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5279fc402a
The clock accuracy is expressed in ppb (parts per billion) and represents the possible clock drift. Say you have a clock (e.g. an oscillator) which provides a fixed clock of 20MHz with an accuracy of +- 20Hz. This accuracy expressed in ppb is 20Hz/20MHz = 1000 ppb (or 1 ppm). Clock users may need the clock accuracy information in order to choose the best clock (the one with the best accuracy) across several available clocks. This patch adds clk accuracy retrieval support for common clk framework by means of a new function called clk_get_accuracy. This function returns the given clock accuracy expressed in ppb. In order to get the clock accuracy, this implementation adds one callback called recalc_accuracy to the clk_ops structure. This callback is given the parent clock accuracy (if the clock is not a root clock) and should recalculate the given clock accuracy. This callback is optional and may be implemented if the clock is not a perfect clock (accuracy != 0 ppb). Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
401 lines
11 KiB
C
401 lines
11 KiB
C
/*
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* linux/include/linux/clk.h
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*
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* Copyright (C) 2004 ARM Limited.
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* Written by Deep Blue Solutions Limited.
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* Copyright (C) 2011-2012 Linaro Ltd <mturquette@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#ifndef __LINUX_CLK_H
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#define __LINUX_CLK_H
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#include <linux/err.h>
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#include <linux/kernel.h>
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#include <linux/notifier.h>
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struct device;
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struct clk;
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#ifdef CONFIG_COMMON_CLK
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/**
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* DOC: clk notifier callback types
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*
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* PRE_RATE_CHANGE - called immediately before the clk rate is changed,
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* to indicate that the rate change will proceed. Drivers must
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* immediately terminate any operations that will be affected by the
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* rate change. Callbacks may either return NOTIFY_DONE, NOTIFY_OK,
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* NOTIFY_STOP or NOTIFY_BAD.
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*
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* ABORT_RATE_CHANGE: called if the rate change failed for some reason
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* after PRE_RATE_CHANGE. In this case, all registered notifiers on
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* the clk will be called with ABORT_RATE_CHANGE. Callbacks must
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* always return NOTIFY_DONE or NOTIFY_OK.
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*
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* POST_RATE_CHANGE - called after the clk rate change has successfully
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* completed. Callbacks must always return NOTIFY_DONE or NOTIFY_OK.
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*
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*/
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#define PRE_RATE_CHANGE BIT(0)
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#define POST_RATE_CHANGE BIT(1)
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#define ABORT_RATE_CHANGE BIT(2)
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/**
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* struct clk_notifier - associate a clk with a notifier
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* @clk: struct clk * to associate the notifier with
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* @notifier_head: a blocking_notifier_head for this clk
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* @node: linked list pointers
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*
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* A list of struct clk_notifier is maintained by the notifier code.
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* An entry is created whenever code registers the first notifier on a
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* particular @clk. Future notifiers on that @clk are added to the
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* @notifier_head.
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*/
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struct clk_notifier {
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struct clk *clk;
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struct srcu_notifier_head notifier_head;
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struct list_head node;
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};
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/**
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* struct clk_notifier_data - rate data to pass to the notifier callback
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* @clk: struct clk * being changed
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* @old_rate: previous rate of this clk
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* @new_rate: new rate of this clk
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*
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* For a pre-notifier, old_rate is the clk's rate before this rate
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* change, and new_rate is what the rate will be in the future. For a
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* post-notifier, old_rate and new_rate are both set to the clk's
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* current rate (this was done to optimize the implementation).
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*/
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struct clk_notifier_data {
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struct clk *clk;
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unsigned long old_rate;
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unsigned long new_rate;
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};
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int clk_notifier_register(struct clk *clk, struct notifier_block *nb);
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int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
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/**
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* clk_get_accuracy - obtain the clock accuracy in ppb (parts per billion)
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* for a clock source.
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* @clk: clock source
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*
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* This gets the clock source accuracy expressed in ppb.
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* A perfect clock returns 0.
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*/
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long clk_get_accuracy(struct clk *clk);
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#else
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static inline long clk_get_accuracy(struct clk *clk)
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{
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return -ENOTSUPP;
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}
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#endif
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/**
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* clk_prepare - prepare a clock source
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* @clk: clock source
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*
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* This prepares the clock source for use.
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*
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* Must not be called from within atomic context.
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*/
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#ifdef CONFIG_HAVE_CLK_PREPARE
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int clk_prepare(struct clk *clk);
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#else
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static inline int clk_prepare(struct clk *clk)
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{
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might_sleep();
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return 0;
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}
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#endif
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/**
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* clk_unprepare - undo preparation of a clock source
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* @clk: clock source
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*
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* This undoes a previously prepared clock. The caller must balance
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* the number of prepare and unprepare calls.
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*
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* Must not be called from within atomic context.
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*/
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#ifdef CONFIG_HAVE_CLK_PREPARE
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void clk_unprepare(struct clk *clk);
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#else
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static inline void clk_unprepare(struct clk *clk)
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{
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might_sleep();
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}
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#endif
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#ifdef CONFIG_HAVE_CLK
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/**
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* clk_get - lookup and obtain a reference to a clock producer.
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* @dev: device for clock "consumer"
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* @id: clock consumer ID
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*
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* Returns a struct clk corresponding to the clock producer, or
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* valid IS_ERR() condition containing errno. The implementation
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* uses @dev and @id to determine the clock consumer, and thereby
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* the clock producer. (IOW, @id may be identical strings, but
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* clk_get may return different clock producers depending on @dev.)
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*
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* Drivers must assume that the clock source is not enabled.
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*
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* clk_get should not be called from within interrupt context.
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*/
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struct clk *clk_get(struct device *dev, const char *id);
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/**
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* devm_clk_get - lookup and obtain a managed reference to a clock producer.
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* @dev: device for clock "consumer"
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* @id: clock consumer ID
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*
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* Returns a struct clk corresponding to the clock producer, or
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* valid IS_ERR() condition containing errno. The implementation
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* uses @dev and @id to determine the clock consumer, and thereby
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* the clock producer. (IOW, @id may be identical strings, but
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* clk_get may return different clock producers depending on @dev.)
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*
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* Drivers must assume that the clock source is not enabled.
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*
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* devm_clk_get should not be called from within interrupt context.
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*
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* The clock will automatically be freed when the device is unbound
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* from the bus.
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*/
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struct clk *devm_clk_get(struct device *dev, const char *id);
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/**
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* clk_enable - inform the system when the clock source should be running.
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* @clk: clock source
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*
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* If the clock can not be enabled/disabled, this should return success.
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*
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* May be called from atomic contexts.
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*
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* Returns success (0) or negative errno.
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*/
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int clk_enable(struct clk *clk);
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/**
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* clk_disable - inform the system when the clock source is no longer required.
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* @clk: clock source
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*
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* Inform the system that a clock source is no longer required by
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* a driver and may be shut down.
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*
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* May be called from atomic contexts.
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*
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* Implementation detail: if the clock source is shared between
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* multiple drivers, clk_enable() calls must be balanced by the
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* same number of clk_disable() calls for the clock source to be
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* disabled.
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*/
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void clk_disable(struct clk *clk);
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/**
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* clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
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* This is only valid once the clock source has been enabled.
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* @clk: clock source
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*/
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unsigned long clk_get_rate(struct clk *clk);
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/**
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* clk_put - "free" the clock source
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* @clk: clock source
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*
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* Note: drivers must ensure that all clk_enable calls made on this
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* clock source are balanced by clk_disable calls prior to calling
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* this function.
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*
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* clk_put should not be called from within interrupt context.
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*/
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void clk_put(struct clk *clk);
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/**
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* devm_clk_put - "free" a managed clock source
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* @dev: device used to acuqire the clock
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* @clk: clock source acquired with devm_clk_get()
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*
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* Note: drivers must ensure that all clk_enable calls made on this
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* clock source are balanced by clk_disable calls prior to calling
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* this function.
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*
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* clk_put should not be called from within interrupt context.
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*/
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void devm_clk_put(struct device *dev, struct clk *clk);
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/*
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* The remaining APIs are optional for machine class support.
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*/
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/**
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* clk_round_rate - adjust a rate to the exact rate a clock can provide
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* @clk: clock source
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* @rate: desired clock rate in Hz
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*
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* Returns rounded clock rate in Hz, or negative errno.
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*/
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long clk_round_rate(struct clk *clk, unsigned long rate);
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/**
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* clk_set_rate - set the clock rate for a clock source
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* @clk: clock source
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* @rate: desired clock rate in Hz
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*
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* Returns success (0) or negative errno.
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*/
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int clk_set_rate(struct clk *clk, unsigned long rate);
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/**
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* clk_set_parent - set the parent clock source for this clock
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* @clk: clock source
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* @parent: parent clock source
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*
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* Returns success (0) or negative errno.
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*/
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int clk_set_parent(struct clk *clk, struct clk *parent);
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/**
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* clk_get_parent - get the parent clock source for this clock
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* @clk: clock source
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*
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* Returns struct clk corresponding to parent clock source, or
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* valid IS_ERR() condition containing errno.
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*/
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struct clk *clk_get_parent(struct clk *clk);
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/**
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* clk_get_sys - get a clock based upon the device name
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* @dev_id: device name
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* @con_id: connection ID
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*
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* Returns a struct clk corresponding to the clock producer, or
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* valid IS_ERR() condition containing errno. The implementation
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* uses @dev_id and @con_id to determine the clock consumer, and
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* thereby the clock producer. In contrast to clk_get() this function
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* takes the device name instead of the device itself for identification.
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*
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* Drivers must assume that the clock source is not enabled.
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*
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* clk_get_sys should not be called from within interrupt context.
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*/
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struct clk *clk_get_sys(const char *dev_id, const char *con_id);
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#else /* !CONFIG_HAVE_CLK */
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static inline struct clk *clk_get(struct device *dev, const char *id)
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{
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return NULL;
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}
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static inline struct clk *devm_clk_get(struct device *dev, const char *id)
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{
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return NULL;
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}
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static inline void clk_put(struct clk *clk) {}
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static inline void devm_clk_put(struct device *dev, struct clk *clk) {}
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static inline int clk_enable(struct clk *clk)
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{
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return 0;
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}
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static inline void clk_disable(struct clk *clk) {}
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static inline unsigned long clk_get_rate(struct clk *clk)
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{
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return 0;
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}
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static inline int clk_set_rate(struct clk *clk, unsigned long rate)
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{
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return 0;
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}
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static inline long clk_round_rate(struct clk *clk, unsigned long rate)
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{
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return 0;
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}
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static inline int clk_set_parent(struct clk *clk, struct clk *parent)
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{
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return 0;
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}
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static inline struct clk *clk_get_parent(struct clk *clk)
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{
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return NULL;
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}
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#endif
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/* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
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static inline int clk_prepare_enable(struct clk *clk)
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{
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int ret;
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ret = clk_prepare(clk);
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if (ret)
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return ret;
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ret = clk_enable(clk);
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if (ret)
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clk_unprepare(clk);
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return ret;
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}
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/* clk_disable_unprepare helps cases using clk_disable in non-atomic context. */
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static inline void clk_disable_unprepare(struct clk *clk)
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{
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clk_disable(clk);
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clk_unprepare(clk);
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}
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/**
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* clk_add_alias - add a new clock alias
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* @alias: name for clock alias
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* @alias_dev_name: device name
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* @id: platform specific clock name
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* @dev: device
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*
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* Allows using generic clock names for drivers by adding a new alias.
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* Assumes clkdev, see clkdev.h for more info.
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*/
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int clk_add_alias(const char *alias, const char *alias_dev_name, char *id,
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struct device *dev);
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struct device_node;
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struct of_phandle_args;
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#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
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struct clk *of_clk_get(struct device_node *np, int index);
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struct clk *of_clk_get_by_name(struct device_node *np, const char *name);
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struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec);
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#else
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static inline struct clk *of_clk_get(struct device_node *np, int index)
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{
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return ERR_PTR(-ENOENT);
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}
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static inline struct clk *of_clk_get_by_name(struct device_node *np,
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const char *name)
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{
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return ERR_PTR(-ENOENT);
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}
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#endif
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#endif
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