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>

3 files changed, 309 insertions, 0 deletions

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index cfd3df8416bb..5ee1d453b3d8 100644
--- a/drivers/iio/light/Kconfig
+++ b/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"
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index b2c31053db0c..4aeee2bd8f49 100644
--- a/drivers/iio/light/Makefile
+++ b/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
diff --git a/drivers/iio/light/bh1780.c b/drivers/iio/light/bh1780.c
new file mode 100644
index 000000000000..72b364e4aa72
--- /dev/null
+++ b/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>");