When prescaler (PSC) is 0, it means div factor is 1: counter clock
frequency is equal to input clk / (PSC + 1).
When reload value is 8 for example, counter counts 9 cycles, from 0 to 8.
This is handled in frequency write routine, by writing respectively:
- prescaler - 1 to PSC
- reload value - 1 to ARR
This fix does the opposite when reading the frequency from PSC and ARR:
- prescaler is PSC + 1
- reload value is ARR + 1
Thus, PSC may be 0, depending on requested sampling frequency (div 1).
In this case, reading freq wrongly reports 0, instead of computing and
reporting correct value.
Remove test on !psc and !arr.
Small test on stm32f4 (example on tim1_trgo), before this fix:
$ cd /sys/bus/iio/devices/triggerX
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
0
After this fix:
$ echo 10000 > sampling_frequency
$ cat sampling_frequency
10000
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Timers IPs can be used to generate triggers for other IPs like
DAC or ADC.
Each trigger may result of timer internals signals like counter enable,
reset or edge, this configuration could be done through "master_mode"
device attribute.
Since triggers could be used by DAC or ADC their names are defined
in include/ nux/iio/timer/stm32-timer-trigger.h and is_stm32_iio_timer_trigger
function could be used to check if the trigger is valid or not.
"trgo" trigger have a "sampling_frequency" attribute which allow to configure
timer sampling frequency.
version 8:
- change kernel version from 4.10 to 4.11 in ABI documentation
version 7:
- remove all iio_device related code
- move driver into trigger directory
version 5:
- simplify tables of triggers
- only create an IIO device when needed
version 4:
- get triggers configuration from "reg" in DT
- add tables of triggers
- sampling frequency is enable/disable when writing in trigger
sampling_frequency attribute
- no more use of interruptions
version 3:
- change compatible to "st,stm32-timer-trigger"
- fix attributes access right
- use string instead of int for master_mode and slave_mode
- document device attributes in sysfs-bus-iio-timer-stm32
version 2:
- keep only one compatible
- use st,input-triggers-names and st,output-triggers-names
to know which triggers are accepted and/or create by the device
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
