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// SPDX-License-Identifier: GPL-2.0
/*
* Theobroma Systems Mule I2C device multiplexer
*
* Copyright (C) 2024 Theobroma Systems Design und Consulting GmbH
*/
#include <linux/i2c-mux.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#define MULE_I2C_MUX_CONFIG_REG 0xff
#define MULE_I2C_MUX_DEFAULT_DEV 0x0
struct mule_i2c_reg_mux {
struct regmap *regmap;
};
static int mule_i2c_mux_select(struct i2c_mux_core *muxc, u32 dev)
{
struct mule_i2c_reg_mux *mux = muxc->priv;
return regmap_write(mux->regmap, MULE_I2C_MUX_CONFIG_REG, dev);
}
static int mule_i2c_mux_deselect(struct i2c_mux_core *muxc, u32 dev)
{
return mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV);
}
static void mule_i2c_mux_remove(void *data)
{
struct i2c_mux_core *muxc = data;
i2c_mux_del_adapters(muxc);
mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV);
}
static int mule_i2c_mux_probe(struct platform_device *pdev)
{
struct device *mux_dev = &pdev->dev;
struct mule_i2c_reg_mux *priv;
struct i2c_client *client;
struct i2c_mux_core *muxc;
struct device_node *dev;
unsigned int readback;
int ndev, ret;
bool old_fw;
/* Count devices on the mux */
ndev = of_get_child_count(mux_dev->of_node);
dev_dbg(mux_dev, "%d devices on the mux\n", ndev);
client = to_i2c_client(mux_dev->parent);
muxc = i2c_mux_alloc(client->adapter, mux_dev, ndev, sizeof(*priv),
I2C_MUX_LOCKED, mule_i2c_mux_select, mule_i2c_mux_deselect);
if (!muxc)
return -ENOMEM;
priv = i2c_mux_priv(muxc);
priv->regmap = dev_get_regmap(mux_dev->parent, NULL);
if (!priv->regmap)
return dev_err_probe(mux_dev, -ENODEV,
"No parent i2c register map\n");
platform_set_drvdata(pdev, muxc);
/*
* MULE_I2C_MUX_DEFAULT_DEV is guaranteed to exist on all old and new
* mule fw. Mule fw without mux support will accept write ops to the
* config register, but readback returns 0xff (register not updated).
*/
ret = mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV);
if (ret)
return dev_err_probe(mux_dev, ret,
"Failed to write config register\n");
ret = regmap_read(priv->regmap, MULE_I2C_MUX_CONFIG_REG, &readback);
if (ret)
return dev_err_probe(mux_dev, ret,
"Failed to read config register\n");
old_fw = (readback != MULE_I2C_MUX_DEFAULT_DEV);
ret = devm_add_action_or_reset(mux_dev, mule_i2c_mux_remove, muxc);
if (ret)
return dev_err_probe(mux_dev, ret,
"Failed to register mux remove\n");
/* Create device adapters */
for_each_child_of_node(mux_dev->of_node, dev) {
u32 reg;
ret = of_property_read_u32(dev, "reg", ®);
if (ret)
return dev_err_probe(mux_dev, ret,
"No reg property found for %s\n",
of_node_full_name(dev));
if (old_fw && reg != 0) {
dev_warn(mux_dev,
"Mux is not supported, please update Mule FW\n");
continue;
}
ret = mule_i2c_mux_select(muxc, reg);
if (ret) {
dev_warn(mux_dev,
"Device %d not supported, please update Mule FW\n", reg);
continue;
}
ret = i2c_mux_add_adapter(muxc, 0, reg);
if (ret)
return ret;
}
mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV);
return 0;
}
static const struct of_device_id mule_i2c_mux_of_match[] = {
{ .compatible = "tsd,mule-i2c-mux", },
{},
};
MODULE_DEVICE_TABLE(of, mule_i2c_mux_of_match);
static struct platform_driver mule_i2c_mux_driver = {
.driver = {
.name = "mule-i2c-mux",
.of_match_table = mule_i2c_mux_of_match,
},
.probe = mule_i2c_mux_probe,
};
module_platform_driver(mule_i2c_mux_driver);
MODULE_AUTHOR("Farouk Bouabid <farouk.bouabid@cherry.de>");
MODULE_DESCRIPTION("I2C mux driver for Theobroma Systems Mule");
MODULE_LICENSE("GPL");
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