Date:	Fri, 08 May 2015 21:20:33 +0200
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	Jonathan Cameron <jic23@...nel.org>
Cc:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	marxin.liska@...il.com, marex@...x.de, rui.zhang@...el.com,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v9] iio: acpi: Add support for ACPI0008 Ambient Light Sensor

On Friday 08 May 2015 10:58:29 Jonathan Cameron wrote:
> On 02/05/15 08:30, Gabriele Mazzotta wrote:
> > This driver adds the initial support for the ACPI Ambient Light Sensor
> > as defined in Section 9.2 of the ACPI specification (Revision 5.0) [1].
> > 
> > Sensors complying with the standard are exposed as ACPI devices with
> > ACPI0008 as hardware ID and provide standard methods by which the OS
> > can query properties of the ambient light environment the system is
> > currently operating in.
> > 
> > This driver currently allows only to get the current ambient light
> > illuminance reading through the _ALI method, but is ready to be
> > extended extended to handle _ALC, _ALT and _ALP as well.
> > 
> > [1] http://www.acpi.info/DOWNLOADS/ACPIspec50.pdf
> > 
> > Signed-off-by: Martin Liska <marxin.liska@...il.com>
> > Signed-off-by: Marek Vasut <marex@...x.de>
> > Signed-off-by: Gabriele Mazzotta <gabriele.mzt@...il.com>
> > Cc: Zhang Rui <rui.zhang@...el.com>
> Sorry, one last point inline that I missed before!
> 
> (just noticed it when taking a last glance before applying the patch).
> 
> Jonathan
> > ---
> > Changes since v8:
> >  - Set realbits to 32
> >  - Fix license mismatch (using GPL v2 or later)
> >  - Drop iio_device_unregister() in favor of devm_iio_device_register()
> > 
> >  drivers/iio/light/Kconfig    |  12 +++
> >  drivers/iio/light/Makefile   |   1 +
> >  drivers/iio/light/acpi-als.c | 232 +++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 245 insertions(+)
> >  create mode 100644 drivers/iio/light/acpi-als.c
> > 
> > diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
> > index 01a1a16..898b2b5 100644
> > --- a/drivers/iio/light/Kconfig
> > +++ b/drivers/iio/light/Kconfig
> > @@ -5,6 +5,18 @@
> >  
> >  menu "Light sensors"
> >  
> > +config ACPI_ALS
> > +	tristate "ACPI Ambient Light Sensor"
> > +	depends on ACPI
> > +	select IIO_TRIGGERED_BUFFER
> > +	select IIO_KFIFO_BUF
> > +	help
> > +	 Say Y here if you want to build a driver for the ACPI0008
> > +	 Ambient Light Sensor.
> > +
> > +	 To compile this driver as a module, choose M here: the module will
> > +	 be called acpi-als.
> > +
> >  config ADJD_S311
> >  	tristate "ADJD-S311-CR999 digital color sensor"
> >  	select IIO_BUFFER
> > diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
> > index ad7c30f..d9aad52a 100644
> > --- a/drivers/iio/light/Makefile
> > +++ b/drivers/iio/light/Makefile
> > @@ -3,6 +3,7 @@
> >  #
> >  
> >  # When adding new entries keep the list in alphabetical order
> > +obj-$(CONFIG_ACPI_ALS)		+= acpi-als.o
> >  obj-$(CONFIG_ADJD_S311)		+= adjd_s311.o
> >  obj-$(CONFIG_AL3320A)		+= al3320a.o
> >  obj-$(CONFIG_APDS9300)		+= apds9300.o
> > diff --git a/drivers/iio/light/acpi-als.c b/drivers/iio/light/acpi-als.c
> > new file mode 100644
> > index 0000000..9839c9a
> > --- /dev/null
> > +++ b/drivers/iio/light/acpi-als.c
> > @@ -0,0 +1,232 @@
> > +/*
> > + * ACPI Ambient Light Sensor Driver
> > + *
> > + * Based on ALS driver:
> > + * Copyright (C) 2009 Zhang Rui <rui.zhang@...el.com>
> > + *
> > + * Rework for IIO subsystem:
> > + * Copyright (C) 2012-2013 Martin Liska <marxin.liska@...il.com>
> > + *
> > + * Final cleanup and debugging:
> > + * Copyright (C) 2013-2014 Marek Vasut <marex@...x.de>
> > + * Copyright (C) 2015 Gabriele Mazzotta <gabriele.mzt@...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.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> > + * with this program; if not, write to the Free Software Foundation, Inc.,
> > + * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/acpi.h>
> > +#include <linux/err.h>
> > +#include <linux/mutex.h>
> > +
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/buffer.h>
> > +#include <linux/iio/kfifo_buf.h>
> > +
> > +#define ACPI_ALS_CLASS			"als"
> > +#define ACPI_ALS_DEVICE_NAME		"acpi-als"
> > +#define ACPI_ALS_NOTIFY_ILLUMINANCE	0x80
> > +
> > +ACPI_MODULE_NAME("acpi-als");
> > +
> > +/*
> > + * So far, there's only one channel in here, but the specification for
> > + * ACPI0008 says there can be more to what the block can report. Like
> > + * chromaticity and such. We are ready for incoming additions!
> > + */
> > +static const struct iio_chan_spec acpi_als_channels[] = {
> > +	{
> > +		.type		= IIO_LIGHT,
> > +		.scan_type	= {
> > +			.sign		= 's',
> > +			.realbits	= 32,
> > +			.storagebits	= 32,
> > +		},
> > +		.info_mask_separate	= BIT(IIO_CHAN_INFO_RAW),
> > +	},
> > +};
> > +
> > +/*
> > + * The event buffer contains timestamp and all the data from
> > + * the ACPI0008 block. There are multiple, but so far we only
> > + * support _ALI (illuminance). Once someone adds new channels
> > + * to acpi_als_channels[], the evt_buffer below will grow
> > + * automatically.
> > + */
> > +#define EVT_NR_SOURCES		ARRAY_SIZE(acpi_als_channels)
> > +#define EVT_BUFFER_SIZE		\
> > +	(sizeof(s64) + (EVT_NR_SOURCES * sizeof(s32)))
> > +
> > +struct acpi_als {
> > +	struct acpi_device	*device;
> > +	struct mutex		lock;
> > +
> > +	s32			evt_buffer[EVT_BUFFER_SIZE];
> > +};
> > +
> > +/*
> > + * All types of properties the ACPI0008 block can report. The ALI, ALC, ALT
> > + * and ALP can all be handled by als_read_value() below, while the ALR is
> > + * special.
> > + *
> > + * The _ALR property returns tables that can be used to fine-tune the values
> > + * reported by the other props based on the particular hardware type and it's
> > + * location (it contains tables for "rainy", "bright inhouse lighting" etc.).
> > + *
> > + * So far, we support only ALI (illuminance).
> > + */
> > +#define ACPI_ALS_ILLUMINANCE	"_ALI"
> > +#define ACPI_ALS_CHROMATICITY	"_ALC"
> > +#define ACPI_ALS_COLOR_TEMP	"_ALT"
> > +#define ACPI_ALS_POLLING	"_ALP"
> > +#define ACPI_ALS_TABLES		"_ALR"
> > +
> > +static int als_read_value(struct acpi_als *als, char *prop, s32 *val)
> > +{
> > +	unsigned long long temp_val;
> > +	acpi_status status;
> > +
> > +	status = acpi_evaluate_integer(als->device->handle, prop, NULL,
> > +				       &temp_val);
> > +
> > +	if (ACPI_FAILURE(status)) {
> > +		ACPI_EXCEPTION((AE_INFO, status, "Error reading ALS %s", prop));
> > +		return -EIO;
> > +	}
> > +
> > +	*val = temp_val;
> > +
> > +	return 0;
> > +}
> > +
> > +static void acpi_als_notify(struct acpi_device *device, u32 event)
> > +{
> > +	struct iio_dev *indio_dev = acpi_driver_data(device);
> > +	struct acpi_als *als = iio_priv(indio_dev);
> > +	s32 *buffer = als->evt_buffer;
> > +	s64 time_ns = iio_get_time_ns();
> > +	s32 val;
> > +	int ret;
> > +
> > +	mutex_lock(&als->lock);
> > +
> > +	memset(buffer, 0, EVT_BUFFER_SIZE);
> > +
> > +	switch (event) {
> > +	case ACPI_ALS_NOTIFY_ILLUMINANCE:
> > +		ret = als_read_value(als, ACPI_ALS_ILLUMINANCE, &val);
> > +		if (ret < 0)
> > +			goto out;
> > +		*buffer++ = val;
> > +		break;
> > +	default:
> > +		/* Unhandled event */
> > +		dev_dbg(&device->dev, "Unhandled ACPI ALS event (%08x)!\n",
> > +			event);
> > +		goto out;
> > +	}
> > +
> > +	iio_push_to_buffers_with_timestamp(indio_dev,
> > +					   (u8 *)als->evt_buffer, time_ns);
> Why the u8* cast, the function takes a void * so there is no need to cast it.

It was there in the previous submissions and I don't know if there was
a reason for it, but I can't find one now.
I must have missed it while updating the patch.

> > +
> > +out:
> > +	mutex_unlock(&als->lock);
> > +}
> > +
> > +static int acpi_als_read_raw(struct iio_dev *indio_dev,
> > +			     struct iio_chan_spec const *chan, int *val,
> > +			     int *val2, long mask)
> > +{
> > +	struct acpi_als *als = iio_priv(indio_dev);
> > +	s32 temp_val;
> > +	int ret;
> > +
> > +	if (mask != IIO_CHAN_INFO_RAW)
> > +		return -EINVAL;
> > +
> > +	/* we support only illumination (_ALI) so far. */
> > +	if (chan->type != IIO_LIGHT)
> > +		return -EINVAL;
> > +
> > +	ret = als_read_value(als, ACPI_ALS_ILLUMINANCE, &temp_val);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	*val = temp_val;
> > +
> > +	return IIO_VAL_INT;
> > +}
> > +
> > +static const struct iio_info acpi_als_info = {
> > +	.driver_module		= THIS_MODULE,
> > +	.read_raw		= acpi_als_read_raw,
> > +};
> > +
> > +static int acpi_als_add(struct acpi_device *device)
> > +{
> > +	struct acpi_als *als;
> > +	struct iio_dev *indio_dev;
> > +	struct iio_buffer *buffer;
> > +
> > +	indio_dev = devm_iio_device_alloc(&device->dev, sizeof(*als));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	als = iio_priv(indio_dev);
> > +
> > +	device->driver_data = indio_dev;
> > +	als->device = device;
> > +	mutex_init(&als->lock);
> > +
> > +	indio_dev->name = ACPI_ALS_DEVICE_NAME;
> > +	indio_dev->dev.parent = &device->dev;
> > +	indio_dev->info = &acpi_als_info;
> > +	indio_dev->modes = INDIO_BUFFER_SOFTWARE;
> > +	indio_dev->channels = acpi_als_channels;
> > +	indio_dev->num_channels = ARRAY_SIZE(acpi_als_channels);
> > +
> > +	buffer = devm_iio_kfifo_allocate(&device->dev);
> > +	if (!buffer)
> > +		return -ENOMEM;
> > +
> > +	iio_device_attach_buffer(indio_dev, buffer);
> > +
> > +	return devm_iio_device_register(&device->dev, indio_dev);
> > +}
> > +
> > +static const struct acpi_device_id acpi_als_device_ids[] = {
> > +	{"ACPI0008", 0},
> > +	{},
> > +};
> > +
> > +MODULE_DEVICE_TABLE(acpi, acpi_als_device_ids);
> > +
> > +static struct acpi_driver acpi_als_driver = {
> > +	.name	= "acpi_als",
> > +	.class	= ACPI_ALS_CLASS,
> > +	.ids	= acpi_als_device_ids,
> > +	.ops = {
> > +		.add	= acpi_als_add,
> > +		.notify	= acpi_als_notify,
> > +	},
> > +};
> > +
> > +module_acpi_driver(acpi_als_driver);
> > +
> > +MODULE_AUTHOR("Zhang Rui <rui.zhang@...el.com>");
> > +MODULE_AUTHOR("Martin Liska <marxin.liska@...il.com>");
> > +MODULE_AUTHOR("Marek Vasut <marex@...x.de>");
> > +MODULE_DESCRIPTION("ACPI Ambient Light Sensor Driver");
> > +MODULE_LICENSE("GPL");
> > 
> 

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