i2c/muxes/i2c-mux-gpmux.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * General Purpose I2C multiplexer
0004  *
0005  * Copyright (C) 2017 Axentia Technologies AB
0006  *
0007  * Author: Peter Rosin <peda@axentia.se>
0008  */
0009
0010 #include <linux/i2c.h>
0011 #include <linux/i2c-mux.h>
0012 #include <linux/module.h>
0013 #include <linux/mux/consumer.h>
0014 #include <linux/of_device.h>
0015 #include <linux/platform_device.h>
0016
0017 struct mux {
0018     struct mux_control *control;
0019
0020     bool do_not_deselect;
0021 };
0022
0023 static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
0024 {
0025     struct mux *mux = i2c_mux_priv(muxc);
0026     int ret;
0027
0028     ret = mux_control_select(mux->control, chan);
0029     mux->do_not_deselect = ret < 0;
0030
0031     return ret;
0032 }
0033
0034 static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
0035 {
0036     struct mux *mux = i2c_mux_priv(muxc);
0037
0038     if (mux->do_not_deselect)
0039         return 0;
0040
0041     return mux_control_deselect(mux->control);
0042 }
0043
0044 static struct i2c_adapter *mux_parent_adapter(struct device *dev)
0045 {
0046     struct device_node *np = dev->of_node;
0047     struct device_node *parent_np;
0048     struct i2c_adapter *parent;
0049
0050     parent_np = of_parse_phandle(np, "i2c-parent", 0);
0051     if (!parent_np) {
0052         dev_err(dev, "Cannot parse i2c-parent\n");
0053         return ERR_PTR(-ENODEV);
0054     }
0055     parent = of_find_i2c_adapter_by_node(parent_np);
0056     of_node_put(parent_np);
0057     if (!parent)
0058         return ERR_PTR(-EPROBE_DEFER);
0059
0060     return parent;
0061 }
0062
0063 static const struct of_device_id i2c_mux_of_match[] = {
0064     { .compatible = "i2c-mux", },
0065     {},
0066 };
0067 MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
0068
0069 static int i2c_mux_probe(struct platform_device *pdev)
0070 {
0071     struct device *dev = &pdev->dev;
0072     struct device_node *np = dev->of_node;
0073     struct device_node *child;
0074     struct i2c_mux_core *muxc;
0075     struct mux *mux;
0076     struct i2c_adapter *parent;
0077     int children;
0078     int ret;
0079
0080     if (!np)
0081         return -ENODEV;
0082
0083     mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
0084     if (!mux)
0085         return -ENOMEM;
0086
0087     mux->control = devm_mux_control_get(dev, NULL);
0088     if (IS_ERR(mux->control))
0089         return dev_err_probe(dev, PTR_ERR(mux->control),
0090                      "failed to get control-mux\n");
0091
0092     parent = mux_parent_adapter(dev);
0093     if (IS_ERR(parent))
0094         return dev_err_probe(dev, PTR_ERR(parent),
0095                      "failed to get i2c-parent adapter\n");
0096
0097     children = of_get_child_count(np);
0098
0099     muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
0100                  i2c_mux_select, i2c_mux_deselect);
0101     if (!muxc) {
0102         ret = -ENOMEM;
0103         goto err_parent;
0104     }
0105     muxc->priv = mux;
0106
0107     platform_set_drvdata(pdev, muxc);
0108
0109     muxc->mux_locked = of_property_read_bool(np, "mux-locked");
0110
0111     for_each_child_of_node(np, child) {
0112         u32 chan;
0113
0114         ret = of_property_read_u32(child, "reg", &chan);
0115         if (ret < 0) {
0116             dev_err(dev, "no reg property for node '%pOFn'\n",
0117                 child);
0118             goto err_children;
0119         }
0120
0121         if (chan >= mux_control_states(mux->control)) {
0122             dev_err(dev, "invalid reg %u\n", chan);
0123             ret = -EINVAL;
0124             goto err_children;
0125         }
0126
0127         ret = i2c_mux_add_adapter(muxc, 0, chan, 0);
0128         if (ret)
0129             goto err_children;
0130     }
0131
0132     dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
0133
0134     return 0;
0135
0136 err_children:
0137     of_node_put(child);
0138     i2c_mux_del_adapters(muxc);
0139 err_parent:
0140     i2c_put_adapter(parent);
0141
0142     return ret;
0143 }
0144
0145 static int i2c_mux_remove(struct platform_device *pdev)
0146 {
0147     struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
0148
0149     i2c_mux_del_adapters(muxc);
0150     i2c_put_adapter(muxc->parent);
0151
0152     return 0;
0153 }
0154
0155 static struct platform_driver i2c_mux_driver = {
0156     .probe  = i2c_mux_probe,
0157     .remove = i2c_mux_remove,
0158     .driver = {
0159         .name   = "i2c-mux-gpmux",
0160         .of_match_table = i2c_mux_of_match,
0161     },
0162 };
0163 module_platform_driver(i2c_mux_driver);
0164
0165 MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
0166 MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
0167 MODULE_LICENSE("GPL v2");