[PATCH] iio: acpi: Add ACPI0008 Ambient Light Sensor

[Gabriele Mazzotta]

Add basic implementation of the ACPI0008 Ambient Light Sensor driver.
This driver currently supports only the ALI property, yet is ready to
be easily extended to handle ALC, ALT, ALP ones as well.

Signed-off-by: Martin Liska <marxin.liska@xxxxxxxxx>
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Signed-off-by: Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>
Cc: Zhang Rui <rui.zhang@xxxxxxxxx>
---
This continues http://marc.info/?t=140163463200002
I've made few adjustments over the original patch:

 - Code aligned with 4.1-rc1 and cleaned up
 - Use signed integers to store values: sensors report 32bit signed
   values. In particular, -1 is reported when the current reading
   is above the supported range of sensitivity.

Most of the changes are just a consequence of the changes in the
iio subsystem.

Gabriele

 drivers/iio/light/Kconfig    |  12 +++
 drivers/iio/light/Makefile   |   1 +
 drivers/iio/light/acpi-als.c | 240 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 253 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..fe9a8a0
--- /dev/null
+++ b/drivers/iio/light/acpi-als.c
@@ -0,0 +1,240 @@
+/*
+ * ACPI Ambient Light Sensor Driver
+ *
+ * Based on ALS driver:
+ * Copyright (C) 2009 Zhang Rui <rui.zhang@xxxxxxxxx>
+ *
+ * Rework for IIO subsystem:
+ * Copyright (C) 2012-2013 Martin Liska <marxin.liska@xxxxxxxxx>
+ *
+ * Final cleanup and debugging:
+ * Copyright (C) 2013-2014 Marek Vasut <marex@xxxxxxx>
+ * Copyright (C) 2015 Gabriele Mazzotta <gabriele.mzt@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#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	= 10,
+			.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);
+
+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 iio_device_register(indio_dev);
+}
+
+static int acpi_als_remove(struct acpi_device *device)
+{
+	struct iio_dev *indio_dev = acpi_driver_data(device);
+
+	iio_device_unregister(indio_dev);
+
+	return 0;
+}
+
+static const struct acpi_device_id acpi_als_device_ids[] = {
+	{"ACPI0008", 0},
+	{"", 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,
+		.remove	= acpi_als_remove,
+		.notify	= acpi_als_notify,
+	},
+};
+
+module_acpi_driver(acpi_als_driver);
+
+MODULE_AUTHOR("Zhang Rui <rui.zhang@xxxxxxxxx>");
+MODULE_AUTHOR("Martin Liska <marxin.liska@xxxxxxxxx>");
+MODULE_AUTHOR("Marek Vasut <marex@xxxxxxx>");
+MODULE_DESCRIPTION("ACPI Ambient Light Sensor Driver");
+MODULE_LICENSE("GPL");
-- 
2.1.4

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