iio: adc: hi8435: Holt HI-8435 threshold detector

Add Holt threshold detector driver for HI-8435 chip

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 546 insertions, 0 deletions

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 27531180d94b..7868c744fd4b 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 fa5723a5ed7c..99b37a963a1e 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 000000000000..c73c6c62a6ac
--- /dev/null
+++ b/drivers/iio/adc/hi8435.c
@@ -0,0 +1,534 @@
+/*
+ * 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>
+#include <linux/gpio/consumer.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;
+	__be16 be_val;
+
+	reg |= HI8435_READ_OPCODE;
+	ret = spi_write_then_read(priv->spi, &reg, 1, &be_val, 2);
+	*val = be16_to_cpu(be_val);
+
+	return ret;
+}
+
+static int hi8435_readl(struct hi8435_priv *priv, u8 reg, u32 *val)
+{
+	int ret;
+	__be32 be_val;
+
+	reg |= HI8435_READ_OPCODE;
+	ret = spi_write_then_read(priv->spi, &reg, 1, &be_val, 4);
+	*val = be32_to_cpu(be_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");