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1// SPDX-License-Identifier: GPL-2.02/*3 * Theobroma Systems Mule I2C device multiplexer4 *5 * Copyright (C) 2024 Theobroma Systems Design und Consulting GmbH6 */7 8#include <linux/i2c-mux.h>9#include <linux/i2c.h>10#include <linux/module.h>11#include <linux/of.h>12#include <linux/platform_device.h>13#include <linux/property.h>14#include <linux/regmap.h>15 16#define MULE_I2C_MUX_CONFIG_REG 0xff17#define MULE_I2C_MUX_DEFAULT_DEV 0x018 19struct mule_i2c_reg_mux {20 struct regmap *regmap;21};22 23static int mule_i2c_mux_select(struct i2c_mux_core *muxc, u32 dev)24{25 struct mule_i2c_reg_mux *mux = muxc->priv;26 27 return regmap_write(mux->regmap, MULE_I2C_MUX_CONFIG_REG, dev);28}29 30static int mule_i2c_mux_deselect(struct i2c_mux_core *muxc, u32 dev)31{32 return mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV);33}34 35static void mule_i2c_mux_remove(void *data)36{37 struct i2c_mux_core *muxc = data;38 39 i2c_mux_del_adapters(muxc);40 41 mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV);42}43 44static int mule_i2c_mux_probe(struct platform_device *pdev)45{46 struct device *mux_dev = &pdev->dev;47 struct mule_i2c_reg_mux *priv;48 struct i2c_client *client;49 struct i2c_mux_core *muxc;50 struct device_node *dev;51 unsigned int readback;52 int ndev, ret;53 bool old_fw;54 55 /* Count devices on the mux */56 ndev = of_get_child_count(mux_dev->of_node);57 dev_dbg(mux_dev, "%d devices on the mux\n", ndev);58 59 client = to_i2c_client(mux_dev->parent);60 61 muxc = i2c_mux_alloc(client->adapter, mux_dev, ndev, sizeof(*priv),62 I2C_MUX_LOCKED, mule_i2c_mux_select, mule_i2c_mux_deselect);63 if (!muxc)64 return -ENOMEM;65 66 priv = i2c_mux_priv(muxc);67 68 priv->regmap = dev_get_regmap(mux_dev->parent, NULL);69 if (!priv->regmap)70 return dev_err_probe(mux_dev, -ENODEV,71 "No parent i2c register map\n");72 73 platform_set_drvdata(pdev, muxc);74 75 /*76 * MULE_I2C_MUX_DEFAULT_DEV is guaranteed to exist on all old and new77 * mule fw. Mule fw without mux support will accept write ops to the78 * config register, but readback returns 0xff (register not updated).79 */80 ret = mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV);81 if (ret)82 return dev_err_probe(mux_dev, ret,83 "Failed to write config register\n");84 85 ret = regmap_read(priv->regmap, MULE_I2C_MUX_CONFIG_REG, &readback);86 if (ret)87 return dev_err_probe(mux_dev, ret,88 "Failed to read config register\n");89 90 old_fw = (readback != MULE_I2C_MUX_DEFAULT_DEV);91 92 ret = devm_add_action_or_reset(mux_dev, mule_i2c_mux_remove, muxc);93 if (ret)94 return dev_err_probe(mux_dev, ret,95 "Failed to register mux remove\n");96 97 /* Create device adapters */98 for_each_child_of_node(mux_dev->of_node, dev) {99 u32 reg;100 101 ret = of_property_read_u32(dev, "reg", ®);102 if (ret)103 return dev_err_probe(mux_dev, ret,104 "No reg property found for %s\n",105 of_node_full_name(dev));106 107 if (old_fw && reg != 0) {108 dev_warn(mux_dev,109 "Mux is not supported, please update Mule FW\n");110 continue;111 }112 113 ret = mule_i2c_mux_select(muxc, reg);114 if (ret) {115 dev_warn(mux_dev,116 "Device %d not supported, please update Mule FW\n", reg);117 continue;118 }119 120 ret = i2c_mux_add_adapter(muxc, 0, reg);121 if (ret)122 return ret;123 }124 125 mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV);126 127 return 0;128}129 130static const struct of_device_id mule_i2c_mux_of_match[] = {131 { .compatible = "tsd,mule-i2c-mux", },132 {},133};134MODULE_DEVICE_TABLE(of, mule_i2c_mux_of_match);135 136static struct platform_driver mule_i2c_mux_driver = {137 .driver = {138 .name = "mule-i2c-mux",139 .of_match_table = mule_i2c_mux_of_match,140 },141 .probe = mule_i2c_mux_probe,142};143 144module_platform_driver(mule_i2c_mux_driver);145 146MODULE_AUTHOR("Farouk Bouabid <farouk.bouabid@cherry.de>");147MODULE_DESCRIPTION("I2C mux driver for Theobroma Systems Mule");148MODULE_LICENSE("GPL");149