@@ -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: 5.15
+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
@@ -311,6 +311,9 @@ static int counter_chrdev_open(struct inode *inode, struct file *filp)
typeof(*counter),
chrdev);
+ if (!mutex_trylock(&counter->chrdev_lock))
+ return -EBUSY;
+
get_device(&counter->dev);
filp->private_data = counter;
@@ -327,6 +330,7 @@ static int counter_chrdev_release(struct inode *inode, struct file *filp)
return err;
put_device(&counter->dev);
+ mutex_unlock(&counter->chrdev_lock);
return 0;
}
@@ -8,7 +8,9 @@
#include <linux/err.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
+#include <linux/kfifo.h>
#include <linux/list.h>
+#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/types.h>
@@ -782,12 +784,48 @@ 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)
+{
+ int err;
+ DECLARE_KFIFO_PTR(events, struct counter_event);
+
+ /* Verify chrdev is not currently being used */
+ if (!mutex_trylock(&counter->chrdev_lock))
+ return -EBUSY;
+
+ /* Allocate new events queue */
+ err = kfifo_alloc(&events, val, GFP_ATOMIC);
+ if (err)
+ return err;
+
+ /* Swap in new events queue */
+ kfifo_free(&counter->events);
+ counter->events.kfifo = events.kfifo;
+
+ mutex_unlock(&counter->chrdev_lock);
+
+ return 0;
+}
+
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 *group)
{
@@ -826,6 +864,12 @@ static int counter_sysfs_attr_add(struct counter_device *const counter,
if (err < 0)
return err;
+ /* Create num_counts attribute */
+ err = counter_attr_create(dev, 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;
@@ -289,6 +289,7 @@ struct counter_ops {
* @priv: optional private data supplied by driver
* @dev: internal device structure
* @chrdev: internal character device structure
+ * @chrdev_lock: lock to limit chrdev to a single open at a time
* @events_list: list of current watching Counter events
* @events_list_lock: lock to protect Counter events list operations
* @next_events_list: list of next watching Counter events
@@ -314,6 +315,7 @@ struct counter_device {
struct device dev;
struct cdev chrdev;
+ struct mutex chrdev_lock;
struct list_head events_list;
spinlock_t events_list_lock;
struct list_head next_events_list;
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-chrdev.c | 4 ++ drivers/counter/counter-sysfs.c | 44 +++++++++++++++++++++ include/linux/counter.h | 2 + 4 files changed, 58 insertions(+)