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

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/*
 * Mellanox i2c mux driver
 *
 * Copyright (C) 2016-2020 Mellanox Technologies
 */

#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/mlxcpld.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

/* mlxcpld_mux - mux control structure:
 * @last_val - last selected register value or -1 if mux deselected
 * @client - I2C device client
 * @pdata: platform data
 */
struct mlxcpld_mux { … };

/* 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)
 *
 */

/* 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.
 */
static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
				 struct mlxcpld_mux *mux, u32 val)
{ … }

static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
{ … }

static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
{ … }

/* Probe/reomove functions */
static int mlxcpld_mux_probe(struct platform_device *pdev)
{ … }

static void mlxcpld_mux_remove(struct platform_device *pdev)
{ … }

static struct platform_driver mlxcpld_mux_driver = …;

module_platform_driver(…) …;

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;
MODULE_ALIAS(…) …;