Commit 1638b6d4 authored by David Lechner's avatar David Lechner Committed by Jonathan Cameron
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staging: iio: resolver: ad2s1210: add register/fault support summary 



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: default avatarDavid Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-14-ec00746840fc@baylibre.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent a5101e91

drivers/staging/iio/resolver/ad2s1210.c

+40 −0
Original line number Diff line number Diff line
@@ -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>