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/version.h>
  44 #include <linux/i2c/mlxcpld.h>
  45
  46 #define CPLD_MUX_MAX_NCHANS     8
  47
  48 /* mlxcpld_mux - mux control structure:
  49  * @last_chan - last register value
  50  * @client - I2C device client
  51  */
  52 struct mlxcpld_mux {
  53         u8 last_chan;
  54         struct i2c_client *client;
  55 };
  56
  57 /* MUX logic description.
  58  * Driver can support different mux control logic, according to CPLD
  59  * implementation.
  60  *
  61  * Connectivity schema.
  62  *
  63  * i2c-mlxcpld                                 Digital               Analog
  64  * driver
  65  * *--------*                                 * -> mux1 (virt bus2) -> mux -> |
  66  * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |
  67  * | bridge | bus 1                 *---------*                               |
  68  * | logic  |---------------------> * mux reg *                               |
  69  * | in CPLD|                       *---------*                               |
  70  * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |
  71  *     |        driver                   |                                    |
  72  *     |        *---------------*        |                              Devices
  73  *     |        * CPLD (i2c bus)* select |
  74  *     |        * registers for *--------*
  75  *     |        * mux selection * deselect
  76  *     |        *---------------*
  77  *     |                 |
  78  * <-------->     <----------->
  79  * i2c cntrl      Board cntrl reg
  80  * reg space      space (mux select,
  81  *                IO, LED, WD, info)
  82  *
  83  */
  84
  85 static const struct i2c_device_id mlxcpld_mux_id[] = {
  86         { "mlxcpld_mux_module", 0 },
  87         { }
  88 };
  89 MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id);
  90
  91 /* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()
  92  * for this as they will try to lock adapter a second time.
  93  */
  94 static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
  95                                  struct i2c_client *client, u8 val)
  96 {
  97         struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
  98         int ret = -ENODEV;
  99
 100         if (adap->algo->master_xfer) {
 101                 struct i2c_msg msg;
 102                 u8 msgbuf[] = {pdata->sel_reg_addr, val};
 103
 104                 msg.addr = client->addr;
 105                 msg.flags = 0;
 106                 msg.len = 2;
 107                 msg.buf = msgbuf;
 108                 ret = __i2c_transfer(adap, &msg, 1);
 109
 110                 if (ret >= 0 && ret != 1)
 111                         ret = -EREMOTEIO;
 112         } else if (adap->algo->smbus_xfer) {
 113                 union i2c_smbus_data data;
 114
 115                 data.byte = val;
 116                 ret = adap->algo->smbus_xfer(adap, client->addr,
 117                                              client->flags, I2C_SMBUS_WRITE,
 118                                              pdata->sel_reg_addr,
 119                                              I2C_SMBUS_BYTE_DATA, &data);
 120         }
 121
 122         return ret;
 123 }
 124
 125 static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
 126 {
 127         struct mlxcpld_mux *data = i2c_mux_priv(muxc);
 128         struct i2c_client *client = data->client;
 129         u8 regval = chan + 1;
 130         int err = 0;
 131
 132         /* Only select the channel if its different from the last channel */
 133         if (data->last_chan != regval) {
 134                 err = mlxcpld_mux_reg_write(muxc->parent, client, regval);
 135                 data->last_chan = err < 0 ? 0 : regval;
 136         }
 137
 138         return err;
 139 }
 140
 141 static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
 142 {
 143         struct mlxcpld_mux *data = i2c_mux_priv(muxc);
 144         struct i2c_client *client = data->client;
 145
 146         /* Deselect active channel */
 147         data->last_chan = 0;
 148
 149         return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan);
 150 }
 151
 152 /* Probe/reomove functions */
 153 static int mlxcpld_mux_probe(struct i2c_client *client,
 154                              const struct i2c_device_id *id)
 155 {
 156         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
 157         struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
 158         struct i2c_mux_core *muxc;
 159         int num, force;
 160         struct mlxcpld_mux *data;
 161         int err;
 162
 163         if (!pdata)
 164                 return -EINVAL;
 165
 166         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
 167                 return -ENODEV;
 168
 169         muxc = i2c_mux_alloc(adap, &client->dev, CPLD_MUX_MAX_NCHANS,
 170                              sizeof(*data), 0, mlxcpld_mux_select_chan,
 171                              mlxcpld_mux_deselect);
 172         if (!muxc)
 173                 return -ENOMEM;
 174
 175         data = i2c_mux_priv(muxc);
 176         i2c_set_clientdata(client, muxc);
 177         data->client = client;
 178         data->last_chan = 0; /* force the first selection */
 179
 180         /* Create an adapter for each channel. */
 181         for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) {
 182                 if (num >= pdata->num_adaps)
 183                         /* discard unconfigured channels */
 184                         break;
 185
 186                 force = pdata->adap_ids[num];
 187
 188                 err = i2c_mux_add_adapter(muxc, force, num, 0);
 189                 if (err)
 190                         goto virt_reg_failed;
 191         }
 192
 193         return 0;
 194
 195 virt_reg_failed:
 196         i2c_mux_del_adapters(muxc);
 197         return err;
 198 }
 199
 200 static int mlxcpld_mux_remove(struct i2c_client *client)
 201 {
 202         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 203
 204         i2c_mux_del_adapters(muxc);
 205         return 0;
 206 }
 207
 208 static struct i2c_driver mlxcpld_mux_driver = {
 209         .driver         = {
 210                 .name   = "mlxcpld-mux",
 211         },
 212         .probe          = mlxcpld_mux_probe,
 213         .remove         = mlxcpld_mux_remove,
 214         .id_table       = mlxcpld_mux_id,
 215 };
 216
 217 module_i2c_driver(mlxcpld_mux_driver);
 218
 219 MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
 220 MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
 221 MODULE_LICENSE("Dual BSD/GPL");
 222 MODULE_ALIAS("platform:i2c-mux-mlxcpld");