counter: chrdev: remove a typo in header file comment

Replace COUNTER_COUNT_SCOPE that doesn't exist by the defined
COUNTER_SCOPE_COUNT.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20230829134029.2402868-3-fabrice.gasnier@foss.st.com
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>

counter: i8254: Introduce the Intel 8254 interface library module

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>

counter: Introduce the Count capture component

Some devices provide a latch function to save historic Count values.
This patch standardizes exposure of such functionality as Count capture
components. A COUNTER_COMP_CAPTURE macro is provided for driver authors
to define a capture component. A new event COUNTER_EVENT_CAPTURE is
introduced to represent Count value capture events.

Cc: Julien Panis <jpanis@baylibre.com>
Link: https://lore.kernel.org/r/c239572ab4208d0d6728136e82a88ad464369a7a.1664204990.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/3cebaa0b807a225eb277d771504fe6dba7269ffd.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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>

counter: add new COUNTER_EVENT_CHANGE_OF_STATE

Add new counter event to notify user space about every new counter
pulse.

Link: https://lore.kernel.org/r/20220203135727.2374052-2-o.rempel@pengutronix.de
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/486a5de67414470449efb84d06a2f2214f4bb31d.1647373009.git.vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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>

counter: Move counter enums to uapi header

This is in preparation for a subsequent patch implementing a character
device interface for the Counter subsystem.

Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/962a5f2027fafcf4f77c10e1baf520463960d1ee.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>