This restores the default clocks registration order as parsed from
devicetree, i.e. as before commit 1771b10d60
"clk: respect the clock dependencies in of_clk_init", for when there
is no explicit parent clock dependencies between clock providers
specified in the device tree.
It prevents regressions (boot failure, division by 0 errors) on
imx and exynos platforms.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Add a new clk_ops->debug_init method to allow a clock hardware
driver to populate the clock's debugfs directory with entries
beyond those common for every clock.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
If a rate change failed it's the opportunity of the caller to handle
this. Do not spam the log with a message.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Until now the clock providers were initialized in the order found in
the device tree. This led to have the dependencies between the clocks
not respected: children clocks could be initialized before their
parent clocks.
Instead of forcing each platform to manage its own initialization order,
this patch adds this work inside the framework itself.
Using the data of the device tree the of_clk_init function now delayed
the initialization of a clock provider if its parent provider was not
ready yet.
The strict dependency check (all parents of a given clk must be
initialized) was added by Boris BREZILLON
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Ensure clk->kref is dereferenced only when clk is not NULL.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
At probe time, a clock device may not be ready when some other device
wants to use it.
This patch lets the functions clk_get/devm_clk_get return a probe defer
when the clock is defined in the DT but not yet available.
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Both the pr_err and the additional kerneldoc aim to help when debugging
errors thrown from within a clock rate-change notifier callback.
Reported-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Add a property called clock-indices to allow clock-output-names
to be used where the index used to lookup a clock is not a 1:1
mapping to the array position in the clock-output-names
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Contradicting to documenation, the notifier callbacks do receive
the original clock rate in struct clk_notifier_data.old_rate and the new
frequency struct clk_notifier_data.new_rate, independent of the
notification reason.
This behavior also seems to make more sense, since callbacks can use the
same code to deterimine whether clocks are scaled up or down. Something
which would not even possible in the post-rate-change case if the
behavior was as documented.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Allow drivers to be compiled as modules by exporting more clock
provider functions.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
ti_dt_clk_init_provider() can now be used to initialize the contents of
a single clock IP block. This parses all the clocks under the IP block
and calls the corresponding init function for them.
This patch also introduces a helper function for the TI clock drivers
to get register info from DT and append the master IP info to this.
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Some of Qualcomm's clocks can change their parent and rate at the
same time with a single register write. Add support for this
hardware to the common clock framework by adding a new
set_rate_and_parent() op. When the clock framework determines
that both the parent and the rate are going to change during
clk_set_rate() it will call the .set_rate_and_parent() op if
available and fall back to calling .set_parent() followed by
.set_rate() otherwise.
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Populate ${DEBUGS_MOUNT_POINT}/clk if CONFIG_DEBUG_FS is set. This
eliminates the extra (annoying) step of enabling the config option
manually.
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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>
clk_unregister() is currently not implemented and it is required when
a clock provider module needs to be unloaded.
Normally the clock supplier module is prevented to be unloaded by
taking reference on the module in clk_get().
For cases when the clock supplier module deinitializes despite the
consumers of its clocks holding a reference on the module, e.g. when
the driver is unbound through "unbind" sysfs attribute, there are
empty clock ops added. These ops are assigned temporarily to struct
clk and used until all consumers release the clock, to avoid invoking
callbacks from the module which just got removed.
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
This patch adds common __clk_get(), __clk_put() clkdev helpers that
replace their platform specific counterparts when the common clock
API is used.
The owner module pointer field is added to struct clk so a reference
to the clock supplier module can be taken by the clock consumers.
The owner module is assigned while the clock is being registered,
in functions _clk_register() and __clk_register().
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add helper functions for the of_clk_providers list locking and
an unlocked variant of of_clk_get_from_provider().
These functions are intended to be used in the clkdev to avoid
race condition in the device tree based clock look up in clk_get().
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
[Maybe the third time will be the charm. -Alex]
If CONFIG_COMMON_CLK_DEBUG is defined, clk_debug_create_one() is
called to populate a debugfs directory with a few entries that are
common for all clock types.
If an error happens after creating the first one debugfs_remove() is
called on the clock's directory. The problem with this is that no
cleanup is done on the debugfs files already created in that
directory, so the directory never actually gets removed. This
problem is silently ignored.
Fix this by calling debugfs_remove_recursive() instead. Reset the
clk->dentry field to null afterward, to ensure it can't be mistaken
as a valid pointer.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
This function is supposed to iterate over all parents of given child
clock to find the index of given parent clock in its parent list,
using parent cache if possible and falling back to string compare
otherwise. However currently the logic falls back to string compare in
every iteration in which clock cache entry does not match given parent,
due to wrong check conditions.
This patch corrects the logic to continue the loop if parent cache entry
is present and does not match requested parent clock. In addition,
redundant checks for parent cache array presence are removed, because it
is always allocated in the beginning of the function.
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Instead of calculating sizes of arrays manually, kcalloc() can be used
to allocate arrays of elements with defined size. This is just a cleanup
patch without any functional changes.
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
There are at least two different error cases that can happen in
clk_fetch_parent_index() function:
- allocation failure,
- parent clock lookup failure,
however it returns only an u8, which is supposed to contain parent clock
index.
This patch modified the function to return full int instead allowing
positive clock indices and negative error codes to be returned. All
users of this function are adjusted as well to handle the return value
correctly.
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
In __clk_init(), after a clock is mostly initialized, a scan is done
of the orphan clocks to see if the clock being registered is the
parent of any of them.
This code assumes that any clock that provides a get_parent method
actually has at least one parent, and that's not a valid assumption.
As a result, an orphan clock with no parent can return *something*
as the parent index, and that value is blindly used to dereference
the orphan's parent_names[] array (which will be ZERO_SIZE_PTR or
NULL).
Fix this by ensuring get_parent is only called for orphans with at
least one parent.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
The __clk_get_flags() symbol is exported immediately following the
clk_unprepare_unused_subtree() function. This is unusual, since a symbol
export typically follows body of the function that it exports.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Commit 71472c0 (clk: add support for clock reparent on set_rate) added a
dereference of the new_parent pointer in clk_reparent(), but as detected
by smatch clk_reparent() later checks whether new_parent is NULL.
The dereference was in order to clear the new parent's new_child pointer
to avoid duplicate POST_RATE_CHANGE notifications, so clearly isn't
necessary if the new parent is NULL, so move it inside the "if
(new_parent)" block.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Currently of_clk_init() finds a matching device node while holding
the device tree spinlock. When a matching device node is found, the
lock is dropped and then re-acquired in order to get a reference
to the matching device id structure.
Acquiring the spinlock twice is unnecessary (and it opens a
vulnerable window that could conceivably lead to errors).
There already exists an interface for both finding and taking a
reference to a device id under lock, so use it.
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Christian Daudt <csd@broadcom.com>
Reviewed-by: Markus Mayer <markus.mayer@linaro.org>
Reviewed-by: Matt Porter <matt.porter@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
At some point changes to clk_set_rate and clk_set_parent introduced a
bug whereby NULL struct clk pointers were treated as an error. This is
in violation of the API in include/linux/clk.h. Reintroduce graceful
handling of NULL clk's by bailing from clk_set_rate and clk_set_parent
with return codes of zero.
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Implement clk-mux remuxing if the CLK_SET_RATE_NO_REPARENT flag isn't
set. This implements determine_rate for clk-mux to propagate to each
parent and to choose the best one (like clk-divider this chooses the
parent which provides the fastest rate <= the requested rate).
The determine_rate op is implemented as a core helper function so that
it can be easily used by more complex clocks which incorporate muxes.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Add core support to allow clock implementations to select the best
parent clock when rounding a rate, e.g. the one which can provide the
closest clock rate to that requested. This is by way of adding a new
clock op, determine_rate(), which is like round_rate() but has an extra
parameter to allow the clock implementation to optionally select a
different parent clock. The core then takes care of reparenting the
clock when setting the rate.
The parent change takes place with the help of some new private data
members. struct clk::new_parent specifies a clock's new parent (NULL
indicates no change), and struct clk::new_child specifies a clock's new
child (whose new_parent member points back to it). The purpose of these
are to allow correct walking of the future tree for notifications prior
to actually reparenting any clocks, specifically to skip child clocks
who are being reparented to another clock (they will be notified via the
new parent), and to include any new child clock. These pointers are set
by clk_calc_subtree(), and the new_child pointer gets cleared when a
child is actually reparented to avoid duplicate POST_RATE_CHANGE
notifications.
Each place where round_rate() is called, determine_rate() is checked
first and called in preference. This restructures a few of the call
sites to simplify the logic into if/else blocks.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Move some parent related functions up in clk.c so they can be used by
the modifications in the following patch which enables clock reparenting
during set_rate. No other changes are made so this patch makes no
functional difference in isolation. This is separate from the following
patch primarily to ease readability of that patch.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Abstract access to the clock parent cache by defining
clk_get_parent_by_index(clk, index). This allows access to parent
clocks from clock drivers.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Mike Turquette <mturquette@linaro.org>
across several different platforms and architectures, fixes to existing
drivers, a MAINTAINERS file fix and improvements to the basic clock
types that allow them to be of use to more platforms than before. Only a
few fixes to the core framework are included with most all of the
changes landing in the various clock drivers themselves.
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Merge tag 'clk-for-linus-3.11' of git://git.linaro.org/people/mturquette/linux
Pull clock framework updates from Mike Turquette:
"The common clock framework changes for 3.11 include new clock drivers
across several different platforms and architectures, fixes to
existing drivers, a MAINTAINERS file fix and improvements to the basic
clock types that allow them to be of use to more platforms than before.
Only a few fixes to the core framework are included with most all of
the changes landing in the various clock drivers themselves."
* tag 'clk-for-linus-3.11' of git://git.linaro.org/people/mturquette/linux: (55 commits)
clk: tegra: fix ifdef for tegra_periph_reset_assert inline
clk: tegra: provide tegra_periph_reset_assert alternative
clk: exynos4: Fix clock aliases for cpufreq related clocks
clk: samsung: Add MUX_FA macro to pass flag and alias
clk: add support for Rockchip gate clocks
clk: vexpress: Make the clock drivers directly available for arm64
clk: vexpress: Use full node name to identify individual clocks
clk: tegra: T114: add DFLL DVCO reset control
clk: tegra: T114: add DFLL source clocks
clk: tegra: T114: add FCPU clock shaper programming, needed by the DFLL
clk: gate: add CLK_GATE_HIWORD_MASK
clk: divider: add CLK_DIVIDER_HIWORD_MASK flag
clk: mux: add CLK_MUX_HIWORD_MASK
clk: Always notify whole subtree when reparenting
MAINTAINERS: make drivers/clk entry match subdirs
clk: honor CLK_GET_RATE_NOCACHE in clk_set_rate
clk: use clk_get_rate() for debugfs
clk: tegra: Use override bits when needed
clk: tegra: override bits for Tegra30 PLLM
clk: tegra: override bits for Tegra114 PLLM
...
A clock's notifier count only reflects notifiers which are registered
directly for that clock. A reparent operation though affects the whole
subtree because of a potential rate change.
When issuing the pre rate change notifications only the notifier count
for the clock to be changed is considered and notifiers for subclocks
may never be called. Resulting in clocks in the subtree which have
registered notifiers, may receive a POST_- or ABORT_RATE_CHANGE
notification, without a PRE_RATE_CHANGE_NOTIFICATION.
Therefore always traverse the whole subtree when issueing pre rate
change notifications during a reparent operation.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
clk_set_rate() uses clk->rate directly. This causes problems if the clock
is marked as CLK_GET_RATE_NOCACHE. Hence call clk_get_rate() to get the
current rate.
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
debugfs uses the rate field directly. However this ignores the
CLK_GET_RATE_NOCACHE flag. Call clk_get_rate() instead.
Tested-by: Mark Zhang <markz@nvidia.com>
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
With deferred probing, late_initcall() is too soon to declare a clock as
unused. Wait for deferred probing to finish before declaring a clock as
unused. Since deferred probing is done in late_initcall(), do the unused
check to late_initcall_sync.
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Without this patch, the following race condition is possible.
* clk-A has two parents - clk-X and clk-Y.
* All three are disabled and clk-X is current parent.
* Thread A: clk_set_parent(clk-A, clk-Y).
* Thread A: <snip execution flow>
* Thread A: Grabs enable lock.
* Thread A: Sees enable count of clk-A is 0, so doesn't enable clk-Y.
* Thread A: Updates clk-A SW parent to clk-Y
* Thread A: Releases enable lock.
* Thread B: clk_enable(clk-A).
* Thread B: clk_enable() enables clk-Y, then enabled clk-A and returns.
clk-A is now enabled in software, but not clocking in hardware since the
hardware parent is still clk-X.
The only way to avoid race conditions between clk_set_parent() and
clk_enable/disable() is to ensure that clk_enable/disable() calls don't
require changes to hardware enable state between changes to software clock
topology and hardware clock topology.
The options to achieve the above are:
1. Grab the enable lock before changing software/hardware topology and
release it afterwards.
2. Keep the clock enabled for the duration of software/hardware topology
change so that any additional enable/disable calls don't try to change
the hardware state. Once the topology change is complete, the clock can
be put back in its original enable state.
Option (1) is not an acceptable solution since the set_parent() ops might
need to sleep.
Therefore, this patch implements option (2).
This patch doesn't violate any API semantics. clk_disable() doesn't
guarantee that the clock is actually disabled. So, no clients of a clock
can assume that a clock is disabled after their last call to clk_disable().
So, enabling the clock during a parent change is not a violation of any API
semantics.
This also has the nice side effect of simplifying the error handling code.
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: fixed up whitespace issue]
This is primarily useful when there's a driver that doesn't claim clocks
properly, but the bootloader leaves them on. It's not expected to be used
in normal cases, but for bringup and debug it's very useful to have the
option to not gate unclaimed clocks that are still on.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: fixed up trivial merge issue]
The common clock api provides some helpers for clk-providers but does
not export these helpers. This hinders clk-providers to be built as modules.
This patch adds __clk_get_flags() to the list of exported symbols.
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Notifiers may return NOTIFY_(OK|DONE|STOP|BAD). The CCF uses an
inconsistent mix of checking against NOTIFY_STOP or NOTIFY_BAD.
This inconsistency leaves errors undetected in some cases:
clk_set_parent() calls __clk_speculate_rates(), which stops when it
hits a NOTIFIER_BAD (STOP is ignored), and passes this value back to the
caller.
clk_set_parent() compares this return value against NOTIFY_STOP only,
ignoring NOTIFY_BAD returns.
Use NOTIFY_STOP_MASK to detect a negative notifier return value and
document all four return value options.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Updating the clock tree topology must be protected with the spinlock
when doing clk_set_parent, otherwise we can not handle the migration
of the enable_count in a safe manner.
While issuing the .set_parent callback to make the clk-hw perform the
switch to the new parent, we can not hold the spinlock since it is must
be allowed to be slow path. This complicates error handling, but is still
possible to achieve.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Fixup the broken feature of allowing reparent of a clk to the
orhpan list and vice verse. When operating on a single-parent
clk, the .set_parent callback for the clk hw is optional to
implement, but for a multi-parent clk it is mandatory.
Moreover improve the errorhandling by verifying the prerequisites
before triggering clk notifiers. This will prevent unnecessary
rollback with ABORT_RATE_CHANGE.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Split __clk_reparent into three pieces, one for doing the actual
reparent for updating the clock tree topology, one for the
COMMON_CLK_DEBUG code and one for doing the rate recalculation.
This patch also makes it possible to hold the spinlock over the
update of the clock tree topology, which could not be done before
when both debugfs updates and clock rate updates was done within
the same function.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Reentrancy into the clock framework is necessary for clock operations
that result in nested calls to the clk api. A common example is a clock
that is prepared via an i2c transaction, such as a clock inside of a
discrete audio chip or a power management IC. The i2c subsystem itself
will use the clk api resulting in a deadlock:
clk_prepare(audio_clk)
i2c_transfer(..)
clk_prepare(i2c_controller_clk)
The ability to reenter the clock framework prevents this deadlock.
Other use cases exist such as allowing .set_rate callbacks to call
clk_set_parent to achieve the best rate, or to save power in certain
configurations. Yet another example is performing pinctrl operations
from a clk_ops callback. Calls into the pinctrl subsystem may call
clk_{un}prepare on an unrelated clock. Allowing for nested calls to
reenter the clock framework enables both of these use cases.
Reentrancy is implemented by two global pointers that track the owner
currently holding a global lock. One pointer tracks the owner during
sleepable, mutex-protected operations and the other one tracks the owner
during non-interruptible, spinlock-protected operations.
When the clk framework is entered we try to hold the global lock. If it
is held we compare the current task against the current owner; a match
implies a nested call and we reenter. If the values do not match then
we block on the lock until it is released.
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Cc: David Brown <davidb@codeaurora.org>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Sylwester Nawrocki