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authorWilliam Breathitt Gray <vilhelm.gray@gmail.com>2021-09-29 06:16:04 +0300
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2021-10-17 12:55:01 +0300
commitfeff17a550c7120009d8ba9431426135661a731b (patch)
tree8cb59727e09272b6ac5ddd75b7e00df961d5d758 /drivers/counter
parent4bdec61d927b5db25f75fa377504d4e127c3682b (diff)
downloadlinux-feff17a550c7120009d8ba9431426135661a731b.tar.xz
counter: Implement events_queue_size sysfs attribute
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> Link: https://lore.kernel.org/r/c914b2db2ea0a2637633bcc3e86ded3c94783f2e.1632884256.git.vilhelm.gray@gmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'drivers/counter')
-rw-r--r--drivers/counter/counter-sysfs.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c
index 97d8d7c2a2b6..1ccd771da25f 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/atomic.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;
+
+ /* Ensure chrdev is not opened more than 1 at a time */
+ if (!atomic_add_unless(&counter->chrdev_lock, 1, 1))
+ 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:
+ atomic_dec(&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];