[PATCH v5 1/2] iio: adc: hi8435: Holt HI-8435 threshold detector

From: Vladimir Barinov
Date: Fri Aug 28 2015 - 10:28:14 EST

Add Holt threshold detector driver for HI-8435 chip

Signed-off-by: Vladimir Barinov <vladimir.barinov@xxxxxxxxxxxxxxxxxx>
---
Changes in version 2:
- Added file sysfs-bus-iio-adc-hi8435
- Changed naming from "discrete ADC" to "threshold detector"
- Replaced swab16p/swab32p with be16_to_cpup/be32_to_cpup
- Made *_show and *_store functions static
- moved out from iio buffers to iio events
- removed hi8436/hi8437 chips from the driver
- moved from debounce_soft_delay/enable to debounce_interval via
IIO_CHAN_INFO_DEBOUNCE_TIME
- added name extention "comparator"
- moved threshold/hysteresis setup via generic iio event sysfs
- added software mask/unmask channel events
- added programming sensor outputs while in test mode via
IIO_CHAN_INFO_RAW
- added channels .ext_info for programming sensing mode
Changes in version 3:
- fixed typos
- moved <linux/interrupt.h> to match alphabetic order
- fixed missed */event/* prefix in the ABI description
- added missed colon in sysfs-bus-iio-adc-hi8435 file after "What"
- moved in_voltageY_comparator_thresh_either_en and debounce_time
to sysfs-bus-iio file
- added error checking for hi8435_write[b|w]
Changes in version 4:
- removed software debounce logic
- fixed typo in comment s/threshold/thresholds
- removed test_enable sysfs entry
- removed *_raw entries
- removed extended_name
- switched to GPIO descriptor API
- added comment describing the need of thresholds initialization
- added debugfs_reg_access
Changes in version 5:
- added ABI description about falling/rising thresholds automatic
adjustment that avoids odd hysteresis
- changed reg_buffer[] size to 3 instead of 4
- modified if/else logic in hi8435_read_event_value function
- modified if/else logic in hi8435_write_event_value function
- modified if/else logic in hi8435_iio_push_event function

Documentation/ABI/testing/sysfs-bus-iio | 1 +
Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435 | 43 ++
drivers/iio/adc/Kconfig | 11 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/hi8435.c | 531 +++++++++++++++++++++
5 files changed, 587 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435
create mode 100644 drivers/iio/adc/hi8435.c

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 42d360f..20312a0 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -581,6 +581,7 @@ What: /sys/.../iio:deviceX/events/in_voltageY_supply_thresh_rising_en
What: /sys/.../iio:deviceX/events/in_voltageY_supply_thresh_falling_en
What: /sys/.../iio:deviceX/events/in_voltageY_thresh_rising_en
What: /sys/.../iio:deviceX/events/in_voltageY_thresh_falling_en
+What: /sys/.../iio:deviceX/events/in_voltageY_thresh_either_en
What: /sys/.../iio:deviceX/events/in_tempY_thresh_rising_en
What: /sys/.../iio:deviceX/events/in_tempY_thresh_falling_en
KernelVersion: 2.6.37
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435 b/Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435
new file mode 100644
index 0000000..f30b4c4
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435
@@ -0,0 +1,43 @@
+What: /sys/bus/iio/devices/iio:deviceX/in_voltageY_sensing_mode
+Date: August 2015
+KernelVersion: 4.2.0
+Contact: source@xxxxxxxxxxxxxxxxxx
+Description:
+ Program sensor type for threshold detector inputs.
+ Could be either "GND-Open" or "Supply-Open" mode. Y is a
+ threshold detector input channel. Channels 0..7, 8..15, 16..23
+ and 24..31 has common sensor types.
+
+What: /sys/bus/iio/devices/iio:deviceX/events/in_voltageY_thresh_falling_value
+Date: August 2015
+KernelVersion: 4.2.0
+Contact: source@xxxxxxxxxxxxxxxxxx
+Description:
+ Channel Y low voltage threshold. If sensor input voltage goes lower then
+ this value then the threshold falling event is pushed.
+ Depending on in_voltageY_sensing_mode the low voltage threshold
+ is separately set for "GND-Open" and "Supply-Open" modes.
+ Channels 0..31 have common low threshold values, but could have different
+ sensing_modes.
+ The low voltage threshold range is between 2..21V.
+ Hysteresis between low and high thresholds can not be lower then 2 and
+ can not be odd.
+ If falling threshold results hysteresis to odd value then rising
+ threshold is automatically subtracted by one.
+
+What: /sys/bus/iio/devices/iio:deviceX/events/in_voltageY_thresh_rising_value
+Date: August 2015
+KernelVersion: 4.2.0
+Contact: source@xxxxxxxxxxxxxxxxxx
+Description:
+ Channel Y high voltage threshold. If sensor input voltage goes higher then
+ this value then the threshold rising event is pushed.
+ Depending on in_voltageY_sensing_mode the high voltage threshold
+ is separately set for "GND-Open" and "Supply-Open" modes.
+ Channels 0..31 have common high threshold values, but could have different
+ sensing_modes.
+ The high voltage threshold range is between 3..22V.
+ Hysteresis between low and high thresholds can not be lower then 2 and
+ can not be odd.
+ If rising threshold results hysteresis to odd value then falling
+ threshold is automatically appended by one.
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index deea62c..4918edc 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -183,6 +183,17 @@ config EXYNOS_ADC
To compile this driver as a module, choose M here: the module will be
called exynos_adc.

+config HI8435
+ tristate "Holt Integrated Circuits HI-8435 threshold detector"
+ select IIO_TRIGGERED_EVENT
+ depends on SPI
+ help
+ If you say yes here you get support for Holt Integrated Circuits
+ HI-8435 chip.
+
+ This driver can also be built as a module. If so, the module will be
+ called hi8435.
+
config LP8788_ADC
tristate "LP8788 ADC driver"
depends on MFD_LP8788
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index fa5723a..99b37a9 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
+obj-$(CONFIG_HI8435) += hi8435.o
obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
obj-$(CONFIG_MAX1027) += max1027.o
obj-$(CONFIG_MAX1363) += max1363.o
diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c
new file mode 100644
index 0000000..f4f8ea6
--- /dev/null
+++ b/drivers/iio/adc/hi8435.c
@@ -0,0 +1,531 @@
+/*
+ * Holt Integrated Circuits HI-8435 threshold detector driver
+ *
+ * Copyright (C) 2015 Zodiac Inflight Innovations
+ * Copyright (C) 2015 Cogent Embedded, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/delay.h>
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_event.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/spi/spi.h>
+
+#define DRV_NAME "hi8435"
+
+/* Register offsets for HI-8435 */
+#define HI8435_CTRL_REG 0x02
+#define HI8435_PSEN_REG 0x04
+#define HI8435_TMDATA_REG 0x1E
+#define HI8435_GOCENHYS_REG 0x3A
+#define HI8435_SOCENHYS_REG 0x3C
+#define HI8435_SO7_0_REG 0x10
+#define HI8435_SO15_8_REG 0x12
+#define HI8435_SO23_16_REG 0x14
+#define HI8435_SO31_24_REG 0x16
+#define HI8435_SO31_0_REG 0x78
+
+#define HI8435_WRITE_OPCODE 0x00
+#define HI8435_READ_OPCODE 0x80
+
+/* CTRL register bits */
+#define HI8435_CTRL_TEST 0x01
+#define HI8435_CTRL_SRST 0x02
+
+struct hi8435_priv {
+ struct spi_device *spi;
+ struct mutex lock;
+
+ unsigned long event_scan_mask; /* soft mask/unmask channels events */
+ unsigned int event_prev_val;
+
+ unsigned threshold_lo[2]; /* GND-Open and Supply-Open thresholds */
+ unsigned threshold_hi[2]; /* GND-Open and Supply-Open thresholds */
+ u8 reg_buffer[3] ____cacheline_aligned;
+};
+
+static int hi8435_readb(struct hi8435_priv *priv, u8 reg, u8 *val)
+{
+ reg |= HI8435_READ_OPCODE;
+ return spi_write_then_read(priv->spi, &reg, 1, val, 1);
+}
+
+static int hi8435_readw(struct hi8435_priv *priv, u8 reg, u16 *val)
+{
+ int ret;
+
+ reg |= HI8435_READ_OPCODE;
+ ret = spi_write_then_read(priv->spi, &reg, 1, val, 2);
+ *val = be16_to_cpup(val);
+
+ return ret;
+}
+
+static int hi8435_readl(struct hi8435_priv *priv, u8 reg, u32 *val)
+{
+ int ret;
+
+ reg |= HI8435_READ_OPCODE;
+ ret = spi_write_then_read(priv->spi, &reg, 1, val, 4);
+ *val = be32_to_cpup(val);
+
+ return ret;
+}
+
+static int hi8435_writeb(struct hi8435_priv *priv, u8 reg, u8 val)
+{
+ priv->reg_buffer[0] = reg | HI8435_WRITE_OPCODE;
+ priv->reg_buffer[1] = val;
+
+ return spi_write(priv->spi, priv->reg_buffer, 2);
+}
+
+static int hi8435_writew(struct hi8435_priv *priv, u8 reg, u16 val)
+{
+ priv->reg_buffer[0] = reg | HI8435_WRITE_OPCODE;
+ priv->reg_buffer[1] = (val >> 8) & 0xff;
+ priv->reg_buffer[2] = val & 0xff;
+
+ return spi_write(priv->spi, priv->reg_buffer, 3);
+}
+
+static int hi8435_read_event_config(struct iio_dev *idev,
+ const struct iio_chan_spec *chan,
+ enum iio_event_type type,
+ enum iio_event_direction dir)
+{
+ struct hi8435_priv *priv = iio_priv(idev);
+
+ return !!(priv->event_scan_mask & BIT(chan->channel));
+}
+
+static int hi8435_write_event_config(struct iio_dev *idev,
+ const struct iio_chan_spec *chan,
+ enum iio_event_type type,
+ enum iio_event_direction dir, int state)
+{
+ struct hi8435_priv *priv = iio_priv(idev);
+
+ priv->event_scan_mask &= ~BIT(chan->channel);
+ if (state)
+ priv->event_scan_mask |= BIT(chan->channel);
+
+ return 0;
+}
+
+static int hi8435_read_event_value(struct iio_dev *idev,
+ 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 hi8435_priv *priv = iio_priv(idev);
+ int ret;
+ u8 mode, psen;
+ u16 reg;
+
+ ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
+ if (ret < 0)
+ return ret;
+
+ /* Supply-Open or GND-Open sensing mode */
+ mode = !!(psen & BIT(chan->channel / 8));
+
+ ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
+ HI8435_GOCENHYS_REG, &reg);
+ if (ret < 0)
+ return ret;
+
+ if (dir == IIO_EV_DIR_FALLING)
+ *val = ((reg & 0xff) - (reg >> 8)) / 2;
+ else if (dir == IIO_EV_DIR_RISING)
+ *val = ((reg & 0xff) + (reg >> 8)) / 2;
+
+ return IIO_VAL_INT;
+}
+
+static int hi8435_write_event_value(struct iio_dev *idev,
+ 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 hi8435_priv *priv = iio_priv(idev);
+ int ret;
+ u8 mode, psen;
+ u16 reg;
+
+ ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
+ if (ret < 0)
+ return ret;
+
+ /* Supply-Open or GND-Open sensing mode */
+ mode = !!(psen & BIT(chan->channel / 8));
+
+ ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
+ HI8435_GOCENHYS_REG, &reg);
+ if (ret < 0)
+ return ret;
+
+ if (dir == IIO_EV_DIR_FALLING) {
+ /* falling threshold range 2..21V, hysteresis minimum 2V */
+ if (val < 2 || val > 21 || (val + 2) > priv->threshold_hi[mode])
+ return -EINVAL;
+
+ if (val == priv->threshold_lo[mode])
+ return 0;
+
+ priv->threshold_lo[mode] = val;
+
+ /* hysteresis must not be odd */
+ if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
+ priv->threshold_hi[mode]--;
+ } else if (dir == IIO_EV_DIR_RISING) {
+ /* rising threshold range 3..22V, hysteresis minimum 2V */
+ if (val < 3 || val > 22 || val < (priv->threshold_lo[mode] + 2))
+ return -EINVAL;
+
+ if (val == priv->threshold_hi[mode])
+ return 0;
+
+ priv->threshold_hi[mode] = val;
+
+ /* hysteresis must not be odd */
+ if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
+ priv->threshold_lo[mode]++;
+ }
+
+ /* program thresholds */
+ mutex_lock(&priv->lock);
+
+ ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
+ HI8435_GOCENHYS_REG, &reg);
+ if (ret < 0) {
+ mutex_unlock(&priv->lock);
+ return ret;
+ }
+
+ /* hysteresis */
+ reg = priv->threshold_hi[mode] - priv->threshold_lo[mode];
+ reg <<= 8;
+ /* threshold center */
+ reg |= (priv->threshold_hi[mode] + priv->threshold_lo[mode]);
+
+ ret = hi8435_writew(priv, mode ? HI8435_SOCENHYS_REG :
+ HI8435_GOCENHYS_REG, reg);
+
+ mutex_unlock(&priv->lock);
+
+ return ret;
+}
+
+static int hi8435_debugfs_reg_access(struct iio_dev *idev,
+ unsigned reg, unsigned writeval,
+ unsigned *readval)
+{
+ struct hi8435_priv *priv = iio_priv(idev);
+ int ret;
+ u8 val;
+
+ if (readval != NULL) {
+ ret = hi8435_readb(priv, reg, &val);
+ *readval = val;
+ } else {
+ val = (u8)writeval;
+ ret = hi8435_writeb(priv, reg, val);
+ }
+
+ return ret;
+}
+
+static const struct iio_event_spec hi8435_events[] = {
+ {
+ .type = IIO_EV_TYPE_THRESH,
+ .dir = IIO_EV_DIR_RISING,
+ .mask_separate = BIT(IIO_EV_INFO_VALUE),
+ }, {
+ .type = IIO_EV_TYPE_THRESH,
+ .dir = IIO_EV_DIR_FALLING,
+ .mask_separate = BIT(IIO_EV_INFO_VALUE),
+ }, {
+ .type = IIO_EV_TYPE_THRESH,
+ .dir = IIO_EV_DIR_EITHER,
+ .mask_separate = BIT(IIO_EV_INFO_ENABLE),
+ },
+};
+
+static int hi8435_get_sensing_mode(struct iio_dev *idev,
+ const struct iio_chan_spec *chan)
+{
+ struct hi8435_priv *priv = iio_priv(idev);
+ int ret;
+ u8 reg;
+
+ ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
+ if (ret < 0)
+ return ret;
+
+ return !!(reg & BIT(chan->channel / 8));
+}
+
+static int hi8435_set_sensing_mode(struct iio_dev *idev,
+ const struct iio_chan_spec *chan,
+ unsigned int mode)
+{
+ struct hi8435_priv *priv = iio_priv(idev);
+ int ret;
+ u8 reg;
+
+ mutex_lock(&priv->lock);
+
+ ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
+ if (ret < 0) {
+ mutex_unlock(&priv->lock);
+ return ret;
+ }
+
+ reg &= ~BIT(chan->channel / 8);
+ if (mode)
+ reg |= BIT(chan->channel / 8);
+
+ ret = hi8435_writeb(priv, HI8435_PSEN_REG, reg);
+
+ mutex_unlock(&priv->lock);
+
+ return ret;
+}
+
+static const char * const hi8435_sensing_modes[] = { "GND-Open",
+ "Supply-Open" };
+
+static const struct iio_enum hi8435_sensing_mode = {
+ .items = hi8435_sensing_modes,
+ .num_items = ARRAY_SIZE(hi8435_sensing_modes),
+ .get = hi8435_get_sensing_mode,
+ .set = hi8435_set_sensing_mode,
+};
+
+static const struct iio_chan_spec_ext_info hi8435_ext_info[] = {
+ IIO_ENUM("sensing_mode", IIO_SEPARATE, &hi8435_sensing_mode),
+ {},
+};
+
+#define HI8435_VOLTAGE_CHANNEL(num) \
+{ \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = num, \
+ .event_spec = hi8435_events, \
+ .num_event_specs = ARRAY_SIZE(hi8435_events), \
+ .ext_info = hi8435_ext_info, \
+}
+
+static const struct iio_chan_spec hi8435_channels[] = {
+ HI8435_VOLTAGE_CHANNEL(0),
+ HI8435_VOLTAGE_CHANNEL(1),
+ HI8435_VOLTAGE_CHANNEL(2),
+ HI8435_VOLTAGE_CHANNEL(3),
+ HI8435_VOLTAGE_CHANNEL(4),
+ HI8435_VOLTAGE_CHANNEL(5),
+ HI8435_VOLTAGE_CHANNEL(6),
+ HI8435_VOLTAGE_CHANNEL(7),
+ HI8435_VOLTAGE_CHANNEL(8),
+ HI8435_VOLTAGE_CHANNEL(9),
+ HI8435_VOLTAGE_CHANNEL(10),
+ HI8435_VOLTAGE_CHANNEL(11),
+ HI8435_VOLTAGE_CHANNEL(12),
+ HI8435_VOLTAGE_CHANNEL(13),
+ HI8435_VOLTAGE_CHANNEL(14),
+ HI8435_VOLTAGE_CHANNEL(15),
+ HI8435_VOLTAGE_CHANNEL(16),
+ HI8435_VOLTAGE_CHANNEL(17),
+ HI8435_VOLTAGE_CHANNEL(18),
+ HI8435_VOLTAGE_CHANNEL(19),
+ HI8435_VOLTAGE_CHANNEL(20),
+ HI8435_VOLTAGE_CHANNEL(21),
+ HI8435_VOLTAGE_CHANNEL(22),
+ HI8435_VOLTAGE_CHANNEL(23),
+ HI8435_VOLTAGE_CHANNEL(24),
+ HI8435_VOLTAGE_CHANNEL(25),
+ HI8435_VOLTAGE_CHANNEL(26),
+ HI8435_VOLTAGE_CHANNEL(27),
+ HI8435_VOLTAGE_CHANNEL(28),
+ HI8435_VOLTAGE_CHANNEL(29),
+ HI8435_VOLTAGE_CHANNEL(30),
+ HI8435_VOLTAGE_CHANNEL(31),
+ IIO_CHAN_SOFT_TIMESTAMP(32),
+};
+
+static const struct iio_info hi8435_info = {
+ .driver_module = THIS_MODULE,
+ .read_event_config = &hi8435_read_event_config,
+ .write_event_config = hi8435_write_event_config,
+ .read_event_value = &hi8435_read_event_value,
+ .write_event_value = &hi8435_write_event_value,
+ .debugfs_reg_access = &hi8435_debugfs_reg_access,
+};
+
+static void hi8435_iio_push_event(struct iio_dev *idev, unsigned int val)
+{
+ struct hi8435_priv *priv = iio_priv(idev);
+ enum iio_event_direction dir;
+ unsigned int i;
+ unsigned int status = priv->event_prev_val ^ val;
+
+ if (!status)
+ return;
+
+ for_each_set_bit(i, &priv->event_scan_mask, 32) {
+ if (status & BIT(i)) {
+ dir = val & BIT(i) ? IIO_EV_DIR_RISING :
+ IIO_EV_DIR_FALLING;
+ iio_push_event(idev,
+ IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, i,
+ IIO_EV_TYPE_THRESH, dir),
+ iio_get_time_ns());
+ }
+ }
+
+ priv->event_prev_val = val;
+}
+
+static irqreturn_t hi8435_trigger_handler(int irq, void *private)
+{
+ struct iio_poll_func *pf = private;
+ struct iio_dev *idev = pf->indio_dev;
+ struct hi8435_priv *priv = iio_priv(idev);
+ u32 val;
+ int ret;
+
+ ret = hi8435_readl(priv, HI8435_SO31_0_REG, &val);
+ if (ret < 0)
+ goto err_read;
+
+ hi8435_iio_push_event(idev, val);
+
+err_read:
+ iio_trigger_notify_done(idev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static int hi8435_probe(struct spi_device *spi)
+{
+ struct iio_dev *idev;
+ struct hi8435_priv *priv;
+ struct gpio_desc *reset_gpio;
+ int ret;
+
+ idev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
+ if (!idev)
+ return -ENOMEM;
+
+ priv = iio_priv(idev);
+ priv->spi = spi;
+
+ reset_gpio = devm_gpiod_get(&spi->dev, NULL, GPIOD_OUT_LOW);
+ if (IS_ERR(reset_gpio)) {
+ /* chip s/w reset if h/w reset failed */
+ hi8435_writeb(priv, HI8435_CTRL_REG, HI8435_CTRL_SRST);
+ hi8435_writeb(priv, HI8435_CTRL_REG, 0);
+ } else {
+ udelay(5);
+ gpiod_set_value(reset_gpio, 1);
+ }
+
+ spi_set_drvdata(spi, idev);
+ mutex_init(&priv->lock);
+
+ idev->dev.parent = &spi->dev;
+ idev->name = spi_get_device_id(spi)->name;
+ idev->modes = INDIO_DIRECT_MODE;
+ idev->info = &hi8435_info;
+ idev->channels = hi8435_channels;
+ idev->num_channels = ARRAY_SIZE(hi8435_channels);
+
+ /* unmask all events */
+ priv->event_scan_mask = ~(0);
+ /*
+ * There is a restriction in the chip - the hysteresis can not be odd.
+ * If the hysteresis is set to odd value then chip gets into lock state
+ * and not functional anymore.
+ * After chip reset the thresholds are in undefined state, so we need to
+ * initialize thresholds to some initial values and then prevent
+ * userspace setting odd hysteresis.
+ *
+ * Set threshold low voltage to 2V, threshold high voltage to 4V
+ * for both GND-Open and Supply-Open sensing modes.
+ */
+ priv->threshold_lo[0] = priv->threshold_lo[1] = 2;
+ priv->threshold_hi[0] = priv->threshold_hi[1] = 4;
+ hi8435_writew(priv, HI8435_GOCENHYS_REG, 0x206);
+ hi8435_writew(priv, HI8435_SOCENHYS_REG, 0x206);
+
+ ret = iio_triggered_event_setup(idev, NULL, hi8435_trigger_handler);
+ if (ret)
+ return ret;
+
+ ret = iio_device_register(idev);
+ if (ret < 0) {
+ dev_err(&spi->dev, "unable to register device\n");
+ goto unregister_triggered_event;
+ }
+
+ return 0;
+
+unregister_triggered_event:
+ iio_triggered_event_cleanup(idev);
+ return ret;
+}
+
+static int hi8435_remove(struct spi_device *spi)
+{
+ struct iio_dev *idev = spi_get_drvdata(spi);
+
+ iio_device_unregister(idev);
+ iio_triggered_event_cleanup(idev);
+
+ return 0;
+}
+
+static const struct of_device_id hi8435_dt_ids[] = {
+ { .compatible = "holt,hi8435" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, hi8435_dt_ids);
+
+static const struct spi_device_id hi8435_id[] = {
+ { "hi8435", 0},
+ { }
+};
+MODULE_DEVICE_TABLE(spi, hi8435_id);
+
+static struct spi_driver hi8435_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .of_match_table = of_match_ptr(hi8435_dt_ids),
+ },
+ .probe = hi8435_probe,
+ .remove = hi8435_remove,
+ .id_table = hi8435_id,
+};
+module_spi_driver(hi8435_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Vladimir Barinov");
+MODULE_DESCRIPTION("HI-8435 threshold detector");
--
1.9.1

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