1 files changed, 208 insertions, 0 deletions
diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
new file mode 100644
index 000000000..45c37525c
--- /dev/null
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+* Copyright (C) 2012 Invensense, Inc.
+*/
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/sysfs.h>
+#include <linux/jiffies.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/poll.h>
+#include <linux/math64.h>
+#include "inv_mpu_iio.h"
+
+/**
+ *  inv_mpu6050_update_period() - Update chip internal period estimation
+ *
+ *  @st:		driver state
+ *  @timestamp:		the interrupt timestamp
+ *  @nb:		number of data set in the fifo
+ *
+ *  This function uses interrupt timestamps to estimate the chip period and
+ *  to choose the data timestamp to come.
+ */
+static void inv_mpu6050_update_period(struct inv_mpu6050_state *st,
+				      s64 timestamp, size_t nb)
+{
+	/* Period boundaries for accepting timestamp */
+	const s64 period_min =
+		(NSEC_PER_MSEC * (100 - INV_MPU6050_TS_PERIOD_JITTER)) / 100;
+	const s64 period_max =
+		(NSEC_PER_MSEC * (100 + INV_MPU6050_TS_PERIOD_JITTER)) / 100;
+	const s32 divider = INV_MPU6050_FREQ_DIVIDER(st);
+	s64 delta, interval;
+	bool use_it_timestamp = false;
+
+	if (st->it_timestamp == 0) {
+		/* not initialized, forced to use it_timestamp */
+		use_it_timestamp = true;
+	} else if (nb == 1) {
+		/*
+		 * Validate the use of it timestamp by checking if interrupt
+		 * has been delayed.
+		 * nb > 1 means interrupt was delayed for more than 1 sample,
+		 * so it's obviously not good.
+		 * Compute the chip period between 2 interrupts for validating.
+		 */
+		delta = div_s64(timestamp - st->it_timestamp, divider);
+		if (delta > period_min && delta < period_max) {
+			/* update chip period and use it timestamp */
+			st->chip_period = (st->chip_period + delta) / 2;
+			use_it_timestamp = true;
+		}
+	}
+
+	if (use_it_timestamp) {
+		/*
+		 * Manage case of multiple samples in the fifo (nb > 1):
+		 * compute timestamp corresponding to the first sample using
+		 * estimated chip period.
+		 */
+		interval = (nb - 1) * st->chip_period * divider;
+		st->data_timestamp = timestamp - interval;
+	}
+
+	/* save it timestamp */
+	st->it_timestamp = timestamp;
+}
+
+/**
+ *  inv_mpu6050_get_timestamp() - Return the current data timestamp
+ *
+ *  @st:		driver state
+ *  @return:		current data timestamp
+ *
+ *  This function returns the current data timestamp and prepares for next one.
+ */
+static s64 inv_mpu6050_get_timestamp(struct inv_mpu6050_state *st)
+{
+	s64 ts;
+
+	/* return current data timestamp and increment */
+	ts = st->data_timestamp;
+	st->data_timestamp += st->chip_period * INV_MPU6050_FREQ_DIVIDER(st);
+
+	return ts;
+}
+
+static int inv_reset_fifo(struct iio_dev *indio_dev)
+{
+	int result;
+	struct inv_mpu6050_state  *st = iio_priv(indio_dev);
+
+	/* disable fifo and reenable it */
+	inv_mpu6050_prepare_fifo(st, false);
+	result = inv_mpu6050_prepare_fifo(st, true);
+	if (result)
+		goto reset_fifo_fail;
+
+	return 0;
+
+reset_fifo_fail:
+	dev_err(regmap_get_device(st->map), "reset fifo failed %d\n", result);
+	result = regmap_write(st->map, st->reg->int_enable,
+			      INV_MPU6050_BIT_DATA_RDY_EN);
+
+	return result;
+}
+
+/*
+ * inv_mpu6050_read_fifo() - Transfer data from hardware FIFO to KFIFO.
+ */
+irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct inv_mpu6050_state *st = iio_priv(indio_dev);
+	size_t bytes_per_datum;
+	int result;
+	u16 fifo_count;
+	s64 timestamp;
+	int int_status;
+	size_t i, nb;
+
+	mutex_lock(&st->lock);
+
+	/* ack interrupt and check status */
+	result = regmap_read(st->map, st->reg->int_status, &int_status);
+	if (result) {
+		dev_err(regmap_get_device(st->map),
+			"failed to ack interrupt\n");
+		goto flush_fifo;
+	}
+	if (!(int_status & INV_MPU6050_BIT_RAW_DATA_RDY_INT))
+		goto end_session;
+
+	if (!(st->chip_config.accl_fifo_enable |
+		st->chip_config.gyro_fifo_enable |
+		st->chip_config.magn_fifo_enable))
+		goto end_session;
+	bytes_per_datum = 0;
+	if (st->chip_config.accl_fifo_enable)
+		bytes_per_datum += INV_MPU6050_BYTES_PER_3AXIS_SENSOR;
+
+	if (st->chip_config.gyro_fifo_enable)
+		bytes_per_datum += INV_MPU6050_BYTES_PER_3AXIS_SENSOR;
+
+	if (st->chip_config.temp_fifo_enable)
+		bytes_per_datum += INV_MPU6050_BYTES_PER_TEMP_SENSOR;
+
+	if (st->chip_config.magn_fifo_enable)
+		bytes_per_datum += INV_MPU9X50_BYTES_MAGN;
+
+	/*
+	 * read fifo_count register to know how many bytes are inside the FIFO
+	 * right now
+	 */
+	result = regmap_bulk_read(st->map, st->reg->fifo_count_h,
+				  st->data, INV_MPU6050_FIFO_COUNT_BYTE);
+	if (result)
+		goto end_session;
+	fifo_count = be16_to_cpup((__be16 *)&st->data[0]);
+
+	/*
+	 * Handle fifo overflow by resetting fifo.
+	 * Reset if there is only 3 data set free remaining to mitigate
+	 * possible delay between reading fifo count and fifo data.
+	 */
+	nb = 3 * bytes_per_datum;
+	if (fifo_count >= st->hw->fifo_size - nb) {
+		dev_warn(regmap_get_device(st->map), "fifo overflow reset\n");
+		goto flush_fifo;
+	}
+
+	/* compute and process all complete datum */
+	nb = fifo_count / bytes_per_datum;
+	inv_mpu6050_update_period(st, pf->timestamp, nb);
+	for (i = 0; i < nb; ++i) {
+		result = regmap_noinc_read(st->map, st->reg->fifo_r_w,
+					   st->data, bytes_per_datum);
+		if (result)
+			goto flush_fifo;
+		/* skip first samples if needed */
+		if (st->skip_samples) {
+			st->skip_samples--;
+			continue;
+		}
+		timestamp = inv_mpu6050_get_timestamp(st);
+		iio_push_to_buffers_with_timestamp(indio_dev, st->data, timestamp);
+	}
+
+end_session:
+	mutex_unlock(&st->lock);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+
+flush_fifo:
+	/* Flush HW and SW FIFOs. */
+	inv_reset_fifo(indio_dev);
+	mutex_unlock(&st->lock);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}