According to the gcc manual functions "whose return value is not
affected by changes to the observable state of the program and that have
no observable effects on such state other than to return a value may
lend themselves to optimizations such as common subexpression
elimination. Declaring such functions with the 'const' attribute allows
GCC to avoid emitting some calls in repeated invocations of the function
with the same argument values."
counter_priv() is such a function and so can be marked with the const
function attribute.
The effect for an arm allyesconfig build according to bloat-o-meter (on
top of v6.5-rc2) is:
add/remove: 0/1 grow/shrink: 2/14 up/down: 524/-1064 (-540)
Function old new delta
rz_mtu3_count_enable_write 632 1152 +520
stm32_count_enable_write 372 376 +4
ti_eqep_action_read 456 452 -4
stm32_lptim_cnt_action_write 400 392 -8
stm32_lptim_cnt_action_read 300 288 -12
rz_mtu3_count_write 296 284 -12
rz_mtu3_count_read 304 292 -12
rz_mtu3_count_function_read 212 200 -12
rz_mtu3_count_direction_read 268 256 -12
rz_mtu3_action_read 628 616 -12
rz_mtu3_count_function_write 328 312 -16
ecap_cnt_suspend 364 340 -24
ecap_cnt_resume 300 276 -24
rz_mtu3_count_ceiling_write 596 560 -36
rz_mtu3_count_enable_read 332 288 -44
rz_mtu3_count_ceiling_read 384 340 -44
rz_mtu3_initialize_counter 792 - -792
Total: Before=60715, After=60175, chg -0.89%
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230718162015.3940148-1-u.kleine-koenig@pengutronix.de/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
A spare warning was reported for drivers/counter/ti-ecap-capture.c::
sparse warnings: (new ones prefixed by >>)
>> drivers/counter/ti-ecap-capture.c:380:8: sparse: sparse: symbol 'ecap_cnt_pol_array' was not declared. Should it be static?
vim +/ecap_cnt_pol_array +380 drivers/counter/ti-ecap-capture.c
379
> 380 static DEFINE_COUNTER_ARRAY_POLARITY(ecap_cnt_pol_array, ecap_cnt_pol_avail, ECAP_NB_CEVT);
381
The first argument to the DEFINE_COUNTER_ARRAY_POLARITY() macro is a
token serving as the symbol name in the definition of a new
struct counter_array structure. However, this macro actually expands to
two statements::
#define DEFINE_COUNTER_ARRAY_POLARITY(_name, _enums, _length) \
DEFINE_COUNTER_AVAILABLE(_name##_available, _enums); \
struct counter_array _name = { \
.type = COUNTER_COMP_SIGNAL_POLARITY, \
.avail = &(_name##_available), \
.length = (_length), \
}
Because of this, the "static" on line 380 only applies to the first
statement. This patch splits out the DEFINE_COUNTER_AVAILABLE() line
and leaves DEFINE_COUNTER_ARRAY_POLARITY() as a simple structure
definition to avoid issues like this.
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202210020619.NQbyomII-lkp@intel.com/
Cc: Julien Panis <jpanis@baylibre.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
The COUNTER_COMP_ARRAY Counter component type is introduced to enable
support for Counter array components. With Counter array components,
exposure for buffers on counter devices can be defined via new Counter
array component macros. This should simplify code for driver authors who
would otherwise need to define individual Counter components for each
array element.
Eight Counter array component macros are introduced::
DEFINE_COUNTER_ARRAY_U64(_name, _length)
DEFINE_COUNTER_ARRAY_CAPTURE(_name, _length)
DEFINE_COUNTER_ARRAY_POLARITY(_name, _enums, _length)
COUNTER_COMP_DEVICE_ARRAY_U64(_name, _read, _write, _array)
COUNTER_COMP_COUNT_ARRAY_U64(_name, _read, _write, _array)
COUNTER_COMP_SIGNAL_ARRAY_U64(_name, _read, _write, _array)
COUNTER_COMP_ARRAY_CAPTURE(_read, _write, _array)
COUNTER_COMP_ARRAY_POLARITY(_read, _write, _array)
Eight Counter array callbacks are introduced as well::
int (*signal_array_u32_read)(struct counter_device *counter,
struct counter_signal *signal,
size_t idx, u32 *val);
int (*signal_array_u32_write)(struct counter_device *counter,
struct counter_signal *signal,
size_t idx, u32 val);
int (*device_array_u64_read)(struct counter_device *counter,
size_t idx, u64 *val);
int (*count_array_u64_read)(struct counter_device *counter,
struct counter_count *count,
size_t idx, u64 *val);
int (*signal_array_u64_read)(struct counter_device *counter,
struct counter_signal *signal,
size_t idx, u64 *val);
int (*device_array_u64_write)(struct counter_device *counter,
size_t idx, u64 val);
int (*count_array_u64_write)(struct counter_device *counter,
struct counter_count *count,
size_t idx, u64 val);
int (*signal_array_u64_write)(struct counter_device *counter,
struct counter_signal *signal,
size_t idx, u64 val);
Driver authors can handle reads/writes for an array component by
receiving an element index via the `idx` parameter and processing the
respective value via the `val` parameter.
For example, suppose a driver wants to expose a Count's read-only
capture buffer of four elements using a callback
`foobar_capture_read()`::
DEFINE_COUNTER_ARRAY_CAPTURE(foobar_capture_array, 4);
COUNTER_COMP_ARRAY_CAPTURE(foobar_capture_read, NULL,
foobar_capture_array)
Respective sysfs attributes for each array element would appear for the
respective Count:
* /sys/bus/counter/devices/counterX/countY/capture0
* /sys/bus/counter/devices/counterX/countY/capture1
* /sys/bus/counter/devices/counterX/countY/capture2
* /sys/bus/counter/devices/counterX/countY/capture3
If a user tries to read _capture2_ for example, `idx` will be `2` when
passed to the `foobar_capture_read()` callback, and thus the driver
knows which array element to handle.
Counter arrays for polarity elements can be defined in a similar
manner as u64 elements::
const enum counter_signal_polarity foobar_polarity_states[] = {
COUNTER_SIGNAL_POLARITY_POSITIVE,
COUNTER_SIGNAL_POLARITY_NEGATIVE,
};
DEFINE_COUNTER_ARRAY_POLARITY(foobar_polarity_array,
foobar_polarity_states, 4);
COUNTER_COMP_ARRAY_POLARITY(foobar_polarity_read,
foobar_polarity_write,
foobar_polarity_array)
Tested-by: Julien Panis <jpanis@baylibre.com>
Link: https://lore.kernel.org/r/5310c22520aeae65b1b74952419f49ac4c8e1ec1.1664204990.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/a51fd608704bdfc5a0efa503fc5481df34241e0a.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Usage of counter_register() yields issues in device lifetime tracking. All
drivers were converted to the new API, so the old one can go away.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-24-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The current implementation gets device lifetime tracking wrong. The
problem is that allocation of struct counter_device is controlled by the
individual drivers but this structure contains a struct device that
might have to live longer than a driver is bound. As a result a command
sequence like:
{ sleep 5; echo bang; } > /dev/counter0 &
sleep 1;
echo 40000000.timer:counter > /sys/bus/platform/drivers/stm32-timer-counter/unbind
can keep a reference to the struct device and unbinding results in
freeing the memory occupied by this device resulting in an oops.
This commit provides two new functions (plus some helpers):
- counter_alloc() to allocate a struct counter_device that is
automatically freed once the embedded struct device is released
- counter_add() to register such a device.
Note that this commit doesn't fix any issues, all drivers have to be
converted to these new functions to correct the lifetime problems.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-14-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For now this just wraps accessing struct counter_device::priv. However
this is about to change and converting drivers to this helper
individually makes fixing device lifetime issues result in easier to
review patches.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-5-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A race condition is possible when writing to events_queue_size where the
events kfifo is freed during the execution of a kfifo_in(), resulting in
a use-after-free. This patch prevents such a scenario by protecting the
events queue in operation with a spinlock and locking before performing
the events queue size adjustment.
The existing events_lock mutex is renamed to events_out_lock to reflect
that it only protects events queue out operations. Because the events
queue in operations can occur in an interrupt context, a new
events_in_lock spinlock is introduced and utilized.
Fixes: feff17a550 ("counter: Implement events_queue_size sysfs attribute")
Cc: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20211021103540.955639-1-vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This removes the chrdev_lock from the counter subsystem. This was
intended to prevent opening the chrdev more than once. However, this
doesn't work in practice since userspace can duplicate file descriptors
and pass file descriptors to other processes. Since this protection
can't be relied on, it is best to just remove it.
Suggested-by: Greg KH <gregkh@linuxfoundation.org>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: David Lechner <david@lechnology.com>
Link: https://lore.kernel.org/r/20211017185521.3468640-1-david@lechnology.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch introduces a character device interface for the Counter
subsystem. Device data is exposed through standard character device read
operations. Device data is gathered when a Counter event is pushed by
the respective Counter device driver. Configuration is handled via ioctl
operations on the respective Counter character device node.
Cc: David Lechner <david@lechnology.com>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/b8b8c64b4065aedff43699ad1f0e2f8d1419c15b.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The Counter subsystem architecture and driver implementations have
changed in order to handle Counter sysfs interactions in a more
consistent way. This patch updates the Generic Counter interface
header file comments to reflect the changes.
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/19da8ae0c05381b0967c8a334b67f86b814eb880.1630031207.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This is a reimplementation of the Generic Counter driver interface.
There are no modifications to the Counter subsystem userspace interface,
so existing userspace applications should continue to run seamlessly.
The purpose of this patch is to internalize the sysfs interface code
among the various counter drivers into a shared module. Counter drivers
pass and take data natively (i.e. u8, u64, etc.) and the shared counter
module handles the translation between the sysfs interface and the
device drivers. This guarantees a standard userspace interface for all
counter drivers, and helps generalize the Generic Counter driver ABI in
order to support the Generic Counter chrdev interface (introduced in a
subsequent patch) without significant changes to the existing counter
drivers.
Note, Counter device registration is the same as before: drivers
populate a struct counter_device with components and callbacks, then
pass the structure to the devm_counter_register function. However,
what's different now is how the Counter subsystem code handles this
registration internally.
Whereas before callbacks would interact directly with sysfs data, this
interaction is now abstracted and instead callbacks interact with native
C data types. The counter_comp structure forms the basis for Counter
extensions.
The counter-sysfs.c file contains the code to parse through the
counter_device structure and register the requested components and
extensions. Attributes are created and populated based on type, with
respective translation functions to handle the mapping between sysfs and
the counter driver callbacks.
The translation performed for each attribute is straightforward: the
attribute type and data is parsed from the counter_attribute structure,
the respective counter driver read/write callback is called, and sysfs
I/O is handled before or after the driver read/write function is called.
Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Patrick Havelange <patrick.havelange@essensium.com>
Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Reviewed-by: David Lechner <david@lechnology.com>
Tested-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com> # for stm32
Link: https://lore.kernel.org/r/c68b4a1ffb195c1a2f65e8dd5ad7b7c14e79c6ef.1630031207.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The phrase "Counter Count function" is verbose and unintentionally
implies that function is a Count extension. This patch adjusts the
Counter subsystem code to use the more direct "Counter function" phrase
to make the intent of this code clearer.
Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Patrick Havelange <patrick.havelange@essensium.com>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: David Lechner <david@lechnology.com>
Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/8268c54d6f42075a19bb08151a37831e22652499.1627990337.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signal values will always be levels so let's be explicit it about it to
make the intent of the code clear.
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/3f17010abe2415859cea9a5fddabd3c97f635ff5.1627990337.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The action_get callback returns a Synapse's action mode.
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The count_read and count_write callbacks are simplified to pass val as
unsigned long rather than as an opaque data structure. The opaque
counter_count_read_value and counter_count_write_value structures,
counter_count_value_type enum, and relevant counter_count_read_value_set
and counter_count_write_value_get functions, are removed as they are no
longer used.
Cc: Patrick Havelange <patrick.havelange@essensium.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This patch introduces the Generic Counter interface for supporting
counter devices.
In the context of the Generic Counter interface, a counter is defined as
a device that reports one or more "counts" based on the state changes of
one or more "signals" as evaluated by a defined "count function."
Driver callbacks should be provided to communicate with the device: to
read and write various Signals and Counts, and to set and get the
"action mode" and "count function" for various Synapses and Counts
respectively.
To support a counter device, a driver must first allocate the available
Counter Signals via counter_signal structures. These Signals should
be stored as an array and set to the signals array member of an
allocated counter_device structure before the Counter is registered to
the system.
Counter Counts may be allocated via counter_count structures, and
respective Counter Signal associations (Synapses) made via
counter_synapse structures. Associated counter_synapse structures are
stored as an array and set to the the synapses array member of the
respective counter_count structure. These counter_count structures are
set to the counts array member of an allocated counter_device structure
before the Counter is registered to the system.
A counter device is registered to the system by passing the respective
initialized counter_device structure to the counter_register function;
similarly, the counter_unregister function unregisters the respective
Counter. The devm_counter_register and devm_counter_unregister functions
serve as device memory-managed versions of the counter_register and
counter_unregister functions respectively.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
