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From: William Breathitt Gray <vilhelm.gray@gmail.com>
To: jic23@kernel.org
Cc: linux-stm32@st-md-mailman.stormreply.com, kernel@pengutronix.de,
	a.fatoum@pengutronix.de, kamel.bouhara@bootlin.com,
	gwendal@chromium.org, alexandre.belloni@bootlin.com,
	david@lechnology.com, linux-iio@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, syednwaris@gmail.com,
	patrick.havelange@essensium.com, fabrice.gasnier@st.com,
	mcoquelin.stm32@gmail.com, alexandre.torgue@st.com,
	o.rempel@pengutronix.de, jarkko.nikula@linux.intel.com,
	William Breathitt Gray <vilhelm.gray@gmail.com>
Subject: [PATCH v16 12/14] counter: Implement events_queue_size sysfs attribute
Date: Fri, 27 Aug 2021 12:47:56 +0900	[thread overview]
Message-ID: <b159f45c8f9dd383e44cdd5629573f28895bea47.1630031207.git.vilhelm.gray@gmail.com> (raw)
In-Reply-To: <cover.1630031207.git.vilhelm.gray@gmail.com>

The events_queue_size sysfs attribute provides a way for users to
dynamically configure the Counter events queue size for the Counter
character device interface. The size is in number of struct
counter_event data structures. The number of elements will be rounded-up
to a power of 2 due to a requirement of the kfifo_alloc function called
during reallocation of the queue.

Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
 Documentation/ABI/testing/sysfs-bus-counter |  8 ++++
 drivers/counter/counter-sysfs.c             | 45 +++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter
index 0ce16669157e..06c2b3e27e0b 100644
--- a/Documentation/ABI/testing/sysfs-bus-counter
+++ b/Documentation/ABI/testing/sysfs-bus-counter
@@ -233,6 +233,14 @@ Description:
 		shorter or equal to configured value are ignored. Value 0 means
 		filter is disabled.
 
+What:		/sys/bus/counter/devices/counterX/events_queue_size
+KernelVersion:	5.16
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Size of the Counter events queue in number of struct
+		counter_event data structures. The number of elements will be
+		rounded-up to a power of 2.
+
 What:		/sys/bus/counter/devices/counterX/name
 KernelVersion:	5.2
 Contact:	linux-iio@vger.kernel.org
diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 97d8d7c2a2b6..b90f404b1fa1 100644
--- a/drivers/counter/counter-sysfs.c
+++ b/drivers/counter/counter-sysfs.c
@@ -3,11 +3,13 @@
  * Generic Counter sysfs interface
  * Copyright (C) 2020 William Breathitt Gray
  */
+#include <linux/bitops.h>
 #include <linux/counter.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/gfp.h>
 #include <linux/kernel.h>
+#include <linux/kfifo.h>
 #include <linux/kstrtox.h>
 #include <linux/list.h>
 #include <linux/string.h>
@@ -783,12 +785,49 @@ static int counter_num_counts_read(struct counter_device *counter, u8 *val)
 	return 0;
 }
 
+static int counter_events_queue_size_read(struct counter_device *counter,
+					  u64 *val)
+{
+	*val = kfifo_size(&counter->events);
+	return 0;
+}
+
+static int counter_events_queue_size_write(struct counter_device *counter,
+					   u64 val)
+{
+	DECLARE_KFIFO_PTR(events, struct counter_event);
+	int err = 0;
+
+	/* Verify chrdev is not currently being used */
+	if (test_and_set_bit_lock(0, counter->chrdev_lock))
+		return -EBUSY;
+
+	/* Allocate new events queue */
+	err = kfifo_alloc(&events, val, GFP_KERNEL);
+	if (err)
+		goto exit_early;
+
+	/* Swap in new events queue */
+	kfifo_free(&counter->events);
+	counter->events.kfifo = events.kfifo;
+
+exit_early:
+	clear_bit_unlock(0, counter->chrdev_lock);
+
+	return err;
+}
+
 static struct counter_comp counter_num_signals_comp =
 	COUNTER_COMP_DEVICE_U8("num_signals", counter_num_signals_read, NULL);
 
 static struct counter_comp counter_num_counts_comp =
 	COUNTER_COMP_DEVICE_U8("num_counts", counter_num_counts_read, NULL);
 
+static struct counter_comp counter_events_queue_size_comp =
+	COUNTER_COMP_DEVICE_U64("events_queue_size",
+				counter_events_queue_size_read,
+				counter_events_queue_size_write);
+
 static int counter_sysfs_attr_add(struct counter_device *const counter,
 				  struct counter_attribute_group *cattr_group)
 {
@@ -827,6 +866,12 @@ static int counter_sysfs_attr_add(struct counter_device *const counter,
 	if (err < 0)
 		return err;
 
+	/* Create events_queue_size attribute */
+	err = counter_attr_create(dev, cattr_group,
+				  &counter_events_queue_size_comp, scope, NULL);
+	if (err < 0)
+		return err;
+
 	/* Create an attribute for each extension */
 	for (i = 0; i < counter->num_ext; i++) {
 		ext = &counter->ext[i];
-- 
2.32.0


  parent reply	other threads:[~2021-08-27  3:49 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-27  3:47 [PATCH v16 00/14] Introduce the Counter character device interface William Breathitt Gray
2021-08-27  3:47 ` [PATCH v16 01/14] counter: stm32-lptimer-cnt: Provide defines for clock polarities William Breathitt Gray
2021-08-31 13:38   ` Fabrice Gasnier
2021-09-08 17:31     ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 02/14] counter: stm32-timer-cnt: Provide defines for slave mode selection William Breathitt Gray
2021-08-31 13:40   ` Fabrice Gasnier
2021-09-08 17:31     ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 03/14] counter: Internalize sysfs interface code William Breathitt Gray
2021-08-31 13:44   ` [Linux-stm32] " Fabrice Gasnier
2021-08-31 14:16     ` William Breathitt Gray
2021-08-31 14:55       ` William Breathitt Gray
2021-09-08 17:44     ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 04/14] counter: Update counter.h comments to reflect sysfs internalization William Breathitt Gray
2021-09-08 17:46   ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 05/14] docs: counter: Update " William Breathitt Gray
2021-09-08 17:48   ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 06/14] counter: Move counter enums to uapi header William Breathitt Gray
2021-08-27  3:47 ` [PATCH v16 07/14] counter: Add character device interface William Breathitt Gray
2021-09-12 16:18   ` Jonathan Cameron
2021-09-20 10:09     ` William Breathitt Gray
2021-09-26 15:15       ` Jonathan Cameron
2021-09-27 10:21         ` William Breathitt Gray
2021-09-27 11:20           ` Jonathan Cameron
2021-09-27 11:33             ` William Breathitt Gray
2021-08-27  3:47 ` [PATCH v16 08/14] docs: counter: Document " William Breathitt Gray
2021-09-12 16:18   ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 09/14] tools/counter: Create Counter tools William Breathitt Gray
2021-09-12 16:26   ` Jonathan Cameron
2021-08-27  3:47 ` [PATCH v16 10/14] counter: Implement signalZ_action_component_id sysfs attribute William Breathitt Gray
2021-08-27  3:47 ` [PATCH v16 11/14] counter: Implement *_component_id sysfs attributes William Breathitt Gray
2021-08-27  3:47 ` William Breathitt Gray [this message]
2021-08-27  3:47 ` [PATCH v16 13/14] counter: 104-quad-8: Replace mutex with spinlock William Breathitt Gray
2021-08-27  3:47 ` [PATCH v16 14/14] counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8 William Breathitt Gray
2021-08-30 17:17 ` [PATCH v16 00/14] Introduce the Counter character device interface Jonathan Cameron
2021-09-12 16:36   ` Jonathan Cameron

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