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@xxxxxxxxxxxx> --- v4 changes: New patch in v4. drivers/staging/iio/resolver/ad2s1210.c | 40 +++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c index d9d51bbbade8..51490fea1647 100644 --- a/drivers/staging/iio/resolver/ad2s1210.c +++ b/drivers/staging/iio/resolver/ad2s1210.c @@ -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> -- 2.42.0
