1 files changed, 258 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..5ca03bd34
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C multiplexer using GPIO API
+ *
+ * Peter Korsgaard <peter.korsgaard@barco.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/overflow.h>
+#include <linux/platform_data/i2c-mux-gpio.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/bits.h>
+#include <linux/gpio/consumer.h>
+/* FIXME: stop poking around inside gpiolib */
+#include "../../gpio/gpiolib.h"
+
+struct gpiomux {
+	struct i2c_mux_gpio_platform_data data;
+	int ngpios;
+	struct gpio_desc **gpios;
+};
+
+static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
+{
+	DECLARE_BITMAP(values, BITS_PER_TYPE(val));
+
+	values[0] = val;
+
+	gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
+}
+
+static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct gpiomux *mux = i2c_mux_priv(muxc);
+
+	i2c_mux_gpio_set(mux, chan);
+
+	return 0;
+}
+
+static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct gpiomux *mux = i2c_mux_priv(muxc);
+
+	i2c_mux_gpio_set(mux, mux->data.idle);
+
+	return 0;
+}
+
+static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
+				 struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
+	struct device_node *np = dev->of_node;
+	struct device_node *adapter_np;
+	struct i2c_adapter *adapter = NULL;
+	struct fwnode_handle *child;
+	unsigned *values;
+	int rc, i = 0;
+
+	if (is_of_node(fwnode)) {
+		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);
+		of_node_put(adapter_np);
+
+	} else if (is_acpi_node(fwnode)) {
+		/*
+		 * In ACPI land the mux should be a direct child of the i2c
+		 * bus it muxes.
+		 */
+		acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
+
+		adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
+	}
+
+	if (!adapter)
+		return -EPROBE_DEFER;
+
+	mux->data.parent = i2c_adapter_id(adapter);
+	put_device(&adapter->dev);
+
+	mux->data.n_values = device_get_child_node_count(dev);
+	values = devm_kcalloc(dev,
+			      mux->data.n_values, sizeof(*mux->data.values),
+			      GFP_KERNEL);
+	if (!values) {
+		dev_err(dev, "Cannot allocate values array");
+		return -ENOMEM;
+	}
+
+	device_for_each_child_node(dev, child) {
+		if (is_of_node(child)) {
+			fwnode_property_read_u32(child, "reg", values + i);
+
+		} else if (is_acpi_node(child)) {
+			rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
+			if (rc) {
+				fwnode_handle_put(child);
+				return dev_err_probe(dev, rc, "Cannot get address\n");
+			}
+		}
+
+		i++;
+	}
+	mux->data.values = values;
+
+	if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
+		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
+
+	return 0;
+}
+
+static int i2c_mux_gpio_probe(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc;
+	struct gpiomux *mux;
+	struct i2c_adapter *parent;
+	struct i2c_adapter *root;
+	unsigned initial_state;
+	int i, ngpios, ret;
+
+	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return -ENOMEM;
+
+	if (!dev_get_platdata(&pdev->dev)) {
+		ret = i2c_mux_gpio_probe_fw(mux, pdev);
+		if (ret < 0)
+			return ret;
+	} else {
+		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
+			sizeof(mux->data));
+	}
+
+	ngpios = gpiod_count(&pdev->dev, "mux");
+	if (ngpios <= 0) {
+		dev_err(&pdev->dev, "no valid gpios provided\n");
+		return ngpios ?: -EINVAL;
+	}
+	mux->ngpios = ngpios;
+
+	parent = i2c_get_adapter(mux->data.parent);
+	if (!parent)
+		return -EPROBE_DEFER;
+
+	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
+			     array_size(ngpios, sizeof(*mux->gpios)), 0,
+			     i2c_mux_gpio_select, NULL);
+	if (!muxc) {
+		ret = -ENOMEM;
+		goto alloc_failed;
+	}
+	mux->gpios = muxc->priv;
+	muxc->priv = mux;
+
+	platform_set_drvdata(pdev, muxc);
+
+	root = i2c_root_adapter(&parent->dev);
+
+	muxc->mux_locked = true;
+
+	if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
+		initial_state = mux->data.idle;
+		muxc->deselect = i2c_mux_gpio_deselect;
+	} else {
+		initial_state = mux->data.values[0];
+	}
+
+	for (i = 0; i < ngpios; i++) {
+		struct device *gpio_dev;
+		struct gpio_desc *gpiod;
+		enum gpiod_flags flag;
+
+		if (initial_state & BIT(i))
+			flag = GPIOD_OUT_HIGH;
+		else
+			flag = GPIOD_OUT_LOW;
+		gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
+		if (IS_ERR(gpiod)) {
+			ret = PTR_ERR(gpiod);
+			goto alloc_failed;
+		}
+
+		mux->gpios[i] = gpiod;
+
+		if (!muxc->mux_locked)
+			continue;
+
+		/* FIXME: find a proper way to access the GPIO device */
+		gpio_dev = &gpiod->gdev->dev;
+		muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
+	}
+
+	if (muxc->mux_locked)
+		dev_info(&pdev->dev, "mux-locked i2c mux\n");
+
+	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;
+
+		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
+		if (ret)
+			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:
+	i2c_mux_del_adapters(muxc);
+alloc_failed:
+	i2c_put_adapter(parent);
+
+	return ret;
+}
+
+static void i2c_mux_gpio_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+}
+
+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_new = 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");