41a7d6718b
We can't duplicate the description of sampling_frequency. This device has some unusual requirements which we solved by giving a sampling_frequency of 0 special meaning. As such add a note about this unusual usage to the main documentation. Whilst I don't particularly like this resolution, it is the best I could come up with given earlier discussion on this topic. Link: https://lore.kernel.org/linux-iio/20210315101217.00002c50@Huawei.com/ Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org> Link: https://lore.kernel.org/r/20220626165511.602202-4-jic23@kernel.org
4.5 KiB
What: /sys/bus/iio/devices/triggerX/master_mode_available KernelVersion: 4.11 Contact: benjamin.gaignard@st.com Description: Reading returns the list possible master modes which are:
- "reset"
The UG bit from the TIMx_EGR register is
used as trigger output (TRGO).
- "enable"
The Counter Enable signal CNT_EN is used
as trigger output.
- "update"
The update event is selected as trigger output.
For instance a master timer can then be used
as a prescaler for a slave timer.
- "compare_pulse"
The trigger output send a positive pulse
when the CC1IF flag is to be set.
- "OC1REF"
OC1REF signal is used as trigger output.
- "OC2REF"
OC2REF signal is used as trigger output.
- "OC3REF"
OC3REF signal is used as trigger output.
- "OC4REF"
OC4REF signal is used as trigger output.
Additional modes (on TRGO2 only):
- "OC5REF"
OC5REF signal is used as trigger output.
- "OC6REF"
OC6REF signal is used as trigger output.
- "compare_pulse_OC4REF":
OC4REF rising or falling edges generate pulses.
- "compare_pulse_OC6REF":
OC6REF rising or falling edges generate pulses.
- "compare_pulse_OC4REF_r_or_OC6REF_r":
OC4REF or OC6REF rising edges generate pulses.
- "compare_pulse_OC4REF_r_or_OC6REF_f":
OC4REF rising or OC6REF falling edges generate
pulses.
- "compare_pulse_OC5REF_r_or_OC6REF_r":
OC5REF or OC6REF rising edges generate pulses.
- "compare_pulse_OC5REF_r_or_OC6REF_f":
OC5REF rising or OC6REF falling edges generate
pulses.
::
+-----------+ +-------------+ +---------+
| Prescaler +-> | Counter | +-> | Master | TRGO(2)
+-----------+ +--+--------+-+ |-> | Control +-->
| | || +---------+
+--v--------+-+ OCxREF || +---------+
| Chx compare +----------> | Output | ChX
+-----------+-+ | | Control +-->
. | | +---------+
. | | .
+-----------v-+ OC6REF | .
| Ch6 compare +---------+>
+-------------+
Example with: "compare_pulse_OC4REF_r_or_OC6REF_r"::
X
X X
X . . X
X . . X
X . . X
count X . . . . X
. . . .
. . . .
+---------------+
OC4REF | . . |
+-+ . . +-+
. +---+ .
OC6REF . | | .
+-------+ +-------+
+-+ +-+
TRGO2 | | | |
+-+ +---+ +---------+
What: /sys/bus/iio/devices/triggerX/master_mode KernelVersion: 4.11 Contact: benjamin.gaignard@st.com Description: Reading returns the current master modes. Writing set the master mode
What: /sys/bus/iio/devices/iio:deviceX/in_count0_preset KernelVersion: 4.12 Contact: benjamin.gaignard@st.com Description: Reading returns the current preset value. Writing sets the preset value. When counting up the counter starts from 0 and fires an event when reach preset value. When counting down the counter start from preset value and fire event when reach 0.
What: /sys/bus/iio/devices/iio:deviceX/in_count_enable_mode_available KernelVersion: 4.12 Contact: benjamin.gaignard@st.com Description: Reading returns the list possible enable modes.
What: /sys/bus/iio/devices/iio:deviceX/in_count0_enable_mode KernelVersion: 4.12 Contact: benjamin.gaignard@st.com Description: Configure the device counter enable modes, in all case counting direction is set by in_count0_count_direction attribute and the counter is clocked by the internal clock.
always:
Counter is always ON.
gated:
Counting is enabled when connected trigger signal
level is high else counting is disabled.
triggered:
Counting is enabled on rising edge of the connected
trigger, and remains enabled for the duration of this
selected mode.
What: /sys/bus/iio/devices/iio:deviceX/in_count_trigger_mode_available KernelVersion: 4.13 Contact: benjamin.gaignard@st.com Description: Reading returns the list possible trigger modes.
What: /sys/bus/iio/devices/iio:deviceX/in_count0_trigger_mode KernelVersion: 4.13 Contact: benjamin.gaignard@st.com Description: Configure the device counter trigger mode counting direction is set by in_count0_count_direction attribute and the counter is clocked by the connected trigger rising edges.