drivers/i2c/muxes/i2c-mux-mlxcpld.c

   1 /*
   2  * drivers/i2c/muxes/i2c-mux-mlxcpld.c
   3  * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
   4  * Copyright (c) 2016 Michael Shych <michaels@mellanox.com>
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the names of the copyright holders nor the names of its
  15  *    contributors may be used to endorse or promote products derived from
  16  *    this software without specific prior written permission.
  17  *
  18  * Alternatively, this software may be distributed under the terms of the
  19  * GNU General Public License ("GPL") version 2 as published by the Free
  20  * Software Foundation.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  23  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  26  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  27  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  28  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  29  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  30  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  31  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  32  * POSSIBILITY OF SUCH DAMAGE.
  33  */
  34
  35 #include <linux/device.h>
  36 #include <linux/i2c.h>
  37 #include <linux/i2c-mux.h>
  38 #include <linux/io.h>
  39 #include <linux/init.h>
  40 #include <linux/module.h>
  41 #include <linux/platform_device.h>
  42 #include <linux/slab.h>
  43 #include <linux/i2c/mlxcpld.h>
  44
  45 #define CPLD_MUX_MAX_NCHANS     8
  46
  47 /* mlxcpld_mux - mux control structure:
  48  * @last_chan - last register value
  49  * @client - I2C device client
  50  */
  51 struct mlxcpld_mux {
  52         u8 last_chan;
  53         struct i2c_client *client;
  54 };
  55
  56 /* MUX logic description.
  57  * Driver can support different mux control logic, according to CPLD
  58  * implementation.
  59  *
  60  * Connectivity schema.
  61  *
  62  * i2c-mlxcpld                                 Digital               Analog
  63  * driver
  64  * *--------*                                 * -> mux1 (virt bus2) -> mux -> |
  65  * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |
  66  * | bridge | bus 1                 *---------*                               |
  67  * | logic  |---------------------> * mux reg *                               |
  68  * | in CPLD|                       *---------*                               |
  69  * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |
  70  *     |        driver                   |                                    |
  71  *     |        *---------------*        |                              Devices
  72  *     |        * CPLD (i2c bus)* select |
  73  *     |        * registers for *--------*
  74  *     |        * mux selection * deselect
  75  *     |        *---------------*
  76  *     |                 |
  77  * <-------->     <----------->
  78  * i2c cntrl      Board cntrl reg
  79  * reg space      space (mux select,
  80  *                IO, LED, WD, info)
  81  *
  82  */
  83
  84 static const struct i2c_device_id mlxcpld_mux_id[] = {
  85         { "mlxcpld_mux_module", 0 },
  86         { }
  87 };
  88 MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id);
  89
  90 /* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
  91  * for this as they will try to lock adapter a second time.
  92  */
  93 static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
  94                                  struct i2c_client *client, u8 val)
  95 {
  96         struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
  97         int ret = -ENODEV;
  98
  99         if (adap->algo->master_xfer) {
 100                 struct i2c_msg msg;
 101                 u8 msgbuf[] = {pdata->sel_reg_addr, val};
 102
 103                 msg.addr = client->addr;
 104                 msg.flags = 0;
 105                 msg.len = 2;
 106                 msg.buf = msgbuf;
 107                 ret = __i2c_transfer(adap, &msg, 1);
 108
 109                 if (ret >= 0 && ret != 1)
 110                         ret = -EREMOTEIO;
 111         } else if (adap->algo->smbus_xfer) {
 112                 union i2c_smbus_data data;
 113
 114                 data.byte = val;
 115                 ret = adap->algo->smbus_xfer(adap, client->addr,
 116                                              client->flags, I2C_SMBUS_WRITE,
 117                                              pdata->sel_reg_addr,
 118                                              I2C_SMBUS_BYTE_DATA, &data);
 119         }
 120
 121         return ret;
 122 }
 123
 124 static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
 125 {
 126         struct mlxcpld_mux *data = i2c_mux_priv(muxc);
 127         struct i2c_client *client = data->client;
 128         u8 regval = chan + 1;
 129         int err = 0;
 130
 131         /* Only select the channel if its different from the last channel */
 132         if (data->last_chan != regval) {
 133                 err = mlxcpld_mux_reg_write(muxc->parent, client, regval);
 134                 data->last_chan = err < 0 ? 0 : regval;
 135         }
 136
 137         return err;
 138 }
 139
 140 static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
 141 {
 142         struct mlxcpld_mux *data = i2c_mux_priv(muxc);
 143         struct i2c_client *client = data->client;
 144
 145         /* Deselect active channel */
 146         data->last_chan = 0;
 147
 148         return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan);
 149 }
 150
 151 /* Probe/reomove functions */
 152 static int mlxcpld_mux_probe(struct i2c_client *client,
 153                              const struct i2c_device_id *id)
 154 {
 155         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 156         struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
 157         struct i2c_mux_core *muxc;
 158         int num, force;
 159         struct mlxcpld_mux *data;
 160         int err;
 161
 162         if (!pdata)
 163                 return -EINVAL;
 164
 165         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
 166                 return -ENODEV;
 167
 168         muxc = i2c_mux_alloc(adap, &client->dev, CPLD_MUX_MAX_NCHANS,
 169                              sizeof(*data), 0, mlxcpld_mux_select_chan,
 170                              mlxcpld_mux_deselect);
 171         if (!muxc)
 172                 return -ENOMEM;
 173
 174         data = i2c_mux_priv(muxc);
 175         i2c_set_clientdata(client, muxc);
 176         data->client = client;
 177         data->last_chan = 0; /* force the first selection */
 178
 179         /* Create an adapter for each channel. */
 180         for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) {
 181                 if (num >= pdata->num_adaps)
 182                         /* discard unconfigured channels */
 183                         break;
 184
 185                 force = pdata->adap_ids[num];
 186
 187                 err = i2c_mux_add_adapter(muxc, force, num, 0);
 188                 if (err)
 189                         goto virt_reg_failed;
 190         }
 191
 192         return 0;
 193
 194 virt_reg_failed:
 195         i2c_mux_del_adapters(muxc);
 196         return err;
 197 }
 198
 199 static int mlxcpld_mux_remove(struct i2c_client *client)
 200 {
 201         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 202
 203         i2c_mux_del_adapters(muxc);
 204         return 0;
 205 }
 206
 207 static struct i2c_driver mlxcpld_mux_driver = {
 208         .driver         = {
 209                 .name   = "mlxcpld-mux",
 210         },
 211         .probe          = mlxcpld_mux_probe,
 212         .remove         = mlxcpld_mux_remove,
 213         .id_table       = mlxcpld_mux_id,
 214 };
 215
 216 module_i2c_driver(mlxcpld_mux_driver);
 217
 218 MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
 219 MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
 220 MODULE_LICENSE("Dual BSD/GPL");
 221 MODULE_ALIAS("platform:i2c-mux-mlxcpld");