// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2020 Invensense, Inc. */ #include <linux/kernel.h> #include <linux/device.h> #include <linux/mutex.h> #include <linux/pm_runtime.h> #include <linux/regmap.h> #include <linux/delay.h> #include <linux/iio/buffer.h> #include <linux/iio/common/inv_sensors_timestamp.h> #include <linux/iio/iio.h> #include "inv_icm42600.h" #include "inv_icm42600_buffer.h" /* FIFO header: 1 byte */ #define INV_ICM42600_FIFO_HEADER_MSG … #define INV_ICM42600_FIFO_HEADER_ACCEL … #define INV_ICM42600_FIFO_HEADER_GYRO … #define INV_ICM42600_FIFO_HEADER_TMST_FSYNC … #define INV_ICM42600_FIFO_HEADER_ODR_ACCEL … #define INV_ICM42600_FIFO_HEADER_ODR_GYRO … struct inv_icm42600_fifo_1sensor_packet { … } __packed; #define INV_ICM42600_FIFO_1SENSOR_PACKET_SIZE … struct inv_icm42600_fifo_2sensors_packet { … } __packed; #define INV_ICM42600_FIFO_2SENSORS_PACKET_SIZE … ssize_t inv_icm42600_fifo_decode_packet(const void *packet, const void **accel, const void **gyro, const int8_t **temp, const void **timestamp, unsigned int *odr) { … } void inv_icm42600_buffer_update_fifo_period(struct inv_icm42600_state *st) { … } int inv_icm42600_buffer_set_fifo_en(struct inv_icm42600_state *st, unsigned int fifo_en) { … } static size_t inv_icm42600_get_packet_size(unsigned int fifo_en) { … } static unsigned int inv_icm42600_wm_truncate(unsigned int watermark, size_t packet_size) { … } /** * inv_icm42600_buffer_update_watermark - update watermark FIFO threshold * @st: driver internal state * * Returns 0 on success, a negative error code otherwise. * * FIFO watermark threshold is computed based on the required watermark values * set for gyro and accel sensors. Since watermark is all about acceptable data * latency, use the smallest setting between the 2. It means choosing the * smallest latency but this is not as simple as choosing the smallest watermark * value. Latency depends on watermark and ODR. It requires several steps: * 1) compute gyro and accel latencies and choose the smallest value. * 2) adapt the choosen latency so that it is a multiple of both gyro and accel * ones. Otherwise it is possible that you don't meet a requirement. (for * example with gyro @100Hz wm 4 and accel @100Hz with wm 6, choosing the * value of 4 will not meet accel latency requirement because 6 is not a * multiple of 4. You need to use the value 2.) * 3) Since all periods are multiple of each others, watermark is computed by * dividing this computed latency by the smallest period, which corresponds * to the FIFO frequency. Beware that this is only true because we are not * using 500Hz frequency which is not a multiple of the others. */ int inv_icm42600_buffer_update_watermark(struct inv_icm42600_state *st) { … } static int inv_icm42600_buffer_preenable(struct iio_dev *indio_dev) { … } /* * update_scan_mode callback is turning sensors on and setting data FIFO enable * bits. */ static int inv_icm42600_buffer_postenable(struct iio_dev *indio_dev) { … } static int inv_icm42600_buffer_predisable(struct iio_dev *indio_dev) { … } static int inv_icm42600_buffer_postdisable(struct iio_dev *indio_dev) { … } const struct iio_buffer_setup_ops inv_icm42600_buffer_ops = …; int inv_icm42600_buffer_fifo_read(struct inv_icm42600_state *st, unsigned int max) { … } int inv_icm42600_buffer_fifo_parse(struct inv_icm42600_state *st) { … } int inv_icm42600_buffer_hwfifo_flush(struct inv_icm42600_state *st, unsigned int count) { … } int inv_icm42600_buffer_init(struct inv_icm42600_state *st) { … }
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