[PATCH 0/2] counter: Introduce the compare component

[PATCH 0/2] counter: Introduce the compare component

[William Breathitt Gray]

In previous drivers, we have exposed compare operations as part of a
larger set of functionalities; such as preseting a Count channel,
defining ceiling and floor boundaries, etc. However, we've lacked a
standard way to expose the compare operation in its strict sense as a
threshold comparison.

The need has become apparent in the microchip-tcb-capture module, which
requires a way to configure the threshold value provided by the RC
register for compare operations. To that end, a new compare component is
introduced with a helper macro COUNTER_COMP_COMPARE() to create such.

Signed-off-by: William Breathitt Gray <wbg@kernel.org>
---
William Breathitt Gray (2):
      counter: Introduce the compare component
      counter: microchip-tcb-capture: Add support for RC Compare

 Documentation/ABI/testing/sysfs-bus-counter |  9 ++++++++
 drivers/counter/microchip-tcb-capture.c     | 33 +++++++++++++++++++++++++++++
 include/linux/counter.h                     |  3 +++
 3 files changed, 45 insertions(+)
---
base-commit: c2a756660324fceca26780a50950e6d91dfdc210
change-id: 20250306-introduce-compare-component-11f22ace88b1

Best regards,
-- 
William Breathitt Gray <wbg@kernel.org>

[PATCH 1/2] counter: Introduce the compare component

[William Breathitt Gray]

Compare registers are used in devices to compare a counter channel
against a particular count value (e.g. to check if a threshold has been
reached). A macro COUNTER_COMP_COMPARE() is introduced to facilitate the
creation of compare components as Count extensions.

Signed-off-by: William Breathitt Gray <wbg@kernel.org>
---
 Documentation/ABI/testing/sysfs-bus-counter | 9 +++++++++
 include/linux/counter.h                     | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index 73ac84c0bca76e013f2534efc40c0f0e8d5fb023..3e8259e56d384225ec6e952b6d5d75208f185736 100644
--- a/Documentation/ABI/testing/sysfs-bus-counter
+++ b/Documentation/ABI/testing/sysfs-bus-counter
@@ -34,6 +34,14 @@ Contact:	linux-iio@vger.kernel.org
 Description:
 		Count data of Count Y represented as a string.
 
+What:		/sys/bus/counter/devices/counterX/countY/compare
+KernelVersion:	6.15
+Contact:	linux-iio@vger.kernel.org
+Description:
+		If the counter device supports compare registers -- registers
+		used to compare counter channels against a particular count --
+		the compare count for channel Y is provided by this attribute.
+
 What:		/sys/bus/counter/devices/counterX/countY/capture
 KernelVersion:	6.1
 Contact:	linux-iio@vger.kernel.org
@@ -301,6 +309,7 @@ Description:
 
 What:		/sys/bus/counter/devices/counterX/cascade_counts_enable_component_id
 What:		/sys/bus/counter/devices/counterX/external_input_phase_clock_select_component_id
+What:		/sys/bus/counter/devices/counterX/countY/compare_component_id
 What:		/sys/bus/counter/devices/counterX/countY/capture_component_id
 What:		/sys/bus/counter/devices/counterX/countY/ceiling_component_id
 What:		/sys/bus/counter/devices/counterX/countY/floor_component_id
diff --git a/include/linux/counter.h b/include/linux/counter.h
index 426b7d58a438d59e5178bc5e76bac82e99737323..f208e867dd0f6995f58cf6a41c67538dad6428d0 100644
--- a/include/linux/counter.h
+++ b/include/linux/counter.h
@@ -580,6 +580,9 @@ struct counter_array {
 #define COUNTER_COMP_CEILING(_read, _write) \
 	COUNTER_COMP_COUNT_U64("ceiling", _read, _write)
 
+#define COUNTER_COMP_COMPARE(_read, _write) \
+	COUNTER_COMP_COUNT_U64("compare", _read, _write)
+
 #define COUNTER_COMP_COUNT_MODE(_read, _write, _available) \
 { \
 	.type = COUNTER_COMP_COUNT_MODE, \

-- 
2.48.1

[PATCH 2/2] counter: microchip-tcb-capture: Add support for RC Compare

[William Breathitt Gray]

In Capture mode, the RC register serves as a compare register for the
Timer Counter Channel. When a the Counter Value reaches the RC value, a
RC Compare event occurs (COUNTER_EVENT_THRESHOLD). This patch exposes
the RC register to userspace as the 'compare' Count extension, thus
allowing users to configure the threshold condition for these events.

Signed-off-by: William Breathitt Gray <wbg@kernel.org>
---
 drivers/counter/microchip-tcb-capture.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c
index 2f096a5b973d18edf5de5a2b33f2f72571deefb7..e32f8d324cb373909e0a093b14d742fa0a93e07e 100644
--- a/drivers/counter/microchip-tcb-capture.c
+++ b/drivers/counter/microchip-tcb-capture.c
@@ -247,6 +247,37 @@ static int mchp_tc_count_read(struct counter_device *counter,
 	return 0;
 }
 
+static int mchp_tc_count_compare_read(struct counter_device *counter, struct counter_count *count,
+				      u64 *val)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	u32 cnt;
+	int ret;
+
+	ret = regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], RC), &cnt);
+	if (ret < 0)
+		return ret;
+
+	*val = cnt;
+
+	return 0;
+}
+
+static int mchp_tc_count_compare_write(struct counter_device *counter, struct counter_count *count,
+				       u64 val)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+
+	if (val > U32_MAX)
+		return -ERANGE;
+
+	return regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], RC), val);
+}
+
+static struct counter_comp mchp_tc_count_ext[] = {
+	COUNTER_COMP_COMPARE(mchp_tc_count_compare_read, mchp_tc_count_compare_write),
+};
+
 static struct counter_count mchp_tc_counts[] = {
 	{
 		.id = 0,
@@ -255,6 +286,8 @@ static struct counter_count mchp_tc_counts[] = {
 		.num_functions = ARRAY_SIZE(mchp_tc_count_functions),
 		.synapses = mchp_tc_count_synapses,
 		.num_synapses = ARRAY_SIZE(mchp_tc_count_synapses),
+		.ext = mchp_tc_count_ext,
+		.num_ext = ARRAY_SIZE(mchp_tc_count_ext),
 	},
 };
 

-- 
2.48.1

Re: [PATCH 2/2] counter: microchip-tcb-capture: Add support for RC Compare

[Csókás Bence]

Hi,

On 2025. 03. 06. 8:05, William Breathitt Gray wrote:
> In Capture mode, the RC register serves as a compare register for the
> Timer Counter Channel. When a the Counter Value reaches the RC value, a
> RC Compare event occurs (COUNTER_EVENT_THRESHOLD). This patch exposes
> the RC register to userspace as the 'compare' Count extension, thus
> allowing users to configure the threshold condition for these events.
> 
> Signed-off-by: William Breathitt Gray <wbg@kernel.org>

I'm assuming you'll merge it with my capture extensions patch. Will this 
`compare` extension be carried over to 104-quad-8 as well? Otherwise:

Acked-by: Bence Csókás <csokas.bence@prolan.hu>

Bence

Re: [PATCH 2/2] counter: microchip-tcb-capture: Add support for RC Compare

[William Breathitt Gray]

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On Mon, Mar 10, 2025 at 09:38:13AM +0100, Csókás Bence wrote:
> Hi,
> 
> On 2025. 03. 06. 8:05, William Breathitt Gray wrote:
> > In Capture mode, the RC register serves as a compare register for the
> > Timer Counter Channel. When a the Counter Value reaches the RC value, a
> > RC Compare event occurs (COUNTER_EVENT_THRESHOLD). This patch exposes
> > the RC register to userspace as the 'compare' Count extension, thus
> > allowing users to configure the threshold condition for these events.
> > 
> > Signed-off-by: William Breathitt Gray <wbg@kernel.org>
> 
> I'm assuming you'll merge it with my capture extensions patch. Will this
> `compare` extension be carried over to 104-quad-8 as well? Otherwise:
> 
> Acked-by: Bence Csókás <csokas.bence@prolan.hu>
> 
> Bence

Thank you for the Ack, I've merged this series now and pushed it to
counter-next.

The compare functionality is already exposed through the `preset`
component in the 104-quad-8 module, so I decided not to add a `compare`
because it felt redundant. However, I'm certain `compare` will be useful
in future drivers so that's why I want to get it merged with the rest of
the microchip-tcb-capture changes. :-)

Best regards,

William Breathitt Gray

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Re: [PATCH 1/2] counter: Introduce the compare component

[David Lechner]

On 3/6/25 1:05 AM, William Breathitt Gray wrote:

...

> @@ -301,6 +309,7 @@ Description:
>  
>  What:		/sys/bus/counter/devices/counterX/cascade_counts_enable_component_id
>  What:		/sys/bus/counter/devices/counterX/external_input_phase_clock_select_component_id
> +What:		/sys/bus/counter/devices/counterX/countY/compare_component_id

Prefer alphabetical order?

>  What:		/sys/bus/counter/devices/counterX/countY/capture_component_id
>  What:		/sys/bus/counter/devices/counterX/countY/ceiling_component_id
>  What:		/sys/bus/counter/devices/counterX/countY/floor_component_id