120 lines
3.1 KiB
C
120 lines
3.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0+
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/* MDIO bus multiplexer using kernel multiplexer subsystem
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*
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* Copyright 2019 NXP
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*/
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#include <linux/mdio-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/platform_device.h>
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struct mdio_mux_multiplexer_state {
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struct mux_control *muxc;
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bool do_deselect;
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void *mux_handle;
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};
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/**
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* mdio_mux_multiplexer_switch_fn - This function is called by the mdio-mux
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* layer when it thinks the mdio bus
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* multiplexer needs to switch.
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* @current_child: current value of the mux register.
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* @desired_child: value of the 'reg' property of the target child MDIO node.
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* @data: Private data used by this switch_fn passed to mdio_mux_init function
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* via mdio_mux_init(.., .., .., .., data, ..).
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*
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* The first time this function is called, current_child == -1.
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* If current_child == desired_child, then the mux is already set to the
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* correct bus.
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*/
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static int mdio_mux_multiplexer_switch_fn(int current_child, int desired_child,
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void *data)
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{
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struct platform_device *pdev;
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struct mdio_mux_multiplexer_state *s;
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int ret = 0;
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pdev = (struct platform_device *)data;
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s = platform_get_drvdata(pdev);
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if (!(current_child ^ desired_child))
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return 0;
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if (s->do_deselect)
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ret = mux_control_deselect(s->muxc);
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if (ret) {
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dev_err(&pdev->dev, "mux_control_deselect failed in %s: %d\n",
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__func__, ret);
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return ret;
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}
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ret = mux_control_select(s->muxc, desired_child);
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if (!ret) {
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dev_dbg(&pdev->dev, "%s %d -> %d\n", __func__, current_child,
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desired_child);
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s->do_deselect = true;
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} else {
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s->do_deselect = false;
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}
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return ret;
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}
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static int mdio_mux_multiplexer_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct mdio_mux_multiplexer_state *s;
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int ret = 0;
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s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
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if (!s)
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return -ENOMEM;
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s->muxc = devm_mux_control_get(dev, NULL);
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if (IS_ERR(s->muxc))
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return dev_err_probe(&pdev->dev, PTR_ERR(s->muxc),
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"Failed to get mux\n");
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platform_set_drvdata(pdev, s);
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ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node,
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mdio_mux_multiplexer_switch_fn, &s->mux_handle,
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pdev, NULL);
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return ret;
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}
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static int mdio_mux_multiplexer_remove(struct platform_device *pdev)
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{
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struct mdio_mux_multiplexer_state *s = platform_get_drvdata(pdev);
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mdio_mux_uninit(s->mux_handle);
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if (s->do_deselect)
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mux_control_deselect(s->muxc);
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return 0;
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}
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static const struct of_device_id mdio_mux_multiplexer_match[] = {
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{ .compatible = "mdio-mux-multiplexer", },
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{},
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};
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MODULE_DEVICE_TABLE(of, mdio_mux_multiplexer_match);
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static struct platform_driver mdio_mux_multiplexer_driver = {
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.driver = {
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.name = "mdio-mux-multiplexer",
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.of_match_table = mdio_mux_multiplexer_match,
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},
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.probe = mdio_mux_multiplexer_probe,
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.remove = mdio_mux_multiplexer_remove,
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};
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module_platform_driver(mdio_mux_multiplexer_driver);
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MODULE_DESCRIPTION("MDIO bus multiplexer using kernel multiplexer subsystem");
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MODULE_AUTHOR("Pankaj Bansal <pankaj.bansal@nxp.com>");
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MODULE_LICENSE("GPL");
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