Message-ID: <08b2bae0-2f88-49b4-b9ba-3b05343f3608@email.android.com>
Date:	Fri, 31 Jan 2014 13:24:16 +0000
From:	Jonathan Cameron <jic23@...nel.org>
To:	Peter Meerwald <pmeerw@...erw.net>,
	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



On January 30, 2014 10:37:19 AM GMT+00:00, Peter Meerwald <pmeerw@...erw.net> wrote:
>
>> AS3935 chipset can detect lightning strikes and reports those
>> back as events and the esimated distance to the storm.
>
>pretty cool :)
Indeed!
>
>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

Couple of quick comments for now.

The driver should not be doing the gpio irq setup. There is no reason it needs to be a gpio that I can see. DT should hence also have interrupt not gpio.

Why all the pinctrl headers.

Curious question... What controls max spi fre
q? I would have thought that was fixed for the part hence not needed in device tree?

Do make sure to add sysfs attr docs as Peter suggested.
>
>> ---
>>  .../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");
>> 

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