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277 lines
6.6 KiB
277 lines
6.6 KiB
/*
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* I2C multiplexer using a single register
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*
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* Copyright 2015 Freescale Semiconductor
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* York Sun <yorksun@freescale.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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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/init.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/platform_data/i2c-mux-reg.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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struct regmux {
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struct i2c_mux_reg_platform_data data;
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};
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static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
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{
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if (!mux->data.reg)
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return -EINVAL;
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/*
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* Write to the register, followed by a read to ensure the write is
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* completed on a "posted" bus, for example PCI or write buffers.
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* The endianness of reading doesn't matter and the return data
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* is not used.
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*/
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switch (mux->data.reg_size) {
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case 4:
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if (mux->data.little_endian)
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iowrite32(chan_id, mux->data.reg);
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else
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iowrite32be(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread32(mux->data.reg);
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break;
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case 2:
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if (mux->data.little_endian)
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iowrite16(chan_id, mux->data.reg);
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else
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iowrite16be(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread16(mux->data.reg);
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break;
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case 1:
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iowrite8(chan_id, mux->data.reg);
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if (!mux->data.write_only)
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ioread8(mux->data.reg);
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break;
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}
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return 0;
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}
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static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
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{
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struct regmux *mux = i2c_mux_priv(muxc);
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return i2c_mux_reg_set(mux, chan);
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}
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static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
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{
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struct regmux *mux = i2c_mux_priv(muxc);
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if (mux->data.idle_in_use)
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return i2c_mux_reg_set(mux, mux->data.idle);
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return 0;
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}
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#ifdef CONFIG_OF
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static int i2c_mux_reg_probe_dt(struct regmux *mux,
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struct platform_device *pdev)
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{
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struct device_node *np = pdev->dev.of_node;
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struct device_node *adapter_np, *child;
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struct i2c_adapter *adapter;
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struct resource res;
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unsigned *values;
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int i = 0;
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if (!np)
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return -ENODEV;
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adapter_np = of_parse_phandle(np, "i2c-parent", 0);
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if (!adapter_np) {
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dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
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return -ENODEV;
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}
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adapter = of_find_i2c_adapter_by_node(adapter_np);
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of_node_put(adapter_np);
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if (!adapter)
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return -EPROBE_DEFER;
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mux->data.parent = i2c_adapter_id(adapter);
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put_device(&adapter->dev);
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mux->data.n_values = of_get_child_count(np);
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if (of_find_property(np, "little-endian", NULL)) {
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mux->data.little_endian = true;
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} else if (of_find_property(np, "big-endian", NULL)) {
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mux->data.little_endian = false;
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} else {
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#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
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defined(__LITTLE_ENDIAN)
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mux->data.little_endian = true;
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#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
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defined(__BIG_ENDIAN)
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mux->data.little_endian = false;
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#else
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#error Endianness not defined?
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#endif
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}
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if (of_find_property(np, "write-only", NULL))
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mux->data.write_only = true;
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else
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mux->data.write_only = false;
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values = devm_kzalloc(&pdev->dev,
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sizeof(*mux->data.values) * mux->data.n_values,
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GFP_KERNEL);
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if (!values) {
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dev_err(&pdev->dev, "Cannot allocate values array");
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return -ENOMEM;
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}
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for_each_child_of_node(np, child) {
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of_property_read_u32(child, "reg", values + i);
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i++;
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}
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mux->data.values = values;
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if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
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mux->data.idle_in_use = true;
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/* map address from "reg" if exists */
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if (of_address_to_resource(np, 0, &res) == 0) {
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mux->data.reg_size = resource_size(&res);
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mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
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if (IS_ERR(mux->data.reg))
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return PTR_ERR(mux->data.reg);
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}
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return 0;
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}
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#else
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static int i2c_mux_reg_probe_dt(struct regmux *mux,
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struct platform_device *pdev)
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{
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return 0;
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}
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#endif
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static int i2c_mux_reg_probe(struct platform_device *pdev)
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{
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struct i2c_mux_core *muxc;
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struct regmux *mux;
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struct i2c_adapter *parent;
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struct resource *res;
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unsigned int class;
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int i, ret, nr;
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mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
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if (!mux)
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return -ENOMEM;
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if (dev_get_platdata(&pdev->dev)) {
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memcpy(&mux->data, dev_get_platdata(&pdev->dev),
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sizeof(mux->data));
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} else {
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ret = i2c_mux_reg_probe_dt(mux, pdev);
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if (ret < 0) {
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dev_err(&pdev->dev, "Error parsing device tree");
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return ret;
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}
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}
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parent = i2c_get_adapter(mux->data.parent);
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if (!parent)
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return -EPROBE_DEFER;
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if (!mux->data.reg) {
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dev_info(&pdev->dev,
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"Register not set, using platform resource\n");
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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mux->data.reg_size = resource_size(res);
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mux->data.reg = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(mux->data.reg)) {
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ret = PTR_ERR(mux->data.reg);
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goto err_put_parent;
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}
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}
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if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
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mux->data.reg_size != 1) {
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dev_err(&pdev->dev, "Invalid register size\n");
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ret = -EINVAL;
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goto err_put_parent;
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}
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muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
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i2c_mux_reg_select, NULL);
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if (!muxc) {
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ret = -ENOMEM;
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goto err_put_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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if (mux->data.idle_in_use)
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muxc->deselect = i2c_mux_reg_deselect;
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for (i = 0; i < mux->data.n_values; i++) {
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nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
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class = mux->data.classes ? mux->data.classes[i] : 0;
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ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
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if (ret)
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goto err_del_mux_adapters;
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}
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dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
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mux->data.n_values, muxc->parent->name);
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return 0;
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err_del_mux_adapters:
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i2c_mux_del_adapters(muxc);
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err_put_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_reg_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 const struct of_device_id i2c_mux_reg_of_match[] = {
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{ .compatible = "i2c-mux-reg", },
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
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static struct platform_driver i2c_mux_reg_driver = {
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.probe = i2c_mux_reg_probe,
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.remove = i2c_mux_reg_remove,
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.driver = {
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.name = "i2c-mux-reg",
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.of_match_table = of_match_ptr(i2c_mux_reg_of_match),
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},
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};
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module_platform_driver(i2c_mux_reg_driver);
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MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
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MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:i2c-mux-reg");
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