drivers/i2c/muxes/i2c-mux-mule.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Theobroma Systems Mule I2C device multiplexer
   4  *
   5  * Copyright (C) 2024 Theobroma Systems Design und Consulting GmbH
   6  */
   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  0xff
  17 #define MULE_I2C_MUX_DEFAULT_DEV 0x0
  18
  19 struct mule_i2c_reg_mux {
  20         struct regmap *regmap;
  21 };
  22
  23 static 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
  30 static 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
  35 static 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
  44 static 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 new
  77          * mule fw. Mule fw without mux support will accept write ops to the
  78          * 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", &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
 130 static const struct of_device_id mule_i2c_mux_of_match[] = {
 131         { .compatible = "tsd,mule-i2c-mux", },
 132         {},
 133 };
 134 MODULE_DEVICE_TABLE(of, mule_i2c_mux_of_match);
 135
 136 static 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
 144 module_platform_driver(mule_i2c_mux_driver);
 145
 146 MODULE_AUTHOR("Farouk Bouabid <farouk.bouabid@cherry.de>");
 147 MODULE_DESCRIPTION("I2C mux driver for Theobroma Systems Mule");
 148 MODULE_LICENSE("GPL");