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Frank LiandLinus Walleij
418a2bbdee
Add an optional .release_mux() callback to struct pinmux_ops.
Some drivers acquire additional resources in .set_mux(), such as software
locks. These resources may need to be released when the mux function is no
longer active. Introducing a dedicated .release_mux() callback allows
drivers to clean up such resources.
The callback is optional and does not affect existing drivers.
Commit 2243a87d90 ("pinctrl: avoid duplicated calling
enable_pinmux_setting for a pin") removed the .disable() callback
to resolve two issues:
1. desc->mux_usecount increasing monotonically
2. Hardware glitches caused by repeated .disable()/.enable() calls
Adding .release_mux() does not reintroduce those problems. The callback is
intended only for releasing driver-side resources (e.g. locks) and must not
modify hardware registers.
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>
102 lines
4.8 KiB
C
102 lines
4.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Interface the pinmux subsystem
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*
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* Copyright (C) 2011 ST-Ericsson SA
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* Written on behalf of Linaro for ST-Ericsson
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* Based on bits of regulator core, gpio core and clk core
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*
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* Author: Linus Walleij <linus.walleij@linaro.org>
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*/
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#ifndef __LINUX_PINCTRL_PINMUX_H
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#define __LINUX_PINCTRL_PINMUX_H
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#include <linux/types.h>
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struct pinctrl_dev;
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struct pinctrl_gpio_range;
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/**
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* struct pinmux_ops - pinmux operations, to be implemented by pin controller
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* drivers that support pinmuxing
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* @request: called by the core to see if a certain pin can be made
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* available for muxing. This is called by the core to acquire the pins
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* before selecting any actual mux setting across a function. The driver
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* is allowed to answer "no" by returning a negative error code
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* @free: the reverse function of the request() callback, frees a pin after
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* being requested
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* @get_functions_count: returns number of selectable named functions available
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* in this pinmux driver
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* @get_function_name: return the function name of the muxing selector,
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* called by the core to figure out which mux setting it shall map a
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* certain device to
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* @get_function_groups: return an array of groups names (in turn
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* referencing pins) connected to a certain function selector. The group
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* name can be used with the generic @pinctrl_ops to retrieve the
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* actual pins affected. The applicable groups will be returned in
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* @groups and the number of groups in @num_groups
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* @function_is_gpio: determine if the indicated function selector passed
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* corresponds to the GPIO function which is used by the accelerated GPIO
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* functions @gpio_request_enable, @gpio_disable_free and
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* @gpio_set_direction. When the pin control core can properly determine
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* if a function is a GPIO function, it is easier to use the @strict mode
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* on the pin controller. Since a single function is passed, this is
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* only useful on pin controllers that use a specific function for GPIO,
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* and that usually presupposes that a one-group-per-pin approach is
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* used, so that a single function can be set on a single pin to turn
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* it to GPIO mode.
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* @set_mux: enable a certain muxing function with a certain pin group. The
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* driver does not need to figure out whether enabling this function
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* conflicts some other use of the pins in that group, such collisions
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* are handled by the pinmux subsystem. The @func_selector selects a
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* certain function whereas @group_selector selects a certain set of pins
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* to be used. On simple controllers the latter argument may be ignored
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* @release_mux: Release software resources acquired by @set_mux. This callback
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* must not change hardware state to avoid glitches when switching mux.
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* @gpio_request_enable: requests and enables GPIO on a certain pin.
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* Implement this only if you can mux every pin individually as GPIO. The
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* affected GPIO range is passed along with an offset(pin number) into that
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* specific GPIO range - function selectors and pin groups are orthogonal
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* to this, the core will however make sure the pins do not collide.
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* @gpio_disable_free: free up GPIO muxing on a certain pin, the reverse of
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* @gpio_request_enable
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* @gpio_set_direction: Since controllers may need different configurations
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* depending on whether the GPIO is configured as input or output,
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* a direction selector function may be implemented as a backing
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* to the GPIO controllers that need pin muxing.
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* @strict: do not allow simultaneous use of the same pin for GPIO and another
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* function. Check both gpio_owner and mux_owner strictly before approving
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* the pin request.
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*/
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struct pinmux_ops {
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int (*request) (struct pinctrl_dev *pctldev, unsigned int offset);
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int (*free) (struct pinctrl_dev *pctldev, unsigned int offset);
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int (*get_functions_count) (struct pinctrl_dev *pctldev);
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const char *(*get_function_name) (struct pinctrl_dev *pctldev,
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unsigned int selector);
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int (*get_function_groups) (struct pinctrl_dev *pctldev,
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unsigned int selector,
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const char * const **groups,
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unsigned int *num_groups);
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bool (*function_is_gpio) (struct pinctrl_dev *pctldev,
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unsigned int selector);
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int (*set_mux) (struct pinctrl_dev *pctldev, unsigned int func_selector,
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unsigned int group_selector);
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void (*release_mux) (struct pinctrl_dev *pctldev,
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unsigned int func_selector,
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unsigned int group_selector);
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int (*gpio_request_enable) (struct pinctrl_dev *pctldev,
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struct pinctrl_gpio_range *range,
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unsigned int offset);
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void (*gpio_disable_free) (struct pinctrl_dev *pctldev,
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struct pinctrl_gpio_range *range,
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unsigned int offset);
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int (*gpio_set_direction) (struct pinctrl_dev *pctldev,
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struct pinctrl_gpio_range *range,
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unsigned int offset,
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bool input);
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bool strict;
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};
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#endif /* __LINUX_PINCTRL_PINMUX_H */
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