On 06/21/2018 04:07 PM, William Breathitt Gray wrote:
This patch adds standard documentation for the userspace sysfs
attributes of the Generic Counter interface.
Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
Signed-off-by: William Breathitt Gray <vilhelm.g...@gmail.com>
---
Documentation/ABI/testing/sysfs-bus-counter | 230 ++++++++++++++++++++
MAINTAINERS | 1 +
2 files changed, 231 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-bus-counter
diff --git a/Documentation/ABI/testing/sysfs-bus-counter
b/Documentation/ABI/testing/sysfs-bus-counter
new file mode 100644
index 000000000000..0bb0dce67bf8
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-counter
@@ -0,0 +1,230 @@
+What: /sys/bus/counter/devices/counterX/countY/count
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Count data of Count Y represented as a string.
+
+What: /sys/bus/counter/devices/counterX/countY/ceiling
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Count value ceiling for Count Y. This is the upper limit for the
+ respective counter.
+
+What: /sys/bus/counter/devices/counterX/countY/floor
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Count value floor for Count Y. This is the lower limit for the
+ respective counter.
+
+What: /sys/bus/counter/devices/counterX/countY/count_mode
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Count mode for channel Y. The ceiling and floor values for
+ Count Y are used by the count mode where required. The following
+ count modes are available:
+
+ Normal:
+ Counting is continuous in either direction.
+
+ Range Limit:
+ An upper or lower limit is set, mimicking limit switches
+ in the mechanical counterpart. The upper limit is set to
+ the Count Y ceiling value, while the lower limit is set
+ to the Count Y floor value. The counter freezes at
+ count = ceiling when counting up, and at count = floor
+ when counting down. At either of these limits, the
+ counting is resumed only when the count direction is
+ reversed.
+
+ Non-Recycle:
+ The counter is disabled whenever a counter overflow or
+ underflow takes place. The counter is re-enabled when a
+ new count value is loaded to the counter via a preset
+ operation or direct write.
+
+ Modulo-N:
+ A count value boundary is set between the Count Y floor
+ value and the Count Y ceiling value. The counter is
+ reset to the Cunt Y floor value at count = ceiling when
+ counting up, while the counter is set to the Count Y
+ ceiling value at count = floor when counting down; the
+ counter does not freeze at the boundary points, but
+ counts continuously throughout.
+
This might be a bit misleading since the values returned are all lower case,
e.g. "rising edge", whereas they are listed here in Title Case.
+What: /sys/bus/counter/devices/counterX/countY/count_mode_available
+What: /sys/bus/counter/devices/counterX/countY/error_noise_available
+What: /sys/bus/counter/devices/counterX/countY/function_available
+What:
/sys/bus/counter/devices/counterX/countY/signalZ_action_available
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Discrete set of available values for the respective Count Y
+ configuration are listed in this file. Values are delineated by
+ newline characters.
+
+What: /sys/bus/counter/devices/counterX/countY/direction
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates the count direction of Count
+ Y. Two count directions are available: forward and backward.
+
+ Some counter devices are able to determine the direction of
+ their counting. For example, quadrature encoding counters can
+ determine the direction of movement by evaluating the leading
+ phase of the respective A and B quadrature encoding signals.
+ This attribute exposes such count directions.
+
+What: /sys/bus/counter/devices/counterX/countY/enable
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Whether channel Y counter is enabled. Valid attribute values are
+ boolean.
+
+ This attribute is intended to serve as a pause/unpause mechanism
+ for Count Y. Suppose a counter device is used to count the total
+ movement of a conveyor belt: this attribute allows an operator
+ to temporarily pause the counter, service the conveyor belt,
+ and then finally unpause the counter to continue where it had
+ left off.
+
+What: /sys/bus/counter/devices/counterX/countY/error_noise
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates whether excessive noise is
+ present at the channel Y counter inputs.
+
+What: /sys/bus/counter/devices/counterX/countY/function
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Count function mode of Count Y; count function evaluation is
+ triggered by conditions specified by the Count Y signalZ_action
+ attributes. The following count functions are available:
+
+ Increase:
+ Accumulated count is incremented.
+
+ Decrease:
+ Accumulated count is decremented.
+
+ Pulse-Direction:
+ Rising edges on signal A updates the respective count.
+ The input level of signal B determines direction.
+
+ Quadrature x1 A:
+ If direction is forward, rising edges on quadrature pair
+ signal A updates the respective count; if the direction
+ is backward, falling edges on quadrature pair signal A
+ updates the respective count. Quadrature encoding
+ determines the direction.
+
+ Quadrature x1 B:
+ If direction is forward, rising edges on quadrature pair
+ signal B updates the respective count; if the direction
+ is backward, falling edges on quadrature pair signal B
+ updates the respective count. Quadrature encoding
+ determines the direction.
+
+ Quadrature x2 A:
+ Any state transition on quadrature pair signal A updates
+ the respective count. Quadrature encoding determines the
+ direction.
+
+ Quadrature x2 B:
+ Any state transition on quadrature pair signal B updates
+ the respective count. Quadrature encoding determines the
+ direction.
+
+ Quadrature x4:
+ Any state transition on either quadrature pair signals
+ updates the respective count. Quadrature encoding
+ determines the direction.
+
Same here about lower case vs. Title Case.
+What: /sys/bus/counter/devices/counterX/countY/name
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates the device-specific name of
+ Count Y. If possible, this should match the name of the
+ respective channel as it appears in the device datasheet.
+
+What: /sys/bus/counter/devices/counterX/countY/preset
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ If the counter device supports preset registers -- registers
+ used to load counter channels to a set count upon device-defined
+ preset operation trigger events -- the preset count for channel
+ Y is provided by this attribute.
Should this be presetZ in case a device has more than one preset?
+
+What: /sys/bus/counter/devices/counterX/countY/preset_enable
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Whether channel Y counter preset operation is enabled. Valid
+ attribute values are boolean.
+
+What: /sys/bus/counter/devices/counterX/countY/signalZ_action
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Action mode of Count Y for Signal Z. This attribute indicates
+ the condition of Signal Z that triggers the count function
+ evaluation for Count Y. The following action modes are
+ available:
+
+ None:
+ Signal does not trigger the count function. In
+ Pulse-Direction count function mode, this Signal is
+ evaluated as Direction.
+
+ Rising Edge:
+ Low state transitions to high state.
+
+ Falling Edge:
+ High state transitions to low state.
+
+ Both Edges:
+ Any state transition.
And again here (Title Case/lower case)
+
+What: /sys/bus/counter/devices/counterX/name
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates the device-specific name of
+ the Counter. This should match the name of the device as it
+ appears in its respective datasheet.
+
+What: /sys/bus/counter/devices/counterX/num_counts
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates the total number of Counts
+ belonging to the Counter.
+
+What: /sys/bus/counter/devices/counterX/num_signals
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates the total number of Signals
+ belonging to the Counter.
+
+What: /sys/bus/counter/devices/counterX/signalY/signal
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Signal data of Signal Y represented as a string.
I guess the actual value returned depends on the type of signal? Would we
need /sys/bus/counter/devices/counterX/signalY/type to indicate this so we
know how to interpret the value?
+
+What: /sys/bus/counter/devices/counterX/signalY/name
+KernelVersion: 4.19
+Contact: linux-...@vger.kernel.org
+Description:
+ Read-only attribute that indicates the device-specific name of
+ Signal Y. If possible, this should match the name of the
+ respective signal as it appears in the device datasheet.
diff --git a/MAINTAINERS b/MAINTAINERS
index f6e995c142ed..f8a47fd197a1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3692,6 +3692,7 @@ COUNTER SUBSYSTEM
M: William Breathitt Gray <vilhelm.g...@gmail.com>
L: linux-...@vger.kernel.org
S: Maintained
+F: Documentation/ABI/testing/sysfs-bus-counter*
F: drivers/counter/
F: include/linux/counter.h
