ef0eebc051
For pinctrl the "default" state is applied to pins before the driver's probe function is called. This is normally a sensible thing to do, but in some cases can cause problems. That's because the pins will change state before the driver is given a chance to program how those pins should behave. As an example you might have a regulator that is controlled by a PWM (output high = high voltage, output low = low voltage). The firmware might leave this pin as driven high. If we allow the driver core to reconfigure this pin as a PWM pin before the PWM's probe function runs then you might end up running at too low of a voltage while we probe. Let's introudce a new "init" state. If this is defined we'll set pinctrl to this state before probe and then "default" after probe (unless the driver explicitly changed states already). An alternative idea that was thought of was to use the pre-existing "sleep" or "idle" states and add a boolean property that we should start in that mode. This was not done because the "init" state is needed for correctness and those other states are only present (and only transitioned in to and out of) when (optional) power management is enabled. Changes in v3: - Moved declarations to pinctrl/devinfo.h - Fixed author/SoB Changes in v2: - Added comment to pinctrl_init_done() as per Linus W. Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Tested-by: Caesar Wang <wxt@rock-chips.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
/*
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* Per-device information from the pin control system.
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* This is the stuff that get included into the device
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* core.
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*
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* Copyright (C) 2012 ST-Ericsson SA
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* Written on behalf of Linaro for ST-Ericsson
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* This interface is used in the core to keep track of pins.
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*
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* Author: Linus Walleij <linus.walleij@linaro.org>
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*
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* License terms: GNU General Public License (GPL) version 2
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*/
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#ifndef PINCTRL_DEVINFO_H
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#define PINCTRL_DEVINFO_H
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#ifdef CONFIG_PINCTRL
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/* The device core acts as a consumer toward pinctrl */
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#include <linux/pinctrl/consumer.h>
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/**
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* struct dev_pin_info - pin state container for devices
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* @p: pinctrl handle for the containing device
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* @default_state: the default state for the handle, if found
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* @init_state: the state at probe time, if found
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* @sleep_state: the state at suspend time, if found
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* @idle_state: the state at idle (runtime suspend) time, if found
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*/
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struct dev_pin_info {
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struct pinctrl *p;
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struct pinctrl_state *default_state;
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struct pinctrl_state *init_state;
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#ifdef CONFIG_PM
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struct pinctrl_state *sleep_state;
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struct pinctrl_state *idle_state;
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#endif
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};
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extern int pinctrl_bind_pins(struct device *dev);
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extern int pinctrl_init_done(struct device *dev);
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#else
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/* Stubs if we're not using pinctrl */
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static inline int pinctrl_bind_pins(struct device *dev)
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{
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return 0;
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}
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static inline int pinctrl_init_done(struct device *dev)
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{
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return 0;
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}
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#endif /* CONFIG_PINCTRL */
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#endif /* PINCTRL_DEVINFO_H */
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