8 files changed, 663 insertions, 1 deletions

diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index af95d6e7f004..d27de18de46f 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -9,6 +9,7 @@ i2c-core-y			:= i2c-core-base.o i2c-core-smbus.o
 i2c-core-$(CONFIG_ACPI)		+= i2c-core-acpi.o
 i2c-core-$(CONFIG_I2C_SLAVE)	+= i2c-core-slave.o
 i2c-core-$(CONFIG_OF)		+= i2c-core-of.o
+i2c-core-$(CONFIG_OF_DYNAMIC)	+= i2c-core-of-prober.o
 
 obj-$(CONFIG_I2C_SMBUS)		+= i2c-smbus.o
 obj-$(CONFIG_I2C_CHARDEV)	+= i2c-dev.o
diff --git a/drivers/i2c/i2c-core-of-prober.c b/drivers/i2c/i2c-core-of-prober.c
new file mode 100644
index 000000000000..b9ca785f8b17
--- /dev/null
+++ b/drivers/i2c/i2c-core-of-prober.c
@@ -0,0 +1,415 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Linux I2C core OF component prober code
+ *
+ * Copyright (C) 2024 Google LLC
+ */
+
+#include <linux/cleanup.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/i2c-of-prober.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+
+/*
+ * Some devices, such as Google Hana Chromebooks, are produced by multiple
+ * vendors each using their preferred components. Such components are all
+ * in the device tree. Instead of having all of them enabled and having each
+ * driver separately try and probe its device while fighting over shared
+ * resources, they can be marked as "fail-needs-probe" and have a prober
+ * figure out which one is actually used beforehand.
+ *
+ * This prober assumes such drop-in parts are on the same I2C bus, have
+ * non-conflicting addresses, and can be directly probed by seeing which
+ * address responds.
+ *
+ * TODO:
+ * - Support I2C muxes
+ */
+
+static struct device_node *i2c_of_probe_get_i2c_node(struct device *dev, const char *type)
+{
+	struct device_node *node __free(device_node) = of_find_node_by_name(NULL, type);
+	if (!node) {
+		dev_err(dev, "Could not find %s device node\n", type);
+		return NULL;
+	}
+
+	struct device_node *i2c_node __free(device_node) = of_get_parent(node);
+	if (!of_node_name_eq(i2c_node, "i2c")) {
+		dev_err(dev, "%s device isn't on I2C bus\n", type);
+		return NULL;
+	}
+
+	if (!of_device_is_available(i2c_node)) {
+		dev_err(dev, "I2C controller not available\n");
+		return NULL;
+	}
+
+	return no_free_ptr(i2c_node);
+}
+
+static int i2c_of_probe_enable_node(struct device *dev, struct device_node *node)
+{
+	int ret;
+
+	dev_dbg(dev, "Enabling %pOF\n", node);
+
+	struct of_changeset *ocs __free(kfree) = kzalloc(sizeof(*ocs), GFP_KERNEL);
+	if (!ocs)
+		return -ENOMEM;
+
+	of_changeset_init(ocs);
+	ret = of_changeset_update_prop_string(ocs, node, "status", "okay");
+	if (ret)
+		return ret;
+
+	ret = of_changeset_apply(ocs);
+	if (ret) {
+		/* ocs needs to be explicitly cleaned up before being freed. */
+		of_changeset_destroy(ocs);
+	} else {
+		/*
+		 * ocs is intentionally kept around as it needs to
+		 * exist as long as the change is applied.
+		 */
+		void *ptr __always_unused = no_free_ptr(ocs);
+	}
+
+	return ret;
+}
+
+static const struct i2c_of_probe_ops i2c_of_probe_dummy_ops;
+
+/**
+ * i2c_of_probe_component() - probe for devices of "type" on the same i2c bus
+ * @dev: Pointer to the &struct device of the caller, only used for dev_printk() messages.
+ * @cfg: Pointer to the &struct i2c_of_probe_cfg containing callbacks and other options
+ *       for the prober.
+ * @ctx: Context data for callbacks.
+ *
+ * Probe for possible I2C components of the same "type" (&i2c_of_probe_cfg->type)
+ * on the same I2C bus that have their status marked as "fail-needs-probe".
+ *
+ * Assumes that across the entire device tree the only instances of nodes
+ * with "type" prefixed node names (not including the address portion) are
+ * the ones that need handling for second source components. In other words,
+ * if "type" is "touchscreen", then all device nodes named "touchscreen*"
+ * are the ones that need probing. There cannot be another "touchscreen*"
+ * node that is already enabled.
+ *
+ * Assumes that for each "type" of component, only one actually exists. In
+ * other words, only one matching and existing device will be enabled.
+ *
+ * Context: Process context only. Does non-atomic I2C transfers.
+ *          Should only be used from a driver probe function, as the function
+ *          can return -EPROBE_DEFER if the I2C adapter or other resources
+ *          are unavailable.
+ * Return: 0 on success or no-op, error code otherwise.
+ *         A no-op can happen when it seems like the device tree already
+ *         has components of the type to be probed already enabled. This
+ *         can happen when the device tree had not been updated to mark
+ *         the status of the to-be-probed components as "fail-needs-probe".
+ *         Or this function was already run with the same parameters and
+ *         succeeded in enabling a component. The latter could happen if
+ *         the user had multiple types of components to probe, and one of
+ *         them down the list caused a deferred probe. This is expected
+ *         behavior.
+ */
+int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx)
+{
+	const struct i2c_of_probe_ops *ops;
+	const char *type;
+	struct i2c_adapter *i2c;
+	int ret;
+
+	ops = cfg->ops ?: &i2c_of_probe_dummy_ops;
+	type = cfg->type;
+
+	struct device_node *i2c_node __free(device_node) = i2c_of_probe_get_i2c_node(dev, type);
+	if (!i2c_node)
+		return -ENODEV;
+
+	/*
+	 * If any devices of the given "type" are already enabled then this function is a no-op.
+	 * Either the device tree hasn't been modified to work with this probe function, or the
+	 * function had already run before and enabled some component.
+	 */
+	for_each_child_of_node_with_prefix(i2c_node, node, type)
+		if (of_device_is_available(node))
+			return 0;
+
+	i2c = of_get_i2c_adapter_by_node(i2c_node);
+	if (!i2c)
+		return dev_err_probe(dev, -EPROBE_DEFER, "Couldn't get I2C adapter\n");
+
+	/* Grab and enable resources */
+	ret = 0;
+	if (ops->enable)
+		ret = ops->enable(dev, i2c_node, ctx);
+	if (ret)
+		goto out_put_i2c_adapter;
+
+	for_each_child_of_node_with_prefix(i2c_node, node, type) {
+		union i2c_smbus_data data;
+		u32 addr;
+
+		if (of_property_read_u32(node, "reg", &addr))
+			continue;
+		if (i2c_smbus_xfer(i2c, addr, 0, I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &data) < 0)
+			continue;
+
+		/* Found a device that is responding */
+		if (ops->cleanup_early)
+			ops->cleanup_early(dev, ctx);
+		ret = i2c_of_probe_enable_node(dev, node);
+		break;
+	}
+
+	if (ops->cleanup)
+		ops->cleanup(dev, ctx);
+out_put_i2c_adapter:
+	i2c_put_adapter(i2c);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_component, I2C_OF_PROBER);
+
+static int i2c_of_probe_simple_get_supply(struct device *dev, struct device_node *node,
+					  struct i2c_of_probe_simple_ctx *ctx)
+{
+	const char *supply_name;
+	struct regulator *supply;
+
+	/*
+	 * It's entirely possible for the component's device node to not have the
+	 * regulator supplies. While it does not make sense from a hardware perspective,
+	 * the supplies could be always on or otherwise not modeled in the device tree,
+	 * but the device would still work.
+	 */
+	supply_name = ctx->opts->supply_name;
+	if (!supply_name)
+		return 0;
+
+	supply = of_regulator_get_optional(dev, node, supply_name);
+	if (IS_ERR(supply)) {
+		return dev_err_probe(dev, PTR_ERR(supply),
+				     "Failed to get regulator supply \"%s\" from %pOF\n",
+				     supply_name, node);
+	}
+
+	ctx->supply = supply;
+
+	return 0;
+}
+
+static void i2c_of_probe_simple_put_supply(struct i2c_of_probe_simple_ctx *ctx)
+{
+	regulator_put(ctx->supply);
+	ctx->supply = NULL;
+}
+
+static int i2c_of_probe_simple_enable_regulator(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
+{
+	int ret;
+
+	if (!ctx->supply)
+		return 0;
+
+	dev_dbg(dev, "Enabling regulator supply \"%s\"\n", ctx->opts->supply_name);
+
+	ret = regulator_enable(ctx->supply);
+	if (ret)
+		return ret;
+
+	if (ctx->opts->post_power_on_delay_ms)
+		msleep(ctx->opts->post_power_on_delay_ms);
+
+	return 0;
+}
+
+static void i2c_of_probe_simple_disable_regulator(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
+{
+	if (!ctx->supply)
+		return;
+
+	dev_dbg(dev, "Disabling regulator supply \"%s\"\n", ctx->opts->supply_name);
+
+	regulator_disable(ctx->supply);
+}
+
+static int i2c_of_probe_simple_get_gpiod(struct device *dev, struct device_node *node,
+					 struct i2c_of_probe_simple_ctx *ctx)
+{
+	struct fwnode_handle *fwnode = of_fwnode_handle(node);
+	struct gpio_desc *gpiod;
+	const char *con_id;
+
+	/* NULL signals no GPIO needed */
+	if (!ctx->opts->gpio_name)
+		return 0;
+
+	/* An empty string signals an unnamed GPIO */
+	if (!ctx->opts->gpio_name[0])
+		con_id = NULL;
+	else
+		con_id = ctx->opts->gpio_name;
+
+	gpiod = fwnode_gpiod_get_index(fwnode, con_id, 0, GPIOD_ASIS, "i2c-of-prober");
+	if (IS_ERR(gpiod))
+		return PTR_ERR(gpiod);
+
+	ctx->gpiod = gpiod;
+
+	return 0;
+}
+
+static void i2c_of_probe_simple_put_gpiod(struct i2c_of_probe_simple_ctx *ctx)
+{
+	gpiod_put(ctx->gpiod);
+	ctx->gpiod = NULL;
+}
+
+static int i2c_of_probe_simple_set_gpio(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
+{
+	int ret;
+
+	if (!ctx->gpiod)
+		return 0;
+
+	dev_dbg(dev, "Configuring GPIO\n");
+
+	ret = gpiod_direction_output(ctx->gpiod, ctx->opts->gpio_assert_to_enable);
+	if (ret)
+		return ret;
+
+	if (ctx->opts->post_gpio_config_delay_ms)
+		msleep(ctx->opts->post_gpio_config_delay_ms);
+
+	return 0;
+}
+
+static void i2c_of_probe_simple_disable_gpio(struct device *dev, struct i2c_of_probe_simple_ctx *ctx)
+{
+	gpiod_set_value(ctx->gpiod, !ctx->opts->gpio_assert_to_enable);
+}
+
+/**
+ * i2c_of_probe_simple_enable - Simple helper for I2C OF prober to get and enable resources
+ * @dev: Pointer to the &struct device of the caller, only used for dev_printk() messages
+ * @bus_node: Pointer to the &struct device_node of the I2C adapter.
+ * @data: Pointer to &struct i2c_of_probe_simple_ctx helper context.
+ *
+ * If &i2c_of_probe_simple_opts->supply_name is given, request the named regulator supply.
+ * If &i2c_of_probe_simple_opts->gpio_name is given, request the named GPIO. Or if it is
+ * the empty string, request the unnamed GPIO.
+ * If a regulator supply was found, enable that regulator.
+ * If a GPIO line was found, configure the GPIO line to output and set value
+ * according to given options.
+ *
+ * Return: %0 on success or no-op, or a negative error number on failure.
+ */
+int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data)
+{
+	struct i2c_of_probe_simple_ctx *ctx = data;
+	struct device_node *node;
+	const char *compat;
+	int ret;
+
+	dev_dbg(dev, "Requesting resources for components under I2C bus %pOF\n", bus_node);
+
+	if (!ctx || !ctx->opts)
+		return -EINVAL;
+
+	compat = ctx->opts->res_node_compatible;
+	if (!compat)
+		return -EINVAL;
+
+	node = of_get_compatible_child(bus_node, compat);
+	if (!node)
+		return dev_err_probe(dev, -ENODEV, "No device compatible with \"%s\" found\n",
+				     compat);
+
+	ret = i2c_of_probe_simple_get_supply(dev, node, ctx);
+	if (ret)
+		goto out_put_node;
+
+	ret = i2c_of_probe_simple_get_gpiod(dev, node, ctx);
+	if (ret)
+		goto out_put_supply;
+
+	ret = i2c_of_probe_simple_enable_regulator(dev, ctx);
+	if (ret)
+		goto out_put_gpiod;
+
+	ret = i2c_of_probe_simple_set_gpio(dev, ctx);
+	if (ret)
+		goto out_disable_regulator;
+
+	return 0;
+
+out_disable_regulator:
+	i2c_of_probe_simple_disable_regulator(dev, ctx);
+out_put_gpiod:
+	i2c_of_probe_simple_put_gpiod(ctx);
+out_put_supply:
+	i2c_of_probe_simple_put_supply(ctx);
+out_put_node:
+	of_node_put(node);
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_enable, I2C_OF_PROBER);
+
+/**
+ * i2c_of_probe_simple_cleanup_early - \
+ *	Simple helper for I2C OF prober to release GPIOs before component is enabled
+ * @dev: Pointer to the &struct device of the caller; unused.
+ * @data: Pointer to &struct i2c_of_probe_simple_ctx helper context.
+ *
+ * GPIO descriptors are exclusive and have to be released before the
+ * actual driver probes so that the latter can acquire them.
+ */
+void i2c_of_probe_simple_cleanup_early(struct device *dev, void *data)
+{
+	struct i2c_of_probe_simple_ctx *ctx = data;
+
+	i2c_of_probe_simple_put_gpiod(ctx);
+}
+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_cleanup_early, I2C_OF_PROBER);
+
+/**
+ * i2c_of_probe_simple_cleanup - Clean up and release resources for I2C OF prober simple helpers
+ * @dev: Pointer to the &struct device of the caller, only used for dev_printk() messages
+ * @data: Pointer to &struct i2c_of_probe_simple_ctx helper context.
+ *
+ * * If a GPIO line was found and not yet released, set its value to the opposite of that
+ *   set in i2c_of_probe_simple_enable() and release it.
+ * * If a regulator supply was found, disable that regulator and release it.
+ */
+void i2c_of_probe_simple_cleanup(struct device *dev, void *data)
+{
+	struct i2c_of_probe_simple_ctx *ctx = data;
+
+	/* GPIO operations here are no-ops if i2c_of_probe_simple_cleanup_early was called. */
+	i2c_of_probe_simple_disable_gpio(dev, ctx);
+	i2c_of_probe_simple_put_gpiod(ctx);
+
+	i2c_of_probe_simple_disable_regulator(dev, ctx);
+	i2c_of_probe_simple_put_supply(ctx);
+}
+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_cleanup, I2C_OF_PROBER);
+
+struct i2c_of_probe_ops i2c_of_probe_simple_ops = {
+	.enable = i2c_of_probe_simple_enable,
+	.cleanup_early = i2c_of_probe_simple_cleanup_early,
+	.cleanup = i2c_of_probe_simple_cleanup,
+};
+EXPORT_SYMBOL_NS_GPL(i2c_of_probe_simple_ops, I2C_OF_PROBER);
diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 0a6bdc6df172..e73afbefe222 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -122,7 +122,7 @@ EXPORT_SYMBOL(i2c_smbus_read_byte);
 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
 {
 	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
-	                      I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
+			      I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
 }
 EXPORT_SYMBOL(i2c_smbus_write_byte);
 
diff --git a/drivers/of/base.c b/drivers/of/base.c
index a8b0c42bdc8e..7dc394255a0a 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -644,6 +644,42 @@ struct device_node *of_get_next_child(const struct device_node *node,
 }
 EXPORT_SYMBOL(of_get_next_child);
 
+/**
+ * of_get_next_child_with_prefix - Find the next child node with prefix
+ * @node:	parent node
+ * @prev:	previous child of the parent node, or NULL to get first
+ * @prefix:	prefix that the node name should have
+ *
+ * This function is like of_get_next_child(), except that it automatically
+ * skips any nodes whose name doesn't have the given prefix.
+ *
+ * Return: A node pointer with refcount incremented, use
+ * of_node_put() on it when done.
+ */
+struct device_node *of_get_next_child_with_prefix(const struct device_node *node,
+						  struct device_node *prev,
+						  const char *prefix)
+{
+	struct device_node *next;
+	unsigned long flags;
+
+	if (!node)
+		return NULL;
+
+	raw_spin_lock_irqsave(&devtree_lock, flags);
+	next = prev ? prev->sibling : node->child;
+	for (; next; next = next->sibling) {
+		if (!of_node_name_prefix(next, prefix))
+			continue;
+		if (of_node_get(next))
+			break;
+	}
+	of_node_put(prev);
+	raw_spin_unlock_irqrestore(&devtree_lock, flags);
+	return next;
+}
+EXPORT_SYMBOL(of_get_next_child_with_prefix);
+
 static struct device_node *of_get_next_status_child(const struct device_node *node,
 						    struct device_node *prev,
 						    bool (*checker)(const struct device_node *))
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index d45a8df61380..0aba760f7577 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -1072,3 +1072,47 @@ int of_changeset_add_prop_bool(struct of_changeset *ocs, struct device_node *np,
 	return of_changeset_add_prop_helper(ocs, np, &prop);
 }
 EXPORT_SYMBOL_GPL(of_changeset_add_prop_bool);
+
+static int of_changeset_update_prop_helper(struct of_changeset *ocs,
+					   struct device_node *np,
+					   const struct property *pp)
+{
+	struct property *new_pp;
+	int ret;
+
+	new_pp = __of_prop_dup(pp, GFP_KERNEL);
+	if (!new_pp)
+		return -ENOMEM;
+
+	ret = of_changeset_update_property(ocs, np, new_pp);
+	if (ret)
+		__of_prop_free(new_pp);
+
+	return ret;
+}
+
+/**
+ * of_changeset_update_prop_string - Add a string property update to a changeset
+ *
+ * @ocs:	changeset pointer
+ * @np:		device node pointer
+ * @prop_name:	name of the property to be updated
+ * @str:	pointer to null terminated string
+ *
+ * Create a string property to be updated and add it to a changeset.
+ *
+ * Return: 0 on success, a negative error value in case of an error.
+ */
+int of_changeset_update_prop_string(struct of_changeset *ocs,
+				    struct device_node *np,
+				    const char *prop_name, const char *str)
+{
+	struct property prop = {
+		.name = (char *)prop_name,
+		.length = strlen(str) + 1,
+		.value = (void *)str,
+	};
+
+	return of_changeset_update_prop_helper(ocs, np, &prop);
+}
+EXPORT_SYMBOL_GPL(of_changeset_update_prop_string);
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 7dbeb786352a..b7dbaf77b6db 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -61,6 +61,17 @@ config CHROMEOS_TBMC
 	  To compile this driver as a module, choose M here: the
 	  module will be called chromeos_tbmc.
 
+config CHROMEOS_OF_HW_PROBER
+	tristate "ChromeOS Device Tree Hardware Prober"
+	depends on OF
+	depends on I2C
+	select OF_DYNAMIC
+	default OF
+	help
+	  This option enables the device tree hardware prober for ChromeOS
+	  devices. The driver will probe the correct component variant in
+	  devices that have multiple drop-in options for one component.
+
 config CROS_EC
 	tristate "ChromeOS Embedded Controller"
 	select CROS_EC_PROTO
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 2dcc6ccc2302..fb8335458a22 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -6,6 +6,7 @@ CFLAGS_cros_ec_sensorhub_ring.o:=	-I$(src)
 
 obj-$(CONFIG_CHROMEOS_ACPI)		+= chromeos_acpi.o
 obj-$(CONFIG_CHROMEOS_LAPTOP)		+= chromeos_laptop.o
+obj-$(CONFIG_CHROMEOS_OF_HW_PROBER)	+= chromeos_of_hw_prober.o
 obj-$(CONFIG_CHROMEOS_PRIVACY_SCREEN)	+= chromeos_privacy_screen.o
 obj-$(CONFIG_CHROMEOS_PSTORE)		+= chromeos_pstore.o
 obj-$(CONFIG_CHROMEOS_TBMC)		+= chromeos_tbmc.o
diff --git a/drivers/platform/chrome/chromeos_of_hw_prober.c b/drivers/platform/chrome/chromeos_of_hw_prober.c
new file mode 100644
index 000000000000..297d4704b75f
--- /dev/null
+++ b/drivers/platform/chrome/chromeos_of_hw_prober.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ChromeOS Device Tree Hardware Prober
+ *
+ * Copyright (c) 2024 Google LLC
+ */
+
+#include <linux/array_size.h>
+#include <linux/errno.h>
+#include <linux/i2c-of-prober.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/stddef.h>
+
+#define DRV_NAME	"chromeos_of_hw_prober"
+
+/**
+ * struct hw_prober_entry - Holds an entry for the hardware prober
+ *
+ * @compatible:	compatible string to match against the machine
+ * @prober:	prober function to call when machine matches
+ * @data:	extra data for the prober function
+ */
+struct hw_prober_entry {
+	const char *compatible;
+	int (*prober)(struct device *dev, const void *data);
+	const void *data;
+};
+
+struct chromeos_i2c_probe_data {
+	const struct i2c_of_probe_cfg *cfg;
+	const struct i2c_of_probe_simple_opts *opts;
+};
+
+static int chromeos_i2c_component_prober(struct device *dev, const void *_data)
+{
+	const struct chromeos_i2c_probe_data *data = _data;
+	struct i2c_of_probe_simple_ctx ctx = {
+		.opts = data->opts,
+	};
+
+	return i2c_of_probe_component(dev, data->cfg, &ctx);
+}
+
+#define DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(_type)					\
+	static const struct i2c_of_probe_cfg chromeos_i2c_probe_simple_ ## _type ## _cfg = {	\
+		.type = #_type,									\
+		.ops = &i2c_of_probe_simple_ops,						\
+	}
+
+#define DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(_type)					\
+	static const struct chromeos_i2c_probe_data chromeos_i2c_probe_dumb_ ## _type = {	\
+		.cfg = &(const struct i2c_of_probe_cfg) {					\
+			.type = #_type,								\
+		},										\
+	}
+
+DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(touchscreen);
+
+DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(trackpad);
+
+static const struct chromeos_i2c_probe_data chromeos_i2c_probe_hana_trackpad = {
+	.cfg = &chromeos_i2c_probe_simple_trackpad_cfg,
+	.opts = &(const struct i2c_of_probe_simple_opts) {
+		.res_node_compatible = "elan,ekth3000",
+		.supply_name = "vcc",
+		/*
+		 * ELAN trackpad needs 2 ms for H/W init and 100 ms for F/W init.
+		 * Synaptics trackpad needs 100 ms.
+		 * However, the regulator is set to "always-on", presumably to
+		 * avoid this delay. The ELAN driver is also missing delays.
+		 */
+		.post_power_on_delay_ms = 0,
+	},
+};
+
+static const struct hw_prober_entry hw_prober_platforms[] = {
+	{
+		.compatible = "google,hana",
+		.prober = chromeos_i2c_component_prober,
+		.data = &chromeos_i2c_probe_dumb_touchscreen,
+	}, {
+		.compatible = "google,hana",
+		.prober = chromeos_i2c_component_prober,
+		.data = &chromeos_i2c_probe_hana_trackpad,
+	},
+};
+
+static int chromeos_of_hw_prober_probe(struct platform_device *pdev)
+{
+	for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) {
+		int ret;
+
+		if (!of_machine_is_compatible(hw_prober_platforms[i].compatible))
+			continue;
+
+		ret = hw_prober_platforms[i].prober(&pdev->dev, hw_prober_platforms[i].data);
+		/* Ignore unrecoverable errors and keep going through other probers */
+		if (ret == -EPROBE_DEFER)
+			return ret;
+	}
+
+	return 0;
+}
+
+static struct platform_driver chromeos_of_hw_prober_driver = {
+	.probe	= chromeos_of_hw_prober_probe,
+	.driver	= {
+		.name = DRV_NAME,
+	},
+};
+
+static struct platform_device *chromeos_of_hw_prober_pdev;
+
+static int chromeos_of_hw_prober_driver_init(void)
+{
+	size_t i;
+	int ret;
+
+	for (i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++)
+		if (of_machine_is_compatible(hw_prober_platforms[i].compatible))
+			break;
+	if (i == ARRAY_SIZE(hw_prober_platforms))
+		return -ENODEV;
+
+	ret = platform_driver_register(&chromeos_of_hw_prober_driver);
+	if (ret)
+		return ret;
+
+	chromeos_of_hw_prober_pdev =
+			platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0);
+	if (IS_ERR(chromeos_of_hw_prober_pdev))
+		goto err;
+
+	return 0;
+
+err:
+	platform_driver_unregister(&chromeos_of_hw_prober_driver);
+
+	return PTR_ERR(chromeos_of_hw_prober_pdev);
+}
+module_init(chromeos_of_hw_prober_driver_init);
+
+static void chromeos_of_hw_prober_driver_exit(void)
+{
+	platform_device_unregister(chromeos_of_hw_prober_pdev);
+	platform_driver_unregister(&chromeos_of_hw_prober_driver);
+}
+module_exit(chromeos_of_hw_prober_driver_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS device tree hardware prober");
+MODULE_IMPORT_NS(I2C_OF_PROBER);