counter: Documentation: Add Generic Counter sysfs documentation
This patch adds standard documentation for the userspace sysfs attributes of the Generic Counter interface. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
William Breathitt Gray
Greg Kroah-Hartman
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What: /sys/bus/counter/devices/counterX/countY/count
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Count data of Count Y represented as a string.
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What: /sys/bus/counter/devices/counterX/countY/ceiling
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Count value ceiling for Count Y. This is the upper limit for the
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respective counter.
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What: /sys/bus/counter/devices/counterX/countY/floor
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Count value floor for Count Y. This is the lower limit for the
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respective counter.
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What: /sys/bus/counter/devices/counterX/countY/count_mode
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Count mode for channel Y. The ceiling and floor values for
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Count Y are used by the count mode where required. The following
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count modes are available:
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normal:
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Counting is continuous in either direction.
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range limit:
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An upper or lower limit is set, mimicking limit switches
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in the mechanical counterpart. The upper limit is set to
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the Count Y ceiling value, while the lower limit is set
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to the Count Y floor value. The counter freezes at
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count = ceiling when counting up, and at count = floor
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when counting down. At either of these limits, the
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counting is resumed only when the count direction is
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reversed.
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non-recycle:
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The counter is disabled whenever a counter overflow or
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underflow takes place. The counter is re-enabled when a
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new count value is loaded to the counter via a preset
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operation or direct write.
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modulo-n:
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A count value boundary is set between the Count Y floor
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value and the Count Y ceiling value. The counter is
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reset to the Count Y floor value at count = ceiling when
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counting up, while the counter is set to the Count Y
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ceiling value at count = floor when counting down; the
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counter does not freeze at the boundary points, but
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counts continuously throughout.
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What: /sys/bus/counter/devices/counterX/countY/count_mode_available
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What: /sys/bus/counter/devices/counterX/countY/error_noise_available
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What: /sys/bus/counter/devices/counterX/countY/function_available
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What: /sys/bus/counter/devices/counterX/countY/signalZ_action_available
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Discrete set of available values for the respective Count Y
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configuration are listed in this file. Values are delimited by
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newline characters.
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What: /sys/bus/counter/devices/counterX/countY/direction
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates the count direction of Count
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Y. Two count directions are available: forward and backward.
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Some counter devices are able to determine the direction of
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their counting. For example, quadrature encoding counters can
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determine the direction of movement by evaluating the leading
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phase of the respective A and B quadrature encoding signals.
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This attribute exposes such count directions.
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What: /sys/bus/counter/devices/counterX/countY/enable
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Whether channel Y counter is enabled. Valid attribute values are
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boolean.
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This attribute is intended to serve as a pause/unpause mechanism
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for Count Y. Suppose a counter device is used to count the total
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movement of a conveyor belt: this attribute allows an operator
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to temporarily pause the counter, service the conveyor belt,
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and then finally unpause the counter to continue where it had
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left off.
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What: /sys/bus/counter/devices/counterX/countY/error_noise
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates whether excessive noise is
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present at the channel Y counter inputs.
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What: /sys/bus/counter/devices/counterX/countY/function
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Count function mode of Count Y; count function evaluation is
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triggered by conditions specified by the Count Y signalZ_action
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attributes. The following count functions are available:
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increase:
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Accumulated count is incremented.
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decrease:
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Accumulated count is decremented.
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pulse-direction:
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Rising edges on signal A updates the respective count.
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The input level of signal B determines direction.
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quadrature x1 a:
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If direction is forward, rising edges on quadrature pair
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signal A updates the respective count; if the direction
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is backward, falling edges on quadrature pair signal A
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updates the respective count. Quadrature encoding
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determines the direction.
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quadrature x1 b:
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If direction is forward, rising edges on quadrature pair
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signal B updates the respective count; if the direction
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is backward, falling edges on quadrature pair signal B
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updates the respective count. Quadrature encoding
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determines the direction.
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quadrature x2 a:
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Any state transition on quadrature pair signal A updates
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the respective count. Quadrature encoding determines the
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direction.
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quadrature x2 b:
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Any state transition on quadrature pair signal B updates
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the respective count. Quadrature encoding determines the
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direction.
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quadrature x4:
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Any state transition on either quadrature pair signals
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updates the respective count. Quadrature encoding
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determines the direction.
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What: /sys/bus/counter/devices/counterX/countY/name
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates the device-specific name of
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Count Y. If possible, this should match the name of the
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respective channel as it appears in the device datasheet.
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What: /sys/bus/counter/devices/counterX/countY/preset
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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If the counter device supports preset registers -- registers
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used to load counter channels to a set count upon device-defined
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preset operation trigger events -- the preset count for channel
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Y is provided by this attribute.
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What: /sys/bus/counter/devices/counterX/countY/preset_enable
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Whether channel Y counter preset operation is enabled. Valid
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attribute values are boolean.
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What: /sys/bus/counter/devices/counterX/countY/signalZ_action
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Action mode of Count Y for Signal Z. This attribute indicates
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the condition of Signal Z that triggers the count function
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evaluation for Count Y. The following action modes are
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available:
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none:
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Signal does not trigger the count function. In
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Pulse-Direction count function mode, this Signal is
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evaluated as Direction.
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rising edge:
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Low state transitions to high state.
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falling edge:
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High state transitions to low state.
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both edges:
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Any state transition.
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What: /sys/bus/counter/devices/counterX/name
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates the device-specific name of
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the Counter. This should match the name of the device as it
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appears in its respective datasheet.
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What: /sys/bus/counter/devices/counterX/num_counts
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates the total number of Counts
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belonging to the Counter.
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What: /sys/bus/counter/devices/counterX/num_signals
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates the total number of Signals
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belonging to the Counter.
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What: /sys/bus/counter/devices/counterX/signalY/signal
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Signal data of Signal Y represented as a string.
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What: /sys/bus/counter/devices/counterX/signalY/name
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KernelVersion: 5.2
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Contact: linux-iio@vger.kernel.org
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Description:
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Read-only attribute that indicates the device-specific name of
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Signal Y. If possible, this should match the name of the
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respective signal as it appears in the device datasheet.
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@ -4058,6 +4058,7 @@ COUNTER SUBSYSTEM
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M: William Breathitt Gray <vilhelm.gray@gmail.com>
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L: linux-iio@vger.kernel.org
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S: Maintained
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F: Documentation/ABI/testing/sysfs-bus-counter*
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F: drivers/counter/
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F: include/linux/counter.h
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F: include/linux/counter_enum.h
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