[PATCH v4 1/2] counter: microchip-tcb-capture: Add IRQ handling

Bence Csókás
2025-02-11T15:21:32Z

Add interrupt servicing to allow userspace to wait for the following events:
* 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()`

MAINTAINERS | 1 +
drivers/counter/microchip-tcb-capture.c | 75 +++++++++++++++++++
.../linux/counter/microchip-tcb-capture.h | 40 ++++++++++
3 files changed, 116 insertions(+)
create mode 100644 include/uapi/linux/counter/microchip-tcb-capture.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 8e047e20fbd8..0a8ce24ff467 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.c

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..b91d8954f06e
--- /dev/null
+++ b/include/uapi/linux/counter/microchip-tcb-capture.h
@@ -0,0 +1,40 @@
+/* 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
+ */
+
+enum counter_mchp_signals {
+ COUNTER_MCHP_SIG_TIOA,
+ COUNTER_MCHP_SIG_TIOB,
+};
+
+enum counter_mchp_event_channels {
+ COUNTER_MCHP_EVCHN_CV = 0,
+ COUNTER_MCHP_EVCHN_RA = 0,
+ COUNTER_MCHP_EVCHN_RB,
+ COUNTER_MCHP_EVCHN_RC,
+};
+
+#endif /* _UAPI_COUNTER_MCHP_TCB_H_ */
--
2.48.1