == NULL) {
 240                         ret = -ENODEV;
 241                         dev_err(&client->dev,
 242                                 "failed to register multiplexed adapter"
 243                                 " %d as bus %d\n", num, force);
 244                         goto virt_reg_failed;
 245                 }
 246         }
 247
 248         dev_info(&client->dev,
 249                  "registered %d multiplexed busses for I2C %s %s\n",
 250                  num, chips[data->type].muxtype == pca954x_ismux
 251                                 ? "mux" : "switch", client->name);
 252
 253         return 0;
 254
 255 virt_reg_failed:
 256         for (num--; num >= 0; num--)
 257                 i2c_del_mux_adapter(data->virt_adaps[num]);
 258         return ret;
 259 }
 260
 261 static int pca954x_remove(struct i2c_client *client)
 262 {
 263         struct pca954x *data = i2c_get_clientdata(client);
 264         const struct chip_desc *chip = &chips[data->type];
 265         int i;
 266
 267         for (i = 0; i < chip->nchans; ++i)
 268                 if (data->virt_adaps[i]) {
 269                         i2c_del_mux_adapter(data->virt_adaps[i]);
 270                         data->virt_adaps[i] = NULL;
 271                 }
 272
 273         return 0;
 274 }
 275
 276 static struct i2c_driver pca954x_driver = {
 277         .driver         = {
 278                 .name   = "pca954x",
 279                 .owner  = THIS_MODULE,
 280         },
 281         .probe          = pca954x_probe,
 282         .remove         = pca954x_remove,
 283         .id_table       = pca954x_id,
 284 };
 285
 286 module_i2c_driver(pca954x_driver);
 287
 288 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
 289 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
 290 MODULE_LICENSE("GPL v2");