|
@@ -0,0 +1,184 @@
|
|
|
+/*
|
|
|
+ * I2C multiplexer using GPIO API
|
|
|
+ *
|
|
|
+ * Peter Korsgaard <peter.korsgaard@barco.com>
|
|
|
+ *
|
|
|
+ * This program is free software; you can redistribute it and/or modify
|
|
|
+ * it under the terms of the GNU General Public License version 2 as
|
|
|
+ * published by the Free Software Foundation.
|
|
|
+ */
|
|
|
+
|
|
|
+#include <linux/i2c.h>
|
|
|
+#include <linux/i2c-mux.h>
|
|
|
+#include <linux/gpio-i2cmux.h>
|
|
|
+#include <linux/platform_device.h>
|
|
|
+#include <linux/init.h>
|
|
|
+#include <linux/module.h>
|
|
|
+#include <linux/slab.h>
|
|
|
+#include <linux/gpio.h>
|
|
|
+
|
|
|
+struct gpiomux {
|
|
|
+ struct i2c_adapter *parent;
|
|
|
+ struct i2c_adapter **adap; /* child busses */
|
|
|
+ struct gpio_i2cmux_platform_data data;
|
|
|
+};
|
|
|
+
|
|
|
+static void gpiomux_set(const struct gpiomux *mux, unsigned val)
|
|
|
+{
|
|
|
+ int i;
|
|
|
+
|
|
|
+ for (i = 0; i < mux->data.n_gpios; i++)
|
|
|
+ gpio_set_value(mux->data.gpios[i], val & (1 << i));
|
|
|
+}
|
|
|
+
|
|
|
+static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan)
|
|
|
+{
|
|
|
+ struct gpiomux *mux = data;
|
|
|
+
|
|
|
+ gpiomux_set(mux, mux->data.values[chan]);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan)
|
|
|
+{
|
|
|
+ struct gpiomux *mux = data;
|
|
|
+
|
|
|
+ gpiomux_set(mux, mux->data.idle);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int __devinit gpiomux_probe(struct platform_device *pdev)
|
|
|
+{
|
|
|
+ struct gpiomux *mux;
|
|
|
+ struct gpio_i2cmux_platform_data *pdata;
|
|
|
+ struct i2c_adapter *parent;
|
|
|
+ int (*deselect) (struct i2c_adapter *, void *, u32);
|
|
|
+ unsigned initial_state;
|
|
|
+ int i, ret;
|
|
|
+
|
|
|
+ pdata = pdev->dev.platform_data;
|
|
|
+ if (!pdata) {
|
|
|
+ dev_err(&pdev->dev, "Missing platform data\n");
|
|
|
+ return -ENODEV;
|
|
|
+ }
|
|
|
+
|
|
|
+ parent = i2c_get_adapter(pdata->parent);
|
|
|
+ if (!parent) {
|
|
|
+ dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
|
|
|
+ pdata->parent);
|
|
|
+ return -ENODEV;
|
|
|
+ }
|
|
|
+
|
|
|
+ mux = kzalloc(sizeof(*mux), GFP_KERNEL);
|
|
|
+ if (!mux) {
|
|
|
+ ret = -ENOMEM;
|
|
|
+ goto alloc_failed;
|
|
|
+ }
|
|
|
+
|
|
|
+ mux->parent = parent;
|
|
|
+ mux->data = *pdata;
|
|
|
+ mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values,
|
|
|
+ GFP_KERNEL);
|
|
|
+ if (!mux->adap) {
|
|
|
+ ret = -ENOMEM;
|
|
|
+ goto alloc_failed2;
|
|
|
+ }
|
|
|
+
|
|
|
+ if (pdata->idle != GPIO_I2CMUX_NO_IDLE) {
|
|
|
+ initial_state = pdata->idle;
|
|
|
+ deselect = gpiomux_deselect;
|
|
|
+ } else {
|
|
|
+ initial_state = pdata->values[0];
|
|
|
+ deselect = NULL;
|
|
|
+ }
|
|
|
+
|
|
|
+ for (i = 0; i < pdata->n_gpios; i++) {
|
|
|
+ ret = gpio_request(pdata->gpios[i], "gpio-i2cmux");
|
|
|
+ if (ret)
|
|
|
+ goto err_request_gpio;
|
|
|
+ gpio_direction_output(pdata->gpios[i],
|
|
|
+ initial_state & (1 << i));
|
|
|
+ }
|
|
|
+
|
|
|
+ for (i = 0; i < pdata->n_values; i++) {
|
|
|
+ u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
|
|
|
+
|
|
|
+ mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i,
|
|
|
+ gpiomux_select, deselect);
|
|
|
+ if (!mux->adap[i]) {
|
|
|
+ ret = -ENODEV;
|
|
|
+ dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
|
|
|
+ goto add_adapter_failed;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ dev_info(&pdev->dev, "%d port mux on %s adapter\n",
|
|
|
+ pdata->n_values, parent->name);
|
|
|
+
|
|
|
+ platform_set_drvdata(pdev, mux);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+
|
|
|
+add_adapter_failed:
|
|
|
+ for (; i > 0; i--)
|
|
|
+ i2c_del_mux_adapter(mux->adap[i - 1]);
|
|
|
+ i = pdata->n_gpios;
|
|
|
+err_request_gpio:
|
|
|
+ for (; i > 0; i--)
|
|
|
+ gpio_free(pdata->gpios[i - 1]);
|
|
|
+ kfree(mux->adap);
|
|
|
+alloc_failed2:
|
|
|
+ kfree(mux);
|
|
|
+alloc_failed:
|
|
|
+ i2c_put_adapter(parent);
|
|
|
+
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+
|
|
|
+static int __devexit gpiomux_remove(struct platform_device *pdev)
|
|
|
+{
|
|
|
+ struct gpiomux *mux = platform_get_drvdata(pdev);
|
|
|
+ int i;
|
|
|
+
|
|
|
+ for (i = 0; i < mux->data.n_values; i++)
|
|
|
+ i2c_del_mux_adapter(mux->adap[i]);
|
|
|
+
|
|
|
+ for (i = 0; i < mux->data.n_gpios; i++)
|
|
|
+ gpio_free(mux->data.gpios[i]);
|
|
|
+
|
|
|
+ platform_set_drvdata(pdev, NULL);
|
|
|
+ i2c_put_adapter(mux->parent);
|
|
|
+ kfree(mux->adap);
|
|
|
+ kfree(mux);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static struct platform_driver gpiomux_driver = {
|
|
|
+ .probe = gpiomux_probe,
|
|
|
+ .remove = __devexit_p(gpiomux_remove),
|
|
|
+ .driver = {
|
|
|
+ .owner = THIS_MODULE,
|
|
|
+ .name = "gpio-i2cmux",
|
|
|
+ },
|
|
|
+};
|
|
|
+
|
|
|
+static int __init gpiomux_init(void)
|
|
|
+{
|
|
|
+ return platform_driver_register(&gpiomux_driver);
|
|
|
+}
|
|
|
+
|
|
|
+static void __exit gpiomux_exit(void)
|
|
|
+{
|
|
|
+ platform_driver_unregister(&gpiomux_driver);
|
|
|
+}
|
|
|
+
|
|
|
+module_init(gpiomux_init);
|
|
|
+module_exit(gpiomux_exit);
|
|
|
+
|
|
|
+MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
|
|
|
+MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
|
|
|
+MODULE_LICENSE("GPL");
|
|
|
+MODULE_ALIAS("platform:gpio-i2cmux");
|