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Exposes consumer library functions providing support for interfaces
compatible with the venerable Intel 8254 Programmable Interval Timer
(PIT).
The Intel 8254 PIT first appeared in the early 1980s and was used
initially in IBM PC compatibles. The popularity of the original Intel
825x family of chips led to many subsequent variants and clones of the
interface in various chips and integrated circuits. Although still
popular, interfaces compatible with the Intel 8254 PIT are nowdays
typically found embedded in larger VLSI processing chips and FPGA
components rather than as discrete ICs.
A CONFIG_I8254 Kconfig option is introduced by this patch. Modules
wanting access to these i8254 library functions should select this
Kconfig option, and import the I8254 symbol namespace.
Link: https://lore.kernel.org/r/f6fe32c2db9525d816ab1a01f45abad56c081652.1681665189.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
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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>
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Counter extensions are handled for the Device, Counts, and Signals. The
code loops through each Counter extension and creates the expected sysfs
attributes. This patch consolidates that code into functions to reduce
redundancy and make the intention of the code clearer.
Link: https://lore.kernel.org/r/6f2121cf52073028c119dbf981a8b72f3eb625d2.1664204990.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/0469c3ae3fbccbca908993c78d94f221761a6a3a.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The Signal polarity component represents the active level of a
respective Signal. There are two possible states: positive (rising edge)
and negative (falling edge); enum counter_signal_polarity represents
these states. A convenience macro COUNTER_COMP_POLARITY() is provided
for driver authors to declare a Signal polarity component.
Cc: Julien Panis <jpanis@baylibre.com>
Link: https://lore.kernel.org/r/8f47d6e1db71a11bb1e2666f8e2a6e9d256d4131.1664204990.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/b6e53438badcb6318997d13dd2fc052f97d808ac.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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dev_get_drvdata() returns NULL since commit b56346ddbd82 ("counter: Use
container_of instead of drvdata to track counter_device") which wrongly
claimed there were no users of drvdata. Convert to container_of() to
fix a null pointer dereference.
Reported-by: Oleksij Rempel <o.rempel@pengutronix.de>
Fixes: b56346ddbd82 ("counter: Use container_of instead of drvdata to track counter_device")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Link: https://lore.kernel.org/all/20220204082556.370348-1-u.kleine-koenig@pengutronix.de/
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/4a14311a3b935b62b33e665a97ecaaf2f078228a.1646957732.git.vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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: feff17a550c7 ("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>
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With the removal of the chrdev_lock atomic flag, the counter-sysfs.c and
counter-chrdev.c no longer needs to include the atomic.h header file.
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20211021103514.955622-1-vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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>
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In the counter subsystem, we are already using sysfs_emit(), but there
were a few places where we were still using sprintf() in *_show()
functions. For consistency and added protections, use sysfs_emit()
everywhere.
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/20211017190106.3472645-1-david@lechnology.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The events_queue_size sysfs attribute provides a way for users to
dynamically configure the Counter events queue size for the Counter
character device interface. The size is in number of struct
counter_event data structures. The number of elements will be rounded-up
to a power of 2 due to a requirement of the kfifo_alloc function called
during reallocation of the queue.
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/c914b2db2ea0a2637633bcc3e86ded3c94783f2e.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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The Generic Counter chrdev interface expects users to supply component
IDs in order to select extensions for requests. In order for users to
know what component ID belongs to which extension this information must
be exposed. The *_component_id attribute provides a way for users to
discover what component ID belongs to which respective extension.
Cc: David Lechner <david@lechnology.com>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/8961a11edbb882fc689e468194f5be75f572443e.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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The Generic Counter chrdev interface expects users to supply component
IDs in order to select Synapses for requests. In order for users to know
what component ID belongs to which Synapse this information must be
exposed. The signalZ_action_component_id attribute provides a way for
users to discover what component ID belongs to the respective Synapse.
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/a6c81b2f1f5d0b8d59b1ebe4f0fed04914b07547.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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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>
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