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