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// 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>
#define CPLD_MUX_MAX_NCHANS 8
/* mlxcpld_mux - mux control structure:
* @last_chan - last register value
* @client - I2C device client
* @pdata: platform data
*/
struct mlxcpld_mux {
u8 last_chan;
struct i2c_client *client;
struct mlxcpld_mux_plat_data pdata;
};
/* 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, u8 val)
{
struct i2c_client *client = mux->client;
union i2c_smbus_data data = { .byte = val };
return __i2c_smbus_xfer(adap, client->addr, client->flags,
I2C_SMBUS_WRITE, mux->pdata.sel_reg_addr,
I2C_SMBUS_BYTE_DATA, &data);
}
static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
{
struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
u8 regval = chan + 1;
int err = 0;
/* Only select the channel if its different from the last channel */
if (mux->last_chan != regval) {
err = mlxcpld_mux_reg_write(muxc->parent, mux, regval);
mux->last_chan = err < 0 ? 0 : regval;
}
return err;
}
static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
{
struct mlxcpld_mux *mux = i2c_mux_priv(muxc);
/* Deselect active channel */
mux->last_chan = 0;
return mlxcpld_mux_reg_write(muxc->parent, mux, mux->last_chan);
}
/* Probe/reomove functions */
static int mlxcpld_mux_probe(struct platform_device *pdev)
{
struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&pdev->dev);
struct i2c_client *client = to_i2c_client(pdev->dev.parent);
struct i2c_mux_core *muxc;
int num, force;
struct mlxcpld_mux *data;
int err;
if (!pdata)
return -EINVAL;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
return -ENODEV;
muxc = i2c_mux_alloc(client->adapter, &pdev->dev, CPLD_MUX_MAX_NCHANS,
sizeof(*data), 0, mlxcpld_mux_select_chan,
mlxcpld_mux_deselect);
if (!muxc)
return -ENOMEM;
platform_set_drvdata(pdev, muxc);
data = i2c_mux_priv(muxc);
data->client = client;
memcpy(&data->pdata, pdata, sizeof(*pdata));
data->last_chan = 0; /* force the first selection */
/* Create an adapter for each channel. */
for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) {
if (num >= pdata->num_adaps)
/* discard unconfigured channels */
break;
force = pdata->adap_ids[num];
err = i2c_mux_add_adapter(muxc, force, num, 0);
if (err)
goto virt_reg_failed;
}
return 0;
virt_reg_failed:
i2c_mux_del_adapters(muxc);
return err;
}
static int mlxcpld_mux_remove(struct platform_device *pdev)
{
struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
i2c_mux_del_adapters(muxc);
return 0;
}
static struct platform_driver mlxcpld_mux_driver = {
.driver = {
.name = "i2c-mux-mlxcpld",
},
.probe = mlxcpld_mux_probe,
.remove = mlxcpld_mux_remove,
};
module_platform_driver(mlxcpld_mux_driver);
MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)");
MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("platform:i2c-mux-mlxcpld");
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