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@@ -0,0 +1,215 @@
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+/*
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+ * Bitbanging I2C bus driver using the GPIO API
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+ *
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+ * Copyright (C) 2007 Atmel Corporation
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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-algo-bit.h>
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+#include <linux/i2c-gpio.h>
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+#include <linux/init.h>
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+#include <linux/module.h>
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+#include <linux/platform_device.h>
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+
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+#include <asm/gpio.h>
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+
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+/* Toggle SDA by changing the direction of the pin */
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+static void i2c_gpio_setsda_dir(void *data, int state)
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+{
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+ struct i2c_gpio_platform_data *pdata = data;
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+
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+ if (state)
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+ gpio_direction_input(pdata->sda_pin);
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+ else
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+ gpio_direction_output(pdata->sda_pin, 0);
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+}
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+
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+/*
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+ * Toggle SDA by changing the output value of the pin. This is only
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+ * valid for pins configured as open drain (i.e. setting the value
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+ * high effectively turns off the output driver.)
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+ */
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+static void i2c_gpio_setsda_val(void *data, int state)
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+{
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+ struct i2c_gpio_platform_data *pdata = data;
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+
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+ gpio_set_value(pdata->sda_pin, state);
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+}
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+
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+/* Toggle SCL by changing the direction of the pin. */
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+static void i2c_gpio_setscl_dir(void *data, int state)
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+{
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+ struct i2c_gpio_platform_data *pdata = data;
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+
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+ if (state)
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+ gpio_direction_input(pdata->scl_pin);
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+ else
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+ gpio_direction_output(pdata->scl_pin, 0);
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+}
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+
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+/*
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+ * Toggle SCL by changing the output value of the pin. This is used
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+ * for pins that are configured as open drain and for output-only
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+ * pins. The latter case will break the i2c protocol, but it will
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+ * often work in practice.
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+ */
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+static void i2c_gpio_setscl_val(void *data, int state)
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+{
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+ struct i2c_gpio_platform_data *pdata = data;
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+
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+ gpio_set_value(pdata->scl_pin, state);
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+}
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+
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+int i2c_gpio_getsda(void *data)
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+{
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+ struct i2c_gpio_platform_data *pdata = data;
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+
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+ return gpio_get_value(pdata->sda_pin);
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+}
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+
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+int i2c_gpio_getscl(void *data)
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+{
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+ struct i2c_gpio_platform_data *pdata = data;
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+
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+ return gpio_get_value(pdata->scl_pin);
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+}
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+
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+static int __init i2c_gpio_probe(struct platform_device *pdev)
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+{
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+ struct i2c_gpio_platform_data *pdata;
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+ struct i2c_algo_bit_data *bit_data;
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+ struct i2c_adapter *adap;
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+ int ret;
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+
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+ pdata = pdev->dev.platform_data;
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+ if (!pdata)
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+ return -ENXIO;
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+
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+ ret = -ENOMEM;
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+ adap = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
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+ if (!adap)
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+ goto err_alloc_adap;
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+ bit_data = kzalloc(sizeof(struct i2c_algo_bit_data), GFP_KERNEL);
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+ if (!bit_data)
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+ goto err_alloc_bit_data;
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+
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+ ret = gpio_request(pdata->sda_pin, "sda");
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+ if (ret)
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+ goto err_request_sda;
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+ ret = gpio_request(pdata->scl_pin, "scl");
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+ if (ret)
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+ goto err_request_scl;
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+
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+ if (pdata->sda_is_open_drain) {
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+ gpio_direction_output(pdata->sda_pin, 1);
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+ bit_data->setsda = i2c_gpio_setsda_val;
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+ } else {
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+ gpio_direction_input(pdata->sda_pin);
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+ bit_data->setsda = i2c_gpio_setsda_dir;
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+ }
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+
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+ if (pdata->scl_is_open_drain || pdata->scl_is_output_only) {
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+ gpio_direction_output(pdata->scl_pin, 1);
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+ bit_data->setscl = i2c_gpio_setscl_val;
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+ } else {
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+ gpio_direction_input(pdata->scl_pin);
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+ bit_data->setscl = i2c_gpio_setscl_dir;
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+ }
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+
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+ if (!pdata->scl_is_output_only)
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+ bit_data->getscl = i2c_gpio_getscl;
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+ bit_data->getsda = i2c_gpio_getsda;
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+
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+ if (pdata->udelay)
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+ bit_data->udelay = pdata->udelay;
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+ else if (pdata->scl_is_output_only)
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+ bit_data->udelay = 50; /* 10 kHz */
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+ else
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+ bit_data->udelay = 5; /* 100 kHz */
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+
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+ if (pdata->timeout)
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+ bit_data->timeout = pdata->timeout;
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+ else
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+ bit_data->timeout = HZ / 10; /* 100 ms */
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+
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+ bit_data->data = pdata;
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+
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+ adap->owner = THIS_MODULE;
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+ snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
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+ adap->algo_data = bit_data;
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+ adap->dev.parent = &pdev->dev;
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+
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+ ret = i2c_bit_add_bus(adap);
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+ if (ret)
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+ goto err_add_bus;
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+
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+ platform_set_drvdata(pdev, adap);
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+
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+ dev_info(&pdev->dev, "using pins %u (SDA) and %u (SCL%s)\n",
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+ pdata->sda_pin, pdata->scl_pin,
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+ pdata->scl_is_output_only
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+ ? ", no clock stretching" : "");
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+
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+ return 0;
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+
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+err_add_bus:
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+ gpio_free(pdata->scl_pin);
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+err_request_scl:
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+ gpio_free(pdata->sda_pin);
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+err_request_sda:
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+ kfree(bit_data);
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+err_alloc_bit_data:
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+ kfree(adap);
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+err_alloc_adap:
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+ return ret;
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+}
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+
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+static int __exit i2c_gpio_remove(struct platform_device *pdev)
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+{
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+ struct i2c_gpio_platform_data *pdata;
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+ struct i2c_adapter *adap;
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+
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+ adap = platform_get_drvdata(pdev);
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+ pdata = pdev->dev.platform_data;
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+
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+ i2c_del_adapter(adap);
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+ gpio_free(pdata->scl_pin);
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+ gpio_free(pdata->sda_pin);
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+ kfree(adap->algo_data);
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+ kfree(adap);
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+
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+ return 0;
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+}
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+
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+static struct platform_driver i2c_gpio_driver = {
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+ .driver = {
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+ .name = "i2c-gpio",
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+ .owner = THIS_MODULE,
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+ },
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+ .remove = __exit_p(i2c_gpio_remove),
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+};
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+
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+static int __init i2c_gpio_init(void)
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+{
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+ int ret;
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+
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+ ret = platform_driver_probe(&i2c_gpio_driver, i2c_gpio_probe);
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+ if (ret)
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+ printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
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+
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+ return ret;
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+}
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+module_init(i2c_gpio_init);
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+
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+static void __exit i2c_gpio_exit(void)
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+{
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+ platform_driver_unregister(&i2c_gpio_driver);
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+}
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+module_exit(i2c_gpio_exit);
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+
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+MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
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+MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
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+MODULE_LICENSE("GPL");
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Haavard Skinnemoen