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_data/x86/mlxcpld.h>
  42 #include <linux/platform_device.h>
  43 #include <linux/slab.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         union i2c_smbus_data data = { .byte = val };
  98
  99         return __i2c_smbus_xfer(adap, client->addr, client->flags,
 100                                 I2C_SMBUS_WRITE, pdata->sel_reg_addr,
 101                                 I2C_SMBUS_BYTE_DATA, &data);
 102 }
 103
 104 static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
 105 {
 106         struct mlxcpld_mux *data = i2c_mux_priv(muxc);
 107         struct i2c_client *client = data->client;
 108         u8 regval = chan + 1;
 109         int err = 0;
 110
 111         /* Only select the channel if its different from the last channel */
 112         if (data->last_chan != regval) {
 113                 err = mlxcpld_mux_reg_write(muxc->parent, client, regval);
 114                 data->last_chan = err < 0 ? 0 : regval;
 115         }
 116
 117         return err;
 118 }
 119
 120 static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
 121 {
 122         struct mlxcpld_mux *data = i2c_mux_priv(muxc);
 123         struct i2c_client *client = data->client;
 124
 125         /* Deselect active channel */
 126         data->last_chan = 0;
 127
 128         return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan);
 129 }
 130
 131 /* Probe/reomove functions */
 132 static int mlxcpld_mux_probe(struct i2c_client *client,
 133                              const struct i2c_device_id *id)
 134 {
 135         struct i2c_adapter *adap = client->adapter;
 136         struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev);
 137         struct i2c_mux_core *muxc;
 138         int num, force;
 139         struct mlxcpld_mux *data;
 140         int err;
 141
 142         if (!pdata)
 143                 return -EINVAL;
 144
 145         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
 146                 return -ENODEV;
 147
 148         muxc = i2c_mux_alloc(adap, &client->dev, CPLD_MUX_MAX_NCHANS,
 149                              sizeof(*data), 0, mlxcpld_mux_select_chan,
 150                              mlxcpld_mux_deselect);
 151         if (!muxc)
 152                 return -ENOMEM;
 153
 154         data = i2c_mux_priv(muxc);
 155         i2c_set_clientdata(client, muxc);
 156         data->client = client;
 157         data->last_chan = 0; /* force the first selection */
 158
 159         /* Create an adapter for each channel. */
 160         for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) {
 161                 if (num >= pdata->num_adaps)
 162                         /* discard unconfigured channels */
 163                         break;
 164
 165                 force = pdata->adap_ids[num];
 166
 167                 err = i2c_mux_add_adapter(muxc, force, num, 0);
 168                 if (err)
 169                         goto virt_reg_failed;
 170         }
 171
 172         return 0;
 173
 174 virt_reg_failed:
 175         i2c_mux_del_adapters(muxc);
 176         return err;
 177 }
 178
 179 static int mlxcpld_mux_remove(struct i2c_client *client)
 180 {
 181         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 182
 183         i2c_mux_del_adapters(muxc);
 184         return 0;
 185 }
 186
 187 static struct i2c_driver mlxcpld_mux_driver = {
 188         .driver         = {
 189                 .name   = "mlxcpld-mux",
 190         },
 191         .probe          = mlxcpld_mux_probe,
 192         .remove         = mlxcpld_mux_remove,
 193         .id_table       = mlxcpld_mux_id,
 194 };
 195
 196 module_i2c_driver(mlxcpld_mux_driver);
 197
 198 MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
 199 MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
 200 MODULE_LICENSE("Dual BSD/GPL");
 201 MODULE_ALIAS("platform:i2c-mux-mlxcpld");