--- /dev/null
+/*
+ * 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/i2c-mux-gpio.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+
+struct gpiomux {
+ struct i2c_adapter *parent;
+ struct i2c_adapter **adap; /* child busses */
+ struct i2c_mux_gpio_platform_data data;
+ unsigned gpio_base;
+};
+
+static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
+{
+ int i;
+
+ for (i = 0; i < mux->data.n_gpios; i++)
+ gpio_set_value_cansleep(mux->gpio_base + mux->data.gpios[i],
+ val & (1 << i));
+}
+
+static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
+{
+ struct gpiomux *mux = data;
+
+ i2c_mux_gpio_set(mux, chan);
+
+ return 0;
+}
+
+static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
+{
+ struct gpiomux *mux = data;
+
+ i2c_mux_gpio_set(mux, mux->data.idle);
+
+ return 0;
+}
+
+static int match_gpio_chip_by_label(struct gpio_chip *chip,
+ void *data)
+{
+ return !strcmp(chip->label, data);
+}
+
+#ifdef CONFIG_OF
+static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *adapter_np, *child;
+ struct i2c_adapter *adapter;
+ unsigned *values, *gpios;
+ int i = 0, ret;
+
+ if (!np)
+ return -ENODEV;
+
+ adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+ if (!adapter_np) {
+ dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+ return -ENODEV;
+ }
+ adapter = of_find_i2c_adapter_by_node(adapter_np);
+ if (!adapter)
+ return -EPROBE_DEFER;
+
+ mux->data.parent = i2c_adapter_id(adapter);
+ put_device(&adapter->dev);
+
+ mux->data.n_values = of_get_child_count(np);
+
+ values = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->data.values) * mux->data.n_values,
+ GFP_KERNEL);
+ if (!values) {
+ dev_err(&pdev->dev, "Cannot allocate values array");
+ return -ENOMEM;
+ }
+
+ for_each_child_of_node(np, child) {
+ of_property_read_u32(child, "reg", values + i);
+ i++;
+ }
+ mux->data.values = values;
+
+ if (of_property_read_u32(np, "idle-state", &mux->data.idle))
+ mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
+
+ mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
+ if (mux->data.n_gpios < 0) {
+ dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
+ return -EINVAL;
+ }
+
+ gpios = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
+ if (!gpios) {
+ dev_err(&pdev->dev, "Cannot allocate gpios array");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < mux->data.n_gpios; i++) {
+ ret = of_get_named_gpio(np, "mux-gpios", i);
+ if (ret < 0)
+ return ret;
+ gpios[i] = ret;
+ }
+
+ mux->data.gpios = gpios;
+
+ return 0;
+}
+#else
+static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ return 0;
+}
+#endif
+
+static int i2c_mux_gpio_probe(struct platform_device *pdev)
+{
+ struct gpiomux *mux;
+ struct i2c_adapter *parent;
+ int (*deselect) (struct i2c_adapter *, void *, u32);
+ unsigned initial_state, gpio_base;
+ int i, ret;
+
+ mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux) {
+ dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
+ return -ENOMEM;
+ }
+
+ platform_set_drvdata(pdev, mux);
+
+ if (!dev_get_platdata(&pdev->dev)) {
+ ret = i2c_mux_gpio_probe_dt(mux, pdev);
+ if (ret < 0)
+ return ret;
+ } else {
+ memcpy(&mux->data, dev_get_platdata(&pdev->dev),
+ sizeof(mux->data));
+ }
+
+ /*
+ * If a GPIO chip name is provided, the GPIO pin numbers provided are
+ * relative to its base GPIO number. Otherwise they are absolute.
+ */
+ if (mux->data.gpio_chip) {
+ struct gpio_chip *gpio;
+
+ gpio = gpiochip_find(mux->data.gpio_chip,
+ match_gpio_chip_by_label);
+ if (!gpio)
+ return -EPROBE_DEFER;
+
+ gpio_base = gpio->base;
+ } else {
+ gpio_base = 0;
+ }
+
+ parent = i2c_get_adapter(mux->data.parent);
+ if (!parent)
+ return -EPROBE_DEFER;
+
+ mux->parent = parent;
+ mux->gpio_base = gpio_base;
+
+ mux->adap = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->adap) * mux->data.n_values,
+ GFP_KERNEL);
+ if (!mux->adap) {
+ dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
+ ret = -ENOMEM;
+ goto alloc_failed;
+ }
+
+ if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
+ initial_state = mux->data.idle;
+ deselect = i2c_mux_gpio_deselect;
+ } else {
+ initial_state = mux->data.values[0];
+ deselect = NULL;
+ }
+
+ for (i = 0; i < mux->data.n_gpios; i++) {
+ ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to request GPIO %d\n",
+ mux->data.gpios[i]);
+ goto err_request_gpio;
+ }
+
+ ret = gpio_direction_output(gpio_base + mux->data.gpios[i],
+ initial_state & (1 << i));
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Failed to set direction of GPIO %d to output\n",
+ mux->data.gpios[i]);
+ i++; /* gpio_request above succeeded, so must free */
+ goto err_request_gpio;
+ }
+ }
+
+ for (i = 0; i < mux->data.n_values; i++) {
+ u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
+ unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
+
+ mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
+ mux->data.values[i], class,
+ i2c_mux_gpio_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",
+ mux->data.n_values, parent->name);
+
+ return 0;
+
+add_adapter_failed:
+ for (; i > 0; i--)
+ i2c_del_mux_adapter(mux->adap[i - 1]);
+ i = mux->data.n_gpios;
+err_request_gpio:
+ for (; i > 0; i--)
+ gpio_free(gpio_base + mux->data.gpios[i - 1]);
+alloc_failed:
+ i2c_put_adapter(parent);
+
+ return ret;
+}
+
+static int i2c_mux_gpio_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->gpio_base + mux->data.gpios[i]);
+
+ i2c_put_adapter(mux->parent);
+
+ return 0;
+}
+
+static const struct of_device_id i2c_mux_gpio_of_match[] = {
+ { .compatible = "i2c-mux-gpio", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
+
+static struct platform_driver i2c_mux_gpio_driver = {
+ .probe = i2c_mux_gpio_probe,
+ .remove = i2c_mux_gpio_remove,
+ .driver = {
+ .name = "i2c-mux-gpio",
+ .of_match_table = i2c_mux_gpio_of_match,
+ },
+};
+
+module_platform_driver(i2c_mux_gpio_driver);
+
+MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
+MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-mux-gpio");
Code Review / kvmfornfv.git / blobdiff