max44000: Initial support

This just adds support for reporting illuminance with default settings.

Important default registers are written on probe because the device
otherwise lacks a reset function.

Signed-off-by: Crestez Dan Leonard <leonard.crestez@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 336 insertions, 0 deletions

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index cbd723236e38..7c566f516572 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -234,6 +234,17 @@ config LTR501
          This driver can also be built as a module.  If so, the module
          will be called ltr501.
 
+config MAX44000
+        tristate "MAX44000 Ambient and Infrared Proximity Sensor"
+        depends on I2C
+        select REGMAP_I2C
+        help
+         Say Y here if you want to build support for Maxim Integrated's
+         MAX44000 ambient and infrared proximity sensor device.
+
+         To compile this driver as a module, choose M here:
+         the module will be called max44000.
+
 config OPT3001
         tristate "Texas Instruments OPT3001 Light Sensor"
         depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index 8b246a604a92..6f2a3c62de27 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_ISL29125)		+= isl29125.o
 obj-$(CONFIG_JSA1212)           += jsa1212.o
 obj-$(CONFIG_SENSORS_LM3533)    += lm3533-als.o
 obj-$(CONFIG_LTR501)            += ltr501.o
+obj-$(CONFIG_MAX44000)          += max44000.o
 obj-$(CONFIG_OPT3001)           += opt3001.o
 obj-$(CONFIG_PA12203001)        += pa12203001.o
 obj-$(CONFIG_RPR0521)           += rpr0521.o
diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c
new file mode 100644
index 000000000000..5ed79345bb42
--- /dev/null
+++ b/drivers/iio/light/max44000.c
@@ -0,0 +1,324 @@
+/*
+ * MAX44000 Ambient and Infrared Proximity Sensor
+ *
+ * Copyright (c) 2016, Intel Corporation.
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * Data sheet: https://datasheets.maximintegrated.com/en/ds/MAX44000.pdf
+ *
+ * 7-bit I2C slave address 0x4a
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/util_macros.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/acpi.h>
+
+#define MAX44000_DRV_NAME               "max44000"
+
+/* Registers in datasheet order */
+#define MAX44000_REG_STATUS             0x00
+#define MAX44000_REG_CFG_MAIN           0x01
+#define MAX44000_REG_CFG_RX             0x02
+#define MAX44000_REG_CFG_TX             0x03
+#define MAX44000_REG_ALS_DATA_HI        0x04
+#define MAX44000_REG_ALS_DATA_LO        0x05
+#define MAX44000_REG_PRX_DATA           0x16
+#define MAX44000_REG_ALS_UPTHR_HI       0x06
+#define MAX44000_REG_ALS_UPTHR_LO       0x07
+#define MAX44000_REG_ALS_LOTHR_HI       0x08
+#define MAX44000_REG_ALS_LOTHR_LO       0x09
+#define MAX44000_REG_PST                0x0a
+#define MAX44000_REG_PRX_IND            0x0b
+#define MAX44000_REG_PRX_THR            0x0c
+#define MAX44000_REG_TRIM_GAIN_GREEN    0x0f
+#define MAX44000_REG_TRIM_GAIN_IR       0x10
+
+/* REG_CFG bits */
+#define MAX44000_CFG_ALSINTE            0x01
+#define MAX44000_CFG_PRXINTE            0x02
+#define MAX44000_CFG_MASK               0x1c
+#define MAX44000_CFG_MODE_SHUTDOWN      0x00
+#define MAX44000_CFG_MODE_ALS_GIR       0x04
+#define MAX44000_CFG_MODE_ALS_G         0x08
+#define MAX44000_CFG_MODE_ALS_IR        0x0c
+#define MAX44000_CFG_MODE_ALS_PRX       0x10
+#define MAX44000_CFG_MODE_PRX           0x14
+#define MAX44000_CFG_TRIM               0x20
+
+/*
+ * Upper 4 bits are not documented but start as 1 on powerup
+ * Setting them to 0 causes proximity to misbehave so set them to 1
+ */
+#define MAX44000_REG_CFG_RX_DEFAULT 0xf0
+
+#define MAX44000_ALSDATA_OVERFLOW       0x4000
+
+struct max44000_data {
+        struct mutex lock;
+        struct regmap *regmap;
+};
+
+/* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */
+#define MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2 5
+
+static const struct iio_chan_spec max44000_channels[] = {
+        {
+                .type = IIO_LIGHT,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+        },
+};
+
+static int max44000_read_alsval(struct max44000_data *data)
+{
+        u16 regval;
+        int ret;
+
+        ret = regmap_bulk_read(data->regmap, MAX44000_REG_ALS_DATA_HI,
+                               &regval, sizeof(regval));
+        if (ret < 0)
+                return ret;
+
+        regval = be16_to_cpu(regval);
+
+        /*
+         * Overflow is explained on datasheet page 17.
+         *
+         * It's a warning that either the G or IR channel has become saturated
+         * and that the value in the register is likely incorrect.
+         *
+         * The recommendation is to change the scale (ALSPGA).
+         * The driver just returns the max representable value.
+         */
+        if (regval & MAX44000_ALSDATA_OVERFLOW)
+                return 0x3FFF;
+
+        return regval;
+}
+
+static int max44000_read_raw(struct iio_dev *indio_dev,
+                             struct iio_chan_spec const *chan,
+                             int *val, int *val2, long mask)
+{
+        struct max44000_data *data = iio_priv(indio_dev);
+        int ret;
+
+        switch (mask) {
+        case IIO_CHAN_INFO_RAW:
+                switch (chan->type) {
+                case IIO_LIGHT:
+                        mutex_lock(&data->lock);
+                        ret = max44000_read_alsval(data);
+                        mutex_unlock(&data->lock);
+                        if (ret < 0)
+                                return ret;
+                        *val = ret;
+                        return IIO_VAL_INT;
+
+                default:
+                        return -EINVAL;
+                }
+
+        case IIO_CHAN_INFO_SCALE:
+                switch (chan->type) {
+                case IIO_LIGHT:
+                        *val = 1;
+                        *val2 = MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2;
+                        return IIO_VAL_FRACTIONAL_LOG2;
+
+                default:
+                        return -EINVAL;
+                }
+
+        default:
+                return -EINVAL;
+        }
+}
+
+static const struct iio_info max44000_info = {
+        .driver_module          = THIS_MODULE,
+        .read_raw               = max44000_read_raw,
+};
+
+static bool max44000_readable_reg(struct device *dev, unsigned int reg)
+{
+        switch (reg) {
+        case MAX44000_REG_STATUS:
+        case MAX44000_REG_CFG_MAIN:
+        case MAX44000_REG_CFG_RX:
+        case MAX44000_REG_CFG_TX:
+        case MAX44000_REG_ALS_DATA_HI:
+        case MAX44000_REG_ALS_DATA_LO:
+        case MAX44000_REG_PRX_DATA:
+        case MAX44000_REG_ALS_UPTHR_HI:
+        case MAX44000_REG_ALS_UPTHR_LO:
+        case MAX44000_REG_ALS_LOTHR_HI:
+        case MAX44000_REG_ALS_LOTHR_LO:
+        case MAX44000_REG_PST:
+        case MAX44000_REG_PRX_IND:
+        case MAX44000_REG_PRX_THR:
+        case MAX44000_REG_TRIM_GAIN_GREEN:
+        case MAX44000_REG_TRIM_GAIN_IR:
+                return true;
+        default:
+                return false;
+        }
+}
+
+static bool max44000_writeable_reg(struct device *dev, unsigned int reg)
+{
+        switch (reg) {
+        case MAX44000_REG_CFG_MAIN:
+        case MAX44000_REG_CFG_RX:
+        case MAX44000_REG_CFG_TX:
+        case MAX44000_REG_ALS_UPTHR_HI:
+        case MAX44000_REG_ALS_UPTHR_LO:
+        case MAX44000_REG_ALS_LOTHR_HI:
+        case MAX44000_REG_ALS_LOTHR_LO:
+        case MAX44000_REG_PST:
+        case MAX44000_REG_PRX_IND:
+        case MAX44000_REG_PRX_THR:
+        case MAX44000_REG_TRIM_GAIN_GREEN:
+        case MAX44000_REG_TRIM_GAIN_IR:
+                return true;
+        default:
+                return false;
+        }
+}
+
+static bool max44000_volatile_reg(struct device *dev, unsigned int reg)
+{
+        switch (reg) {
+        case MAX44000_REG_STATUS:
+        case MAX44000_REG_ALS_DATA_HI:
+        case MAX44000_REG_ALS_DATA_LO:
+        case MAX44000_REG_PRX_DATA:
+                return true;
+        default:
+                return false;
+        }
+}
+
+static bool max44000_precious_reg(struct device *dev, unsigned int reg)
+{
+        return reg == MAX44000_REG_STATUS;
+}
+
+static const struct regmap_config max44000_regmap_config = {
+        .reg_bits       = 8,
+        .val_bits       = 8,
+
+        .max_register   = MAX44000_REG_PRX_DATA,
+        .readable_reg   = max44000_readable_reg,
+        .writeable_reg  = max44000_writeable_reg,
+        .volatile_reg   = max44000_volatile_reg,
+        .precious_reg   = max44000_precious_reg,
+
+        .use_single_rw  = 1,
+        .cache_type     = REGCACHE_RBTREE,
+};
+
+static int max44000_probe(struct i2c_client *client,
+                          const struct i2c_device_id *id)
+{
+        struct max44000_data *data;
+        struct iio_dev *indio_dev;
+        int ret, reg;
+
+        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+        if (!indio_dev)
+                return -ENOMEM;
+        data = iio_priv(indio_dev);
+        data->regmap = devm_regmap_init_i2c(client, &max44000_regmap_config);
+        if (IS_ERR(data->regmap)) {
+                dev_err(&client->dev, "regmap_init failed!\n");
+                return PTR_ERR(data->regmap);
+        }
+
+        i2c_set_clientdata(client, indio_dev);
+        mutex_init(&data->lock);
+        indio_dev->dev.parent = &client->dev;
+        indio_dev->info = &max44000_info;
+        indio_dev->name = MAX44000_DRV_NAME;
+        indio_dev->channels = max44000_channels;
+        indio_dev->num_channels = ARRAY_SIZE(max44000_channels);
+
+        /*
+         * The device doesn't have a reset function so we just clear some
+         * important bits at probe time to ensure sane operation.
+         *
+         * Since we don't support interrupts/events the threshold values are
+         * not important. We also don't touch trim values.
+         */
+
+        /* Reset ALS scaling bits */
+        ret = regmap_write(data->regmap, MAX44000_REG_CFG_RX, MAX44000_REG_CFG_RX_DEFAULT);
+        if (ret < 0) {
+                dev_err(&client->dev, "failed to write default CFG_RX: %d\n", ret);
+                return ret;
+        }
+
+        /* Reset CFG bits to ALS-only mode and no interrupts */
+        reg = MAX44000_CFG_TRIM | MAX44000_CFG_MODE_ALS_GIR;
+        ret = regmap_write(data->regmap, MAX44000_REG_CFG_MAIN, reg);
+        if (ret < 0) {
+                dev_err(&client->dev, "failed to write init config: %d\n", ret);
+                return ret;
+        }
+
+        /* Read status at least once to clear any stale interrupt bits. */
+        ret = regmap_read(data->regmap, MAX44000_REG_STATUS, &reg);
+        if (ret < 0) {
+                dev_err(&client->dev, "failed to read init status: %d\n", ret);
+                return ret;
+        }
+
+        return iio_device_register(indio_dev);
+}
+
+static int max44000_remove(struct i2c_client *client)
+{
+        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+        iio_device_unregister(indio_dev);
+
+        return 0;
+}
+
+static const struct i2c_device_id max44000_id[] = {
+        {"max44000", 0},
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, max44000_id);
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id max44000_acpi_match[] = {
+        {"MAX44000", 0},
+        { }
+};
+MODULE_DEVICE_TABLE(acpi, max44000_acpi_match);
+#endif
+
+static struct i2c_driver max44000_driver = {
+        .driver = {
+                .name   = MAX44000_DRV_NAME,
+                .acpi_match_table = ACPI_PTR(max44000_acpi_match),
+        },
+        .probe          = max44000_probe,
+        .remove         = max44000_remove,
+        .id_table       = max44000_id,
+};
+
+module_i2c_driver(max44000_driver);
+
+MODULE_AUTHOR("Crestez Dan Leonard <leonard.crestez@intel.com>");
+MODULE_DESCRIPTION("MAX44000 Ambient and Infrared Proximity Sensor");
+MODULE_LICENSE("GPL v2");