174 lines
3.7 KiB
C
174 lines
3.7 KiB
C
/*
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* General Purpose I2C multiplexer
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*
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* Copyright (C) 2017 Axentia Technologies AB
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*
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* Author: Peter Rosin <peda@axentia.se>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/i2c.h>
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#include <linux/i2c-mux.h>
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#include <linux/module.h>
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#include <linux/mux/consumer.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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struct mux {
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struct mux_control *control;
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bool do_not_deselect;
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};
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static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
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{
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struct mux *mux = i2c_mux_priv(muxc);
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int ret;
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ret = mux_control_select(mux->control, chan);
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mux->do_not_deselect = ret < 0;
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return ret;
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}
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static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
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{
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struct mux *mux = i2c_mux_priv(muxc);
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if (mux->do_not_deselect)
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return 0;
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return mux_control_deselect(mux->control);
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}
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static struct i2c_adapter *mux_parent_adapter(struct device *dev)
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{
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struct device_node *np = dev->of_node;
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struct device_node *parent_np;
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struct i2c_adapter *parent;
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parent_np = of_parse_phandle(np, "i2c-parent", 0);
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if (!parent_np) {
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dev_err(dev, "Cannot parse i2c-parent\n");
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return ERR_PTR(-ENODEV);
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}
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parent = of_find_i2c_adapter_by_node(parent_np);
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of_node_put(parent_np);
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if (!parent)
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return ERR_PTR(-EPROBE_DEFER);
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return parent;
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}
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static const struct of_device_id i2c_mux_of_match[] = {
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{ .compatible = "i2c-mux", },
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
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static int i2c_mux_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct device_node *np = dev->of_node;
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struct device_node *child;
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struct i2c_mux_core *muxc;
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struct mux *mux;
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struct i2c_adapter *parent;
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int children;
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int ret;
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if (!np)
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return -ENODEV;
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mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
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if (!mux)
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return -ENOMEM;
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mux->control = devm_mux_control_get(dev, NULL);
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if (IS_ERR(mux->control)) {
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if (PTR_ERR(mux->control) != -EPROBE_DEFER)
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dev_err(dev, "failed to get control-mux\n");
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return PTR_ERR(mux->control);
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}
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parent = mux_parent_adapter(dev);
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if (IS_ERR(parent)) {
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if (PTR_ERR(parent) != -EPROBE_DEFER)
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dev_err(dev, "failed to get i2c-parent adapter\n");
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return PTR_ERR(parent);
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}
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children = of_get_child_count(np);
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muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
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i2c_mux_select, i2c_mux_deselect);
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if (!muxc) {
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ret = -ENOMEM;
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goto err_parent;
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}
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muxc->priv = mux;
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platform_set_drvdata(pdev, muxc);
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muxc->mux_locked = of_property_read_bool(np, "mux-locked");
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for_each_child_of_node(np, child) {
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u32 chan;
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ret = of_property_read_u32(child, "reg", &chan);
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if (ret < 0) {
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dev_err(dev, "no reg property for node '%s'\n",
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child->name);
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goto err_children;
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}
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if (chan >= mux_control_states(mux->control)) {
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dev_err(dev, "invalid reg %u\n", chan);
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ret = -EINVAL;
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goto err_children;
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}
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ret = i2c_mux_add_adapter(muxc, 0, chan, 0);
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if (ret)
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goto err_children;
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}
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dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
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return 0;
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err_children:
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i2c_mux_del_adapters(muxc);
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err_parent:
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i2c_put_adapter(parent);
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return ret;
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}
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static int i2c_mux_remove(struct platform_device *pdev)
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{
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struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
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i2c_mux_del_adapters(muxc);
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i2c_put_adapter(muxc->parent);
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return 0;
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}
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static struct platform_driver i2c_mux_driver = {
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.probe = i2c_mux_probe,
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.remove = i2c_mux_remove,
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.driver = {
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.name = "i2c-mux-gpmux",
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.of_match_table = i2c_mux_of_match,
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},
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};
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module_platform_driver(i2c_mux_driver);
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MODULE_DESCRIPTION("General Purpose I2C multiplexer driver");
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MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
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MODULE_LICENSE("GPL v2");
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