174 lines
3.8 KiB
C
174 lines
3.8 KiB
C
/*
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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/gpio-i2cmux.h>
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#include <linux/platform_device.h>
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#include <linux/init.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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struct gpiomux {
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struct i2c_adapter *parent;
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struct i2c_adapter **adap; /* child busses */
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struct gpio_i2cmux_platform_data data;
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};
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static void gpiomux_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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gpio_set_value(mux->data.gpios[i], val & (1 << i));
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}
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static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan)
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{
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struct gpiomux *mux = data;
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gpiomux_set(mux, mux->data.values[chan]);
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return 0;
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}
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static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan)
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{
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struct gpiomux *mux = data;
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gpiomux_set(mux, mux->data.idle);
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return 0;
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}
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static int __devinit gpiomux_probe(struct platform_device *pdev)
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{
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struct gpiomux *mux;
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struct gpio_i2cmux_platform_data *pdata;
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struct i2c_adapter *parent;
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int (*deselect) (struct i2c_adapter *, void *, u32);
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unsigned initial_state;
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int i, ret;
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pdata = pdev->dev.platform_data;
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if (!pdata) {
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dev_err(&pdev->dev, "Missing platform data\n");
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return -ENODEV;
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}
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parent = i2c_get_adapter(pdata->parent);
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if (!parent) {
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dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
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pdata->parent);
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return -ENODEV;
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}
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mux = kzalloc(sizeof(*mux), GFP_KERNEL);
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if (!mux) {
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ret = -ENOMEM;
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goto alloc_failed;
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}
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mux->parent = parent;
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mux->data = *pdata;
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mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values,
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GFP_KERNEL);
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if (!mux->adap) {
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ret = -ENOMEM;
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goto alloc_failed2;
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}
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if (pdata->idle != GPIO_I2CMUX_NO_IDLE) {
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initial_state = pdata->idle;
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deselect = gpiomux_deselect;
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} else {
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initial_state = pdata->values[0];
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deselect = NULL;
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}
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for (i = 0; i < pdata->n_gpios; i++) {
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ret = gpio_request(pdata->gpios[i], "gpio-i2cmux");
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if (ret)
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goto err_request_gpio;
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gpio_direction_output(pdata->gpios[i],
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initial_state & (1 << i));
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}
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for (i = 0; i < pdata->n_values; i++) {
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u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
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mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i,
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gpiomux_select, deselect);
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if (!mux->adap[i]) {
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ret = -ENODEV;
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dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
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goto add_adapter_failed;
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}
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}
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dev_info(&pdev->dev, "%d port mux on %s adapter\n",
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pdata->n_values, parent->name);
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platform_set_drvdata(pdev, mux);
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return 0;
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add_adapter_failed:
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for (; i > 0; i--)
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i2c_del_mux_adapter(mux->adap[i - 1]);
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i = pdata->n_gpios;
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err_request_gpio:
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for (; i > 0; i--)
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gpio_free(pdata->gpios[i - 1]);
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kfree(mux->adap);
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alloc_failed2:
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kfree(mux);
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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 __devexit gpiomux_remove(struct platform_device *pdev)
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{
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struct gpiomux *mux = platform_get_drvdata(pdev);
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int i;
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for (i = 0; i < mux->data.n_values; i++)
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i2c_del_mux_adapter(mux->adap[i]);
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for (i = 0; i < mux->data.n_gpios; i++)
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gpio_free(mux->data.gpios[i]);
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platform_set_drvdata(pdev, NULL);
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i2c_put_adapter(mux->parent);
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kfree(mux->adap);
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kfree(mux);
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return 0;
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}
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static struct platform_driver gpiomux_driver = {
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.probe = gpiomux_probe,
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.remove = __devexit_p(gpiomux_remove),
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.driver = {
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.owner = THIS_MODULE,
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.name = "gpio-i2cmux",
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},
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};
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module_platform_driver(gpiomux_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:gpio-i2cmux");
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