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Diffstat (limited to 'drivers/i2c/muxes/i2c-mux-gpio.c')
-rw-r--r--drivers/i2c/muxes/i2c-mux-gpio.c258
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 0000000000..5ca03bd34c
--- /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");