From 81de291d86b704de1809cfb06672902d003cf3a3 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Wed, 6 Nov 2024 17:33:28 +0800 Subject: of: dynamic: Add of_changeset_update_prop_string Add a helper function to add string property updates to an OF changeset. This is similar to of_changeset_add_prop_string(), but instead of adding the property (and failing if it exists), it will update the property. This shall be used later in the DT hardware prober. Signed-off-by: Chen-Yu Tsai Reviewed-by: Rob Herring (Arm) Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Wolfram Sang --- include/linux/of.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/of.h b/include/linux/of.h index 086a60f3b8a6..d0307e3b093d 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -1651,6 +1651,10 @@ static inline int of_changeset_add_prop_u32(struct of_changeset *ocs, return of_changeset_add_prop_u32_array(ocs, np, prop_name, &val, 1); } +int of_changeset_update_prop_string(struct of_changeset *ocs, + struct device_node *np, + const char *prop_name, const char *str); + int of_changeset_add_prop_bool(struct of_changeset *ocs, struct device_node *np, const char *prop_name); -- cgit v1.2.3 From 1fcc67e3a354865775355eafec1fb061a755c971 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Wed, 6 Nov 2024 17:33:29 +0800 Subject: of: base: Add for_each_child_of_node_with_prefix() There are cases where drivers would go through child device nodes and operate on only the ones whose node name starts with a given prefix. Provide a helper for these users. This will mainly be used in a subsequent patch that implements a hardware component prober for I2C busses. Signed-off-by: Chen-Yu Tsai Reviewed-by: Rob Herring (Arm) Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Wolfram Sang --- include/linux/of.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include') diff --git a/include/linux/of.h b/include/linux/of.h index d0307e3b093d..f921786cb8ac 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -289,6 +289,9 @@ extern struct device_node *of_get_parent(const struct device_node *node); extern struct device_node *of_get_next_parent(struct device_node *node); extern struct device_node *of_get_next_child(const struct device_node *node, struct device_node *prev); +extern struct device_node *of_get_next_child_with_prefix(const struct device_node *node, + struct device_node *prev, + const char *prefix); extern struct device_node *of_get_next_available_child( const struct device_node *node, struct device_node *prev); extern struct device_node *of_get_next_reserved_child( @@ -1468,6 +1471,12 @@ static inline int of_property_read_s32(const struct device_node *np, child != NULL; \ child = of_get_next_child(parent, child)) +#define for_each_child_of_node_with_prefix(parent, child, prefix) \ + for (struct device_node *child __free(device_node) = \ + of_get_next_child_with_prefix(parent, NULL, prefix); \ + child != NULL; \ + child = of_get_next_child_with_prefix(parent, child, prefix)) + #define for_each_available_child_of_node(parent, child) \ for (child = of_get_next_available_child(parent, NULL); child != NULL; \ child = of_get_next_available_child(parent, child)) -- cgit v1.2.3 From 157ce8f381efe264933e9366db828d845bade3a1 Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Wed, 6 Nov 2024 17:33:30 +0800 Subject: i2c: Introduce OF component probe function 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. This change attempts to make the "probe each device" case cleaner. The current approach is to have all options added and enabled in the device tree. The kernel would then bind each device and run each driver's probe function. This works, but has been broken before due to the introduction of asynchronous probing, causing multiple instances requesting "shared" resources, such as pinmuxes, GPIO pins, interrupt lines, at the same time, with only one instance succeeding. Work arounds for these include moving the pinmux to the parent I2C controller, using GPIO hogs or pinmux settings to keep the GPIO pins in some fixed configuration, and requesting the interrupt line very late. Such configurations can be seen on the MT8183 Krane Chromebook tablets, and the Qualcomm sc8280xp-based Lenovo Thinkpad 13S. Instead of this 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. This requires some minor modifications in the existing device tree. The status for all the device nodes for the component options must be set to "fail-needs-probe". This makes it clear that some mechanism is needed to enable one of them, and also prevents the prober and device drivers running at the same time. Signed-off-by: Chen-Yu Tsai Reviewed-by: Andy Shevchenko Reviewed-by: Douglas Anderson Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Wolfram Sang --- include/linux/i2c-of-prober.h | 75 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 include/linux/i2c-of-prober.h (limited to 'include') diff --git a/include/linux/i2c-of-prober.h b/include/linux/i2c-of-prober.h new file mode 100644 index 000000000000..e7e052ac9e48 --- /dev/null +++ b/include/linux/i2c-of-prober.h @@ -0,0 +1,75 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Definitions for the Linux I2C OF component prober + * + * Copyright (C) 2024 Google LLC + */ + +#ifndef _LINUX_I2C_OF_PROBER_H +#define _LINUX_I2C_OF_PROBER_H + +#include + +struct device; +struct device_node; + +/** + * struct i2c_of_probe_ops - I2C OF component prober callbacks + * + * A set of callbacks to be used by i2c_of_probe_component(). + * + * All callbacks are optional. Callbacks are called only once per run, and are + * used in the order they are defined in this structure. + * + * All callbacks that have return values shall return %0 on success, + * or a negative error number on failure. + * + * The @dev parameter passed to the callbacks is the same as @dev passed to + * i2c_of_probe_component(). It should only be used for dev_printk() calls + * and nothing else, especially not managed device resource (devres) APIs. + */ +struct i2c_of_probe_ops { + /** + * @enable: Retrieve and enable resources so that the components respond to probes. + * + * It is OK for this callback to return -EPROBE_DEFER since the intended use includes + * retrieving resources and enables them. Resources should be reverted to their initial + * state and released before returning if this fails. + */ + int (*enable)(struct device *dev, struct device_node *bus_node, void *data); + + /** + * @cleanup_early: Release exclusive resources prior to calling probe() on a + * detected component. + * + * Only called if a matching component is actually found. If none are found, + * resources that would have been released in this callback should be released in + * @free_resourcs_late instead. + */ + void (*cleanup_early)(struct device *dev, void *data); + + /** + * @cleanup: Opposite of @enable to balance refcounts and free resources after probing. + * + * Should check if resources were already freed by @cleanup_early. + */ + void (*cleanup)(struct device *dev, void *data); +}; + +/** + * struct i2c_of_probe_cfg - I2C OF component prober configuration + * @ops: Callbacks for the prober to use. + * @type: A string to match the device node name prefix to probe for. + */ +struct i2c_of_probe_cfg { + const struct i2c_of_probe_ops *ops; + const char *type; +}; + +#if IS_ENABLED(CONFIG_OF_DYNAMIC) + +int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx); + +#endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */ + +#endif /* _LINUX_I2C_OF_PROBER_H */ -- cgit v1.2.3 From 897261149d255d03fc90bec6782e3835cacbfdde Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Wed, 6 Nov 2024 17:33:31 +0800 Subject: i2c: of-prober: Add simple helpers for regulator support Add helpers to do regulator management for the I2C OF component prober. Components that the prober intends to probe likely require their regulator supplies be enabled, and GPIOs be toggled to enable them or bring them out of reset before they will respond to probe attempts. GPIOs will be handled in the next patch. The assumption is that the same class of components to be probed are always connected in the same fashion with the same regulator supply and GPIO. The names may vary due to binding differences, but the physical layout does not change. This set of helpers supports at most one regulator supply. The user must specify the node from which the supply is retrieved. The supply name and the amount of time to wait after the supply is enabled are also given by the user. Signed-off-by: Chen-Yu Tsai Reviewed-by: Douglas Anderson Reviewed-by: Andy Shevchenko Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Wolfram Sang --- include/linux/i2c-of-prober.h | 44 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'include') diff --git a/include/linux/i2c-of-prober.h b/include/linux/i2c-of-prober.h index e7e052ac9e48..df95aa6ad90e 100644 --- a/include/linux/i2c-of-prober.h +++ b/include/linux/i2c-of-prober.h @@ -70,6 +70,50 @@ struct i2c_of_probe_cfg { int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cfg, void *ctx); +/** + * DOC: I2C OF component prober simple helpers + * + * Components such as trackpads are commonly connected to a devices baseboard + * with a 6-pin ribbon cable. That gives at most one voltage supply and one + * GPIO (commonly a "enable" or "reset" line) besides the I2C bus, interrupt + * pin, and common ground. Touchscreens, while integrated into the display + * panel's connection, typically have the same set of connections. + * + * A simple set of helpers are provided here for use with the I2C OF component + * prober. This implementation targets such components, allowing for at most + * one regulator supply. + * + * The following helpers are provided: + * * i2c_of_probe_simple_enable() + * * i2c_of_probe_simple_cleanup() + */ + +/** + * struct i2c_of_probe_simple_opts - Options for simple I2C component prober callbacks + * @res_node_compatible: Compatible string of device node to retrieve resources from. + * @supply_name: Name of regulator supply. + * @post_power_on_delay_ms: Delay after regulators are powered on. Passed to msleep(). + */ +struct i2c_of_probe_simple_opts { + const char *res_node_compatible; + const char *supply_name; + unsigned int post_power_on_delay_ms; +}; + +struct regulator; + +struct i2c_of_probe_simple_ctx { + /* public: provided by user before helpers are used. */ + const struct i2c_of_probe_simple_opts *opts; + /* private: internal fields for helpers. */ + struct regulator *supply; +}; + +int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data); +void i2c_of_probe_simple_cleanup(struct device *dev, void *data); + +extern struct i2c_of_probe_ops i2c_of_probe_simple_ops; + #endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */ #endif /* _LINUX_I2C_OF_PROBER_H */ -- cgit v1.2.3 From 39b415f84654892003cebb7c026b7daa3380610b Mon Sep 17 00:00:00 2001 From: Chen-Yu Tsai Date: Wed, 6 Nov 2024 17:33:32 +0800 Subject: i2c: of-prober: Add GPIO support to simple helpers Add GPIO support to the simple helpers for the I2C OF component prober. Components that the prober intends to probe likely require their regulator supplies be enabled, and GPIOs be toggled to enable them or bring them out of reset before they will respond to probe attempts. Regulator supplies were handled in the previous patch. The assumption is that the same class of components to be probed are always connected in the same fashion with the same regulator supply and GPIO. The names may vary due to binding differences, but the physical layout does not change. This supports at most one GPIO pin. The user must specify the GPIO name, the polarity, and the amount of time to wait after the GPIO is toggled. Devices with more than one GPIO pin likely require specific power sequencing beyond what generic code can easily support. Signed-off-by: Chen-Yu Tsai Reviewed-by: Douglas Anderson Reviewed-by: Andy Shevchenko Tested-by: Andrey Skvortsov Reviewed-by: AngeloGioacchino Del Regno Signed-off-by: Wolfram Sang --- include/linux/i2c-of-prober.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'include') diff --git a/include/linux/i2c-of-prober.h b/include/linux/i2c-of-prober.h index df95aa6ad90e..bb6d47f50ee5 100644 --- a/include/linux/i2c-of-prober.h +++ b/include/linux/i2c-of-prober.h @@ -9,6 +9,7 @@ #define _LINUX_I2C_OF_PROBER_H #include +#include struct device; struct device_node; @@ -85,6 +86,7 @@ int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cf * * The following helpers are provided: * * i2c_of_probe_simple_enable() + * * i2c_of_probe_simple_cleanup_early() * * i2c_of_probe_simple_cleanup() */ @@ -92,14 +94,31 @@ int i2c_of_probe_component(struct device *dev, const struct i2c_of_probe_cfg *cf * struct i2c_of_probe_simple_opts - Options for simple I2C component prober callbacks * @res_node_compatible: Compatible string of device node to retrieve resources from. * @supply_name: Name of regulator supply. + * @gpio_name: Name of GPIO. NULL if no GPIO line is used. Empty string ("") if GPIO + * line is unnamed. * @post_power_on_delay_ms: Delay after regulators are powered on. Passed to msleep(). + * @post_gpio_config_delay_ms: Delay after GPIO is configured. Passed to msleep(). + * @gpio_assert_to_enable: %true if GPIO should be asserted, i.e. set to logical high, + * to enable the component. + * + * This describes power sequences common for the class of components supported by the + * simple component prober: + * * @gpio_name is configured to the non-active setting according to @gpio_assert_to_enable. + * * @supply_name regulator supply is enabled. + * * Wait for @post_power_on_delay_ms to pass. + * * @gpio_name is configured to the active setting according to @gpio_assert_to_enable. + * * Wait for @post_gpio_config_delay_ms to pass. */ struct i2c_of_probe_simple_opts { const char *res_node_compatible; const char *supply_name; + const char *gpio_name; unsigned int post_power_on_delay_ms; + unsigned int post_gpio_config_delay_ms; + bool gpio_assert_to_enable; }; +struct gpio_desc; struct regulator; struct i2c_of_probe_simple_ctx { @@ -107,9 +126,11 @@ struct i2c_of_probe_simple_ctx { const struct i2c_of_probe_simple_opts *opts; /* private: internal fields for helpers. */ struct regulator *supply; + struct gpio_desc *gpiod; }; int i2c_of_probe_simple_enable(struct device *dev, struct device_node *bus_node, void *data); +void i2c_of_probe_simple_cleanup_early(struct device *dev, void *data); void i2c_of_probe_simple_cleanup(struct device *dev, void *data); extern struct i2c_of_probe_ops i2c_of_probe_simple_ops; -- cgit v1.2.3