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.Cameron@xxxxxxxxxx> Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx> --- 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-iio@xxxxxxxxxxxxxxx +Description: + Count data of Count Y represented as a string. + +What: /sys/bus/counter/devices/counterX/countY/ceiling +KernelVersion: 4.19 +Contact: linux-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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-iio@xxxxxxxxxxxxxxx +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.gray@xxxxxxxxx> L: linux-iio@xxxxxxxxxxxxxxx S: Maintained +F: Documentation/ABI/testing/sysfs-bus-counter* F: drivers/counter/ F: include/linux/counter.h
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