[PATCH 18/36] staging: iio: gyro: new driver for ADIS16251 devices

[Mike Frysinger <vapier@gentoo.org>]

From: Barry Song <barry.song@analog.com>

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
---
 drivers/staging/iio/gyro/Kconfig          |   10 +
 drivers/staging/iio/gyro/Makefile         |    3 +
 drivers/staging/iio/gyro/adis16251.h      |  185 +++++++
 drivers/staging/iio/gyro/adis16251_core.c |  777 +++++++++++++++++++++++++++++
 drivers/staging/iio/sysfs.h               |    6 +
 5 files changed, 981 insertions(+), 0 deletions(-)
 create mode 100644 drivers/staging/iio/gyro/adis16251.h
 create mode 100644 drivers/staging/iio/gyro/adis16251_core.c

diff --git a/drivers/staging/iio/gyro/Kconfig b/drivers/staging/iio/gyro/Kconfig
index d1dde82..c7a7d29 100644
--- a/drivers/staging/iio/gyro/Kconfig
+++ b/drivers/staging/iio/gyro/Kconfig
@@ -14,3 +14,13 @@ config ADIS16260
 
 	  This driver can also be built as a module.  If so, the module
 	  will be called adis16260.
+
+config ADIS16251
+	tristate "Analog Devices ADIS16251 Digital Gyroscope Sensor SPI driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices adis16261 programmable
+	  digital gyroscope sensor.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called adis16251.
diff --git a/drivers/staging/iio/gyro/Makefile b/drivers/staging/iio/gyro/Makefile
index b5f0dc0..8a592d8 100644
--- a/drivers/staging/iio/gyro/Makefile
+++ b/drivers/staging/iio/gyro/Makefile
@@ -5,3 +5,6 @@
 adis16260-y             := adis16260_core.o
 adis16260-$(CONFIG_IIO_RING_BUFFER) += adis16260_ring.o adis16260_trigger.o
 obj-$(CONFIG_ADIS16260) += adis16260.o
+
+adis16251-y             := adis16251_core.o
+obj-$(CONFIG_ADIS16251) += adis16251.o
diff --git a/drivers/staging/iio/gyro/adis16251.h b/drivers/staging/iio/gyro/adis16251.h
new file mode 100644
index 0000000..999db49
--- /dev/null
+++ b/drivers/staging/iio/gyro/adis16251.h
@@ -0,0 +1,185 @@
+#ifndef SPI_ADIS16251_H_
+#define SPI_ADIS16251_H_
+
+#define ADIS16251_STARTUP_DELAY	220 /* ms */
+
+#define ADIS16251_READ_REG(a)    a
+#define ADIS16251_WRITE_REG(a) ((a) | 0x80)
+
+#define ADIS16251_ENDURANCE  0x00 /* Flash memory write count */
+#define ADIS16251_SUPPLY_OUT 0x02 /* Power supply measurement */
+#define ADIS16251_GYRO_OUT   0x04 /* X-axis gyroscope output */
+#define ADIS16251_AUX_ADC    0x0A /* analog input channel measurement */
+#define ADIS16251_TEMP_OUT   0x0C /* internal temperature measurement */
+#define ADIS16251_ANGL_OUT   0x0E /* angle displacement */
+#define ADIS16251_GYRO_OFF   0x14 /* Calibration, offset/bias adjustment */
+#define ADIS16251_GYRO_SCALE 0x16 /* Calibration, scale adjustment */
+#define ADIS16251_ALM_MAG1   0x20 /* Alarm 1 magnitude/polarity setting */
+#define ADIS16251_ALM_MAG2   0x22 /* Alarm 2 magnitude/polarity setting */
+#define ADIS16251_ALM_SMPL1  0x24 /* Alarm 1 dynamic rate of change setting */
+#define ADIS16251_ALM_SMPL2  0x26 /* Alarm 2 dynamic rate of change setting */
+#define ADIS16251_ALM_CTRL   0x28 /* Alarm control */
+#define ADIS16251_AUX_DAC    0x30 /* Auxiliary DAC data */
+#define ADIS16251_GPIO_CTRL  0x32 /* Control, digital I/O line */
+#define ADIS16251_MSC_CTRL   0x34 /* Control, data ready, self-test settings */
+#define ADIS16251_SMPL_PRD   0x36 /* Control, internal sample rate */
+#define ADIS16251_SENS_AVG   0x38 /* Control, dynamic range, filtering */
+#define ADIS16251_SLP_CNT    0x3A /* Control, sleep mode initiation */
+#define ADIS16251_DIAG_STAT  0x3C /* Diagnostic, error flags */
+#define ADIS16251_GLOB_CMD   0x3E /* Control, global commands */
+
+#define ADIS16251_ERROR_ACTIVE			(1<<14)
+#define ADIS16251_NEW_DATA			(1<<14)
+
+/* MSC_CTRL */
+#define ADIS16251_MSC_CTRL_INT_SELF_TEST	(1<<10) /* Internal self-test enable */
+#define ADIS16251_MSC_CTRL_NEG_SELF_TEST	(1<<9)
+#define ADIS16251_MSC_CTRL_POS_SELF_TEST	(1<<8)
+#define ADIS16251_MSC_CTRL_DATA_RDY_EN		(1<<2)
+#define ADIS16251_MSC_CTRL_DATA_RDY_POL_HIGH	(1<<1)
+#define ADIS16251_MSC_CTRL_DATA_RDY_DIO2	(1<<0)
+
+/* SMPL_PRD */
+#define ADIS16251_SMPL_PRD_TIME_BASE	(1<<7) /* Time base (tB): 0 = 1.953 ms, 1 = 60.54 ms */
+#define ADIS16251_SMPL_PRD_DIV_MASK	0x7F
+
+/* SLP_CNT */
+#define ADIS16251_SLP_CNT_POWER_OFF     0x80
+
+/* DIAG_STAT */
+#define ADIS16251_DIAG_STAT_ALARM2	(1<<9)
+#define ADIS16251_DIAG_STAT_ALARM1	(1<<8)
+#define ADIS16251_DIAG_STAT_SELF_TEST	(1<<5)
+#define ADIS16251_DIAG_STAT_OVERFLOW	(1<<4)
+#define ADIS16251_DIAG_STAT_SPI_FAIL	(1<<3)
+#define ADIS16251_DIAG_STAT_FLASH_UPT	(1<<2)
+#define ADIS16251_DIAG_STAT_POWER_HIGH	(1<<1)
+#define ADIS16251_DIAG_STAT_POWER_LOW	(1<<0)
+
+#define ADIS16251_DIAG_STAT_ERR_MASK (ADIS16261_DIAG_STAT_ALARM2 | \
+				      ADIS16261_DIAG_STAT_ALARM1 | \
+				      ADIS16261_DIAG_STAT_SELF_TEST | \
+				      ADIS16261_DIAG_STAT_OVERFLOW | \
+				      ADIS16261_DIAG_STAT_SPI_FAIL | \
+				      ADIS16261_DIAG_STAT_FLASH_UPT | \
+				      ADIS16261_DIAG_STAT_POWER_HIGH | \
+				      ADIS16261_DIAG_STAT_POWER_LOW)
+
+/* GLOB_CMD */
+#define ADIS16251_GLOB_CMD_SW_RESET	(1<<7)
+#define ADIS16251_GLOB_CMD_FLASH_UPD	(1<<3)
+#define ADIS16251_GLOB_CMD_DAC_LATCH	(1<<2)
+#define ADIS16251_GLOB_CMD_FAC_CALIB	(1<<1)
+#define ADIS16251_GLOB_CMD_AUTO_NULL	(1<<0)
+
+#define ADIS16251_MAX_TX 24
+#define ADIS16251_MAX_RX 24
+
+#define ADIS16251_SPI_SLOW	(u32)(300 * 1000)
+#define ADIS16251_SPI_BURST	(u32)(1000 * 1000)
+#define ADIS16251_SPI_FAST	(u32)(2000 * 1000)
+
+/**
+ * struct adis16251_state - device instance specific data
+ * @us:			actual spi_device
+ * @work_trigger_to_ring: bh for triggered event handling
+ * @inter:		used to check if new interrupt has been triggered
+ * @last_timestamp:	passing timestamp from th to bh of interrupt handler
+ * @indio_dev:		industrial I/O device structure
+ * @trig:		data ready trigger registered with iio
+ * @tx:			transmit buffer
+ * @rx:			recieve buffer
+ * @buf_lock:		mutex to protect tx and rx
+ **/
+struct adis16251_state {
+	struct spi_device		*us;
+	struct work_struct		work_trigger_to_ring;
+	s64				last_timestamp;
+	struct iio_dev			*indio_dev;
+	struct iio_trigger		*trig;
+	u8				*tx;
+	u8				*rx;
+	struct mutex			buf_lock;
+};
+
+int adis16251_spi_write_reg_8(struct device *dev,
+			      u8 reg_address,
+			      u8 val);
+
+int adis16251_spi_read_burst(struct device *dev, u8 *rx);
+
+int adis16251_spi_read_sequence(struct device *dev,
+				      u8 *tx, u8 *rx, int num);
+
+int adis16251_set_irq(struct device *dev, bool enable);
+
+int adis16251_reset(struct device *dev);
+
+int adis16251_stop_device(struct device *dev);
+
+int adis16251_check_status(struct device *dev);
+
+#if defined(CONFIG_IIO_RING_BUFFER) && defined(THIS_HAS_RING_BUFFER_SUPPORT)
+/* At the moment triggers are only used for ring buffer
+ * filling. This may change!
+ */
+
+enum adis16251_scan {
+	ADIS16251_SCAN_SUPPLY,
+	ADIS16251_SCAN_GYRO,
+	ADIS16251_SCAN_TEMP,
+	ADIS16251_SCAN_ADC_0,
+};
+
+void adis16251_remove_trigger(struct iio_dev *indio_dev);
+int adis16251_probe_trigger(struct iio_dev *indio_dev);
+
+ssize_t adis16251_read_data_from_ring(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf);
+
+
+int adis16251_configure_ring(struct iio_dev *indio_dev);
+void adis16251_unconfigure_ring(struct iio_dev *indio_dev);
+
+int adis16251_initialize_ring(struct iio_ring_buffer *ring);
+void adis16251_uninitialize_ring(struct iio_ring_buffer *ring);
+#else /* CONFIG_IIO_RING_BUFFER */
+
+static inline void adis16251_remove_trigger(struct iio_dev *indio_dev)
+{
+}
+
+static inline int adis16251_probe_trigger(struct iio_dev *indio_dev)
+{
+	return 0;
+}
+
+static inline ssize_t
+adis16251_read_data_from_ring(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	return 0;
+}
+
+static int adis16251_configure_ring(struct iio_dev *indio_dev)
+{
+	return 0;
+}
+
+static inline void adis16251_unconfigure_ring(struct iio_dev *indio_dev)
+{
+}
+
+static inline int adis16251_initialize_ring(struct iio_ring_buffer *ring)
+{
+	return 0;
+}
+
+static inline void adis16251_uninitialize_ring(struct iio_ring_buffer *ring)
+{
+}
+
+#endif /* CONFIG_IIO_RING_BUFFER */
+#endif /* SPI_ADIS16251_H_ */
diff --git a/drivers/staging/iio/gyro/adis16251_core.c b/drivers/staging/iio/gyro/adis16251_core.c
new file mode 100644
index 0000000..a0d400f
--- /dev/null
+++ b/drivers/staging/iio/gyro/adis16251_core.c
@@ -0,0 +1,777 @@
+/*
+ * ADIS16251 Programmable Digital Gyroscope Sensor Driver
+ *
+ * Copyright 2010 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+#include "gyro.h"
+#include "../adc/adc.h"
+
+#include "adis16251.h"
+
+#define DRIVER_NAME		"adis16251"
+
+/* At the moment the spi framework doesn't allow global setting of cs_change.
+ * It's in the likely to be added comment at the top of spi.h.
+ * This means that use cannot be made of spi_write etc.
+ */
+
+/**
+ * adis16251_spi_write_reg_8() - write single byte to a register
+ * @dev: device associated with child of actual device (iio_dev or iio_trig)
+ * @reg_address: the address of the register to be written
+ * @val: the value to write
+ **/
+int adis16251_spi_write_reg_8(struct device *dev,
+		u8 reg_address,
+		u8 val)
+{
+	int ret;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct adis16251_state *st = iio_dev_get_devdata(indio_dev);
+
+	mutex_lock(&st->buf_lock);
+	st->tx[0] = ADIS16251_WRITE_REG(reg_address);
+	st->tx[1] = val;
+
+	ret = spi_write(st->us, st->tx, 2);
+	mutex_unlock(&st->buf_lock);
+
+	return ret;
+}
+
+/**
+ * adis16251_spi_write_reg_16() - write 2 bytes to a pair of registers
+ * @dev: device associated with child of actual device (iio_dev or iio_trig)
+ * @reg_address: the address of the lower of the two registers. Second register
+ *               is assumed to have address one greater.
+ * @val: value to be written
+ **/
+static int adis16251_spi_write_reg_16(struct device *dev,
+		u8 lower_reg_address,
+		u16 value)
+{
+	int ret;
+	struct spi_message msg;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct adis16251_state *st = iio_dev_get_devdata(indio_dev);
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = st->tx,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 1,
+		}, {
+			.tx_buf = st->tx + 2,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 1,
+		},
+	};
+
+	mutex_lock(&st->buf_lock);
+	st->tx[0] = ADIS16251_WRITE_REG(lower_reg_address);
+	st->tx[1] = value & 0xFF;
+	st->tx[2] = ADIS16251_WRITE_REG(lower_reg_address + 1);
+	st->tx[3] = (value >> 8) & 0xFF;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfers[0], &msg);
+	spi_message_add_tail(&xfers[1], &msg);
+	ret = spi_sync(st->us, &msg);
+	mutex_unlock(&st->buf_lock);
+
+	return ret;
+}
+
+/**
+ * adis16251_spi_read_reg_16() - read 2 bytes from a 16-bit register
+ * @dev: device associated with child of actual device (iio_dev or iio_trig)
+ * @reg_address: the address of the lower of the two registers. Second register
+ *               is assumed to have address one greater.
+ * @val: somewhere to pass back the value read
+ **/
+static int adis16251_spi_read_reg_16(struct device *dev,
+		u8 lower_reg_address,
+		u16 *val)
+{
+	struct spi_message msg;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct adis16251_state *st = iio_dev_get_devdata(indio_dev);
+	int ret;
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = st->tx,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 1,
+		}, {
+			.rx_buf = st->rx,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 1,
+		},
+	};
+
+	mutex_lock(&st->buf_lock);
+	st->tx[0] = ADIS16251_READ_REG(lower_reg_address);
+	st->tx[1] = 0;
+	st->tx[2] = 0;
+	st->tx[3] = 0;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfers[0], &msg);
+	spi_message_add_tail(&xfers[1], &msg);
+	ret = spi_sync(st->us, &msg);
+	if (ret) {
+		dev_err(&st->us->dev, "problem when reading 16 bit register 0x%02X",
+				lower_reg_address);
+		goto error_ret;
+	}
+	*val = (st->rx[0] << 8) | st->rx[1];
+
+error_ret:
+	mutex_unlock(&st->buf_lock);
+	return ret;
+}
+
+/**
+ * adis16251_spi_read_burst() - read all data registers
+ * @dev: device associated with child of actual device (iio_dev or iio_trig)
+ * @rx: somewhere to pass back the value read (min size is 24 bytes)
+ **/
+int adis16251_spi_read_burst(struct device *dev, u8 *rx)
+{
+	struct spi_message msg;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct adis16251_state *st = iio_dev_get_devdata(indio_dev);
+	u32 old_speed_hz = st->us->max_speed_hz;
+	int ret;
+
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = st->tx,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 0,
+		}, {
+			.rx_buf = rx,
+			.bits_per_word = 8,
+			.len = 24,
+			.cs_change = 1,
+		},
+	};
+
+	mutex_lock(&st->buf_lock);
+	st->tx[0] = ADIS16251_READ_REG(ADIS16251_GLOB_CMD);
+	st->tx[1] = 0;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfers[0], &msg);
+	spi_message_add_tail(&xfers[1], &msg);
+
+	st->us->max_speed_hz = min(ADIS16251_SPI_BURST, old_speed_hz);
+	spi_setup(st->us);
+
+	ret = spi_sync(st->us, &msg);
+	if (ret)
+		dev_err(&st->us->dev, "problem when burst reading");
+
+	st->us->max_speed_hz = old_speed_hz;
+	spi_setup(st->us);
+	mutex_unlock(&st->buf_lock);
+	return ret;
+}
+
+/**
+ * adis16251_spi_read_sequence() - read a sequence of 16-bit registers
+ * @dev: device associated with child of actual device (iio_dev or iio_trig)
+ * @tx: register addresses in bytes 0,2,4,6... (min size is 2*num bytes)
+ * @rx: somewhere to pass back the value read (min size is 2*num bytes)
+ **/
+int adis16251_spi_read_sequence(struct device *dev,
+		u8 *tx, u8 *rx, int num)
+{
+	struct spi_message msg;
+	struct spi_transfer *xfers;
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct adis16251_state *st = iio_dev_get_devdata(indio_dev);
+	int ret, i;
+
+	xfers = kzalloc(num + 1, GFP_KERNEL);
+	if (xfers == NULL) {
+		dev_err(&st->us->dev, "memory alloc failed");
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	/* tx: |add1|addr2|addr3|...|addrN |zero|
+	 * rx: |zero|res1 |res2 |...|resN-1|resN| */
+	spi_message_init(&msg);
+	for (i = 0; i < num + 1; i++) {
+		if (i > 0)
+			xfers[i].rx_buf = st->rx + 2*(i - 1);
+		if (i < num)
+			xfers[i].tx_buf = st->tx + 2*i;
+		xfers[i].bits_per_word = 8;
+		xfers[i].len = 2;
+		xfers[i].cs_change = 1;
+		spi_message_add_tail(&xfers[i], &msg);
+	}
+
+	mutex_lock(&st->buf_lock);
+
+	ret = spi_sync(st->us, &msg);
+	if (ret)
+		dev_err(&st->us->dev, "problem when reading sequence");
+
+	mutex_unlock(&st->buf_lock);
+	kfree(xfers);
+
+error_ret:
+	return ret;
+}
+
+static ssize_t adis16251_spi_read_signed(struct device *dev,
+		struct device_attribute *attr,
+		char *buf,
+		unsigned bits)
+{
+	int ret;
+	s16 val = 0;
+	unsigned shift = 16 - bits;
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+
+	ret = adis16251_spi_read_reg_16(dev, this_attr->address, (u16 *)&val);
+	if (ret)
+		return ret;
+
+	if (val & ADIS16251_ERROR_ACTIVE)
+		adis16251_check_status(dev);
+	val = ((s16)(val << shift) >> shift);
+	return sprintf(buf, "%d\n", val);
+}
+
+static ssize_t adis16251_read_12bit_unsigned(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int ret;
+	u16 val = 0;
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+
+	ret = adis16251_spi_read_reg_16(dev, this_attr->address, &val);
+	if (ret)
+		return ret;
+
+	if (val & ADIS16251_ERROR_ACTIVE)
+		adis16251_check_status(dev);
+
+	return sprintf(buf, "%u\n", val & 0x0FFF);
+}
+
+static ssize_t adis16251_read_14bit_signed(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	ssize_t ret;
+
+	/* Take the iio_dev status lock */
+	mutex_lock(&indio_dev->mlock);
+	ret =  adis16251_spi_read_signed(dev, attr, buf, 14);
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
+static ssize_t adis16251_read_12bit_signed(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	ssize_t ret;
+
+	/* Take the iio_dev status lock */
+	mutex_lock(&indio_dev->mlock);
+	ret =  adis16251_spi_read_signed(dev, attr, buf, 12);
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
+static ssize_t adis16251_write_16bit(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+	int ret;
+	long val;
+
+	ret = strict_strtol(buf, 10, &val);
+	if (ret)
+		goto error_ret;
+	ret = adis16251_spi_write_reg_16(dev, this_attr->address, val);
+
+error_ret:
+	return ret ? ret : len;
+}
+
+static ssize_t adis16251_read_frequency(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int ret, len = 0;
+	u16 t;
+	int sps;
+	ret = adis16251_spi_read_reg_16(dev,
+			ADIS16251_SMPL_PRD,
+			&t);
+	if (ret)
+		return ret;
+	sps =  (t & ADIS16251_SMPL_PRD_TIME_BASE) ? 8 : 256;
+	sps /= (t & ADIS16251_SMPL_PRD_DIV_MASK) + 1;
+	len = sprintf(buf, "%d SPS\n", sps);
+	return len;
+}
+
+static ssize_t adis16251_write_frequency(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf,
+		size_t len)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct adis16251_state *st = iio_dev_get_devdata(indio_dev);
+	long val;
+	int ret;
+	u8 t;
+
+	ret = strict_strtol(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	mutex_lock(&indio_dev->mlock);
+
+	t = (256 / val);
+	if (t > 0)
+		t--;
+	t &= ADIS16251_SMPL_PRD_DIV_MASK;
+	if ((t & ADIS16251_SMPL_PRD_DIV_MASK) >= 0x0A)
+		st->us->max_speed_hz = ADIS16251_SPI_SLOW;
+	else
+		st->us->max_speed_hz = ADIS16251_SPI_FAST;
+
+	ret = adis16251_spi_write_reg_8(dev,
+			ADIS16251_SMPL_PRD,
+			t);
+
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret ? ret : len;
+}
+
+static ssize_t adis16251_write_reset(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t len)
+{
+	if (len < 1)
+		return -1;
+	switch (buf[0]) {
+	case '1':
+	case 'y':
+	case 'Y':
+		return adis16251_reset(dev);
+	}
+	return -1;
+}
+
+
+
+int adis16251_set_irq(struct device *dev, bool enable)
+{
+	int ret;
+	u16 msc;
+	ret = adis16251_spi_read_reg_16(dev, ADIS16251_MSC_CTRL, &msc);
+	if (ret)
+		goto error_ret;
+
+	msc |= ADIS16251_MSC_CTRL_DATA_RDY_POL_HIGH;
+	if (enable)
+		msc |= ADIS16251_MSC_CTRL_DATA_RDY_EN;
+	else
+		msc &= ~ADIS16251_MSC_CTRL_DATA_RDY_EN;
+
+	ret = adis16251_spi_write_reg_16(dev, ADIS16251_MSC_CTRL, msc);
+	if (ret)
+		goto error_ret;
+
+error_ret:
+	return ret;
+}
+
+int adis16251_reset(struct device *dev)
+{
+	int ret;
+	ret = adis16251_spi_write_reg_8(dev,
+			ADIS16251_GLOB_CMD,
+			ADIS16251_GLOB_CMD_SW_RESET);
+	if (ret)
+		dev_err(dev, "problem resetting device");
+
+	return ret;
+}
+
+/* Power down the device */
+int adis16251_stop_device(struct device *dev)
+{
+	int ret;
+	u16 val = ADIS16251_SLP_CNT_POWER_OFF;
+
+	ret = adis16251_spi_write_reg_16(dev, ADIS16251_SLP_CNT, val);
+	if (ret)
+		dev_err(dev, "problem with turning device off: SLP_CNT");
+
+	return ret;
+}
+
+static int adis16251_self_test(struct device *dev)
+{
+	int ret;
+
+	ret = adis16251_spi_write_reg_16(dev,
+			ADIS16251_MSC_CTRL,
+			ADIS16251_MSC_CTRL_INT_SELF_TEST);
+	if (ret) {
+		dev_err(dev, "problem starting self test");
+		goto err_ret;
+	}
+
+	adis16251_check_status(dev);
+
+err_ret:
+	return ret;
+}
+
+int adis16251_check_status(struct device *dev)
+{
+	u16 status;
+	int ret;
+
+	ret = adis16251_spi_read_reg_16(dev, ADIS16251_DIAG_STAT, &status);
+
+	if (ret < 0) {
+		dev_err(dev, "Reading status failed\n");
+		goto error_ret;
+	}
+
+	if (!(status & ADIS16251_DIAG_STAT_ERR_MASK)) {
+		ret = 0;
+		goto error_ret;
+	}
+
+	ret = -EFAULT;
+
+	if (status & ADIS16251_DIAG_STAT_ALARM2)
+		dev_err(dev, "Alarm 2 active\n");
+	if (status & ADIS16251_DIAG_STAT_ALARM1)
+		dev_err(dev, "Alarm 1 active\n");
+	if (status & ADIS16251_DIAG_STAT_SELF_TEST)
+		dev_err(dev, "Self test error\n");
+	if (status & ADIS16251_DIAG_STAT_OVERFLOW)
+		dev_err(dev, "Sensor overrange\n");
+	if (status & ADIS16251_DIAG_STAT_SPI_FAIL)
+		dev_err(dev, "SPI failure\n");
+	if (status & ADIS16251_DIAG_STAT_FLASH_UPT)
+		dev_err(dev, "Flash update failed\n");
+	if (status & ADIS16251_DIAG_STAT_POWER_HIGH)
+		dev_err(dev, "Power supply above 5.25V\n");
+	if (status & ADIS16251_DIAG_STAT_POWER_LOW)
+		dev_err(dev, "Power supply below 4.75V\n");
+
+error_ret:
+	return ret;
+}
+
+static int adis16251_initial_setup(struct adis16251_state *st)
+{
+	int ret;
+	u16 smp_prd;
+	struct device *dev = &st->indio_dev->dev;
+
+	/* use low spi speed for init */
+	st->us->max_speed_hz = ADIS16251_SPI_SLOW;
+	st->us->mode = SPI_MODE_3;
+	spi_setup(st->us);
+
+	/* Disable IRQ */
+	ret = adis16251_set_irq(dev, false);
+	if (ret) {
+		dev_err(dev, "disable irq failed");
+		goto err_ret;
+	}
+
+	/* Do self test */
+
+	/* Read status register to check the result */
+	ret = adis16251_check_status(dev);
+	if (ret) {
+		adis16251_reset(dev);
+		dev_err(dev, "device not playing ball -> reset");
+		msleep(ADIS16251_STARTUP_DELAY);
+		ret = adis16251_check_status(dev);
+		if (ret) {
+			dev_err(dev, "giving up");
+			goto err_ret;
+		}
+	}
+
+	printk(KERN_INFO DRIVER_NAME ": at CS%d (irq %d)\n",
+			st->us->chip_select, st->us->irq);
+
+	/* use high spi speed if possible */
+	ret = adis16251_spi_read_reg_16(dev, ADIS16251_SMPL_PRD, &smp_prd);
+	if (!ret && (smp_prd & ADIS16251_SMPL_PRD_DIV_MASK) < 0x0A) {
+		st->us->max_speed_hz = ADIS16251_SPI_SLOW;
+		spi_setup(st->us);
+	}
+
+err_ret:
+	return ret;
+}
+
+static IIO_DEV_ATTR_IN_NAMED_RAW(0, supply, adis16251_read_12bit_signed,
+		ADIS16251_SUPPLY_OUT);
+static IIO_CONST_ATTR(in0_supply_scale, "0.0018315");
+
+static IIO_DEV_ATTR_GYRO(adis16251_read_14bit_signed,
+		ADIS16251_GYRO_OUT);
+static IIO_DEV_ATTR_GYRO_SCALE(S_IWUSR | S_IRUGO,
+		adis16251_read_12bit_signed,
+		adis16251_write_16bit,
+		ADIS16251_GYRO_SCALE);
+static IIO_DEV_ATTR_GYRO_OFFSET(S_IWUSR | S_IRUGO,
+		adis16251_read_12bit_signed,
+		adis16251_write_16bit,
+		ADIS16251_GYRO_OFF);
+
+static IIO_DEV_ATTR_TEMP_RAW(adis16251_read_12bit_signed);
+static IIO_CONST_ATTR(temp_offset, "25 K");
+static IIO_CONST_ATTR(temp_scale, "0.1453 K");
+
+static IIO_DEV_ATTR_IN_NAMED_RAW(1, aux, adis16251_read_12bit_unsigned,
+		ADIS16251_AUX_ADC);
+static IIO_CONST_ATTR(in1_aux_scale, "0.0006105");
+
+static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
+		adis16251_read_frequency,
+		adis16251_write_frequency);
+static IIO_DEV_ATTR_ANGL(adis16251_read_14bit_signed,
+		ADIS16251_ANGL_OUT);
+
+static IIO_DEV_ATTR_RESET(adis16251_write_reset);
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("0.129 ~ 256");
+
+static IIO_CONST_ATTR(name, "adis16251");
+
+static struct attribute *adis16251_event_attributes[] = {
+	NULL
+};
+
+static struct attribute_group adis16251_event_attribute_group = {
+	.attrs = adis16251_event_attributes,
+};
+
+static struct attribute *adis16251_attributes[] = {
+	&iio_dev_attr_in0_supply_raw.dev_attr.attr,
+	&iio_const_attr_in0_supply_scale.dev_attr.attr,
+	&iio_dev_attr_gyro_raw.dev_attr.attr,
+	&iio_dev_attr_gyro_scale.dev_attr.attr,
+	&iio_dev_attr_gyro_offset.dev_attr.attr,
+	&iio_dev_attr_angl_raw.dev_attr.attr,
+	&iio_dev_attr_temp_raw.dev_attr.attr,
+	&iio_const_attr_temp_offset.dev_attr.attr,
+	&iio_const_attr_temp_scale.dev_attr.attr,
+	&iio_dev_attr_in1_aux_raw.dev_attr.attr,
+	&iio_const_attr_in1_aux_scale.dev_attr.attr,
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_reset.dev_attr.attr,
+	&iio_const_attr_name.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group adis16251_attribute_group = {
+	.attrs = adis16251_attributes,
+};
+
+static int __devinit adis16251_probe(struct spi_device *spi)
+{
+	int ret, regdone = 0;
+	struct adis16251_state *st = kzalloc(sizeof *st, GFP_KERNEL);
+	if (!st) {
+		ret =  -ENOMEM;
+		goto error_ret;
+	}
+	/* this is only used for removal purposes */
+	spi_set_drvdata(spi, st);
+
+	/* Allocate the comms buffers */
+	st->rx = kzalloc(sizeof(*st->rx)*ADIS16251_MAX_RX, GFP_KERNEL);
+	if (st->rx == NULL) {
+		ret = -ENOMEM;
+		goto error_free_st;
+	}
+	st->tx = kzalloc(sizeof(*st->tx)*ADIS16251_MAX_TX, GFP_KERNEL);
+	if (st->tx == NULL) {
+		ret = -ENOMEM;
+		goto error_free_rx;
+	}
+	st->us = spi;
+	mutex_init(&st->buf_lock);
+	/* setup the industrialio driver allocated elements */
+	st->indio_dev = iio_allocate_device();
+	if (st->indio_dev == NULL) {
+		ret = -ENOMEM;
+		goto error_free_tx;
+	}
+
+	st->indio_dev->dev.parent = &spi->dev;
+	st->indio_dev->num_interrupt_lines = 1;
+	st->indio_dev->event_attrs = &adis16251_event_attribute_group;
+	st->indio_dev->attrs = &adis16251_attribute_group;
+	st->indio_dev->dev_data = (void *)(st);
+	st->indio_dev->driver_module = THIS_MODULE;
+	st->indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = adis16251_configure_ring(st->indio_dev);
+	if (ret)
+		goto error_free_dev;
+
+	ret = iio_device_register(st->indio_dev);
+	if (ret)
+		goto error_unreg_ring_funcs;
+	regdone = 1;
+
+	ret = adis16251_initialize_ring(st->indio_dev->ring);
+	if (ret) {
+		printk(KERN_ERR "failed to initialize the ring\n");
+		goto error_unreg_ring_funcs;
+	}
+
+	if (spi->irq && gpio_is_valid(irq_to_gpio(spi->irq)) > 0) {
+		ret = iio_register_interrupt_line(spi->irq,
+				st->indio_dev,
+				0,
+				IRQF_TRIGGER_RISING,
+				"adis16251");
+		if (ret)
+			goto error_uninitialize_ring;
+
+		ret = adis16251_probe_trigger(st->indio_dev);
+		if (ret)
+			goto error_unregister_line;
+	}
+
+	/* Get the device into a sane initial state */
+	ret = adis16251_initial_setup(st);
+	if (ret)
+		goto error_remove_trigger;
+	return 0;
+
+error_remove_trigger:
+	if (st->indio_dev->modes & INDIO_RING_TRIGGERED)
+		adis16251_remove_trigger(st->indio_dev);
+error_unregister_line:
+	if (st->indio_dev->modes & INDIO_RING_TRIGGERED)
+		iio_unregister_interrupt_line(st->indio_dev, 0);
+error_uninitialize_ring:
+	adis16251_uninitialize_ring(st->indio_dev->ring);
+error_unreg_ring_funcs:
+	adis16251_unconfigure_ring(st->indio_dev);
+error_free_dev:
+	if (regdone)
+		iio_device_unregister(st->indio_dev);
+	else
+		iio_free_device(st->indio_dev);
+error_free_tx:
+	kfree(st->tx);
+error_free_rx:
+	kfree(st->rx);
+error_free_st:
+	kfree(st);
+error_ret:
+	return ret;
+}
+
+/* fixme, confirm ordering in this function */
+static int adis16251_remove(struct spi_device *spi)
+{
+	int ret;
+	struct adis16251_state *st = spi_get_drvdata(spi);
+	struct iio_dev *indio_dev = st->indio_dev;
+
+	ret = adis16251_stop_device(&(indio_dev->dev));
+	if (ret)
+		goto err_ret;
+
+	flush_scheduled_work();
+
+	adis16251_remove_trigger(indio_dev);
+	if (spi->irq && gpio_is_valid(irq_to_gpio(spi->irq)) > 0)
+		iio_unregister_interrupt_line(indio_dev, 0);
+
+	adis16251_uninitialize_ring(indio_dev->ring);
+	adis16251_unconfigure_ring(indio_dev);
+	iio_device_unregister(indio_dev);
+	kfree(st->tx);
+	kfree(st->rx);
+	kfree(st);
+
+	return 0;
+
+err_ret:
+	return ret;
+}
+
+static struct spi_driver adis16251_driver = {
+	.driver = {
+		.name = "adis16251",
+		.owner = THIS_MODULE,
+	},
+	.probe = adis16251_probe,
+	.remove = __devexit_p(adis16251_remove),
+};
+
+static __init int adis16251_init(void)
+{
+	return spi_register_driver(&adis16251_driver);
+}
+module_init(adis16251_init);
+
+static __exit void adis16251_exit(void)
+{
+	spi_unregister_driver(&adis16251_driver);
+}
+module_exit(adis16251_exit);
+
+MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>");
+MODULE_DESCRIPTION("Analog Devices ADIS16251 Digital Gyroscope Sensor SPI driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/staging/iio/sysfs.h b/drivers/staging/iio/sysfs.h
index ee91a95..18bdaac 100644
--- a/drivers/staging/iio/sysfs.h
+++ b/drivers/staging/iio/sysfs.h
@@ -108,6 +108,12 @@ struct iio_const_attr {
 	IIO_DEVICE_ATTR(name, S_IRUGO, _show, NULL, 0)
 
 /**
+ * IIO_DEV_ATTR_RESET: resets the device
+ **/
+#define IIO_DEV_ATTR_RESET(_store)			\
+	IIO_DEVICE_ATTR(reset, S_IWUGO, NULL, _store, 0)
+
+/**
  * IIO_CONST_ATTR_NAME - constant identifier
  * @_string: the name
  **/
-- 
1.7.3.2