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counter: Add character device interface

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This patch introduces a character device interface for the Counter
subsystem. Device data is exposed through standard character device read
operations. Device data is gathered when a Counter event is pushed by
the respective Counter device driver. Configuration is handled via ioctl
operations on the respective Counter character device node.

Cc: David Lechner <david@lechnology.com>
Cc: Gwendal Grignou <gwendal@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/b8b8c64b4065aedff43699ad1f0e2f8d1419c15b.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
William Breathitt Gray 2021-09-29 12:15:59 +09:00 • committed by Jonathan Cameron
parent e65c26f413
commit b6c50affda
6 changed files with 798 additions and 6 deletions
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98
include/uapi/linux/counter.h
View file

@ -6,6 +6,19 @@
#ifndef _UAPI_COUNTER_H_
#define _UAPI_COUNTER_H_
#include <linux/ioctl.h>
#include <linux/types.h>
/* Component type definitions */
enum counter_component_type {
COUNTER_COMPONENT_NONE,
COUNTER_COMPONENT_SIGNAL,
COUNTER_COMPONENT_COUNT,
COUNTER_COMPONENT_FUNCTION,
COUNTER_COMPONENT_SYNAPSE_ACTION,
COUNTER_COMPONENT_EXTENSION,
};
/* Component scope definitions */
enum counter_scope {
COUNTER_SCOPE_DEVICE,
@ -13,6 +26,91 @@ enum counter_scope {
COUNTER_SCOPE_COUNT,
};
/**
* struct counter_component - Counter component identification
* @type: component type (one of enum counter_component_type)
* @scope: component scope (one of enum counter_scope)
* @parent: parent ID (matching the ID suffix of the respective parent sysfs
* path as described by the ABI documentation file
* Documentation/ABI/testing/sysfs-bus-counter)
* @id: component ID (matching the ID provided by the respective *_component_id
* sysfs attribute of the desired component)
*
* For example, if the Count 2 ceiling extension of Counter device 4 is desired,
* set type equal to COUNTER_COMPONENT_EXTENSION, scope equal to
* COUNTER_COUNT_SCOPE, parent equal to 2, and id equal to the value provided by
* the respective /sys/bus/counter/devices/counter4/count2/ceiling_component_id
* sysfs attribute.
*/
struct counter_component {
__u8 type;
__u8 scope;
__u8 parent;
__u8 id;
};
/* Event type definitions */
enum counter_event_type {
/* Count value increased past ceiling */
COUNTER_EVENT_OVERFLOW,
/* Count value decreased past floor */
COUNTER_EVENT_UNDERFLOW,
/* Count value increased past ceiling, or decreased past floor */
COUNTER_EVENT_OVERFLOW_UNDERFLOW,
/* Count value reached threshold */
COUNTER_EVENT_THRESHOLD,
/* Index signal detected */
COUNTER_EVENT_INDEX,
};
/**
* struct counter_watch - Counter component watch configuration
* @component: component to watch when event triggers
* @event: event that triggers (one of enum counter_event_type)
* @channel: event channel (typically 0 unless the device supports concurrent
* events of the same type)
*/
struct counter_watch {
struct counter_component component;
__u8 event;
__u8 channel;
};
/*
* Queues a Counter watch for the specified event.
*
* The queued watches will not be applied until COUNTER_ENABLE_EVENTS_IOCTL is
* called.
*/
#define COUNTER_ADD_WATCH_IOCTL _IOW(0x3E, 0x00, struct counter_watch)
/*
* Enables monitoring the events specified by the Counter watches that were
* queued by COUNTER_ADD_WATCH_IOCTL.
*
* If events are already enabled, the new set of watches replaces the old one.
* Calling this ioctl also has the effect of clearing the queue of watches added
* by COUNTER_ADD_WATCH_IOCTL.
*/
#define COUNTER_ENABLE_EVENTS_IOCTL _IO(0x3E, 0x01)
/*
* Stops monitoring the previously enabled events.
*/
#define COUNTER_DISABLE_EVENTS_IOCTL _IO(0x3E, 0x02)
/**
* struct counter_event - Counter event data
* @timestamp: best estimate of time of event occurrence, in nanoseconds
* @value: component value
* @watch: component watch configuration
* @status: return status (system error number)
*/
struct counter_event {
__aligned_u64 timestamp;
__aligned_u64 value;
struct counter_watch watch;
__u8 status;
};
/* Count direction values */
enum counter_count_direction {
COUNTER_COUNT_DIRECTION_FORWARD,