307 lines
7.1 KiB
C
307 lines
7.1 KiB
C
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/*
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* I2C multiplexer using GPIO API
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*
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* Peter Korsgaard <peter.korsgaard@barco.com>
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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/platform_data/i2c-mux-gpio.h>
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#include <linux/platform_device.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/gpio.h>
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#include "../../gpio/gpiolib.h"
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#include <linux/of_gpio.h>
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struct gpiomux {
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struct i2c_mux_gpio_platform_data data;
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unsigned gpio_base;
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struct gpio_desc **gpios;
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int *values;
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};
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static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
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{
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int i;
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for (i = 0; i < mux->data.n_gpios; i++)
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mux->values[i] = (val >> i) & 1;
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gpiod_set_array_value_cansleep(mux->data.n_gpios,
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mux->gpios, mux->values);
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}
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static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
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{
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struct gpiomux *mux = i2c_mux_priv(muxc);
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i2c_mux_gpio_set(mux, chan);
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return 0;
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}
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static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
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{
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struct gpiomux *mux = i2c_mux_priv(muxc);
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i2c_mux_gpio_set(mux, mux->data.idle);
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return 0;
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}
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static int match_gpio_chip_by_label(struct gpio_chip *chip,
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void *data)
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{
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return !strcmp(chip->label, data);
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}
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#ifdef CONFIG_OF
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static int i2c_mux_gpio_probe_dt(struct gpiomux *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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unsigned *values, *gpios;
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int i = 0, ret;
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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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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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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 = I2C_MUX_GPIO_NO_IDLE;
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mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
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if (mux->data.n_gpios < 0) {
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dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
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return -EINVAL;
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}
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gpios = devm_kcalloc(&pdev->dev,
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mux->data.n_gpios, sizeof(*mux->data.gpios),
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GFP_KERNEL);
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if (!gpios) {
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dev_err(&pdev->dev, "Cannot allocate gpios array");
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return -ENOMEM;
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}
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for (i = 0; i < mux->data.n_gpios; i++) {
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ret = of_get_named_gpio(np, "mux-gpios", i);
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if (ret < 0)
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return ret;
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gpios[i] = ret;
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}
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mux->data.gpios = gpios;
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return 0;
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}
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#else
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static int i2c_mux_gpio_probe_dt(struct gpiomux *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_gpio_probe(struct platform_device *pdev)
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{
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struct i2c_mux_core *muxc;
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struct gpiomux *mux;
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struct i2c_adapter *parent;
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struct i2c_adapter *root;
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unsigned initial_state, gpio_base;
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int i, ret;
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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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ret = i2c_mux_gpio_probe_dt(mux, pdev);
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if (ret < 0)
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return ret;
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} else {
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memcpy(&mux->data, dev_get_platdata(&pdev->dev),
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sizeof(mux->data));
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}
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/*
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* If a GPIO chip name is provided, the GPIO pin numbers provided are
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* relative to its base GPIO number. Otherwise they are absolute.
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*/
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if (mux->data.gpio_chip) {
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struct gpio_chip *gpio;
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gpio = gpiochip_find(mux->data.gpio_chip,
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match_gpio_chip_by_label);
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if (!gpio)
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return -EPROBE_DEFER;
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gpio_base = gpio->base;
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} else {
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gpio_base = 0;
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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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muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
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mux->data.n_gpios * sizeof(*mux->gpios) +
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mux->data.n_gpios * sizeof(*mux->values), 0,
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i2c_mux_gpio_select, NULL);
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if (!muxc) {
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ret = -ENOMEM;
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goto alloc_failed;
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}
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mux->gpios = muxc->priv;
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mux->values = (int *)(mux->gpios + mux->data.n_gpios);
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muxc->priv = mux;
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platform_set_drvdata(pdev, muxc);
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root = i2c_root_adapter(&parent->dev);
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muxc->mux_locked = true;
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mux->gpio_base = gpio_base;
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if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
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initial_state = mux->data.idle;
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muxc->deselect = i2c_mux_gpio_deselect;
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} else {
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initial_state = mux->data.values[0];
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}
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for (i = 0; i < mux->data.n_gpios; i++) {
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struct device *gpio_dev;
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struct gpio_desc *gpio_desc;
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ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
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if (ret) {
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dev_err(&pdev->dev, "Failed to request GPIO %d\n",
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mux->data.gpios[i]);
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goto err_request_gpio;
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}
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ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
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initial_state & (1 << i));
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if (ret) {
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dev_err(&pdev->dev,
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"Failed to set direction of GPIO %d to output\n",
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mux->data.gpios[i]);
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i++; /* gpio_request above succeeded, so must free */
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goto err_request_gpio;
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}
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gpio_desc = gpio_to_desc(gpio_base + mux->data.gpios[i]);
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mux->gpios[i] = gpio_desc;
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if (!muxc->mux_locked)
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continue;
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gpio_dev = &gpio_desc->gdev->dev;
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muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
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}
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if (muxc->mux_locked)
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dev_info(&pdev->dev, "mux-locked i2c mux\n");
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for (i = 0; i < mux->data.n_values; i++) {
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u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
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unsigned int 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 add_adapter_failed;
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}
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dev_info(&pdev->dev, "%d port mux on %s adapter\n",
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mux->data.n_values, parent->name);
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return 0;
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add_adapter_failed:
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i2c_mux_del_adapters(muxc);
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i = mux->data.n_gpios;
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err_request_gpio:
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for (; i > 0; i--)
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gpio_free(gpio_base + mux->data.gpios[i - 1]);
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alloc_failed:
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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_gpio_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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struct gpiomux *mux = i2c_mux_priv(muxc);
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int i;
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i2c_mux_del_adapters(muxc);
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for (i = 0; i < mux->data.n_gpios; i++)
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gpio_free(mux->gpio_base + mux->data.gpios[i]);
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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_gpio_of_match[] = {
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{ .compatible = "i2c-mux-gpio", },
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
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static struct platform_driver i2c_mux_gpio_driver = {
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.probe = i2c_mux_gpio_probe,
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.remove = i2c_mux_gpio_remove,
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.driver = {
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.name = "i2c-mux-gpio",
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.of_match_table = i2c_mux_gpio_of_match,
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},
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};
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module_platform_driver(i2c_mux_gpio_driver);
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MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
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MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:i2c-mux-gpio");
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