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c721f189e8
Devices sharing a reset GPIO could use the reset framework for coordinated handling of that shared GPIO line. We have several cases of such needs, at least for Devicetree-based platforms. If Devicetree-based device requests a reset line, while "resets" Devicetree property is missing but there is a "reset-gpios" one, instantiate a new "reset-gpio" platform device which will handle such reset line. This allows seamless handling of such shared reset-gpios without need of changing Devicetree binding [1]. To avoid creating multiple "reset-gpio" platform devices, store the Devicetree "reset-gpios" GPIO specifiers used for new devices on a linked list. Later such Devicetree GPIO specifier (phandle to GPIO controller, GPIO number and GPIO flags) is used to check if reset controller for given GPIO was already registered. If two devices have conflicting "reset-gpios" property, e.g. with different ACTIVE_xxx flags, this would allow to spawn two separate "reset-gpio" devices, where the second would fail probing on busy GPIO request. Link: https://lore.kernel.org/all/YXi5CUCEi7YmNxXM@robh.at.kernel.org/ [1] Cc: Bartosz Golaszewski <brgl@bgdev.pl> Cc: Chris Packham <chris.packham@alliedtelesis.co.nz> Cc: Sean Anderson <sean.anderson@seco.com> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Acked-by: Linus Walleij <linus.walleij@linaro.org> Link: https://lore.kernel.org/r/20240129115216.96479-5-krzysztof.kozlowski@linaro.org Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
118 lines
3.8 KiB
C
118 lines
3.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_RESET_CONTROLLER_H_
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#define _LINUX_RESET_CONTROLLER_H_
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#include <linux/list.h>
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struct reset_controller_dev;
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/**
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* struct reset_control_ops - reset controller driver callbacks
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*
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* @reset: for self-deasserting resets, does all necessary
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* things to reset the device
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* @assert: manually assert the reset line, if supported
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* @deassert: manually deassert the reset line, if supported
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* @status: return the status of the reset line, if supported
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*/
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struct reset_control_ops {
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int (*reset)(struct reset_controller_dev *rcdev, unsigned long id);
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int (*assert)(struct reset_controller_dev *rcdev, unsigned long id);
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int (*deassert)(struct reset_controller_dev *rcdev, unsigned long id);
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int (*status)(struct reset_controller_dev *rcdev, unsigned long id);
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};
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struct module;
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struct device_node;
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struct of_phandle_args;
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/**
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* struct reset_control_lookup - represents a single lookup entry
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*
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* @list: internal list of all reset lookup entries
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* @provider: name of the reset controller device controlling this reset line
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* @index: ID of the reset controller in the reset controller device
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* @dev_id: name of the device associated with this reset line
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* @con_id: name of the reset line (can be NULL)
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*/
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struct reset_control_lookup {
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struct list_head list;
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const char *provider;
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unsigned int index;
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const char *dev_id;
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const char *con_id;
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};
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#define RESET_LOOKUP(_provider, _index, _dev_id, _con_id) \
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{ \
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.provider = _provider, \
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.index = _index, \
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.dev_id = _dev_id, \
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.con_id = _con_id, \
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}
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/**
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* struct reset_controller_dev - reset controller entity that might
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* provide multiple reset controls
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* @ops: a pointer to device specific struct reset_control_ops
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* @owner: kernel module of the reset controller driver
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* @list: internal list of reset controller devices
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* @reset_control_head: head of internal list of requested reset controls
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* @dev: corresponding driver model device struct
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* @of_node: corresponding device tree node as phandle target
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* @of_args: for reset-gpios controllers: corresponding phandle args with
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* of_node and GPIO number complementing of_node; either this or
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* of_node should be present
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* @of_reset_n_cells: number of cells in reset line specifiers
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* @of_xlate: translation function to translate from specifier as found in the
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* device tree to id as given to the reset control ops, defaults
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* to :c:func:`of_reset_simple_xlate`.
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* @nr_resets: number of reset controls in this reset controller device
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*/
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struct reset_controller_dev {
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const struct reset_control_ops *ops;
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struct module *owner;
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struct list_head list;
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struct list_head reset_control_head;
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struct device *dev;
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struct device_node *of_node;
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const struct of_phandle_args *of_args;
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int of_reset_n_cells;
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int (*of_xlate)(struct reset_controller_dev *rcdev,
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const struct of_phandle_args *reset_spec);
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unsigned int nr_resets;
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};
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#if IS_ENABLED(CONFIG_RESET_CONTROLLER)
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int reset_controller_register(struct reset_controller_dev *rcdev);
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void reset_controller_unregister(struct reset_controller_dev *rcdev);
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struct device;
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int devm_reset_controller_register(struct device *dev,
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struct reset_controller_dev *rcdev);
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void reset_controller_add_lookup(struct reset_control_lookup *lookup,
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unsigned int num_entries);
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#else
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static inline int reset_controller_register(struct reset_controller_dev *rcdev)
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{
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return 0;
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}
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static inline void reset_controller_unregister(struct reset_controller_dev *rcdev)
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{
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}
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static inline int devm_reset_controller_register(struct device *dev,
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struct reset_controller_dev *rcdev)
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{
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return 0;
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}
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static inline void reset_controller_add_lookup(struct reset_control_lookup *lookup,
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unsigned int num_entries)
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{
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}
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#endif
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#endif
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