text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * as3935.c - Support for AS3935 Franklin lightning sensor
   *
   * Copyright (C) 2014, 2017-2018
   * Author: Matt Ranostay <matt.ranostay@konsulko.com>
   */
  
  #include <linux/module.h>
  #include <linux/mod_devicetable.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/delay.h>
  #include <linux/workqueue.h>
  #include <linux/mutex.h>
  #include <linux/err.h>
  #include <linux/irq.h>
  #include <linux/spi/spi.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/buffer.h>
  #include <linux/iio/triggered_buffer.h>
  
  #define AS3935_AFE_GAIN		0x00
  #define AS3935_AFE_MASK		0x3F
  #define AS3935_AFE_GAIN_MAX	0x1F
  #define AS3935_AFE_PWR_BIT	BIT(0)
  
  #define AS3935_NFLWDTH		0x01
  #define AS3935_NFLWDTH_MASK	0x7f
  
  #define AS3935_INT		0x03
  #define AS3935_INT_MASK		0x0f
  #define AS3935_DISTURB_INT	BIT(2)
  #define AS3935_EVENT_INT	BIT(3)
  #define AS3935_NOISE_INT	BIT(0)
  
  #define AS3935_DATA		0x07
  #define AS3935_DATA_MASK	0x3F
  
  #define AS3935_TUNE_CAP		0x08
  #define AS3935_DEFAULTS		0x3C
  #define AS3935_CALIBRATE	0x3D
  
  #define AS3935_READ_DATA	BIT(14)
  #define AS3935_ADDRESS(x)	((x) << 8)
  
  #define MAX_PF_CAP		120
  #define TUNE_CAP_DIV		8
  
  struct as3935_state {
  	struct spi_device *spi;
  	struct iio_trigger *trig;
  	struct mutex lock;
  	struct delayed_work work;
  
  	unsigned long noise_tripped;
  	u32 tune_cap;
  	u32 nflwdth_reg;
  	u8 buffer[16]; /* 8-bit data + 56-bit padding + 64-bit timestamp */
  	u8 buf[2] ____cacheline_aligned;
  };
  
  static const struct iio_chan_spec as3935_channels[] = {
  	{
  		.type           = IIO_PROXIMITY,
  		.info_mask_separate =
  			BIT(IIO_CHAN_INFO_RAW) |
  			BIT(IIO_CHAN_INFO_PROCESSED) |
  			BIT(IIO_CHAN_INFO_SCALE),
  		.scan_index     = 0,
  		.scan_type = {
  			.sign           = 'u',
  			.realbits       = 6,
  			.storagebits    = 8,
  		},
  	},
  	IIO_CHAN_SOFT_TIMESTAMP(1),
  };
  
  static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
  {
  	u8 cmd;
  	int ret;
  
  	cmd = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
  	ret = spi_w8r8(st->spi, cmd);
  	if (ret < 0)
  		return ret;
  	*val = ret;
  
  	return 0;
  }
  
  static int as3935_write(struct as3935_state *st,
  				unsigned int reg,
  				unsigned int val)
  {
  	u8 *buf = st->buf;
  
  	buf[0] = AS3935_ADDRESS(reg) >> 8;
  	buf[1] = val;
  
  	return spi_write(st->spi, buf, 2);
  }
  
  static ssize_t as3935_sensor_sensitivity_show(struct device *dev,
  					struct device_attribute *attr,
  					char *buf)
  {
  	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
  	int val, ret;
  
  	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
  	if (ret)
  		return ret;
  	val = (val & AS3935_AFE_MASK) >> 1;
  
  	return sprintf(buf, "%d\n", val);
  }
  
  static ssize_t as3935_sensor_sensitivity_store(struct device *dev,
  					struct device_attribute *attr,
  					const char *buf, size_t len)
  {
  	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
  	unsigned long val;
  	int ret;
  
  	ret = kstrtoul((const char *) buf, 10, &val);
  	if (ret)
  		return -EINVAL;
  
  	if (val > AS3935_AFE_GAIN_MAX)
  		return -EINVAL;
  
  	as3935_write(st, AS3935_AFE_GAIN, val << 1);
  
  	return len;
  }
  
  static ssize_t as3935_noise_level_tripped_show(struct device *dev,
  					struct device_attribute *attr,
  					char *buf)
  {
  	struct as3935_state *st = iio_priv(dev_to_iio_dev(dev));
  	int ret;
  
  	mutex_lock(&st->lock);
  	ret = sprintf(buf, "%d\n", !time_after(jiffies, st->noise_tripped + HZ));
  	mutex_unlock(&st->lock);
  
  	return ret;
  }
  
  static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
  	as3935_sensor_sensitivity_show, as3935_sensor_sensitivity_store, 0);
  
  static IIO_DEVICE_ATTR(noise_level_tripped, S_IRUGO,
  	as3935_noise_level_tripped_show, NULL, 0);
  
  static struct attribute *as3935_attributes[] = {
  	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
  	&iio_dev_attr_noise_level_tripped.dev_attr.attr,
  	NULL,
  };
  
  static const struct attribute_group as3935_attribute_group = {
  	.attrs = as3935_attributes,
  };
  
  static int as3935_read_raw(struct iio_dev *indio_dev,
  			   struct iio_chan_spec const *chan,
  			   int *val,
  			   int *val2,
  			   long m)
  {
  	struct as3935_state *st = iio_priv(indio_dev);
  	int ret;
  
  
  	switch (m) {
  	case IIO_CHAN_INFO_PROCESSED:
  	case IIO_CHAN_INFO_RAW:
  		*val2 = 0;
  		ret = as3935_read(st, AS3935_DATA, val);
  		if (ret)
  			return ret;
  
  		/* storm out of range */
  		if (*val == AS3935_DATA_MASK)
  			return -EINVAL;
  
  		if (m == IIO_CHAN_INFO_RAW)
  			return IIO_VAL_INT;
  
  		if (m == IIO_CHAN_INFO_PROCESSED)
  			*val *= 1000;
  		break;
  	case IIO_CHAN_INFO_SCALE:
  		*val = 1000;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return IIO_VAL_INT;
  }
  
  static const struct iio_info as3935_info = {
  	.attrs = &as3935_attribute_group,
  	.read_raw = &as3935_read_raw,
  };
  
  static irqreturn_t as3935_trigger_handler(int irq, void *private)
  {
  	struct iio_poll_func *pf = private;
  	struct iio_dev *indio_dev = pf->indio_dev;
  	struct as3935_state *st = iio_priv(indio_dev);
  	int val, ret;
  
  	ret = as3935_read(st, AS3935_DATA, &val);
  	if (ret)
  		goto err_read;
  
  	st->buffer[0] = val & AS3935_DATA_MASK;
  	iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
  					   iio_get_time_ns(indio_dev));
  err_read:
  	iio_trigger_notify_done(indio_dev->trig);
  
  	return IRQ_HANDLED;
  }
  
  static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
  };
  
  static void as3935_event_work(struct work_struct *work)
  {
  	struct as3935_state *st;
  	int val;
  	int ret;
  
  	st = container_of(work, struct as3935_state, work.work);
  
  	ret = as3935_read(st, AS3935_INT, &val);
  	if (ret) {
  		dev_warn(&st->spi->dev, "read error\n");
  		return;
  	}
  
  	val &= AS3935_INT_MASK;
  
  	switch (val) {
  	case AS3935_EVENT_INT:
  		iio_trigger_poll_chained(st->trig);
  		break;
  	case AS3935_DISTURB_INT:
  	case AS3935_NOISE_INT:
  		mutex_lock(&st->lock);
  		st->noise_tripped = jiffies;
  		mutex_unlock(&st->lock);
  		dev_warn(&st->spi->dev, "noise level is too high\n");
  		break;
  	}
  }
  
  static irqreturn_t as3935_interrupt_handler(int irq, void *private)
  {
  	struct iio_dev *indio_dev = private;
  	struct as3935_state *st = iio_priv(indio_dev);
  
  	/*
  	 * Delay work for >2 milliseconds after an interrupt to allow
  	 * estimated distance to recalculated.
  	 */
  
  	schedule_delayed_work(&st->work, msecs_to_jiffies(3));
  
  	return IRQ_HANDLED;
  }
  
  static void calibrate_as3935(struct as3935_state *st)
  {
  	as3935_write(st, AS3935_DEFAULTS, 0x96);
  	as3935_write(st, AS3935_CALIBRATE, 0x96);
  	as3935_write(st, AS3935_TUNE_CAP,
  		BIT(5) | (st->tune_cap / TUNE_CAP_DIV));
  
  	mdelay(2);
  	as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
  	as3935_write(st, AS3935_NFLWDTH, st->nflwdth_reg);
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int as3935_suspend(struct device *dev)
  {
  	struct iio_dev *indio_dev = dev_get_drvdata(dev);
  	struct as3935_state *st = iio_priv(indio_dev);
  	int val, ret;
  
  	mutex_lock(&st->lock);
  	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
  	if (ret)
  		goto err_suspend;
  	val |= AS3935_AFE_PWR_BIT;
  
  	ret = as3935_write(st, AS3935_AFE_GAIN, val);
  
  err_suspend:
  	mutex_unlock(&st->lock);
  
  	return ret;
  }
  
  static int as3935_resume(struct device *dev)
  {
  	struct iio_dev *indio_dev = dev_get_drvdata(dev);
  	struct as3935_state *st = iio_priv(indio_dev);
  	int val, ret;
  
  	mutex_lock(&st->lock);
  	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
  	if (ret)
  		goto err_resume;
  	val &= ~AS3935_AFE_PWR_BIT;
  	ret = as3935_write(st, AS3935_AFE_GAIN, val);
  
  	calibrate_as3935(st);
  
  err_resume:
  	mutex_unlock(&st->lock);
  
  	return ret;
  }
  
  static SIMPLE_DEV_PM_OPS(as3935_pm_ops, as3935_suspend, as3935_resume);
  #define AS3935_PM_OPS (&as3935_pm_ops)
  
  #else
  #define AS3935_PM_OPS NULL
  #endif
  
  static void as3935_stop_work(void *data)
  {
  	struct iio_dev *indio_dev = data;
  	struct as3935_state *st = iio_priv(indio_dev);
  
  	cancel_delayed_work_sync(&st->work);
  }
  
  static int as3935_probe(struct spi_device *spi)
  {
  	struct device *dev = &spi->dev;
  	struct iio_dev *indio_dev;
  	struct iio_trigger *trig;
  	struct as3935_state *st;
  	int ret;
  
  	/* Be sure lightning event interrupt is specified */
  	if (!spi->irq) {
  		dev_err(dev, "unable to get event interrupt\n");
  		return -EINVAL;
  	}
  
  	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
  	if (!indio_dev)
  		return -ENOMEM;
  
  	st = iio_priv(indio_dev);
  	st->spi = spi;
  
  	spi_set_drvdata(spi, indio_dev);
  	mutex_init(&st->lock);
  
  	ret = device_property_read_u32(dev,
  			"ams,tuning-capacitor-pf", &st->tune_cap);
  	if (ret) {
  		st->tune_cap = 0;
  		dev_warn(dev, "no tuning-capacitor-pf set, defaulting to %d",
  			st->tune_cap);
  	}
  
  	if (st->tune_cap > MAX_PF_CAP) {
  		dev_err(dev, "wrong tuning-capacitor-pf setting of %d\n",
  			st->tune_cap);
  		return -EINVAL;
  	}
  
  	ret = device_property_read_u32(dev,
  			"ams,nflwdth", &st->nflwdth_reg);
  	if (!ret && st->nflwdth_reg > AS3935_NFLWDTH_MASK) {
  		dev_err(dev, "invalid nflwdth setting of %d\n",
  			st->nflwdth_reg);
  		return -EINVAL;
  	}
  
  	indio_dev->name = spi_get_device_id(spi)->name;
  	indio_dev->channels = as3935_channels;
  	indio_dev->num_channels = ARRAY_SIZE(as3935_channels);
  	indio_dev->modes = INDIO_DIRECT_MODE;
  	indio_dev->info = &as3935_info;
  
  	trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
  				      indio_dev->name, indio_dev->id);
  
  	if (!trig)
  		return -ENOMEM;
  
  	st->trig = trig;
  	st->noise_tripped = jiffies - HZ;
  	trig->dev.parent = indio_dev->dev.parent;
  	iio_trigger_set_drvdata(trig, indio_dev);
  	trig->ops = &iio_interrupt_trigger_ops;
  
  	ret = devm_iio_trigger_register(dev, trig);
  	if (ret) {
  		dev_err(dev, "failed to register trigger\n");
  		return ret;
  	}
  
  	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
  					      iio_pollfunc_store_time,
  					      as3935_trigger_handler, NULL);
  
  	if (ret) {
  		dev_err(dev, "cannot setup iio trigger\n");
  		return ret;
  	}
  
  	calibrate_as3935(st);
  
  	INIT_DELAYED_WORK(&st->work, as3935_event_work);
  	ret = devm_add_action(dev, as3935_stop_work, indio_dev);
  	if (ret)
  		return ret;
  
  	ret = devm_request_irq(dev, spi->irq,
  				&as3935_interrupt_handler,
  				IRQF_TRIGGER_RISING,
  				dev_name(dev),
  				indio_dev);
  
  	if (ret) {
  		dev_err(dev, "unable to request irq\n");
  		return ret;
  	}
  
  	ret = devm_iio_device_register(dev, indio_dev);
  	if (ret < 0) {
  		dev_err(dev, "unable to register device\n");
  		return ret;
  	}
  	return 0;
  }
  
  static const struct of_device_id as3935_of_match[] = {
  	{ .compatible = "ams,as3935", },
  	{ /* sentinel */ },
  };
  MODULE_DEVICE_TABLE(of, as3935_of_match);
  
  static const struct spi_device_id as3935_id[] = {
  	{"as3935", 0},
  	{},
  };
  MODULE_DEVICE_TABLE(spi, as3935_id);
  
  static struct spi_driver as3935_driver = {
  	.driver = {
  		.name	= "as3935",
  		.of_match_table = as3935_of_match,
  		.pm	= AS3935_PM_OPS,
  	},
  	.probe		= as3935_probe,
  	.id_table	= as3935_id,
  };
  module_spi_driver(as3935_driver);
  
  MODULE_AUTHOR("Matt Ranostay <matt.ranostay@konsulko.com>");
  MODULE_DESCRIPTION("AS3935 lightning sensor");
  MODULE_LICENSE("GPL");
  