1 files changed, 289 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
new file mode 100644
index 000000000..70db99264
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -0,0 +1,289 @@
+/*
+ * 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");