[PATCH v3 2/2] iio: light: noa1305: Add support for NOA1305

[Martyn Welch <martyn.welch@collabora.com>]

This driver adds the initial support for the ON Semiconductor
NOA1305 Ambient Light Sensor.

Originally written by Sergei Miroshnichenko. Found here:
  https://github.com/EmcraftSystems/linux-upstream/commit/196d6cf897e632d2cb82d45484bd7a1bfdd5b6d9

Signed-off-by: Sergei M <fizik1@yandex.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
---

Changes:
v2:
 - Correcting authorship and SOB.
v3:
 - Improve register define naming.
 - Follow IIO convention of interleaving register bit definitions with
   register defintions.
 - Use proper endian swapping.
 - Process raw sensor count into Lux.
 - Avoid setting variables to zero when not needed.
 - Check return value of i2c writes.
 - Implement disabling of regulator as a devm action.
 - Remove excessive white spacing.

 drivers/iio/light/Kconfig   |  10 ++
 drivers/iio/light/Makefile  |   1 +
 drivers/iio/light/noa1305.c | 278 ++++++++++++++++++++++++++++++++++++
 3 files changed, 289 insertions(+)
 create mode 100644 drivers/iio/light/noa1305.c

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 954c958cfc43..d1db0ec0d0f5 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -309,6 +309,16 @@ config MAX44009
 	 To compile this driver as a module, choose M here:
 	 the module will be called max44009.
 
+config NOA1305
+	tristate "ON Semiconductor NOA1305 ambient light sensor"
+	depends on I2C
+	help
+	 Say Y here if you want to build support for the ON Semiconductor
+	 NOA1305 ambient light sensor.
+
+	 To compile this driver as a module, choose M here:
+	 The module will be called noa1305.
+
 config OPT3001
 	tristate "Texas Instruments OPT3001 Light Sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index e40794fbb435..00d1f9b98f39 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_LTR501)		+= ltr501.o
 obj-$(CONFIG_LV0104CS)		+= lv0104cs.o
 obj-$(CONFIG_MAX44000)		+= max44000.o
 obj-$(CONFIG_MAX44009)		+= max44009.o
+obj-$(CONFIG_NOA1305)		+= noa1305.o
 obj-$(CONFIG_OPT3001)		+= opt3001.o
 obj-$(CONFIG_PA12203001)	+= pa12203001.o
 obj-$(CONFIG_RPR0521)		+= rpr0521.o
diff --git a/drivers/iio/light/noa1305.c b/drivers/iio/light/noa1305.c
new file mode 100644
index 000000000000..02b0cf48c2be
--- /dev/null
+++ b/drivers/iio/light/noa1305.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Support for ON Semiconductor NOA1305 ambient light sensor
+ *
+ * Copyright (C) 2016 Emcraft Systems
+ * Copyright (C) 2019 Collabora Ltd.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+#define NOA1305_REG_POWER_CONTROL	0x0
+#define   NOA1305_POWER_CONTROL_DOWN	0x00
+#define   NOA1305_POWER_CONTROL_ON	0x08
+#define NOA1305_REG_RESET		0x1
+#define   NOA1305_RESET_RESET		0x10
+#define NOA1305_REG_INTEGRATION_TIME	0x2
+#define   NOA1305_INTEGR_TIME_800MS	0x00
+#define   NOA1305_INTEGR_TIME_400MS	0x01
+#define   NOA1305_INTEGR_TIME_200MS	0x02
+#define   NOA1305_INTEGR_TIME_100MS	0x03
+#define   NOA1305_INTEGR_TIME_50MS	0x04
+#define   NOA1305_INTEGR_TIME_25MS	0x05
+#define   NOA1305_INTEGR_TIME_12_5MS	0x06
+#define   NOA1305_INTEGR_TIME_6_25MS	0x07
+#define NOA1305_REG_INT_SELECT		0x3
+#define   NOA1305_INT_SEL_ACTIVE_HIGH	0x01
+#define   NOA1305_INT_SEL_ACTIVE_LOW	0x02
+#define   NOA1305_INT_SEL_INACTIVE	0x03
+#define NOA1305_REG_INT_THRESH_LSB	0x4
+#define NOA1305_REG_INT_THRESH_MSB	0x5
+#define NOA1305_REG_ALS_DATA_LSB	0x6
+#define NOA1305_REG_ALS_DATA_MSB	0x7
+#define NOA1305_REG_DEVICE_ID_LSB	0x8
+#define NOA1305_REG_DEVICE_ID_MSB	0x9
+
+#define NOA1305_DEVICE_ID	0x0519
+#define NOA1305_DRIVER_NAME	"noa1305"
+
+struct noa1305_priv {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct regulator *vin_reg;
+};
+
+static int noa1305_measure(struct noa1305_priv *priv)
+{
+	__le16 data;
+	int count;
+	int ret;
+
+	ret = regmap_bulk_read(priv->regmap, NOA1305_REG_ALS_DATA_LSB, &data,
+			       2);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Lux = count / (<Integration Constant> * <Integration Time>)
+	 *
+	 * Integration Constant = 7.7
+	 * Integration Time in Seconds (currently) = 800ms
+	 */
+	return (le16_to_cpu(data) * 100) / (77 * 8);
+}
+
+static const struct iio_chan_spec noa1305_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+	}
+};
+
+static int noa1305_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	int ret = -EINVAL;
+	struct noa1305_priv *priv = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (chan->type) {
+		case IIO_LIGHT:
+			ret = noa1305_measure(priv);
+			if (ret < 0)
+				return ret;
+			*val = ret;
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return ret;
+}
+
+static const struct iio_info noa1305_info = {
+	.read_raw = noa1305_read_raw,
+};
+
+static bool noa1305_writable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case NOA1305_REG_POWER_CONTROL:
+	case NOA1305_REG_RESET:
+	case NOA1305_REG_INTEGRATION_TIME:
+	case NOA1305_REG_INT_SELECT:
+	case NOA1305_REG_INT_THRESH_LSB:
+	case NOA1305_REG_INT_THRESH_MSB:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config noa1305_regmap_config = {
+	.name = NOA1305_DRIVER_NAME,
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = NOA1305_REG_DEVICE_ID_MSB,
+	.writeable_reg = noa1305_writable_reg,
+};
+
+static void noa1305_reg_remove(void *data)
+{
+	struct noa1305_priv *priv = data;
+
+	regulator_disable(priv->vin_reg);
+}
+
+static int noa1305_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct noa1305_priv *priv;
+	struct iio_dev *indio_dev;
+	struct regmap *regmap;
+	__le16 data;
+	unsigned int dev_id;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*priv));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	regmap = devm_regmap_init_i2c(client, &noa1305_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "Regmap initialization failed.\n");
+		return PTR_ERR(regmap);
+	}
+
+	priv = iio_priv(indio_dev);
+
+	priv->vin_reg = devm_regulator_get(&client->dev, "vin");
+	if (IS_ERR(priv->vin_reg)) {
+		dev_err(&client->dev, "get regulator vin failed\n");
+		return PTR_ERR(priv->vin_reg);
+	}
+
+	ret = regulator_enable(priv->vin_reg);
+	if (ret) {
+		dev_err(&client->dev, "enable regulator vin failed\n");
+		return ret;
+	}
+
+	ret = devm_add_action_or_reset(&client->dev, noa1305_reg_remove, priv);
+	if (ret) {
+		dev_err(&client->dev, "addition of devm action failed\n");
+		return ret;
+	}
+
+	i2c_set_clientdata(client, indio_dev);
+	priv->client = client;
+	priv->regmap = regmap;
+
+	ret = regmap_bulk_read(regmap, NOA1305_REG_DEVICE_ID_LSB, &data, 2);
+	if (ret < 0) {
+		dev_err(&client->dev, "ID reading failed: %d\n", ret);
+		return ret;
+	}
+
+	dev_id = le16_to_cpu(data);
+	if (dev_id != NOA1305_DEVICE_ID) {
+		dev_err(&client->dev, "Unknown device ID: 0x%x\n", dev_id);
+		ret = -ENODEV;
+		return ret;
+	}
+
+	ret = regmap_write(regmap, NOA1305_REG_POWER_CONTROL,
+			   NOA1305_POWER_CONTROL_ON);
+	if (ret < 0) {
+		dev_err(&client->dev, "Enabling power control failed\n");
+		return ret;
+	}
+
+	ret = regmap_write(regmap, NOA1305_REG_RESET, NOA1305_RESET_RESET);
+	if (ret < 0) {
+		dev_err(&client->dev, "Device reset failed\n");
+		return ret;
+	}
+
+	ret = regmap_write(regmap, NOA1305_REG_INTEGRATION_TIME,
+			   NOA1305_INTEGR_TIME_800MS);
+	if (ret < 0) {
+		dev_err(&client->dev, "Setting integration time failed\n");
+		return ret;
+	}
+
+	ret = regmap_write(regmap, NOA1305_REG_INT_SELECT,
+			   NOA1305_INT_SEL_INACTIVE);
+	if (ret < 0) {
+		dev_err(&client->dev, "Disabling interrupts failed\n");
+		return ret;
+	}
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &noa1305_info;
+	indio_dev->channels = noa1305_channels;
+	indio_dev->num_channels = ARRAY_SIZE(noa1305_channels);
+	indio_dev->name = NOA1305_DRIVER_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "registering device failed\n");
+		return ret;
+	}
+
+	return ret;
+}
+
+static int noa1305_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct noa1305_priv *priv = iio_priv(indio_dev);
+
+	regulator_disable(priv->vin_reg);
+
+	return 0;
+}
+
+static const struct of_device_id noa1305_of_match[] = {
+	{ .compatible = "onnn,noa1305" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, noa1305_of_match);
+
+static const struct i2c_device_id noa1305_ids[] = {
+	{ "noa1305", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, noa1305_id);
+
+static struct i2c_driver noa1305_driver = {
+	.driver = {
+		.name		= NOA1305_DRIVER_NAME,
+		.of_match_table	= noa1305_of_match,
+	},
+	.probe		= noa1305_probe,
+	.remove		= noa1305_remove,
+	.id_table	= noa1305_ids,
+};
+
+module_i2c_driver(noa1305_driver);
+
+MODULE_AUTHOR("Sergei Miroshnichenko <sergeimir@emcraft.com>");
+MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.com");
+MODULE_DESCRIPTION("ON Semiconductor NOA1305 ambient light sensor");
+MODULE_LICENSE("GPL");
-- 
2.20.1