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

   1 /*
   2  * General Purpose I2C multiplexer
   3  *
   4  * Copyright (C) 2017 Axentia Technologies AB
   5  *
   6  * Author: Peter Rosin <peda@axentia.se>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/i2c.h>
  14 #include <linux/i2c-mux.h>
  15 #include <linux/module.h>
  16 #include <linux/mux/consumer.h>
  17 #include <linux/of_device.h>
  18 #include <linux/platform_device.h>
  19
  20 struct mux {
  21         struct mux_control *control;
  22
  23         bool do_not_deselect;
  24 };
  25
  26 static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
  27 {
  28         struct mux *mux = i2c_mux_priv(muxc);
  29         int ret;
  30
  31         ret = mux_control_select(mux->control, chan);
  32         mux->do_not_deselect = ret < 0;
  33
  34         return ret;
  35 }
  36
  37 static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
  38 {
  39         struct mux *mux = i2c_mux_priv(muxc);
  40
  41         if (mux->do_not_deselect)
  42                 return 0;
  43
  44         return mux_control_deselect(mux->control);
  45 }
  46
  47 static struct i2c_adapter *mux_parent_adapter(struct device *dev)
  48 {
  49         struct device_node *np = dev->of_node;
  50         struct device_node *parent_np;
  51         struct i2c_adapter *parent;
  52
  53         parent_np = of_parse_phandle(np, "i2c-parent", 0);
  54         if (!parent_np) {
  55                 dev_err(dev, "Cannot parse i2c-parent\n");
  56                 return ERR_PTR(-ENODEV);
  57         }
  58         parent = of_find_i2c_adapter_by_node(parent_np);
  59         of_node_put(parent_np);
  60         if (!parent)
  61                 return ERR_PTR(-EPROBE_DEFER);
  62
  63         return parent;
  64 }
  65
  66 static const struct of_device_id i2c_mux_of_match[] = {
  67         { .compatible = "i2c-mux", },
  68         {},
  69 };
  70 MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
  71
  72 static int i2c_mux_probe(struct platform_device *pdev)
  73 {
  74         struct device *dev = &pdev->dev;
  75         struct device_node *np = dev->of_node;
  76         struct device_node *child;
  77         struct i2c_mux_core *muxc;
  78         struct mux *mux;
  79         struct i2c_adapter *parent;
  80         int children;
  81         int ret;
  82
  83         if (!np)
  84                 return -ENODEV;
  85
  86         mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
  87         if (!mux)
  88                 return -ENOMEM;
  89
  90         mux->control = devm_mux_control_get(dev, NULL);
  91         if (IS_ERR(mux->control)) {
  92                 if (PTR_ERR(mux->control) != -EPROBE_DEFER)
  93                         dev_err(dev, "failed to get control-mux\n");
  94                 return PTR_ERR(mux->control);
  95         }
  96
  97         parent = mux_parent_adapter(dev);
  98         if (IS_ERR(parent)) {
  99                 if (PTR_ERR(parent) != -EPROBE_DEFER)
 100                         dev_err(dev, "failed to get i2c-parent adapter\n");
 101                 return PTR_ERR(parent);
 102         }
 103
 104         children = of_get_child_count(np);
 105
 106         muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
 107                              i2c_mux_select, i2c_mux_deselect);
 108         if (!muxc) {
 109                 ret = -ENOMEM;
 110                 goto err_parent;
 111         }
 112         muxc->priv = mux;
 113
 114         platform_set_drvdata(pdev, muxc);
 115
 116         muxc->mux_locked = of_property_read_bool(np, "mux-locked");
 117
 118         for_each_child_of_node(np, child) {
 119                 u32 chan;
 120
 121                 ret = of_property_read_u32(child, "reg", &chan);
 122                 if (ret < 0) {
 123                         dev_err(dev, "no reg property for node '%s'\n",
 124                                 child->name);
 125                         goto err_children;
 126                 }
 127
 128                 if (chan >= mux_control_states(mux->control)) {
 129                         dev_err(dev, "invalid reg %u\n", chan);
 130                         ret = -EINVAL;
 131                         goto err_children;
 132                 }
 133
 134                 ret = i2c_mux_add_adapter(muxc, 0, chan, 0);
 135                 if (ret)
 136                         goto err_children;
 137         }
 138
 139         dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
 140
 141         return 0;
 142
 143 err_children:
 144         of_node_put(child);
 145         i2c_mux_del_adapters(muxc);
 146 err_parent:
 147         i2c_put_adapter(parent);
 148
 149         return ret;
 150 }
 151
 152 static int i2c_mux_remove(struct platform_device *pdev)
 153 {
 154         struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
 155
 156         i2c_mux_del_adapters(muxc);
 157         i2c_put_adapter(muxc->parent);
 158
 159         return 0;
 160 }
 161
 162 static struct platform_driver i2c_mux_driver = {
 163         .probe  = i2c_mux_probe,
 164         .remove = i2c_mux_remove,
 165         .driver = {
 166                 .name   = "i2c-mux-gpmux",
 167                 .of_match_table = i2c_mux_of_match,
 168         },
 169 };
 170 module_platform_driver(i2c_mux_driver);
 171
 172 MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
 173 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
 174 MODULE_LICENSE("GPL v2");