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>

counter: ti-eqep: Convert to new counter registration

This fixes device lifetime issues where it was possible to free a live
struct device.

Fixes: f213729f6796 ("counter: new TI eQEP driver")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Acked-by: David Lechner <david@lechnology.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-23-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

counter: ti-eqep: Convert to counter_priv() wrapper

This is a straight forward conversion to the new counter_priv() wrapper.

Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Acked-by: David Lechner <david@lechnology.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-11-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

counter: ti-eqep: Use container_of instead of struct counter_device::priv

Using counter->priv is a memory read and so more expensive than
container_of which is only an addition. (In this case even a noop
because the offset is 0.)

So container_of is expected to be a tad faster, it's type-safe, and
produces smaller code (ARCH=arm allmodconfig):

$ source/scripts/bloat-o-meter drivers/counter/ti-eqep.o-pre drivers/counter/ti-eqep.o
add/remove: 0/0 grow/shrink: 0/9 up/down: 0/-108 (-108)
Function old new delta
ti_eqep_position_enable_write 132 120 -12
ti_eqep_position_enable_read 260 248 -12
ti_eqep_position_ceiling_write 132 120 -12
ti_eqep_position_ceiling_read 236 224 -12
ti_eqep_function_write 220 208 -12
ti_eqep_function_read 372 360 -12
ti_eqep_count_write 312 300 -12
ti_eqep_count_read 236 224 -12
ti_eqep_action_read 664 652 -12
Total: Before=4598, After=4490, chg -2.35%

Acked-by: David Lechner <david@lechnology.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/4bde7cbd9e43a5909208102094444219d3154466.1640072891.git.vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

counter: Internalize sysfs interface code

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>

counter: Rename counter_count_function to counter_function

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>

counter: Return error code on invalid modes

Only a select set of modes (function, action, etc.) are valid for a
given device configuration. This patch ensures that invalid modes result
in a return -EINVAL. Such a situation should never occur in reality, but
it's good to define a default switch case for the sake of making the
intent of the code clear.

Cc: Kamel Bouhara <kamel.bouhara@bootlin.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Acked-by: 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/7af82d4e39610da11edce0ee370285fe1cb1eac8.1627990337.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

counter:ti-eqep: remove floor

The hardware doesn't support this. QPOSINIT is an initialization value
that is triggered by other things. When the counter overflows, it
always wraps around to zero.

Fixes: f213729f6796 "counter: new TI eQEP driver"
Signed-off-by: David Lechner <david@lechnology.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20201214000927.1793062-1-david@lechnology.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

counter/ti-eqep: Fix regmap max_register

The values given were the offset of the register after the last
register instead of the actual last register in each range. Fix
by using the correct last register of each range.

Fixes: f213729f6796 ("counter: new TI eQEP driver")
Signed-off-by: David Lechner <david@lechnology.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20201025165122.607866-1-david@lechnology.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

counter: use semicolons rather than commas to separate statements

Replace commas with semicolons. What is done is essentially described by
the following Coccinelle semantic patch (http://coccinelle.lip6.fr/):

// <smpl>
@@ expression e1,e2; @@
e1
-,
+;
e2
... when any
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Reviewed-by: David Lechner <david@lechnology.com>
Link: https://lore.kernel.org/r/1601233948-11629-16-git-send-email-Julia.Lawall@inria.fr
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

counter: Simplify the count_read and count_write callbacks

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>

counter: new TI eQEP driver

This adds a new counter driver for the Texas Instruments Enhanced
Quadrature Encoder Pulse (eQEP) module.

Only very basic functionality is currently implemented - only enough to
be able to read the position. The actual device has many more features
which can be added to the driver on an as-needed basis.

It is not possible to read the QEPA/B signal values in hardware, so
that feature is omitted.

The TI_PWMSS kernel option is selected in Kconfig to enable the parent
bus, which is needed for power management.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>