Re: [PATCH v7 2/2] iio: Add AS3935 lightning sensor support

[Matt Ranostay]

On Thu, Mar 6, 2014 at 11:04 AM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 12/02/14 04:31, Matt Ranostay wrote:
>>
>> AS3935 chipset can detect lightning strikes and reports those back as
>> events and the estimated distance to the storm.
>>
>> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
>
> Given the resounding lack of support for my spherical coordinates
> suggestion, assuming nothing changes, I'll take this as a proximity driver.
>
> However, some outstanding bits and pieces and I'm not keen on a custom
> driver attribute for the boost gain if we can manage something more general.
>
Ok comments below :)

>> ---
>>   .../ABI/testing/sysfs-bus-iio-proximity-as3935     |  18 +
>>   drivers/iio/Kconfig                                |   1 +
>>   drivers/iio/Makefile                               |   1 +
>>   drivers/iio/proximity/Kconfig                      |  19 +
>>   drivers/iio/proximity/Makefile                     |   6 +
>>   drivers/iio/proximity/as3935.c                     | 446
>> +++++++++++++++++++++
>>   6 files changed, 491 insertions(+)
>>   create mode 100644
>> Documentation/ABI/testing/sysfs-bus-iio-proximity-as3935
>>   create mode 100644 drivers/iio/proximity/Kconfig
>>   create mode 100644 drivers/iio/proximity/Makefile
>>   create mode 100644 drivers/iio/proximity/as3935.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-proximity-as3935
>> b/Documentation/ABI/testing/sysfs-bus-iio-proximity-as3935
>> new file mode 100644
>> index 0000000..fc92bce
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-proximity-as3935
>> @@ -0,0 +1,18 @@
>> +What           /sys/bus/iio/devices/iio:deviceX/in_proximity_raw
>> +Date:          January 2014
>> +KernelVersion: 3.15
>> +Contact:       Matt Ranostay <mranostay@xxxxxxxxx>
>> +Description:
>> +               Get the current distance in meters of storm (1km steps)
>> +               1000       = storm overhead
>> +               1000-40000 = distance in meters
>> +               63000      = out of range
>
> If these are 'real' units then it should be in_proximity_input
> (IIO_INFO_PROCESSED).  The overhead one is a litle interesting.  I'd be
> tempted to just define
> it as meters and neglect to mention that it is meaningless any nearer.
> Also we proximity is a standard type so we the help should be in the main
> file and not device specific.  I wonder if for out of range it should return
> an error as it means it really doesn't have any answer rather than anything
> else...
>

Yeah the 63000 seems weird to me even. Would -EINVAL be a correct
error code to return for that state?
As for overhead the sensor can only do 1km intervals...

Would a better plan just to have...

    Description:
                  Get the current distance in meters of storm (1km steps)
                  1000-40000 = distance in meters



>> +
>> +What           /sys/bus/iio/devices/iio:deviceX/gain_boost
>> +Date:          January 2014
>> +KernelVersion: 3.15
>> +Contact:       Matt Ranostay <mranostay@xxxxxxxxx>
>> +Description:
>> +               Show or set the gain boost of the amp, from 0-31 range.
>> +               18 = indoors (default)
>> +               14 = outdoors
>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>> index 5dd0e12..743485e 100644
>> --- a/drivers/iio/Kconfig
>> +++ b/drivers/iio/Kconfig
>> @@ -74,6 +74,7 @@ if IIO_TRIGGER
>>      source "drivers/iio/trigger/Kconfig"
>>   endif #IIO_TRIGGER
>>   source "drivers/iio/pressure/Kconfig"
>> +source "drivers/iio/proximity/Kconfig"
>>   source "drivers/iio/temperature/Kconfig"
>>
>>   endif # IIO
>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>> index 887d390..698afc2 100644
>> --- a/drivers/iio/Makefile
>> +++ b/drivers/iio/Makefile
>> @@ -24,5 +24,6 @@ obj-y += light/
>>   obj-y += magnetometer/
>>   obj-y += orientation/
>>   obj-y += pressure/
>> +obj-y += proximity/
>>   obj-y += temperature/
>>   obj-y += trigger/
>> diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
>> new file mode 100644
>> index 0000000..0c8cdf5
>> --- /dev/null
>> +++ b/drivers/iio/proximity/Kconfig
>> @@ -0,0 +1,19 @@
>> +#
>> +# Proximity sensors
>> +#
>> +
>> +menu "Lightning sensors"
>> +
>> +config AS3935
>> +       tristate "AS3935 Franklin lightning sensor"
>> +       select IIO_BUFFER
>> +       select IIO_TRIGGERED_BUFFER
>> +       depends on SPI
>> +       help
>> +         Say Y here to build SPI interface support for the Austrian
>> +         Microsystems AS3935 lightning detection sensor.
>> +
>> +         To compile this driver as a module, choose M here: the
>> +         module will be called as3935
>> +
>> +endmenu
>> diff --git a/drivers/iio/proximity/Makefile
>> b/drivers/iio/proximity/Makefile
>> new file mode 100644
>> index 0000000..743adee
>> --- /dev/null
>> +++ b/drivers/iio/proximity/Makefile
>> @@ -0,0 +1,6 @@
>> +#
>> +# Makefile for IIO proximity sensors
>> +#
>> +
>> +# When adding new entries keep the list in alphabetical order
>> +obj-$(CONFIG_AS3935)           += as3935.o
>> diff --git a/drivers/iio/proximity/as3935.c
>> b/drivers/iio/proximity/as3935.c
>> new file mode 100644
>> index 0000000..75ef034
>> --- /dev/null
>> +++ b/drivers/iio/proximity/as3935.c
>> @@ -0,0 +1,446 @@
>> +/*
>> + * as3935.c - Support for AS3935 Franklin lightning sensor
>> + *
>> + * Copyright (C) 2014 Matt Ranostay <mranostay@xxxxxxxxx>
>> + *
>> + * 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.
>> + *
>
> No blank line here.
>
>> + */
>> +
>> +#include <linux/module.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/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/pm_runtime.h>
>
> This isn't doing runtime pm so is this the right header?
>
>
>> +#include <linux/of_gpio.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_INT             0x03
>> +#define AS3935_INT_MASK                0x07
>> +#define AS3935_EVENT_INT       BIT(3)
>> +#define AS3935_NOISE_INT       BIT(1)
>> +
>> +#define AS3935_DATA            0x07
>> +#define AS3935_DATA_MASK       0x3F
>> +
>> +#define AS3935_TUNE_CAP                0x08
>> +#define AS3935_CALIBRATE       0x3D
>> +
>> +#define AS3935_WRITE_DATA      BIT(15)
>> +#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;
>> +
>
> The point of the ____cacheline_aligned is to ensure that when allocated
> the buffer does not share a cacheline with anything else.  It does this
> by fixing teh starting location.   Nothing is done about the end location.
> Hence this *must* be the last element in the structure.   Care is taken
> in the iio_dev allocation to ensure that the start of the private structure
> is appropriately aligned and there is nothing after it.
>
> i.e. tune_cap must be above the next line.
>

Thanks... didn't know this.

>> +       u8 buf[2] ____cacheline_aligned;
>> +       u32 tune_cap;
>> +};
>> +
>> +static const struct iio_chan_spec as3935_channels[] = {
>> +       {
>> +               .type           = IIO_PROXIMITY,
>> +               .info_mask_separate =
>> +                       BIT(IIO_CHAN_INFO_RAW),
>> +               .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)
>> +{
>
> I wouldn't bother with the local pointer copy. Slightly
> obscures what is giong on to save a few character.
>
>> +       u8 *buf = st->buf;
>> +
>> +       buf[0] = (AS3935_WRITE_DATA | AS3935_ADDRESS(reg)) >> 8;
>> +       buf[1] = val;
>> +
>> +       return spi_write(st->spi, (u8 *) buf, 2);
>
> Why the typecast? It's already a u8 *
>
>> +};
>> +
>> +static ssize_t as3935_gain_boost_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_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,
>> +       as3935_gain_boost_show, as3935_gain_boost_store, 0);
>> +
>> +
>> +static struct attribute *as3935_attributes[] = {
>> +       &iio_dev_attr_gain_boost.dev_attr.attr,
>
>
> So what is this really?  Could it be considered a calibration scale?
> Or a straight _scale?  Is it effecting the measurement, or
> the sensitivity to make a measurement?  If the second then
> we probably want a more general naming.
>
> Perhaps
> in_detectionsensitivy or similar (that's a quick random suggestion
> - I'd prefer something better thought out ;)
>
>
>> +       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);
>> +       int ret;
>> +
>> +       if (m != IIO_CHAN_INFO_RAW)
>> +               return -EINVAL;
>> +
>> +       *val2 = 0;
>> +       ret = as3935_read(st, AS3935_DATA, val);
>> +       if (ret)
>> +               return ret;
>> +       *val *= 1000;
>> +
>> +       return IIO_VAL_INT;
>> +}
>> +
>> +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,
>> +};
>
> These are the defaults - don't provide any and you'll get the same thing
> (see industrialio-triggered-buffer.c)
>

Ok cruft will be removed in next series

>> +
>> +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;
>> +       val *= 1000;
>> +
>> +       iio_push_to_buffers_with_timestamp(indio_dev, &val,
>> pf->timestamp);
>> +err_read:
>> +       iio_trigger_notify_done(indio_dev->trig);
>> +
>> +       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;
>> +       int val;
>> +
>> +       st = container_of(work, struct as3935_state, work.work);
>> +
>> +       as3935_read(st, AS3935_INT, &val);
>> +       val &= AS3935_INT_MASK;
>> +
>> +       switch (val) {
>> +       case AS3935_EVENT_INT:
>> +               iio_trigger_poll(st->trig, iio_get_time_ns());
>> +               break;
>> +       case AS3935_NOISE_INT:
>
> This could be provided as an event perhaps?  Not sure, but splurging in
> the log is probably going to be missed.
>
>
>> +               dev_warn(&st->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);
>> +
>
> /*
>  * Delay..
>
>> +       /* 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)
>> +{
>> +       mutex_lock(&st->lock);
>> +
>> +       /* mask disturber interrupt bit */
>> +       as3935_write(st, AS3935_INT, 1<<5);
>> +
>> +       as3935_write(st, AS3935_CALIBRATE, 0x96);
>
> 1 << 5 as it's a binary operator.
>
>> +       as3935_write(st, AS3935_TUNE_CAP, 1<<5 | (st->tune_cap /
>> TUNE_CAP_DIV));
>> +
>> +       mdelay(2);
>> +       as3935_write(st, AS3935_TUNE_CAP, (st->tune_cap / TUNE_CAP_DIV));
>> +
>> +       mutex_unlock(&st->lock);
>> +}
>> +
>> +#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;
>> +
>> +       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 spi_device *spi)
>> +{
>> +       struct iio_dev *indio_dev = spi_get_drvdata(spi);
>> +       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);
>> +
>> +err_resume:
>> +       mutex_unlock(&st->lock);
>> +
>> +       return ret;
>> +}
>> +#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 ret;
>> +
>
> ... is specified?
>
>> +       /* Be sure lightning event interrupt */
>> +       if (!spi->irq) {
>> +               dev_err(&spi->dev, "unable to get event interrupt\n");
>> +               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);
>> +
>> +       ret = of_property_read_u32(np,
>> +                       "ams,tuning-capacitor-pf", &st->tune_cap);
>> +       if (ret) {
>> +               st->tune_cap = 0;
>> +               dev_warn(&spi->dev,
>> +                       "no tuning-capacitor-pf set, defaulting to %d",
>> +                       st->tune_cap);
>> +       }
>> +
>> +       if (st->tune_cap > MAX_PF_CAP) {
>> +               dev_err(&spi->dev,
>> +                       "wrong tuning-capacitor-pf 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->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");
>
> This will unroll the triggered_buffer_setup that has errored out.
> Hence you will unregister a buffer that was never registered.
> This should have it's own label to goto that only unregisters the
> trigger.
>
>
>> +               goto unregister_trigger;
>> +       }
>> +
>> +       calibrate_as3935(st);
>> +
>> +       ret = devm_request_irq(&spi->dev, spi->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 unregister_trigger;
>> +       }
>> +
>> +       ret = iio_device_register(indio_dev);
>> +       if (ret < 0) {
>> +               dev_err(&spi->dev, "unable to register device\n");
>> +               goto unregister_trigger;
>> +       }
>> +       return 0;
>> +
>> +unregister_trigger:
>
> These should be in the opposite order to conform to standard
> error unrolling (undo things in reverse order.
>

Oops... I knew that..

>
>> +       iio_trigger_unregister(st->trig);
>> +       iio_triggered_buffer_cleanup(indio_dev);
>> +
>> +       return ret;
>> +};
>> +
>> +static int as3935_remove(struct spi_device *spi)
>> +{
>> +       struct iio_dev *indio_dev = spi_get_drvdata(spi);
>> +       struct as3935_state *st = iio_priv(indio_dev);
>> +
>> +       iio_device_unregister(indio_dev);
>> +       iio_triggered_buffer_cleanup(indio_dev);
>> +       iio_trigger_unregister(st->trig);
>> +
>> +       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@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("AS3935 lightning sensor");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("spi:as3935");
>>
>
--
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