linux-imx

/*

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

 * Copyright (c) 2016 Mellanox Technologies. All rights reserved.

 * Copyright (c) 2016 Michael Shych <michaels@mellanox.com>

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the names of the copyright holders nor the names of its

 *    contributors may be used to endorse or promote products derived from

 *    this software without specific prior written permission.

 *

 * Alternatively, this software may be distributed under the terms of the

 * GNU General Public License ("GPL") version 2 as published by the Free

 * Software Foundation.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 */

​

#include <linux/device.h>

#include <linux/i2c.h>

#include <linux/i2c-mux.h>

#include <linux/io.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/platform_data/x86/mlxcpld.h>

#include <linux/platform_device.h>

#include <linux/slab.h>

​

#define CPLD_MUX_MAX_NCHANS 8

​

/* mlxcpld_mux - mux control structure:

 * @last_chan - last register value

 * @client - I2C device client

 */

struct mlxcpld_mux {

    u8 last_chan;

    struct i2c_client *client;

};

​

/* MUX logic description.

 * Driver can support different mux control logic, according to CPLD

 * implementation.

 *

 * Connectivity schema.

 *

 * i2c-mlxcpld                                 Digital               Analog

 * driver

 * *--------*                                 * -> mux1 (virt bus2) -> mux -> |

 * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |

 * | bridge | bus 1                 *---------*                               |

 * | logic  |---------------------> * mux reg *                               |

 * | in CPLD|                       *---------*                               |

 * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |

 *     |        driver                   |                                    |

 *     |        *---------------*        |                              Devices

 *     |        * CPLD (i2c bus)* select |

 *     |        * registers for *--------*

 *     |        * mux selection * deselect

 *     |        *---------------*

 *     |                 |

 * <-------->     <----------->

 * i2c cntrl      Board cntrl reg

 * reg space      space (mux select,

 *                IO, LED, WD, info)

 *

 */

​

static const struct i2c_device_id mlxcpld_mux_id[] = {

    { "mlxcpld_mux_module", 0 },

    { }

};

MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id);

​

/* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer()

 * for this as they will try to lock adapter a second time.

 */