Merge tag 'i2c-for-6.13-rc1-part3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c component probing support from Wolfram Sang:
 "Add OF component probing.

  Some devices are designed and manufactured with some components having
  multiple drop-in replacement options. These components are often
  connected to the mainboard via ribbon cables, having the same signals
  and pin assignments across all options. These may include the display
  panel and touchscreen on laptops and tablets, and the trackpad on
  laptops. Sometimes which component option is used in a particular
  device can be detected by some firmware provided identifier, other
  times that information is not available, and the kernel has to try to
  probe each device.

  Instead of a delicate dance between drivers and device tree quirks,
  this change introduces a simple I2C component probe function. For a
  given class of devices on the same I2C bus, it will go through all of
  them, doing a simple I2C read transfer and see which one of them
  responds. It will then enable the device that responds"

* tag 'i2c-for-6.13-rc1-part3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  MAINTAINERS: fix typo in I2C OF COMPONENT PROBER
  of: base: Document prefix argument for of_get_next_child_with_prefix()
  i2c: Fix whitespace style issue
  arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail
  platform/chrome: Introduce device tree hardware prober
  i2c: of-prober: Add GPIO support to simple helpers
  i2c: of-prober: Add simple helpers for regulator support
  i2c: Introduce OF component probe function
  of: base: Add for_each_child_of_node_with_prefix()
  of: dynamic: Add of_changeset_update_prop_string

3 files changed, 166 insertions, 0 deletions

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);