Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1571 insertions, 0 deletions

diff --git a/drivers/iio/accel/sca3000.c b/drivers/iio/accel/sca3000.c
new file mode 100644
index 000000000..7218acf1a
--- /dev/null
+++ b/drivers/iio/accel/sca3000.c
@@ -0,0 +1,1571 @@
+/*
+ * sca3000_core.c -- support VTI sca3000 series accelerometers via SPI
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * Copyright (c) 2009 Jonathan Cameron <jic23@kernel.org>
+ *
+ * See industrialio/accels/sca3000.h for comments.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+
+#define SCA3000_WRITE_REG(a) (((a) << 2) | 0x02)
+#define SCA3000_READ_REG(a) ((a) << 2)
+
+#define SCA3000_REG_REVID_ADDR				0x00
+#define   SCA3000_REG_REVID_MAJOR_MASK			GENMASK(8, 4)
+#define   SCA3000_REG_REVID_MINOR_MASK			GENMASK(3, 0)
+
+#define SCA3000_REG_STATUS_ADDR				0x02
+#define   SCA3000_LOCKED				BIT(5)
+#define   SCA3000_EEPROM_CS_ERROR			BIT(1)
+#define   SCA3000_SPI_FRAME_ERROR			BIT(0)
+
+/* All reads done using register decrement so no need to directly access LSBs */
+#define SCA3000_REG_X_MSB_ADDR				0x05
+#define SCA3000_REG_Y_MSB_ADDR				0x07
+#define SCA3000_REG_Z_MSB_ADDR				0x09
+
+#define SCA3000_REG_RING_OUT_ADDR			0x0f
+
+/* Temp read untested - the e05 doesn't have the sensor */
+#define SCA3000_REG_TEMP_MSB_ADDR			0x13
+
+#define SCA3000_REG_MODE_ADDR				0x14
+#define SCA3000_MODE_PROT_MASK				0x28
+#define   SCA3000_REG_MODE_RING_BUF_ENABLE		BIT(7)
+#define   SCA3000_REG_MODE_RING_BUF_8BIT		BIT(6)
+
+/*
+ * Free fall detection triggers an interrupt if the acceleration
+ * is below a threshold for equivalent of 25cm drop
+ */
+#define   SCA3000_REG_MODE_FREE_FALL_DETECT		BIT(4)
+#define   SCA3000_REG_MODE_MEAS_MODE_NORMAL		0x00
+#define   SCA3000_REG_MODE_MEAS_MODE_OP_1		0x01
+#define   SCA3000_REG_MODE_MEAS_MODE_OP_2		0x02
+
+/*
+ * In motion detection mode the accelerations are band pass filtered
+ * (approx 1 - 25Hz) and then a programmable threshold used to trigger
+ * and interrupt.
+ */
+#define   SCA3000_REG_MODE_MEAS_MODE_MOT_DET		0x03
+#define   SCA3000_REG_MODE_MODE_MASK			0x03
+
+#define SCA3000_REG_BUF_COUNT_ADDR			0x15
+
+#define SCA3000_REG_INT_STATUS_ADDR			0x16
+#define   SCA3000_REG_INT_STATUS_THREE_QUARTERS		BIT(7)
+#define   SCA3000_REG_INT_STATUS_HALF			BIT(6)
+
+#define SCA3000_INT_STATUS_FREE_FALL			BIT(3)
+#define SCA3000_INT_STATUS_Y_TRIGGER			BIT(2)
+#define SCA3000_INT_STATUS_X_TRIGGER			BIT(1)
+#define SCA3000_INT_STATUS_Z_TRIGGER			BIT(0)
+
+/* Used to allow access to multiplexed registers */
+#define SCA3000_REG_CTRL_SEL_ADDR			0x18
+/* Only available for SCA3000-D03 and SCA3000-D01 */
+#define   SCA3000_REG_CTRL_SEL_I2C_DISABLE		0x01
+#define   SCA3000_REG_CTRL_SEL_MD_CTRL			0x02
+#define   SCA3000_REG_CTRL_SEL_MD_Y_TH			0x03
+#define   SCA3000_REG_CTRL_SEL_MD_X_TH			0x04
+#define   SCA3000_REG_CTRL_SEL_MD_Z_TH			0x05
+/*
+ * BE VERY CAREFUL WITH THIS, IF 3 BITS ARE NOT SET the device
+ * will not function
+ */
+#define   SCA3000_REG_CTRL_SEL_OUT_CTRL			0x0B
+
+#define     SCA3000_REG_OUT_CTRL_PROT_MASK		0xE0
+#define     SCA3000_REG_OUT_CTRL_BUF_X_EN		0x10
+#define     SCA3000_REG_OUT_CTRL_BUF_Y_EN		0x08
+#define     SCA3000_REG_OUT_CTRL_BUF_Z_EN		0x04
+#define     SCA3000_REG_OUT_CTRL_BUF_DIV_MASK		0x03
+#define     SCA3000_REG_OUT_CTRL_BUF_DIV_4		0x02
+#define     SCA3000_REG_OUT_CTRL_BUF_DIV_2		0x01
+
+
+/*
+ * Control which motion detector interrupts are on.
+ * For now only OR combinations are supported.
+ */
+#define SCA3000_MD_CTRL_PROT_MASK			0xC0
+#define SCA3000_MD_CTRL_OR_Y				BIT(0)
+#define SCA3000_MD_CTRL_OR_X				BIT(1)
+#define SCA3000_MD_CTRL_OR_Z				BIT(2)
+/* Currently unsupported */
+#define SCA3000_MD_CTRL_AND_Y				BIT(3)
+#define SCA3000_MD_CTRL_AND_X				BIT(4)
+#define SAC3000_MD_CTRL_AND_Z				BIT(5)
+
+/*
+ * Some control registers of complex access methods requiring this register to
+ * be used to remove a lock.
+ */
+#define SCA3000_REG_UNLOCK_ADDR				0x1e
+
+#define SCA3000_REG_INT_MASK_ADDR			0x21
+#define   SCA3000_REG_INT_MASK_PROT_MASK		0x1C
+
+#define   SCA3000_REG_INT_MASK_RING_THREE_QUARTER	BIT(7)
+#define   SCA3000_REG_INT_MASK_RING_HALF		BIT(6)
+
+#define SCA3000_REG_INT_MASK_ALL_INTS			0x02
+#define SCA3000_REG_INT_MASK_ACTIVE_HIGH		0x01
+#define SCA3000_REG_INT_MASK_ACTIVE_LOW			0x00
+/* Values of multiplexed registers (write to ctrl_data after select) */
+#define SCA3000_REG_CTRL_DATA_ADDR			0x22
+
+/*
+ * Measurement modes available on some sca3000 series chips. Code assumes others
+ * may become available in the future.
+ *
+ * Bypass - Bypass the low-pass filter in the signal channel so as to increase
+ *          signal bandwidth.
+ *
+ * Narrow - Narrow low-pass filtering of the signal channel and half output
+ *          data rate by decimation.
+ *
+ * Wide - Widen low-pass filtering of signal channel to increase bandwidth
+ */
+#define SCA3000_OP_MODE_BYPASS				0x01
+#define SCA3000_OP_MODE_NARROW				0x02
+#define SCA3000_OP_MODE_WIDE				0x04
+#define SCA3000_MAX_TX 6
+#define SCA3000_MAX_RX 2
+
+/**
+ * struct sca3000_state - device instance state information
+ * @us:			the associated spi device
+ * @info:			chip variant information
+ * @last_timestamp:		the timestamp of the last event
+ * @mo_det_use_count:		reference counter for the motion detection unit
+ * @lock:			lock used to protect elements of sca3000_state
+ *				and the underlying device state.
+ * @tx:			dma-able transmit buffer
+ * @rx:			dma-able receive buffer
+ **/
+struct sca3000_state {
+	struct spi_device		*us;
+	const struct sca3000_chip_info	*info;
+	s64				last_timestamp;
+	int				mo_det_use_count;
+	struct mutex			lock;
+	/* Can these share a cacheline ? */
+	u8				rx[384] ____cacheline_aligned;
+	u8				tx[6] ____cacheline_aligned;
+};
+
+/**
+ * struct sca3000_chip_info - model dependent parameters
+ * @scale:			scale * 10^-6
+ * @temp_output:		some devices have temperature sensors.
+ * @measurement_mode_freq:	normal mode sampling frequency
+ * @measurement_mode_3db_freq:	3db cutoff frequency of the low pass filter for
+ * the normal measurement mode.
+ * @option_mode_1:		first optional mode. Not all models have one
+ * @option_mode_1_freq:		option mode 1 sampling frequency
+ * @option_mode_1_3db_freq:	3db cutoff frequency of the low pass filter for
+ * the first option mode.
+ * @option_mode_2:		second optional mode. Not all chips have one
+ * @option_mode_2_freq:		option mode 2 sampling frequency
+ * @option_mode_2_3db_freq:	3db cutoff frequency of the low pass filter for
+ * the second option mode.
+ * @mod_det_mult_xz:		Bit wise multipliers to calculate the threshold
+ * for motion detection in the x and z axis.
+ * @mod_det_mult_y:		Bit wise multipliers to calculate the threshold
+ * for motion detection in the y axis.
+ *
+ * This structure is used to hold information about the functionality of a given
+ * sca3000 variant.
+ **/
+struct sca3000_chip_info {
+	unsigned int		scale;
+	bool			temp_output;
+	int			measurement_mode_freq;
+	int			measurement_mode_3db_freq;
+	int			option_mode_1;
+	int			option_mode_1_freq;
+	int			option_mode_1_3db_freq;
+	int			option_mode_2;
+	int			option_mode_2_freq;
+	int			option_mode_2_3db_freq;
+	int			mot_det_mult_xz[6];
+	int			mot_det_mult_y[7];
+};
+
+enum sca3000_variant {
+	d01,
+	e02,
+	e04,
+	e05,
+};
+
+/*
+ * Note where option modes are not defined, the chip simply does not
+ * support any.
+ * Other chips in the sca3000 series use i2c and are not included here.
+ *
+ * Some of these devices are only listed in the family data sheet and
+ * do not actually appear to be available.
+ */
+static const struct sca3000_chip_info sca3000_spi_chip_info_tbl[] = {
+	[d01] = {
+		.scale = 7357,
+		.temp_output = true,
+		.measurement_mode_freq = 250,
+		.measurement_mode_3db_freq = 45,
+		.option_mode_1 = SCA3000_OP_MODE_BYPASS,
+		.option_mode_1_freq = 250,
+		.option_mode_1_3db_freq = 70,
+		.mot_det_mult_xz = {50, 100, 200, 350, 650, 1300},
+		.mot_det_mult_y = {50, 100, 150, 250, 450, 850, 1750},
+	},
+	[e02] = {
+		.scale = 9810,
+		.measurement_mode_freq = 125,
+		.measurement_mode_3db_freq = 40,
+		.option_mode_1 = SCA3000_OP_MODE_NARROW,
+		.option_mode_1_freq = 63,
+		.option_mode_1_3db_freq = 11,
+		.mot_det_mult_xz = {100, 150, 300, 550, 1050, 2050},
+		.mot_det_mult_y = {50, 100, 200, 350, 700, 1350, 2700},
+	},
+	[e04] = {
+		.scale = 19620,
+		.measurement_mode_freq = 100,
+		.measurement_mode_3db_freq = 38,
+		.option_mode_1 = SCA3000_OP_MODE_NARROW,
+		.option_mode_1_freq = 50,
+		.option_mode_1_3db_freq = 9,
+		.option_mode_2 = SCA3000_OP_MODE_WIDE,
+		.option_mode_2_freq = 400,
+		.option_mode_2_3db_freq = 70,
+		.mot_det_mult_xz = {200, 300, 600, 1100, 2100, 4100},
+		.mot_det_mult_y = {100, 200, 400, 7000, 1400, 2700, 54000},
+	},
+	[e05] = {
+		.scale = 61313,
+		.measurement_mode_freq = 200,
+		.measurement_mode_3db_freq = 60,
+		.option_mode_1 = SCA3000_OP_MODE_NARROW,
+		.option_mode_1_freq = 50,
+		.option_mode_1_3db_freq = 9,
+		.option_mode_2 = SCA3000_OP_MODE_WIDE,
+		.option_mode_2_freq = 400,
+		.option_mode_2_3db_freq = 75,
+		.mot_det_mult_xz = {600, 900, 1700, 3200, 6100, 11900},
+		.mot_det_mult_y = {300, 600, 1200, 2000, 4100, 7800, 15600},
+	},
+};
+
+static int sca3000_write_reg(struct sca3000_state *st, u8 address, u8 val)
+{
+	st->tx[0] = SCA3000_WRITE_REG(address);
+	st->tx[1] = val;
+	return spi_write(st->us, st->tx, 2);
+}
+
+static int sca3000_read_data_short(struct sca3000_state *st,
+				   u8 reg_address_high,
+				   int len)
+{
+	struct spi_transfer xfer[2] = {
+		{
+			.len = 1,
+			.tx_buf = st->tx,
+		}, {
+			.len = len,
+			.rx_buf = st->rx,
+		}
+	};
+	st->tx[0] = SCA3000_READ_REG(reg_address_high);
+
+	return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
+}
+
+/**
+ * sca3000_reg_lock_on() - test if the ctrl register lock is on
+ * @st: Driver specific device instance data.
+ *
+ * Lock must be held.
+ **/
+static int sca3000_reg_lock_on(struct sca3000_state *st)
+{
+	int ret;
+
+	ret = sca3000_read_data_short(st, SCA3000_REG_STATUS_ADDR, 1);
+	if (ret < 0)
+		return ret;
+
+	return !(st->rx[0] & SCA3000_LOCKED);
+}
+
+/**
+ * __sca3000_unlock_reg_lock() - unlock the control registers
+ * @st: Driver specific device instance data.
+ *
+ * Note the device does not appear to support doing this in a single transfer.
+ * This should only ever be used as part of ctrl reg read.
+ * Lock must be held before calling this
+ */
+static int __sca3000_unlock_reg_lock(struct sca3000_state *st)
+{
+	struct spi_transfer xfer[3] = {
+		{
+			.len = 2,
+			.cs_change = 1,
+			.tx_buf = st->tx,
+		}, {
+			.len = 2,
+			.cs_change = 1,
+			.tx_buf = st->tx + 2,
+		}, {
+			.len = 2,
+			.tx_buf = st->tx + 4,
+		},
+	};
+	st->tx[0] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
+	st->tx[1] = 0x00;
+	st->tx[2] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
+	st->tx[3] = 0x50;
+	st->tx[4] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
+	st->tx[5] = 0xA0;
+
+	return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
+}
+
+/**
+ * sca3000_write_ctrl_reg() write to a lock protect ctrl register
+ * @st: Driver specific device instance data.
+ * @sel: selects which registers we wish to write to
+ * @val: the value to be written
+ *
+ * Certain control registers are protected against overwriting by the lock
+ * register and use a shared write address. This function allows writing of
+ * these registers.
+ * Lock must be held.
+ */
+static int sca3000_write_ctrl_reg(struct sca3000_state *st,
+				  u8 sel,
+				  uint8_t val)
+{
+	int ret;
+
+	ret = sca3000_reg_lock_on(st);
+	if (ret < 0)
+		goto error_ret;
+	if (ret) {
+		ret = __sca3000_unlock_reg_lock(st);
+		if (ret)
+			goto error_ret;
+	}
+
+	/* Set the control select register */
+	ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, sel);
+	if (ret)
+		goto error_ret;
+
+	/* Write the actual value into the register */
+	ret = sca3000_write_reg(st, SCA3000_REG_CTRL_DATA_ADDR, val);
+
+error_ret:
+	return ret;
+}
+
+/**
+ * sca3000_read_ctrl_reg() read from lock protected control register.
+ * @st: Driver specific device instance data.
+ * @ctrl_reg: Which ctrl register do we want to read.
+ *
+ * Lock must be held.
+ */
+static int sca3000_read_ctrl_reg(struct sca3000_state *st,
+				 u8 ctrl_reg)
+{
+	int ret;
+
+	ret = sca3000_reg_lock_on(st);
+	if (ret < 0)
+		goto error_ret;
+	if (ret) {
+		ret = __sca3000_unlock_reg_lock(st);
+		if (ret)
+			goto error_ret;
+	}
+	/* Set the control select register */
+	ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, ctrl_reg);
+	if (ret)
+		goto error_ret;
+	ret = sca3000_read_data_short(st, SCA3000_REG_CTRL_DATA_ADDR, 1);
+	if (ret)
+		goto error_ret;
+	return st->rx[0];
+error_ret:
+	return ret;
+}
+
+/**
+ * sca3000_show_rev() - sysfs interface to read the chip revision number
+ * @indio_dev: Device instance specific generic IIO data.
+ * Driver specific device instance data can be obtained via
+ * via iio_priv(indio_dev)
+ */
+static int sca3000_print_rev(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_REVID_ADDR, 1);
+	if (ret < 0)
+		goto error_ret;
+	dev_info(&indio_dev->dev,
+		 "sca3000 revision major=%lu, minor=%lu\n",
+		 st->rx[0] & SCA3000_REG_REVID_MAJOR_MASK,
+		 st->rx[0] & SCA3000_REG_REVID_MINOR_MASK);
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static ssize_t
+sca3000_show_available_3db_freqs(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int len;
+
+	len = sprintf(buf, "%d", st->info->measurement_mode_3db_freq);
+	if (st->info->option_mode_1)
+		len += sprintf(buf + len, " %d",
+			       st->info->option_mode_1_3db_freq);
+	if (st->info->option_mode_2)
+		len += sprintf(buf + len, " %d",
+			       st->info->option_mode_2_3db_freq);
+	len += sprintf(buf + len, "\n");
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR(in_accel_filter_low_pass_3db_frequency_available,
+		       S_IRUGO, sca3000_show_available_3db_freqs,
+		       NULL, 0);
+
+static const struct iio_event_spec sca3000_event = {
+	.type = IIO_EV_TYPE_MAG,
+	.dir = IIO_EV_DIR_RISING,
+	.mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
+};
+
+/*
+ * Note the hack in the number of bits to pretend we have 2 more than
+ * we do in the fifo.
+ */
+#define SCA3000_CHAN(index, mod)				\
+	{							\
+		.type = IIO_ACCEL,				\
+		.modified = 1,					\
+		.channel2 = mod,				\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |\
+			BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+		.address = index,				\
+		.scan_index = index,				\
+		.scan_type = {					\
+			.sign = 's',				\
+			.realbits = 13,				\
+			.storagebits = 16,			\
+			.shift = 3,				\
+			.endianness = IIO_BE,			\
+		},						\
+		.event_spec = &sca3000_event,			\
+		.num_event_specs = 1,				\
+	}
+
+static const struct iio_event_spec sca3000_freefall_event_spec = {
+	.type = IIO_EV_TYPE_MAG,
+	.dir = IIO_EV_DIR_FALLING,
+	.mask_separate = BIT(IIO_EV_INFO_ENABLE) |
+		BIT(IIO_EV_INFO_PERIOD),
+};
+
+static const struct iio_chan_spec sca3000_channels[] = {
+	SCA3000_CHAN(0, IIO_MOD_X),
+	SCA3000_CHAN(1, IIO_MOD_Y),
+	SCA3000_CHAN(2, IIO_MOD_Z),
+	{
+		.type = IIO_ACCEL,
+		.modified = 1,
+		.channel2 = IIO_MOD_X_AND_Y_AND_Z,
+		.scan_index = -1, /* Fake channel */
+		.event_spec = &sca3000_freefall_event_spec,
+		.num_event_specs = 1,
+	},
+};
+
+static const struct iio_chan_spec sca3000_channels_with_temp[] = {
+	SCA3000_CHAN(0, IIO_MOD_X),
+	SCA3000_CHAN(1, IIO_MOD_Y),
+	SCA3000_CHAN(2, IIO_MOD_Z),
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_OFFSET),
+		/* No buffer support */
+		.scan_index = -1,
+	},
+	{
+		.type = IIO_ACCEL,
+		.modified = 1,
+		.channel2 = IIO_MOD_X_AND_Y_AND_Z,
+		.scan_index = -1, /* Fake channel */
+		.event_spec = &sca3000_freefall_event_spec,
+		.num_event_specs = 1,
+	},
+};
+
+static u8 sca3000_addresses[3][3] = {
+	[0] = {SCA3000_REG_X_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_X_TH,
+	       SCA3000_MD_CTRL_OR_X},
+	[1] = {SCA3000_REG_Y_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_Y_TH,
+	       SCA3000_MD_CTRL_OR_Y},
+	[2] = {SCA3000_REG_Z_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_Z_TH,
+	       SCA3000_MD_CTRL_OR_Z},
+};
+
+/**
+ * __sca3000_get_base_freq() - obtain mode specific base frequency
+ * @st: Private driver specific device instance specific state.
+ * @info: chip type specific information.
+ * @base_freq: Base frequency for the current measurement mode.
+ *
+ * lock must be held
+ */
+static inline int __sca3000_get_base_freq(struct sca3000_state *st,
+					  const struct sca3000_chip_info *info,
+					  int *base_freq)
+{
+	int ret;
+
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		goto error_ret;
+	switch (SCA3000_REG_MODE_MODE_MASK & st->rx[0]) {
+	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
+		*base_freq = info->measurement_mode_freq;
+		break;
+	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
+		*base_freq = info->option_mode_1_freq;
+		break;
+	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
+		*base_freq = info->option_mode_2_freq;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+error_ret:
+	return ret;
+}
+
+/**
+ * sca3000_read_raw_samp_freq() - read_raw handler for IIO_CHAN_INFO_SAMP_FREQ
+ * @st: Private driver specific device instance specific state.
+ * @val: The frequency read back.
+ *
+ * lock must be held
+ **/
+static int sca3000_read_raw_samp_freq(struct sca3000_state *st, int *val)
+{
+	int ret;
+
+	ret = __sca3000_get_base_freq(st, st->info, val);
+	if (ret)
+		return ret;
+
+	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
+	if (ret < 0)
+		return ret;
+
+	if (*val > 0) {
+		ret &= SCA3000_REG_OUT_CTRL_BUF_DIV_MASK;
+		switch (ret) {
+		case SCA3000_REG_OUT_CTRL_BUF_DIV_2:
+			*val /= 2;
+			break;
+		case SCA3000_REG_OUT_CTRL_BUF_DIV_4:
+			*val /= 4;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * sca3000_write_raw_samp_freq() - write_raw handler for IIO_CHAN_INFO_SAMP_FREQ
+ * @st: Private driver specific device instance specific state.
+ * @val: The frequency desired.
+ *
+ * lock must be held
+ */
+static int sca3000_write_raw_samp_freq(struct sca3000_state *st, int val)
+{
+	int ret, base_freq, ctrlval;
+
+	ret = __sca3000_get_base_freq(st, st->info, &base_freq);
+	if (ret)
+		return ret;
+
+	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
+	if (ret < 0)
+		return ret;
+
+	ctrlval = ret & ~SCA3000_REG_OUT_CTRL_BUF_DIV_MASK;
+
+	if (val == base_freq / 2)
+		ctrlval |= SCA3000_REG_OUT_CTRL_BUF_DIV_2;
+	if (val == base_freq / 4)
+		ctrlval |= SCA3000_REG_OUT_CTRL_BUF_DIV_4;
+	else if (val != base_freq)
+		return -EINVAL;
+
+	return sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL,
+				     ctrlval);
+}
+
+static int sca3000_read_3db_freq(struct sca3000_state *st, int *val)
+{
+	int ret;
+
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		return ret;
+
+	/* mask bottom 2 bits - only ones that are relevant */
+	st->rx[0] &= SCA3000_REG_MODE_MODE_MASK;
+	switch (st->rx[0]) {
+	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
+		*val = st->info->measurement_mode_3db_freq;
+		return IIO_VAL_INT;
+	case SCA3000_REG_MODE_MEAS_MODE_MOT_DET:
+		return -EBUSY;
+	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
+		*val = st->info->option_mode_1_3db_freq;
+		return IIO_VAL_INT;
+	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
+		*val = st->info->option_mode_2_3db_freq;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sca3000_write_3db_freq(struct sca3000_state *st, int val)
+{
+	int ret;
+	int mode;
+
+	if (val == st->info->measurement_mode_3db_freq)
+		mode = SCA3000_REG_MODE_MEAS_MODE_NORMAL;
+	else if (st->info->option_mode_1 &&
+		 (val == st->info->option_mode_1_3db_freq))
+		mode = SCA3000_REG_MODE_MEAS_MODE_OP_1;
+	else if (st->info->option_mode_2 &&
+		 (val == st->info->option_mode_2_3db_freq))
+		mode = SCA3000_REG_MODE_MEAS_MODE_OP_2;
+	else
+		return -EINVAL;
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		return ret;
+
+	st->rx[0] &= ~SCA3000_REG_MODE_MODE_MASK;
+	st->rx[0] |= (mode & SCA3000_REG_MODE_MODE_MASK);
+
+	return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR, st->rx[0]);
+}
+
+static int sca3000_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val,
+			    int *val2,
+			    long mask)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+	u8 address;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&st->lock);
+		if (chan->type == IIO_ACCEL) {
+			if (st->mo_det_use_count) {
+				mutex_unlock(&st->lock);
+				return -EBUSY;
+			}
+			address = sca3000_addresses[chan->address][0];
+			ret = sca3000_read_data_short(st, address, 2);
+			if (ret < 0) {
+				mutex_unlock(&st->lock);
+				return ret;
+			}
+			*val = (be16_to_cpup((__be16 *)st->rx) >> 3) & 0x1FFF;
+			*val = ((*val) << (sizeof(*val) * 8 - 13)) >>
+				(sizeof(*val) * 8 - 13);
+		} else {
+			/* get the temperature when available */
+			ret = sca3000_read_data_short(st,
+						      SCA3000_REG_TEMP_MSB_ADDR,
+						      2);
+			if (ret < 0) {
+				mutex_unlock(&st->lock);
+				return ret;
+			}
+			*val = ((st->rx[0] & 0x3F) << 3) |
+			       ((st->rx[1] & 0xE0) >> 5);
+		}
+		mutex_unlock(&st->lock);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		if (chan->type == IIO_ACCEL)
+			*val2 = st->info->scale;
+		else /* temperature */
+			*val2 = 555556;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = -214;
+		*val2 = 600000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		mutex_lock(&st->lock);
+		ret = sca3000_read_raw_samp_freq(st, val);
+		mutex_unlock(&st->lock);
+		return ret ? ret : IIO_VAL_INT;
+	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		mutex_lock(&st->lock);
+		ret = sca3000_read_3db_freq(st, val);
+		mutex_unlock(&st->lock);
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sca3000_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		if (val2)
+			return -EINVAL;
+		mutex_lock(&st->lock);
+		ret = sca3000_write_raw_samp_freq(st, val);
+		mutex_unlock(&st->lock);
+		return ret;
+	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		if (val2)
+			return -EINVAL;
+		mutex_lock(&st->lock);
+		ret = sca3000_write_3db_freq(st, val);
+		mutex_unlock(&st->lock);
+		return ret;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+/**
+ * sca3000_read_av_freq() - sysfs function to get available frequencies
+ * @dev: Device structure for this device.
+ * @attr: Description of the attribute.
+ * @buf: Incoming string
+ *
+ * The later modes are only relevant to the ring buffer - and depend on current
+ * mode. Note that data sheet gives rather wide tolerances for these so integer
+ * division will give good enough answer and not all chips have them specified
+ * at all.
+ **/
+static ssize_t sca3000_read_av_freq(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int len = 0, ret, val;
+
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	val = st->rx[0];
+	mutex_unlock(&st->lock);
+	if (ret)
+		goto error_ret;
+
+	switch (val & SCA3000_REG_MODE_MODE_MASK) {
+	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
+		len += sprintf(buf + len, "%d %d %d\n",
+			       st->info->measurement_mode_freq,
+			       st->info->measurement_mode_freq / 2,
+			       st->info->measurement_mode_freq / 4);
+		break;
+	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
+		len += sprintf(buf + len, "%d %d %d\n",
+			       st->info->option_mode_1_freq,
+			       st->info->option_mode_1_freq / 2,
+			       st->info->option_mode_1_freq / 4);
+		break;
+	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
+		len += sprintf(buf + len, "%d %d %d\n",
+			       st->info->option_mode_2_freq,
+			       st->info->option_mode_2_freq / 2,
+			       st->info->option_mode_2_freq / 4);
+		break;
+	}
+	return len;
+error_ret:
+	return ret;
+}
+
+/*
+ * Should only really be registered if ring buffer support is compiled in.
+ * Does no harm however and doing it right would add a fair bit of complexity
+ */
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(sca3000_read_av_freq);
+
+/**
+ * sca3000_read_event_value() - query of a threshold or period
+ **/
+static int sca3000_read_event_value(struct iio_dev *indio_dev,
+				    const struct iio_chan_spec *chan,
+				    enum iio_event_type type,
+				    enum iio_event_direction dir,
+				    enum iio_event_info info,
+				    int *val, int *val2)
+{
+	int ret, i;
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		mutex_lock(&st->lock);
+		ret = sca3000_read_ctrl_reg(st,
+					    sca3000_addresses[chan->address][1]);
+		mutex_unlock(&st->lock);
+		if (ret < 0)
+			return ret;
+		*val = 0;
+		if (chan->channel2 == IIO_MOD_Y)
+			for_each_set_bit(i, (unsigned long *)&ret,
+					 ARRAY_SIZE(st->info->mot_det_mult_y))
+				*val += st->info->mot_det_mult_y[i];
+		else
+			for_each_set_bit(i, (unsigned long *)&ret,
+					 ARRAY_SIZE(st->info->mot_det_mult_xz))
+				*val += st->info->mot_det_mult_xz[i];
+
+		return IIO_VAL_INT;
+	case IIO_EV_INFO_PERIOD:
+		*val = 0;
+		*val2 = 226000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
+ * sca3000_write_value() - control of threshold and period
+ * @indio_dev: Device instance specific IIO information.
+ * @chan: Description of the channel for which the event is being
+ * configured.
+ * @type: The type of event being configured, here magnitude rising
+ * as everything else is read only.
+ * @dir: Direction of the event (here rising)
+ * @info: What information about the event are we configuring.
+ * Here the threshold only.
+ * @val: Integer part of the value being written..
+ * @val2: Non integer part of the value being written. Here always 0.
+ */
+static int sca3000_write_event_value(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir,
+				     enum iio_event_info info,
+				     int val, int val2)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+	int i;
+	u8 nonlinear = 0;
+
+	if (chan->channel2 == IIO_MOD_Y) {
+		i = ARRAY_SIZE(st->info->mot_det_mult_y);
+		while (i > 0)
+			if (val >= st->info->mot_det_mult_y[--i]) {
+				nonlinear |= (1 << i);
+				val -= st->info->mot_det_mult_y[i];
+			}
+	} else {
+		i = ARRAY_SIZE(st->info->mot_det_mult_xz);
+		while (i > 0)
+			if (val >= st->info->mot_det_mult_xz[--i]) {
+				nonlinear |= (1 << i);
+				val -= st->info->mot_det_mult_xz[i];
+			}
+	}
+
+	mutex_lock(&st->lock);
+	ret = sca3000_write_ctrl_reg(st,
+				     sca3000_addresses[chan->address][1],
+				     nonlinear);
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static struct attribute *sca3000_attributes[] = {
+	&iio_dev_attr_in_accel_filter_low_pass_3db_frequency_available.dev_attr.attr,
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group sca3000_attribute_group = {
+	.attrs = sca3000_attributes,
+};
+
+static int sca3000_read_data(struct sca3000_state *st,
+			     u8 reg_address_high,
+			     u8 *rx,
+			     int len)
+{
+	int ret;
+	struct spi_transfer xfer[2] = {
+		{
+			.len = 1,
+			.tx_buf = st->tx,
+		}, {
+			.len = len,
+			.rx_buf = rx,
+		}
+	};
+
+	st->tx[0] = SCA3000_READ_REG(reg_address_high);
+	ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
+	if (ret) {
+		dev_err(&st->us->dev, "problem reading register\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * sca3000_ring_int_process() - ring specific interrupt handling.
+ * @val: Value of the interrupt status register.
+ * @indio_dev: Device instance specific IIO device structure.
+ */
+static void sca3000_ring_int_process(u8 val, struct iio_dev *indio_dev)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret, i, num_available;
+
+	mutex_lock(&st->lock);
+
+	if (val & SCA3000_REG_INT_STATUS_HALF) {
+		ret = sca3000_read_data_short(st, SCA3000_REG_BUF_COUNT_ADDR,
+					      1);
+		if (ret)
+			goto error_ret;
+		num_available = st->rx[0];
+		/*
+		 * num_available is the total number of samples available
+		 * i.e. number of time points * number of channels.
+		 */
+		ret = sca3000_read_data(st, SCA3000_REG_RING_OUT_ADDR, st->rx,
+					num_available * 2);
+		if (ret)
+			goto error_ret;
+		for (i = 0; i < num_available / 3; i++) {
+			/*
+			 * Dirty hack to cover for 11 bit in fifo, 13 bit
+			 * direct reading.
+			 *
+			 * In theory the bottom two bits are undefined.
+			 * In reality they appear to always be 0.
+			 */
+			iio_push_to_buffers(indio_dev, st->rx + i * 3 * 2);
+		}
+	}
+error_ret:
+	mutex_unlock(&st->lock);
+}
+
+/**
+ * sca3000_event_handler() - handling ring and non ring events
+ * @irq: The irq being handled.
+ * @private: struct iio_device pointer for the device.
+ *
+ * Ring related interrupt handler. Depending on event, push to
+ * the ring buffer event chrdev or the event one.
+ *
+ * This function is complicated by the fact that the devices can signify ring
+ * and non ring events via the same interrupt line and they can only
+ * be distinguished via a read of the relevant status register.
+ */
+static irqreturn_t sca3000_event_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret, val;
+	s64 last_timestamp = iio_get_time_ns(indio_dev);
+
+	/*
+	 * Could lead if badly timed to an extra read of status reg,
+	 * but ensures no interrupt is missed.
+	 */
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_INT_STATUS_ADDR, 1);
+	val = st->rx[0];
+	mutex_unlock(&st->lock);
+	if (ret)
+		goto done;
+
+	sca3000_ring_int_process(val, indio_dev);
+
+	if (val & SCA3000_INT_STATUS_FREE_FALL)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
+						  0,
+						  IIO_MOD_X_AND_Y_AND_Z,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_FALLING),
+			       last_timestamp);
+
+	if (val & SCA3000_INT_STATUS_Y_TRIGGER)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
+						  0,
+						  IIO_MOD_Y,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_RISING),
+			       last_timestamp);
+
+	if (val & SCA3000_INT_STATUS_X_TRIGGER)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
+						  0,
+						  IIO_MOD_X,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_RISING),
+			       last_timestamp);
+
+	if (val & SCA3000_INT_STATUS_Z_TRIGGER)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
+						  0,
+						  IIO_MOD_Z,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_RISING),
+			       last_timestamp);
+
+done:
+	return IRQ_HANDLED;
+}
+
+/**
+ * sca3000_read_event_config() what events are enabled
+ **/
+static int sca3000_read_event_config(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+	/* read current value of mode register */
+	mutex_lock(&st->lock);
+
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		goto error_ret;
+
+	switch (chan->channel2) {
+	case IIO_MOD_X_AND_Y_AND_Z:
+		ret = !!(st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT);
+		break;
+	case IIO_MOD_X:
+	case IIO_MOD_Y:
+	case IIO_MOD_Z:
+		/*
+		 * Motion detection mode cannot run at the same time as
+		 * acceleration data being read.
+		 */
+		if ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
+		    != SCA3000_REG_MODE_MEAS_MODE_MOT_DET) {
+			ret = 0;
+		} else {
+			ret = sca3000_read_ctrl_reg(st,
+						SCA3000_REG_CTRL_SEL_MD_CTRL);
+			if (ret < 0)
+				goto error_ret;
+			/* only supporting logical or's for now */
+			ret = !!(ret & sca3000_addresses[chan->address][2]);
+		}
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int sca3000_freefall_set_state(struct iio_dev *indio_dev, int state)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+
+	/* read current value of mode register */
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		return ret;
+
+	/* if off and should be on */
+	if (state && !(st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT))
+		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
+					 st->rx[0] | SCA3000_REG_MODE_FREE_FALL_DETECT);
+	/* if on and should be off */
+	else if (!state && (st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT))
+		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
+					 st->rx[0] & ~SCA3000_REG_MODE_FREE_FALL_DETECT);
+	else
+		return 0;
+}
+
+static int sca3000_motion_detect_set_state(struct iio_dev *indio_dev, int axis,
+					   int state)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret, ctrlval;
+
+	/*
+	 * First read the motion detector config to find out if
+	 * this axis is on
+	 */
+	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL);
+	if (ret < 0)
+		return ret;
+	ctrlval = ret;
+	/* if off and should be on */
+	if (state && !(ctrlval & sca3000_addresses[axis][2])) {
+		ret = sca3000_write_ctrl_reg(st,
+					     SCA3000_REG_CTRL_SEL_MD_CTRL,
+					     ctrlval |
+					     sca3000_addresses[axis][2]);
+		if (ret)
+			return ret;
+		st->mo_det_use_count++;
+	} else if (!state && (ctrlval & sca3000_addresses[axis][2])) {
+		ret = sca3000_write_ctrl_reg(st,
+					     SCA3000_REG_CTRL_SEL_MD_CTRL,
+					     ctrlval &
+					     ~(sca3000_addresses[axis][2]));
+		if (ret)
+			return ret;
+		st->mo_det_use_count--;
+	}
+
+	/* read current value of mode register */
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		return ret;
+	/* if off and should be on */
+	if ((st->mo_det_use_count) &&
+	    ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
+	     != SCA3000_REG_MODE_MEAS_MODE_MOT_DET))
+		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
+			(st->rx[0] & ~SCA3000_REG_MODE_MODE_MASK)
+			| SCA3000_REG_MODE_MEAS_MODE_MOT_DET);
+	/* if on and should be off */
+	else if (!(st->mo_det_use_count) &&
+		 ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
+		  == SCA3000_REG_MODE_MEAS_MODE_MOT_DET))
+		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
+			st->rx[0] & SCA3000_REG_MODE_MODE_MASK);
+	else
+		return 0;
+}
+
+/**
+ * sca3000_write_event_config() - simple on off control for motion detector
+ * @indio_dev: IIO device instance specific structure. Data specific to this
+ * particular driver may be accessed via iio_priv(indio_dev).
+ * @chan: Description of the channel whose event we are configuring.
+ * @type: The type of event.
+ * @dir: The direction of the event.
+ * @state: Desired state of event being configured.
+ *
+ * This is a per axis control, but enabling any will result in the
+ * motion detector unit being enabled.
+ * N.B. enabling motion detector stops normal data acquisition.
+ * There is a complexity in knowing which mode to return to when
+ * this mode is disabled.  Currently normal mode is assumed.
+ **/
+static int sca3000_write_event_config(struct iio_dev *indio_dev,
+				      const struct iio_chan_spec *chan,
+				      enum iio_event_type type,
+				      enum iio_event_direction dir,
+				      int state)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&st->lock);
+	switch (chan->channel2) {
+	case IIO_MOD_X_AND_Y_AND_Z:
+		ret = sca3000_freefall_set_state(indio_dev, state);
+		break;
+
+	case IIO_MOD_X:
+	case IIO_MOD_Y:
+	case IIO_MOD_Z:
+		ret = sca3000_motion_detect_set_state(indio_dev,
+						      chan->address,
+						      state);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int sca3000_configure_ring(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buffer;
+
+	buffer = devm_iio_kfifo_allocate(&indio_dev->dev);
+	if (!buffer)
+		return -ENOMEM;
+
+	iio_device_attach_buffer(indio_dev, buffer);
+	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
+
+	return 0;
+}
+
+static inline
+int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
+{
+	struct sca3000_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		goto error_ret;
+	if (state) {
+		dev_info(&indio_dev->dev, "supposedly enabling ring buffer\n");
+		ret = sca3000_write_reg(st,
+			SCA3000_REG_MODE_ADDR,
+			(st->rx[0] | SCA3000_REG_MODE_RING_BUF_ENABLE));
+	} else
+		ret = sca3000_write_reg(st,
+			SCA3000_REG_MODE_ADDR,
+			(st->rx[0] & ~SCA3000_REG_MODE_RING_BUF_ENABLE));
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+/**
+ * sca3000_hw_ring_preenable() - hw ring buffer preenable function
+ * @indio_dev: structure representing the IIO device. Device instance
+ * specific state can be accessed via iio_priv(indio_dev).
+ *
+ * Very simple enable function as the chip will allows normal reads
+ * during ring buffer operation so as long as it is indeed running
+ * before we notify the core, the precise ordering does not matter.
+ */
+static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	mutex_lock(&st->lock);
+
+	/* Enable the 50% full interrupt */
+	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
+	if (ret)
+		goto error_unlock;
+	ret = sca3000_write_reg(st,
+				SCA3000_REG_INT_MASK_ADDR,
+				st->rx[0] | SCA3000_REG_INT_MASK_RING_HALF);
+	if (ret)
+		goto error_unlock;
+
+	mutex_unlock(&st->lock);
+
+	return __sca3000_hw_ring_state_set(indio_dev, 1);
+
+error_unlock:
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	ret = __sca3000_hw_ring_state_set(indio_dev, 0);
+	if (ret)
+		return ret;
+
+	/* Disable the 50% full interrupt */
+	mutex_lock(&st->lock);
+
+	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
+	if (ret)
+		goto unlock;
+	ret = sca3000_write_reg(st,
+				SCA3000_REG_INT_MASK_ADDR,
+				st->rx[0] & ~SCA3000_REG_INT_MASK_RING_HALF);
+unlock:
+	mutex_unlock(&st->lock);
+	return ret;
+}
+
+static const struct iio_buffer_setup_ops sca3000_ring_setup_ops = {
+	.preenable = &sca3000_hw_ring_preenable,
+	.postdisable = &sca3000_hw_ring_postdisable,
+};
+
+/**
+ * sca3000_clean_setup() - get the device into a predictable state
+ * @st: Device instance specific private data structure
+ *
+ * Devices use flash memory to store many of the register values
+ * and hence can come up in somewhat unpredictable states.
+ * Hence reset everything on driver load.
+ */
+static int sca3000_clean_setup(struct sca3000_state *st)
+{
+	int ret;
+
+	mutex_lock(&st->lock);
+	/* Ensure all interrupts have been acknowledged */
+	ret = sca3000_read_data_short(st, SCA3000_REG_INT_STATUS_ADDR, 1);
+	if (ret)
+		goto error_ret;
+
+	/* Turn off all motion detection channels */
+	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL);
+	if (ret < 0)
+		goto error_ret;
+	ret = sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL,
+				     ret & SCA3000_MD_CTRL_PROT_MASK);
+	if (ret)
+		goto error_ret;
+
+	/* Disable ring buffer */
+	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
+	if (ret < 0)
+		goto error_ret;
+	ret = sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL,
+				     (ret & SCA3000_REG_OUT_CTRL_PROT_MASK)
+				     | SCA3000_REG_OUT_CTRL_BUF_X_EN
+				     | SCA3000_REG_OUT_CTRL_BUF_Y_EN
+				     | SCA3000_REG_OUT_CTRL_BUF_Z_EN
+				     | SCA3000_REG_OUT_CTRL_BUF_DIV_4);
+	if (ret)
+		goto error_ret;
+	/* Enable interrupts, relevant to mode and set up as active low */
+	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
+	if (ret)
+		goto error_ret;
+	ret = sca3000_write_reg(st,
+				SCA3000_REG_INT_MASK_ADDR,
+				(ret & SCA3000_REG_INT_MASK_PROT_MASK)
+				| SCA3000_REG_INT_MASK_ACTIVE_LOW);
+	if (ret)
+		goto error_ret;
+	/*
+	 * Select normal measurement mode, free fall off, ring off
+	 * Ring in 12 bit mode - it is fine to overwrite reserved bits 3,5
+	 * as that occurs in one of the example on the datasheet
+	 */
+	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
+	if (ret)
+		goto error_ret;
+	ret = sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
+				(st->rx[0] & SCA3000_MODE_PROT_MASK));
+
+error_ret:
+	mutex_unlock(&st->lock);
+	return ret;
+}
+
+static const struct iio_info sca3000_info = {
+	.attrs = &sca3000_attribute_group,
+	.read_raw = &sca3000_read_raw,
+	.write_raw = &sca3000_write_raw,
+	.read_event_value = &sca3000_read_event_value,
+	.write_event_value = &sca3000_write_event_value,
+	.read_event_config = &sca3000_read_event_config,
+	.write_event_config = &sca3000_write_event_config,
+};
+
+static int sca3000_probe(struct spi_device *spi)
+{
+	int ret;
+	struct sca3000_state *st;
+	struct iio_dev *indio_dev;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	spi_set_drvdata(spi, indio_dev);
+	st->us = spi;
+	mutex_init(&st->lock);
+	st->info = &sca3000_spi_chip_info_tbl[spi_get_device_id(spi)
+					      ->driver_data];
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->info = &sca3000_info;
+	if (st->info->temp_output) {
+		indio_dev->channels = sca3000_channels_with_temp;
+		indio_dev->num_channels =
+			ARRAY_SIZE(sca3000_channels_with_temp);
+	} else {
+		indio_dev->channels = sca3000_channels;
+		indio_dev->num_channels = ARRAY_SIZE(sca3000_channels);
+	}
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = sca3000_configure_ring(indio_dev);
+	if (ret)
+		return ret;
+
+	if (spi->irq) {
+		ret = request_threaded_irq(spi->irq,
+					   NULL,
+					   &sca3000_event_handler,
+					   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					   "sca3000",
+					   indio_dev);
+		if (ret)
+			return ret;
+	}
+	indio_dev->setup_ops = &sca3000_ring_setup_ops;
+	ret = sca3000_clean_setup(st);
+	if (ret)
+		goto error_free_irq;
+
+	ret = sca3000_print_rev(indio_dev);
+	if (ret)
+		goto error_free_irq;
+
+	return iio_device_register(indio_dev);
+
+error_free_irq:
+	if (spi->irq)
+		free_irq(spi->irq, indio_dev);
+
+	return ret;
+}
+
+static int sca3000_stop_all_interrupts(struct sca3000_state *st)
+{
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
+	if (ret)
+		goto error_ret;
+	ret = sca3000_write_reg(st, SCA3000_REG_INT_MASK_ADDR,
+				(st->rx[0] &
+				 ~(SCA3000_REG_INT_MASK_RING_THREE_QUARTER |
+				   SCA3000_REG_INT_MASK_RING_HALF |
+				   SCA3000_REG_INT_MASK_ALL_INTS)));
+error_ret:
+	mutex_unlock(&st->lock);
+	return ret;
+}
+
+static int sca3000_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct sca3000_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	/* Must ensure no interrupts can be generated after this! */
+	sca3000_stop_all_interrupts(st);
+	if (spi->irq)
+		free_irq(spi->irq, indio_dev);
+
+	return 0;
+}
+
+static const struct spi_device_id sca3000_id[] = {
+	{"sca3000_d01", d01},
+	{"sca3000_e02", e02},
+	{"sca3000_e04", e04},
+	{"sca3000_e05", e05},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, sca3000_id);
+
+static struct spi_driver sca3000_driver = {
+	.driver = {
+		.name = "sca3000",
+	},
+	.probe = sca3000_probe,
+	.remove = sca3000_remove,
+	.id_table = sca3000_id,
+};
+module_spi_driver(sca3000_driver);
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
+MODULE_DESCRIPTION("VTI SCA3000 Series Accelerometers SPI driver");
+MODULE_LICENSE("GPL v2");