iio: light: new driver for the ROHM BH1780

This is a reimplementation of the old misc device driver for the
ROHM BH1780 ambient light sensor (drivers/misc/bh1780gli.c).

Differences from the old driver:
- Uses the IIO framework
- Uses runtime PM to idle the hardware after 5 seconds
- No weird custom power management from userspace
- No homebrewn values in sysfs

This uses the same (undocumented) device tree compatible-string
as the old driver ("rohm,bh1780gli").

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/light/Kconfig

@@ -73,6 +73,17 @@ config BH1750
 	 To compile this driver as a module, choose M here: the module will
 	 be called bh1750.
 
+config BH1780
+	tristate "ROHM BH1780 ambient light sensor"
+	depends on I2C
+	depends on !SENSORS_BH1780
+	help
+	 Say Y here to build support for the ROHM BH1780GLI ambient
+	 light sensor.
+
+	 To compile this driver as a module, choose M here: the module will
+	 be called bh1780.
+
 config CM32181
 	depends on I2C
 	tristate "CM32181 driver"

drivers/iio/light/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_AL3320A)		+= al3320a.o
 obj-$(CONFIG_APDS9300)		+= apds9300.o
 obj-$(CONFIG_APDS9960)		+= apds9960.o
 obj-$(CONFIG_BH1750)		+= bh1750.o
+obj-$(CONFIG_BH1780)		+= bh1780.o
 obj-$(CONFIG_CM32181)		+= cm32181.o
 obj-$(CONFIG_CM3232)		+= cm3232.o
 obj-$(CONFIG_CM3323)		+= cm3323.o

drivers/iio/light/bh1780.c

@@ -0,0 +1,297 @@
+/*
+ * ROHM 1780GLI Ambient Light Sensor Driver
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ * Author: Linus Walleij <linus.walleij@linaro.org>
+ * Loosely based on the previous BH1780 ALS misc driver
+ * Copyright (C) 2010 Texas Instruments
+ * Author: Hemanth V <hemanthv@ti.com>
+ */
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm_runtime.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/bitops.h>
+
+#define BH1780_CMD_BIT		BIT(7)
+#define BH1780_REG_CONTROL	0x00
+#define BH1780_REG_PARTID	0x0A
+#define BH1780_REG_MANFID	0x0B
+#define BH1780_REG_DLOW		0x0C
+#define BH1780_REG_DHIGH	0x0D
+
+#define BH1780_REVMASK		GENMASK(3,0)
+#define BH1780_POWMASK		GENMASK(1,0)
+#define BH1780_POFF		(0x0)
+#define BH1780_PON		(0x3)
+
+/* power on settling time in ms */
+#define BH1780_PON_DELAY	2
+/* max time before value available in ms */
+#define BH1780_INTERVAL		250
+
+struct bh1780_data {
+	struct i2c_client *client;
+};
+
+static int bh1780_write(struct bh1780_data *bh1780, u8 reg, u8 val)
+{
+	int ret = i2c_smbus_write_byte_data(bh1780->client,
+					    BH1780_CMD_BIT | reg,
+					    val);
+	if (ret < 0)
+		dev_err(&bh1780->client->dev,
+			"i2c_smbus_write_byte_data failed error "
+			"%d, register %01x\n",
+			ret, reg);
+	return ret;
+}
+
+static int bh1780_read(struct bh1780_data *bh1780, u8 reg)
+{
+	int ret = i2c_smbus_read_byte_data(bh1780->client,
+					   BH1780_CMD_BIT | reg);
+	if (ret < 0)
+		dev_err(&bh1780->client->dev,
+			"i2c_smbus_read_byte_data failed error "
+			"%d, register %01x\n",
+			ret, reg);
+	return ret;
+}
+
+static int bh1780_read_word(struct bh1780_data *bh1780, u8 reg)
+{
+	int ret = i2c_smbus_read_word_data(bh1780->client,
+					   BH1780_CMD_BIT | reg);
+	if (ret < 0)
+		dev_err(&bh1780->client->dev,
+			"i2c_smbus_read_word_data failed error "
+			"%d, register %01x\n",
+			ret, reg);
+	return ret;
+}
+
+static int bh1780_debugfs_reg_access(struct iio_dev *indio_dev,
+			      unsigned int reg, unsigned int writeval,
+			      unsigned int *readval)
+{
+	struct bh1780_data *bh1780 = iio_priv(indio_dev);
+	int ret;
+
+	if (!readval)
+		bh1780_write(bh1780, (u8)reg, (u8)writeval);
+
+	ret = bh1780_read(bh1780, (u8)reg);
+	if (ret < 0)
+		return ret;
+
+	*readval = ret;
+
+	return 0;
+}
+
+static int bh1780_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct bh1780_data *bh1780 = iio_priv(indio_dev);
+	int value;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_LIGHT:
+			pm_runtime_get_sync(&bh1780->client->dev);
+			value = bh1780_read_word(bh1780, BH1780_REG_DLOW);
+			if (value < 0)
+				return value;
+			pm_runtime_mark_last_busy(&bh1780->client->dev);
+			pm_runtime_put_autosuspend(&bh1780->client->dev);
+			*val = value;
+
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = BH1780_INTERVAL * 1000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info bh1780_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = bh1780_read_raw,
+	.debugfs_reg_access = bh1780_debugfs_reg_access,
+};
+
+static const struct iio_chan_spec bh1780_channels[] = {
+	{
+		.type = IIO_LIGHT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_INT_TIME)
+	}
+};
+
+static int bh1780_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int ret;
+	struct bh1780_data *bh1780;
+	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+	struct iio_dev *indio_dev;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
+		return -EIO;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*bh1780));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	bh1780 = iio_priv(indio_dev);
+	bh1780->client = client;
+	i2c_set_clientdata(client, indio_dev);
+
+	/* Power up the device */
+	ret = bh1780_write(bh1780, BH1780_REG_CONTROL, BH1780_PON);
+	if (ret < 0)
+		return ret;
+	msleep(BH1780_PON_DELAY);
+	pm_runtime_get_noresume(&client->dev);
+	pm_runtime_set_active(&client->dev);
+	pm_runtime_enable(&client->dev);
+
+	ret = bh1780_read(bh1780, BH1780_REG_PARTID);
+	if (ret < 0)
+		goto out_disable_pm;
+	dev_info(&client->dev,
+		 "Ambient Light Sensor, Rev : %lu\n",
+		 (ret & BH1780_REVMASK));
+
+	/*
+	 * As the device takes 250 ms to even come up with a fresh
+	 * measurement after power-on, do not shut it down unnecessarily.
+	 * Set autosuspend to a five seconds.
+	 */
+	pm_runtime_set_autosuspend_delay(&client->dev, 5000);
+	pm_runtime_use_autosuspend(&client->dev);
+	pm_runtime_put(&client->dev);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &bh1780_info;
+	indio_dev->name = id->name;
+	indio_dev->channels = bh1780_channels;
+	indio_dev->num_channels = ARRAY_SIZE(bh1780_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto out_disable_pm;
+	return 0;
+
+out_disable_pm:
+	pm_runtime_put_noidle(&client->dev);
+	pm_runtime_disable(&client->dev);
+	return ret;
+}
+
+static int bh1780_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct bh1780_data *bh1780 = iio_priv(indio_dev);
+	int ret;
+
+	iio_device_unregister(indio_dev);
+	pm_runtime_get_sync(&client->dev);
+	pm_runtime_put_noidle(&client->dev);
+	pm_runtime_disable(&client->dev);
+	ret = bh1780_write(bh1780, BH1780_REG_CONTROL, BH1780_POFF);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to power off\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int bh1780_runtime_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct bh1780_data *bh1780 = i2c_get_clientdata(client);
+	int ret;
+
+	ret = bh1780_write(bh1780, BH1780_REG_CONTROL, BH1780_POFF);
+	if (ret < 0) {
+		dev_err(dev, "failed to runtime suspend\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int bh1780_runtime_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct bh1780_data *bh1780 = i2c_get_clientdata(client);
+	int ret;
+
+	ret = bh1780_write(bh1780, BH1780_REG_CONTROL, BH1780_PON);
+	if (ret < 0) {
+		dev_err(dev, "failed to runtime resume\n");
+		return ret;
+	}
+
+	/* Wait for power on, then for a value to be available */
+	msleep(BH1780_PON_DELAY + BH1780_INTERVAL);
+
+	return 0;
+}
+#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops bh1780_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(bh1780_runtime_suspend,
+			   bh1780_runtime_resume, NULL)
+};
+
+static const struct i2c_device_id bh1780_id[] = {
+	{ "bh1780", 0 },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(i2c, bh1780_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id of_bh1780_match[] = {
+	{ .compatible = "rohm,bh1780gli", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_bh1780_match);
+#endif
+
+static struct i2c_driver bh1780_driver = {
+	.probe		= bh1780_probe,
+	.remove		= bh1780_remove,
+	.id_table	= bh1780_id,
+	.driver = {
+		.name = "bh1780",
+		.pm = &bh1780_dev_pm_ops,
+		.of_match_table = of_match_ptr(of_bh1780_match),
+	},
+};
+
+module_i2c_driver(bh1780_driver);
+
+MODULE_DESCRIPTION("ROHM BH1780GLI Ambient Light Sensor Driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");