History log of /linux-master/drivers/counter/counter-chrdev.c
Revision Date Author Comments
# 3170256d 29-Aug-2023 Fabrice Gasnier <fabrice.gasnier@foss.st.com>

counter: chrdev: fix getting array extensions

When trying to watch a component array extension, and the array isn't the
first extended element, it fails as the type comparison is always done on
the 1st element. Fix it by indexing the 'ext' array.

Example on a dummy struct counter_comp:
static struct counter_comp dummy[] = {
COUNTER_COMP_DIRECTION(..),
...,
COUNTER_COMP_ARRAY_CAPTURE(...),
};
static struct counter_count dummy_cnt = {
...
.ext = dummy,
.num_ext = ARRAY_SIZE(dummy),
}

Currently, counter_get_ext() returns -EINVAL when trying to add a watch
event on one of the capture array element in such example.

Fixes: d2011be1e22f ("counter: Introduce the COUNTER_COMP_ARRAY component type")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20230829134029.2402868-2-fabrice.gasnier@foss.st.com
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>


# d2011be1 27-Sep-2022 William Breathitt Gray <william.gray@linaro.org>

counter: Introduce the COUNTER_COMP_ARRAY component type

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>


# 650ae67b 27-Sep-2022 William Breathitt Gray <william.gray@linaro.org>

counter: Introduce the Signal polarity component

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>


# 3216e551 27-Sep-2022 William Breathitt Gray <william.gray@linaro.org>

counter: Move symbols into COUNTER namespace

Counter subsystem symbols are only relevant to counter drivers. A
COUNTER namespace is created to control the availability of these
symbols to modules that import this namespace explicitly.

Cc: Patrick Havelange <patrick.havelange@essensium.com>
Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Oleksij Rempel <linux@rempel-privat.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Acked-by: David Lechner <david@lechnology.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20220815220321.74161-1-william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/8a756df96c24946547a7ece5caa5f654809c5e7f.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


# 04c63387 15-Mar-2022 Tom Rix <trix@redhat.com>

counter: add defaults to switch-statements

Clang static analysis reports this representative problem
counter-chrdev.c:482:3: warning: Undefined or garbage value
returned to caller
return ret;
^~~~~~~~~~

counter_get_data() has a multilevel switches, some without
defaults, so ret is sometimes not set.
Add returning -EINVAL similar to other defaults.

Link: https://lore.kernel.org/r/20220227161746.82776-1-trix@redhat.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/b98d1a3ed4b0b324b261b23defd1bdddddba4d44.1647373009.git.vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


# 8ac33b8b 21-Oct-2021 William Breathitt Gray <vilhelm.gray@gmail.com>

counter: Fix use-after-free race condition for events_queue_size write

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>


# 310e75c7 21-Oct-2021 William Breathitt Gray <vilhelm.gray@gmail.com>

counter: Cleanup lingering atomic.h includes

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>


# f5245a5f 17-Oct-2021 David Lechner <david@lechnology.com>

counter: drop chrdev_lock

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>


# b6c50aff 28-Sep-2021 William Breathitt Gray <vilhelm.gray@gmail.com>

counter: Add character device interface

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>