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staging: iio: resolver: ad2s1210: add register/fault support summary

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The ad2s1210 driver shoe-horns the register and fault support into IIO
events. The mapping between the registers/faults and the events is not
obvious. To save users from having to read the entire driver to figure
out how to use it, add a summary of the register/fault support to the
top of the file.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-14-ec00746840fc@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
David Lechner 2023-10-05 19:50:31 -05:00 committed by Jonathan Cameron
parent a5101e91e9
commit 1638b6d4f7
1 changed files with 40 additions and 0 deletions
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40
drivers/staging/iio/resolver/ad2s1210.c
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@ -4,7 +4,47 @@
*
* Copyright (c) 2010-2010 Analog Devices Inc.
* Copyright (c) 2023 BayLibre, SAS
*
* Device register to IIO ABI mapping:
*
* Register | Addr | IIO ABI (sysfs)
* ----------------------------|------|-------------------------------------------
* DOS Overrange Threshold | 0x89 | events/in_altvoltage0_thresh_rising_value
* DOS Mismatch Threshold | 0x8A | events/in_altvoltage0_mag_rising_value
* DOS Reset Maximum Threshold | 0x8B | events/in_altvoltage0_mag_rising_reset_max
* DOS Reset Minimum Threshold | 0x8C | events/in_altvoltage0_mag_rising_reset_min
* LOT High Threshold | 0x8D | events/in_angl1_thresh_rising_value
* LOT Low Threshold [1] | 0x8E | events/in_angl1_thresh_rising_hysteresis
* Excitation Frequency | 0x91 | out_altvoltage0_frequency
* Control | 0x92 | *as bit fields*
* Phase lock range | D5 | events/in_phase0_mag_rising_value
* Hysteresis | D4 | in_angl0_hysteresis
* Encoder resolution | D3:2 | *not implemented*
* Resolution | D1:0 | *device tree: assigned-resolution-bits*
* Soft Reset | 0xF0 | [2]
* Fault | 0xFF | *not implemented*
*
* [1]: The value written to the LOT low register is high value minus the
* hysteresis.
* [2]: Soft reset is performed when `out_altvoltage0_frequency` is written.
*
* Fault to event mapping:
*
* Fault | | Channel | Type | Direction
* ----------------------------------------|----|---------------------------------
* Sine/cosine inputs clipped [3] | D7 | altvoltage1 | mag | either
* Sine/cosine inputs below LOS | D6 | altvoltage0 | thresh | falling
* Sine/cosine inputs exceed DOS overrange | D5 | altvoltage0 | thresh | rising
* Sine/cosine inputs exceed DOS mismatch | D4 | altvoltage0 | mag | rising
* Tracking error exceeds LOT | D3 | angl1 | thresh | rising
* Velocity exceeds maximum tracking rate | D2 | anglvel0 | mag | rising
* Phase error exceeds phase lock range | D1 | phase0 | mag | rising
* Configuration parity error | D0 | *writes to kernel log*
*
* [3]: The chip does not differentiate between fault on sine vs. cosine so
* there will also be an event on the altvoltage2 channel.
*/
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/clk.h>