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267 lines
6.3 KiB
267 lines
6.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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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 <[email protected]> |
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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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/* |
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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_property_read_bool(np, "little-endian")) { |
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mux->data.little_endian = true; |
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} else if (of_property_read_bool(np, "big-endian")) { |
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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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mux->data.write_only = of_property_read_bool(np, "write-only"); |
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values = devm_kcalloc(&pdev->dev, |
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mux->data.n_values, sizeof(*mux->data.values), |
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GFP_KERNEL); |
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if (!values) |
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return -ENOMEM; |
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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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return dev_err_probe(&pdev->dev, ret, |
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"Error parsing device tree"); |
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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 <[email protected]>"); |
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MODULE_LICENSE("GPL"); |
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MODULE_ALIAS("platform:i2c-mux-reg");
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