Message-ID: <alpine.DEB.2.01.1401301119560.30431@pmeerw.net>
Date:	Thu, 30 Jan 2014 11:37:19 +0100 (CET)
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Matt Ranostay <mranostay@...il.com>
cc:	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	matt.porter@...aro.org, koen@...inion.thruhere.net,
	pantelis.antoniou@...il.com
Subject: Re: [PATCH 2/2] iio: Add AS3935 lightning sensor support


> AS3935 chipset can detect lightning strikes and reports those
> back as events and the esimated distance to the storm.

pretty cool :)

the distance thing should be documented in 
Documentation/ABI/testing/sysfs-bus-iio -- which unit (meters?) for 
example

sysfs attributes such as boost should be documented as well; or better use 
a writable scale attribute if possible

nitpicking inline

> ---
>  .../devicetree/bindings/iio/distance/as3935.txt    |  25 ++
>  drivers/iio/Kconfig                                |   1 +
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/distance/Kconfig                       |  19 +
>  drivers/iio/distance/Makefile                      |   6 +
>  drivers/iio/distance/as3935.c                      | 459 +++++++++++++++++++++
>  6 files changed, 511 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/distance/as3935.txt
>  create mode 100644 drivers/iio/distance/Kconfig
>  create mode 100644 drivers/iio/distance/Makefile
>  create mode 100644 drivers/iio/distance/as3935.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/distance/as3935.txt b/Documentation/devicetree/bindings/iio/distance/as3935.txt
> new file mode 100644
> index 0000000..af35827
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/distance/as3935.txt
> @@ -0,0 +1,25 @@
> +Austrian Microsystems AS3935 Franklin lightning sensor device driver
> +
> +Required properties:
> +	- compatible: must be "ams,as3935"
> +	- reg: SPI chip select number for the device
> +	- spi-max-frequency: Max SPI frequency to use
> +	- spi-cpha: SPI Mode 1
> +	- gpios: GPIO input of interrupt line from IRQ pin of AS3935 IC
> +
> +Optional properties:
> +	- ams,tune-cap: Calibration tuning capacitor stepping value 0 - 15.
> +	  Range of 0 to 120 pF, 8pF steps. This will require using the calibration
> +	  data from the manufacturer.
> +
> +
> +Example:
> +
> +		as3935@0 {
> +			compatible = "ams,as3935";
> +			reg = <0>;
> +			spi-max-frequency = <100000>;
> +			spi-cpha;
> +			ams,tune-cap = /bits/ 8 <10>;
> +			gpios = <&gpio1 16 10>;
> +		};
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 5dd0e12..5164a68 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -63,6 +63,7 @@ source "drivers/iio/adc/Kconfig"
>  source "drivers/iio/amplifiers/Kconfig"
>  source "drivers/iio/common/Kconfig"
>  source "drivers/iio/dac/Kconfig"
> +source "drivers/iio/distance/Kconfig"
>  source "drivers/iio/frequency/Kconfig"
>  source "drivers/iio/gyro/Kconfig"
>  source "drivers/iio/humidity/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 887d390..1574731 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -16,6 +16,7 @@ obj-y += adc/
>  obj-y += amplifiers/
>  obj-y += common/
>  obj-y += dac/
> +obj-y += distance/
>  obj-y += gyro/
>  obj-y += frequency/
>  obj-y += humidity/
> diff --git a/drivers/iio/distance/Kconfig b/drivers/iio/distance/Kconfig
> new file mode 100644
> index 0000000..753352c
> --- /dev/null
> +++ b/drivers/iio/distance/Kconfig
> @@ -0,0 +1,19 @@
> +#
> +# Distance sensors
> +#
> +
> +menu "Lightning sensors"
> +
> +config AS3935
> +	tristate "AS3935 Franklin lightning sensor"
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	depends on SPI
> +	help
> +	 If you say yes here you get support for the Austrian Microsystems
> +	 AS3935 lightning detection sensor.
> +
> +	 This driver can also be built as a module. If so, the module
> +	 will be called as3935
> +
> +endmenu
> diff --git a/drivers/iio/distance/Makefile b/drivers/iio/distance/Makefile
> new file mode 100644
> index 0000000..f63b70d
> --- /dev/null
> +++ b/drivers/iio/distance/Makefile
> @@ -0,0 +1,6 @@
> +#
> +# Makefile for IIO distance sensors
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_AS3935)		+= as3935.o
> diff --git a/drivers/iio/distance/as3935.c b/drivers/iio/distance/as3935.c
> new file mode 100644
> index 0000000..1a8f48d
> --- /dev/null
> +++ b/drivers/iio/distance/as3935.c
> @@ -0,0 +1,459 @@
> +/*
> + * as3935.c - Support for AS3935 Franklin lightning sensor
> + *
> + * Copyright (C) 2014 Matt Ranostay <mranostay@...il.com>
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/mutex.h>
> +#include <linux/workqueue.h>
> +#include <linux/err.h>
> +#include <linux/irq.h>
> +#include <linux/gpio.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>
> +#include <linux/pinctrl/pinctrl.h>
> +#include <linux/pinctrl/pinmux.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/of_gpio.h>
> +
> +
> +#define AS3935_AFE_GAIN		0x00
> +#define AS3935_AFE_MASK		0x3F
> +#define AS3935_AFE_GAIN_MAX	0x1F
> +
> +#define AS3935_INT		0x03
> +#define AS3935_INT_MASK		0x07
> +#define AS3935_DATA		0x07
> +#define AS3935_DATA_MASK	0x1F
> +
> +#define AS3935_TUNE_CAP		0x08
> +#define AS3935_CALIBRATE	0x3D
> +
> +#define AS3935_WRITE_DATA	(0x1 << 15)
> +#define AS3935_READ_DATA	(0x1 << 14)
> +#define AS3935_ADDRESS(x)	(x << 8)
> +
> +#define AS3935_EVENT_INT	(1<<3)
> +#define AS3935_NOISE_INT	(1<<0)
> +
> +struct as3935_state {
> +	struct spi_device *spi;
> +	struct mutex lock;
> +
> +	struct iio_trigger *trig;
> +	struct delayed_work work;
> +
> +	u8 tune_cap;
> +};
> +
> +static const struct iio_chan_spec as3935_channels[] = {
> +	{
> +		.type           = IIO_DISTANCE,
> +		.channel        = 0,
> +		.info_mask_separate =
> +			BIT(IIO_CHAN_INFO_RAW),
> +		.scan_index     = 0,
> +		.scan_type = {
> +			.sign           = 'u',
> +			.realbits       = 6,
> +			.storagebits    = 6,
> +		},
> +		.modified = 0,

channel and modified are not needed
storagebits should be a multiple of 8

> +	},
> +	IIO_CHAN_SOFT_TIMESTAMP(1),
> +};
> +
> +static const unsigned long as3935_available_scan_masks[] = { 0x01, 0x0 };

is this needed? there is just one channel

> +
> +static int as3935_read(struct as3935_state *st, unsigned int reg, int *val)
> +{
> +	u8 tx, rx;
> +	int ret;
> +
> +	struct spi_transfer xfers[] = {
> +		{
> +			.tx_buf = &tx,
> +			.bits_per_word = 8,
> +			.len = 1,
> +		}, {
> +			.rx_buf = &rx,
> +			.bits_per_word = 8,
> +			.len = 1,
> +		},
> +	};
> +
> +	mutex_lock(&st->lock);
> +	tx = (AS3935_READ_DATA | AS3935_ADDRESS(reg)) >> 8;
> +
> +	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
> +	mutex_unlock(&st->lock);
> +
> +	*val = rx;
> +
> +	return ret;
> +};
> +
> +static int as3935_write(struct as3935_state *st,
> +				unsigned int reg,
> +				unsigned int val)
> +{
> +	u8 buf[2];
> +	int ret;
> +
> +	mutex_lock(&st->lock);
> +	buf[0] = AS3935_WRITE_DATA | AS3935_ADDRESS(reg) >> 8;
> +	buf[1] = val;
> +
> +	ret = spi_write(st->spi, (u8 *) &buf, 2);
> +	mutex_unlock(&st->lock);
> +
> +	return ret;
> +};
> +
> +static ssize_t gain_boost_show(struct device *dev,

not prefixed with as3935_

> +				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 gain_boost_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 IIO_DEVICE_ATTR(gain_boost, S_IRUGO | S_IWUSR,
> +	gain_boost_show, gain_boost_store, 0);
> +
> +
> +static struct attribute *as3935_attributes[] = {
> +	&iio_dev_attr_gain_boost.dev_attr.attr,
> +	NULL,
> +};
> +
> +static 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);
> +
> +	if (m == IIO_CHAN_INFO_RAW) {
> +		int ret;
> +		*val = 0;
> +		ret = as3935_read(st, AS3935_DATA, val2);

huh, this always returns 0?
only val is return if IIO_VAL_INT

> +		if (ret)
> +			return ret;
> +		return IIO_VAL_INT;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info as3935_info = {
> +	.driver_module = THIS_MODULE,
> +	.attrs = &as3935_attribute_group,
> +	.read_raw = &as3935_read_raw,
> +};
> +
> +static const struct iio_buffer_setup_ops iio_triggered_buffer_setup_ops = {
> +	.postenable = &iio_triggered_buffer_postenable,
> +	.predisable = &iio_triggered_buffer_predisable,
> +};
> +
> +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;
> +	val &= AS3935_DATA_MASK;
> +	iio_push_to_buffers_with_timestamp(indio_dev, &val, iio_get_time_ns());
> +
> +	iio_trigger_notify_done(indio_dev->trig);

iio_trigger_notify_done() must always be called, most past err_read

> +err_read:
> +
> +	return IRQ_HANDLED;
> +};
> +
> +static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
> +	.owner = THIS_MODULE,
> +};
> +
> +static void as3935_event_work(struct work_struct *work)
> +{
> +	struct as3935_state *st;
> +	struct spi_device *spi;
> +	int val;
> +
> +	st = container_of(work, struct as3935_state, work.work);
> +	spi = st->spi;
> +
> +	as3935_read(st, AS3935_INT, &val);
> +	val &= AS3935_INT_MASK;
> +
> +	switch (val) {
> +	case AS3935_EVENT_INT:
> +		iio_trigger_poll(st->trig, 0);
> +		break;
> +	case AS3935_NOISE_INT:
> +		dev_warn(&spi->dev, "noise level is too high");
> +		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);
> +
> +	cancel_delayed_work(&st->work);
> +	schedule_delayed_work(&st->work, jiffies_to_msecs(3));
> +	return IRQ_HANDLED;
> +}
> +
> +static void calibrate_as3935(struct as3935_state *st)
> +{
> +	/* mask disturber interrupt bit */
> +	as3935_write(st, AS3935_INT, 1 << 5);
> +
> +	as3935_write(st, AS3935_CALIBRATE, 0x96);
> +	as3935_write(st, AS3935_TUNE_CAP, 1 << 5 | st->tune_cap);
> +
> +	mdelay(2);
> +	as3935_write(st, AS3935_TUNE_CAP, st->tune_cap);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int as3935_suspend(struct spi_device *spi, pm_message_t msg)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct as3935_state *st = iio_priv(indio_dev);
> +	int val, ret;
> +
> +	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
> +	if (ret)
> +		return ret;
> +	val |= 0x01;
> +
> +	return as3935_write(st, AS3935_AFE_GAIN, val);
> +}
> +
> +static int as3935_resume(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct as3935_state *st = iio_priv(indio_dev);
> +	int val, ret;
> +
> +	ret = as3935_read(st, AS3935_AFE_GAIN, &val);
> +	if (ret)
> +		return ret;
> +	val &= ~1;
> +
> +	return as3935_write(st, AS3935_AFE_GAIN, val);
> +}
> +#else
> +#define as3935_suspend	NULL
> +#define as3935_resume	NULL
> +#endif
> +
> +static int as3935_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct iio_trigger *trig;
> +	struct as3935_state *st;
> +	struct device_node *np = spi->dev.of_node;
> +	int gpio;
> +	int irq;
> +	int ret;
> +
> +	/* Grab the GPIO to use for lightning event interrupt */
> +	if (np)
> +		gpio = of_get_gpio(spi->dev.of_node, 0);
> +	else {
> +		dev_err(&spi->dev, "unable to get interrupt gpio\n");
> +		return -EINVAL;
> +	}
> +
> +	/* GPIO event setup */
> +	ret = devm_gpio_request(&spi->dev, gpio, "as3935");
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to request GPIO %u\n", gpio);
> +		return ret;
> +	}
> +
> +	ret = gpio_direction_input(gpio);
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to set pin direction\n");
> +		return -EINVAL;
> +	}
> +
> +	/* IRQ setup */
> +	irq = gpio_to_irq(gpio);
> +	if (irq < 0) {
> +		dev_err(&spi->dev, "failed to map GPIO to IRQ: %d\n", irq);
> +		return -EINVAL;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	st->spi = spi;
> +	st->tune_cap = 0;
> +	spi_set_drvdata(spi, indio_dev);
> +	mutex_init(&st->lock);
> +	INIT_DELAYED_WORK(&st->work, as3935_event_work);
> +
> +	of_property_read_u8(np, "ams,tune-cap", &st->tune_cap);
> +	if (st->tune_cap > 15) {
> +		dev_err(&spi->dev,
> +			"wrong tune_cap setting of %d\n", st->tune_cap);
> +		return -EINVAL;
> +	}
> +
> +	indio_dev->dev.parent = &spi->dev;
> +	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->available_scan_masks = as3935_available_scan_masks;
> +	indio_dev->info = &as3935_info;
> +
> +	trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
> +				      indio_dev->name, indio_dev->id);
> +
> +	if (!trig)
> +		return -ENOMEM;
> +
> +	st->trig = trig;
> +	trig->dev.parent = indio_dev->dev.parent;
> +	iio_trigger_set_drvdata(trig, indio_dev);
> +	trig->ops = &iio_interrupt_trigger_ops;
> +
> +	ret = iio_trigger_register(trig);
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to register trigger\n");
> +		return ret;
> +	}
> +
> +	ret = iio_triggered_buffer_setup(indio_dev, NULL,
> +					&as3935_trigger_handler,
> +					&iio_triggered_buffer_setup_ops);
> +
> +	if (ret) {
> +		dev_err(&spi->dev, "cannot setup iio trigger\n");
> +		return -EINVAL;
> +	}
> +
> +	calibrate_as3935(st);
> +
> +	ret = devm_request_irq(&spi->dev, irq,
> +				&as3935_interrupt_handler,
> +				IRQF_TRIGGER_RISING,
> +				dev_name(&spi->dev),
> +				indio_dev);
> +
> +	if (ret) {
> +		dev_err(&spi->dev, "unable to request irq\n");
> +		goto uninit_buffer;
> +	}
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "unable to register device\n");
> +		goto uninit_buffer;
> +	}
> +
> +	return 0;
> +
> +uninit_buffer:
> +	iio_triggered_buffer_cleanup(indio_dev);

iio_trigger_unregister()?

> +
> +	return ret;
> +};
> +
> +static int as3935_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +

iio_trigger_unregister()?
iio_triggered_buffer_cleanup()?

> +	iio_device_unregister(indio_dev);
> +	return 0;
> +};
> +
> +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",
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= as3935_probe,
> +	.remove		= as3935_remove,
> +	.id_table	= as3935_id,
> +	.suspend	= as3935_suspend,
> +	.resume		= as3935_resume,
> +};
> +module_spi_driver(as3935_driver);
> +
> +MODULE_AUTHOR("Matt Ranostay <mranostay@...il.com>");
> +MODULE_DESCRIPTION("AS3935 lightning sensor");
> +MODULE_LICENSE("GPL");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
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