LXR linux/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 */
  51struct 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
  84static const struct i2c_device_id mlxcpld_mux_id[] = {
  85        { "mlxcpld_mux_module", 0 },
  86        { }
  87};
  88MODULE_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 */
  93static 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
 104static 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
 120static 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 */
 132static 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
 174virt_reg_failed:
 175        i2c_mux_del_adapters(muxc);
 176        return err;
 177}
 178
 179static 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
 187static 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
 196module_i2c_driver(mlxcpld_mux_driver);
 197
 198MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
 199MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
 200MODULE_LICENSE("Dual BSD/GPL");
 201MODULE_ALIAS("platform:i2c-mux-mlxcpld");
 202