[PATCH v7 0/2] microchip-tcb-capture: Add Capture, Compare, Overflow etc. events

[PATCH v7 0/2] microchip-tcb-capture: Add Capture, Compare, Overflow etc. events

[Bence Csókás]

The TCB has three R/W-able "general purpose" hardware registers:
RA, RB and RC. The hardware is capable of:
* sampling Counter Value Register (CV) to RA/RB on a trigger edge
* sending an interrupt of this change
* sending an interrupt on CV change due to trigger
* triggering an interrupt on CV compare to RC
* stop counting after sampling to RB

To enable using these features in user-space, an interrupt handler
was added, generating the necessary counter events. On top, RA/RB
registers are added as Count Extensions. To aid interoperation, a
uapi header was also added, containing the various numeral IDs of
the Extensions, Event channels etc.

Bence Csókás (2):
  counter: microchip-tcb-capture: Add IRQ handling
  counter: microchip-tcb-capture: Add capture extensions for registers
    RA/RB

 MAINTAINERS                                   |   1 +
 drivers/counter/microchip-tcb-capture.c       | 133 ++++++++++++++++++
 .../linux/counter/microchip-tcb-capture.h     |  40 ++++++
 3 files changed, 174 insertions(+)
 create mode 100644 include/uapi/linux/counter/microchip-tcb-capture.h

-- 
2.48.1

[PATCH v7 1/2] counter: microchip-tcb-capture: Add IRQ handling

[Bence Csókás]

Add interrupt servicing to allow userspace to wait for the following:
* Change-of-state caused by external trigger
* Capture of timer value into RA/RB
* Compare to RC register
* Overflow

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

Notes:
    New in v2
    Changes in v3:
    * Add IRQs for Capture events (from next patch)
    * Add IRQ for RC Compare
    * Add events as bullet points to commit msg
    Changes in v4:
    * Add uapi header, names for the event channels
    * Add check for -EPROBE_DEFER from `of_irq_get()`
    Changes in v5:
    * Split out UAPI header introduction
    Changes in v7:
    * Revert split-out
    * Drop `enum counter_mchp_signals` from UAPI
    * Change enums to #define's in UAPI header

 MAINTAINERS                                   |  1 +
 drivers/counter/microchip-tcb-capture.c       | 75 +++++++++++++++++++
 .../linux/counter/microchip-tcb-capture.h     | 34 +++++++++
 3 files changed, 110 insertions(+)
 create mode 100644 include/uapi/linux/counter/microchip-tcb-capture.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 8e047e20fbd8..d1d264210690 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15579,6 +15579,7 @@ L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	drivers/counter/microchip-tcb-capture.c
+F:	include/uapi/linux/counter/microchip-tcb-capture.h
 
 MICROCHIP USB251XB DRIVER
 M:	Richard Leitner <richard.leitner@skidata.com>
diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c
index 2f096a5b973d..cc12c2e2113a 100644
--- a/drivers/counter/microchip-tcb-capture.c
+++ b/drivers/counter/microchip-tcb-capture.c
@@ -6,18 +6,24 @@
  */
 #include <linux/clk.h>
 #include <linux/counter.h>
+#include <linux/interrupt.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
+#include <uapi/linux/counter/microchip-tcb-capture.h>
 #include <soc/at91/atmel_tcb.h>
 
 #define ATMEL_TC_CMR_MASK	(ATMEL_TC_LDRA_RISING | ATMEL_TC_LDRB_FALLING | \
 				 ATMEL_TC_ETRGEDG_RISING | ATMEL_TC_LDBDIS | \
 				 ATMEL_TC_LDBSTOP)
 
+#define ATMEL_TC_DEF_IRQS	(ATMEL_TC_ETRGS | ATMEL_TC_COVFS | \
+				 ATMEL_TC_LDRAS | ATMEL_TC_LDRBS | ATMEL_TC_CPCS)
+
 #define ATMEL_TC_QDEN			BIT(8)
 #define ATMEL_TC_POSEN			BIT(9)
 
@@ -27,6 +33,7 @@ struct mchp_tc_data {
 	int qdec_mode;
 	int num_channels;
 	int channel[2];
+	int irq;
 };
 
 static const enum counter_function mchp_tc_count_functions[] = {
@@ -294,6 +301,65 @@ static const struct of_device_id atmel_tc_of_match[] = {
 	{ /* sentinel */ }
 };
 
+static irqreturn_t mchp_tc_isr(int irq, void *dev_id)
+{
+	struct counter_device *const counter = dev_id;
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	u32 sr, mask;
+
+	regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], SR), &sr);
+	regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], IMR), &mask);
+
+	sr &= mask;
+	if (!(sr & ATMEL_TC_ALL_IRQ))
+		return IRQ_NONE;
+
+	if (sr & ATMEL_TC_ETRGS)
+		counter_push_event(counter, COUNTER_EVENT_CHANGE_OF_STATE,
+				   COUNTER_MCHP_EVCHN_CV);
+	if (sr & ATMEL_TC_LDRAS)
+		counter_push_event(counter, COUNTER_EVENT_CAPTURE,
+				   COUNTER_MCHP_EVCHN_RA);
+	if (sr & ATMEL_TC_LDRBS)
+		counter_push_event(counter, COUNTER_EVENT_CAPTURE,
+				   COUNTER_MCHP_EVCHN_RB);
+	if (sr & ATMEL_TC_CPCS)
+		counter_push_event(counter, COUNTER_EVENT_THRESHOLD,
+				   COUNTER_MCHP_EVCHN_RC);
+	if (sr & ATMEL_TC_COVFS)
+		counter_push_event(counter, COUNTER_EVENT_OVERFLOW,
+				   COUNTER_MCHP_EVCHN_CV);
+
+	return IRQ_HANDLED;
+}
+
+static void mchp_tc_irq_remove(void *ptr)
+{
+	struct mchp_tc_data *priv = ptr;
+
+	regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], IDR), ATMEL_TC_DEF_IRQS);
+}
+
+static int mchp_tc_irq_enable(struct counter_device *const counter)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	int ret = devm_request_irq(counter->parent, priv->irq, mchp_tc_isr, 0,
+				   dev_name(counter->parent), counter);
+
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], IER), ATMEL_TC_DEF_IRQS);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_add_action_or_reset(counter->parent, mchp_tc_irq_remove, priv);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static void mchp_tc_clk_remove(void *ptr)
 {
 	clk_disable_unprepare((struct clk *)ptr);
@@ -378,6 +444,15 @@ static int mchp_tc_probe(struct platform_device *pdev)
 	counter->num_signals = ARRAY_SIZE(mchp_tc_count_signals);
 	counter->signals = mchp_tc_count_signals;
 
+	priv->irq = of_irq_get(np->parent, 0);
+	if (priv->irq == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+	if (priv->irq > 0) {
+		ret = mchp_tc_irq_enable(counter);
+		if (ret < 0)
+			return dev_err_probe(&pdev->dev, ret, "Failed to set up IRQ");
+	}
+
 	ret = devm_counter_add(&pdev->dev, counter);
 	if (ret < 0)
 		return dev_err_probe(&pdev->dev, ret, "Failed to add counter\n");
diff --git a/include/uapi/linux/counter/microchip-tcb-capture.h b/include/uapi/linux/counter/microchip-tcb-capture.h
new file mode 100644
index 000000000000..f3ef315fe9f6
--- /dev/null
+++ b/include/uapi/linux/counter/microchip-tcb-capture.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Channel numbers used by the microchip-tcb-capture driver
+ * Copyright (C) 2025 Bence Csókás
+ */
+#ifndef _UAPI_COUNTER_MCHP_TCB_H_
+#define _UAPI_COUNTER_MCHP_TCB_H_
+
+/*
+ * The driver defines the following components:
+ *
+ * Count 0
+ * \__  Synapse 0 -- Signal 0 (Channel A, i.e. TIOA)
+ * \__  Synapse 1 -- Signal 1 (Channel B, i.e. TIOB)
+ *
+ * It also supports the following events:
+ *
+ * Channel 0:
+ * - CV register changed
+ * - CV overflowed
+ * - RA captured
+ * Channel 1:
+ * - RB captured
+ * Channel 2:
+ * - RC compare triggered
+ */
+
+/* Event channels */
+#define COUNTER_MCHP_EVCHN_CV 0
+#define COUNTER_MCHP_EVCHN_RA 0
+#define COUNTER_MCHP_EVCHN_RB 1
+#define COUNTER_MCHP_EVCHN_RC 2
+
+#endif /* _UAPI_COUNTER_MCHP_TCB_H_ */
-- 
2.48.1

[PATCH v7 2/2] counter: microchip-tcb-capture: Add capture extensions for registers RA/RB

[Bence Csókás]

TCB hardware is capable of capturing the timer value to registers RA and
RB. Add these registers as capture extensions.

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

Notes:
    Changes in v2:
    * Add IRQs
    Changes in v3:
    * Move IRQs to previous patch
    Changes in v4:
    * Return the status of the regmap_*() operations
    * Add names for the extension numbers
    Changes in v6:
    * Remove RC, as it is not a capture register
    Changes in v7:
    * Change enums to #define's in UAPI header
    * Return early on error in `mchp_tc_count_cap_read()`

 drivers/counter/microchip-tcb-capture.c       | 58 +++++++++++++++++++
 .../linux/counter/microchip-tcb-capture.h     |  6 ++
 2 files changed, 64 insertions(+)

diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c
index cc12c2e2113a..52493f7e8b57 100644
--- a/drivers/counter/microchip-tcb-capture.c
+++ b/drivers/counter/microchip-tcb-capture.c
@@ -254,6 +254,62 @@ static int mchp_tc_count_read(struct counter_device *counter,
 	return 0;
 }
 
+static int mchp_tc_count_cap_read(struct counter_device *counter,
+				  struct counter_count *count, size_t idx, u64 *val)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	u32 cnt;
+	int ret;
+
+	switch (idx) {
+	case COUNTER_MCHP_EXCAP_RA:
+		ret = regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], RA), &cnt);
+		break;
+	case COUNTER_MCHP_EXCAP_RB:
+		ret = regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], RB), &cnt);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (ret < 0)
+		return ret;
+
+	*val = cnt;
+
+	return 0;
+}
+
+static int mchp_tc_count_cap_write(struct counter_device *counter,
+				   struct counter_count *count, size_t idx, u64 val)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	int ret;
+
+	if (val > U32_MAX)
+		return -ERANGE;
+
+	switch (idx) {
+	case COUNTER_MCHP_EXCAP_RA:
+		ret = regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], RA), val);
+		break;
+	case COUNTER_MCHP_EXCAP_RB:
+		ret = regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], RB), val);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static DEFINE_COUNTER_ARRAY_CAPTURE(mchp_tc_cnt_cap_array, 2);
+
+static struct counter_comp mchp_tc_count_ext[] = {
+	COUNTER_COMP_ARRAY_CAPTURE(mchp_tc_count_cap_read, mchp_tc_count_cap_write,
+				   mchp_tc_cnt_cap_array),
+};
+
 static struct counter_count mchp_tc_counts[] = {
 	{
 		.id = 0,
@@ -262,6 +318,8 @@ 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),
 	},
 };
 
diff --git a/include/uapi/linux/counter/microchip-tcb-capture.h b/include/uapi/linux/counter/microchip-tcb-capture.h
index f3ef315fe9f6..136e2faa7730 100644
--- a/include/uapi/linux/counter/microchip-tcb-capture.h
+++ b/include/uapi/linux/counter/microchip-tcb-capture.h
@@ -12,6 +12,8 @@
  * Count 0
  * \__  Synapse 0 -- Signal 0 (Channel A, i.e. TIOA)
  * \__  Synapse 1 -- Signal 1 (Channel B, i.e. TIOB)
+ * \__  Extension capture0    (RA register)
+ * \__  Extension capture1    (RB register)
  *
  * It also supports the following events:
  *
@@ -25,6 +27,10 @@
  * - RC compare triggered
  */
 
+/* Capture extensions */
+#define COUNTER_MCHP_EXCAP_RA 0
+#define COUNTER_MCHP_EXCAP_RB 1
+
 /* Event channels */
 #define COUNTER_MCHP_EVCHN_CV 0
 #define COUNTER_MCHP_EVCHN_RA 0
-- 
2.48.1

Re: [PATCH v7 1/2] counter: microchip-tcb-capture: Add IRQ handling

[William Breathitt Gray]

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On Tue, Mar 04, 2025 at 04:51:51PM +0100, Bence Csókás wrote:
> Add interrupt servicing to allow userspace to wait for the following:
> * Change-of-state caused by external trigger
> * Capture of timer value into RA/RB
> * Compare to RC register
> * Overflow
> 
> Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>

Hi Bence,

I'm mostly statisfied with this patch now, but I have one minor
suggestion below.

> @@ -27,6 +33,7 @@ struct mchp_tc_data {
>  	int qdec_mode;
>  	int num_channels;
>  	int channel[2];
> +	int irq;

We don't use the irq member during the driver operation, so I don't
think this value needs to be saved here with the driver data. It seems
to only be needed in mchp_tc_irq_enable() for devm_request_irq().
Perhaps you can pass the irq value as a parameter to
mchp_tc_irq_enable() instead.

With that change made, I think I'll be ready to pick up this patchset
and merge it into counter-next.

William Breathitt Gray

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Re: [PATCH v7 2/2] counter: microchip-tcb-capture: Add capture extensions for registers RA/RB

[William Breathitt Gray]

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On Tue, Mar 04, 2025 at 04:51:52PM +0100, Bence Csókás wrote:
> TCB hardware is capable of capturing the timer value to registers RA and
> RB. Add these registers as capture extensions.
> 
> Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>

I'm putting my Acked-by line here to be a remainder for myself in the
next revision that this patch is fine and I already reviewed it.

Acked-by: William Breathitt Gray <wbg@kernel.org>

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