[PATCH v7 2/2] iio: light: Add support for ltrf216a sensor

From: Shreeya Patel
Date: Mon Jul 11 2022 - 07:42:10 EST

From: Zhigang Shi <Zhigang.Shi@xxxxxxxxxx>

Add initial support for ltrf216a ambient light sensor.

Datasheet: https://gitlab.steamos.cloud/shreeya/iio/-/blob/main/LTRF216A.pdf
Co-developed-by: Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>
Signed-off-by: Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>
Signed-off-by: Zhigang Shi <Zhigang.Shi@xxxxxxxxxx>
---

Note :-

This patch generates the below mentioned warnings due to not documenting
the 'ltr' string in vendors-prefix.yaml and liteon,ltrf216a.yaml files.
The thread for the discussion of not documenting 'ltr' as deprecated
prefix can be found here.
https://lore.kernel.org/lkml/20220511094024.175994-2-shreeya.patel@xxxxxxxxxxxxx/

There are released devices which uses ltr216a light sensor and exposes the
vendor prefix name as 'ltr' through ACPI. Hence, we would like to add
this string under compatible property which would help probe the light sensor
driver.

WARNING: DT compatible string "ltr,ltrf216a" appears un-documented
-- check ./Documentation/devicetree/bindings/
#474: FILE: drivers/iio/light/ltrf216a.c:421:
+ { .compatible = "ltr,ltrf216a", },

WARNING: DT compatible string vendor "ltr" appears un-documented
-- check ./Documentation/devicetree/bindings/vendor-prefixes.yaml
#474: FILE: drivers/iio/light/ltrf216a.c:421:
+ { .compatible = "ltr,ltrf216a", },


Changes in v7
- Add regmap support.
- Fix runtime power management implementation.
- Fix the ordering of devm and non-devm functions.
- Use DEFINE_RUNTIME_DEV_PM_OPS macro

Changes in v6
- Fix some errors reported by kernel test robot.
- Add protocol details for the datasheet link.
- Remove useless assignments.
- Add unit details for read data delay macro.
- Use pm_sleep_ptr().

Changes in v5
- Add power management support.
- Add reset functionality.
- Use readx_poll_timeout() to get data.
- Cleanup some of the redundant code.
- Update int_time_fac after I2C write is successful.
- Rename mutex to lock.
- Use Reverse Xmas tree pattern for all variable definitions.
- Improve error handling messages and add error codes.
- Add one more MODULE_AUTHOR.
- Remove cleardata which was reading data for infrared light.

Changes in v4
- Add more descriptive comment for mutex lock
- Fix mutex locking in read_raw()
- Use i2c_smbus_read_i2c_block_data()

Changes in v3
- Use u16 instead of u8 for int_time_fac
- Reorder headers in ltrf216a.c file
- Remove int_time_mapping table and use int_time_available

Changes in v2
- Add support for 25ms and 50ms integration time.
- Rename some of the macros as per names given in datasheet
- Add a comment for the mutex lock
- Use read_avail callback instead of attributes and set the
appropriate _available bit.
- Use FIELD_PREP() at appropriate places.
- Add a constant lookup table for integration time and reg val
- Use BIT() macro for magic numbers.
- Improve error handling at few places.
- Use get_unaligned_le24() and div_u64()
- Use probe_new() callback and devm functions
- Return errors in probe using dev_err_probe()
- Use DEFINE_SIMPLE_DEV_PM_OPS()
- Correct the formula for lux to use 0.45 instead of 0.8


drivers/iio/light/Kconfig | 11 +
drivers/iio/light/Makefile | 1 +
drivers/iio/light/ltrf216a.c | 423 +++++++++++++++++++++++++++++++++++
3 files changed, 435 insertions(+)
create mode 100644 drivers/iio/light/ltrf216a.c

diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index 8537e88f02e3..7cf6e8490123 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -331,6 +331,17 @@ config LTR501
This driver can also be built as a module. If so, the module
will be called ltr501.

+config LTRF216A
+ tristate "Liteon LTRF216A Light Sensor"
+ depends on I2C
+ select REGMAP_I2C
+ help
+ If you say Y or M here, you get support for Liteon LTRF216A
+ Ambient Light Sensor.
+
+ If built as a dynamically linked module, it will be called
+ ltrf216a.
+
config LV0104CS
tristate "LV0104CS Ambient Light Sensor"
depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index d10912faf964..6f23817fae6f 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_ISL29125) += isl29125.o
obj-$(CONFIG_JSA1212) += jsa1212.o
obj-$(CONFIG_SENSORS_LM3533) += lm3533-als.o
obj-$(CONFIG_LTR501) += ltr501.o
+obj-$(CONFIG_LTRF216A) += ltrf216a.o
obj-$(CONFIG_LV0104CS) += lv0104cs.o
obj-$(CONFIG_MAX44000) += max44000.o
obj-$(CONFIG_MAX44009) += max44009.o
diff --git a/drivers/iio/light/ltrf216a.c b/drivers/iio/light/ltrf216a.c
new file mode 100644
index 000000000000..085d0ff229b8
--- /dev/null
+++ b/drivers/iio/light/ltrf216a.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * LTRF216A Ambient Light Sensor
+ *
+ * Copyright (C) 2021 Lite-On Technology Corp (Singapore)
+ * Author: Shi Zhigang <Zhigang.Shi@xxxxxxxxxx>
+ *
+ * IIO driver for LTRF216A (7-bit I2C slave address 0x53).
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/iopoll.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/iio.h>
+
+#include <asm/unaligned.h>
+
+#define LTRF216A_DRV_NAME "ltrf216a"
+
+#define LTRF216A_ALS_DATA_STATUS BIT(3)
+#define LTRF216A_ALS_ENABLE_MASK BIT(1)
+#define LTRF216A_MAIN_CTRL 0x00
+#define LTRF216A_ALS_MEAS_RES 0x04
+#define LTRF216A_MAIN_STATUS 0x07
+#define LTRF216A_ALS_DATA_0 0x0D
+#define LTRF216A_ALS_RESET 0x10
+#define LTRF216A_MAX_REG 0x26
+#define LTRF216A_ALS_READ_DATA_DELAY_US 20000
+
+static const int ltrf216a_int_time_available[][2] = {
+ {0, 400000},
+ {0, 200000},
+ {0, 100000},
+ {0, 50000},
+ {0, 25000},
+};
+
+static const int ltrf216a_int_time_reg[][2] = {
+ {400, 0x03},
+ {200, 0x13},
+ {100, 0x22},
+ {50, 0x31},
+ {25, 0x40},
+};
+
+/*
+ * Window Factor is needed when the device is under Window glass
+ * with coated tinted ink. This is to compensate for the light loss
+ * due to the lower transmission rate of the window glass and helps
+ * in calculating lux.
+ */
+#define LTRF216A_WIN_FAC 1
+
+struct ltrf216a_data {
+ struct regmap *regmap;
+ struct i2c_client *client;
+ u32 int_time;
+ u16 int_time_fac;
+ u8 als_gain_fac;
+ /*
+ * Ensure cached value of integration time is consistent
+ * with hardware setting and remains constant during a
+ * measurement of Lux.
+ */
+ struct mutex lock;
+};
+
+static const struct iio_chan_spec ltrf216a_channels[] = {
+ {
+ .type = IIO_LIGHT,
+ .info_mask_separate =
+ BIT(IIO_CHAN_INFO_PROCESSED) |
+ BIT(IIO_CHAN_INFO_INT_TIME),
+ .info_mask_separate_available =
+ BIT(IIO_CHAN_INFO_INT_TIME),
+ },
+};
+
+static int ltrf216a_init(struct iio_dev *indio_dev)
+{
+ struct ltrf216a_data *data = iio_priv(indio_dev);
+ struct device *dev = &data->client->dev;
+ int ret;
+
+ /* enable sensor */
+ ret = regmap_set_bits(data->regmap, LTRF216A_MAIN_CTRL, LTRF216A_ALS_ENABLE_MASK);
+ if (ret < 0)
+ dev_err(dev, "Error writing to LTRF216A_MAIN_CTRL while enabling the sensor: %d\n",
+ ret);
+
+ return ret;
+}
+
+static void ltrf216a_reset(struct iio_dev *indio_dev)
+{
+ struct ltrf216a_data *data = iio_priv(indio_dev);
+
+ /* reset sensor, chip fails to respond to this, so ignore any errors */
+ regmap_write(data->regmap, LTRF216A_MAIN_CTRL, LTRF216A_ALS_RESET);
+
+ /* reset time */
+ usleep_range(1000, 2000);
+}
+
+static int ltrf216a_disable(struct iio_dev *indio_dev)
+{
+ struct ltrf216a_data *data = iio_priv(indio_dev);
+ struct device *dev = &data->client->dev;
+ int ret;
+
+ ret = regmap_write(data->regmap, LTRF216A_MAIN_CTRL, 0);
+ if (ret < 0)
+ dev_err(dev, "Error writing to LTRF216A_MAIN_CTRL while disabling the sensor: %d\n",
+ ret);
+
+ return ret;
+}
+
+static void als_ltrf216a_disable(void *data)
+{
+ struct iio_dev *indio_dev = data;
+
+ ltrf216a_disable(indio_dev);
+}
+
+static int ltrf216a_set_int_time(struct ltrf216a_data *data, int itime)
+{
+ struct device *dev = &data->client->dev;
+ unsigned int i;
+ u8 reg_val;
+ int ret;
+
+ for (i = 0; i < ARRAY_SIZE(ltrf216a_int_time_available); i++) {
+ if (ltrf216a_int_time_available[i][1] == itime)
+ break;
+ }
+ if (i == ARRAY_SIZE(ltrf216a_int_time_available))
+ return -EINVAL;
+
+ reg_val = ltrf216a_int_time_reg[i][1];
+
+ ret = regmap_write(data->regmap, LTRF216A_ALS_MEAS_RES, reg_val);
+ if (ret < 0) {
+ dev_err(dev, "Error writing to LTRF216A_ALS_MEAS_RES: %d\n", ret);
+ return ret;
+ }
+
+ data->int_time_fac = ltrf216a_int_time_reg[i][0];
+ data->int_time = itime;
+
+ return 0;
+}
+
+static int ltrf216a_get_int_time(struct ltrf216a_data *data, int *val, int *val2)
+{
+ *val = 0;
+ *val2 = data->int_time;
+ return IIO_VAL_INT_PLUS_MICRO;
+}
+
+static int ltrf216a_set_power_state(struct ltrf216a_data *data, bool on)
+{
+ struct device *dev = &data->client->dev;
+ int ret;
+
+ if (on) {
+ ret = pm_runtime_resume_and_get(dev);
+ if (ret < 0) {
+ dev_err(dev, "Failed to resume runtime PM: %d\n", ret);
+ return ret;
+ }
+
+ } else {
+ pm_runtime_mark_last_busy(dev);
+ ret = pm_runtime_put_autosuspend(dev);
+ }
+
+ return ret;
+}
+
+static int ltrf216a_read_data(struct ltrf216a_data *data, u8 addr)
+{
+ struct device *dev = &data->client->dev;
+ int ret, val;
+ u8 buf[3];
+
+ ret = regmap_read_poll_timeout(data->regmap, LTRF216A_MAIN_STATUS,
+ val, val & LTRF216A_ALS_DATA_STATUS,
+ LTRF216A_ALS_READ_DATA_DELAY_US,
+ LTRF216A_ALS_READ_DATA_DELAY_US * 50);
+ if (ret) {
+ dev_err(dev, "Timed out waiting for valid data from LTRF216A_MAIN_STATUS reg: %d\n",
+ ret);
+ return ret;
+ }
+
+ ret = regmap_bulk_read(data->regmap, addr, buf, sizeof(buf));
+ if (ret < 0) {
+ dev_err(dev, "Error reading measurement data: %d\n", ret);
+ return ret;
+ }
+
+ return get_unaligned_le24(&buf[0]);
+}
+
+static int ltrf216a_get_lux(struct ltrf216a_data *data)
+{
+ int ret, greendata;
+ u64 lux, div;
+
+ ret = ltrf216a_set_power_state(data, true);
+ if (ret < 0)
+ return ret;
+
+ greendata = ltrf216a_read_data(data, LTRF216A_ALS_DATA_0);
+ if (greendata < 0)
+ return greendata;
+
+ ret = ltrf216a_set_power_state(data, false);
+ if (ret < 0)
+ return ret;
+
+ lux = greendata * 45 * LTRF216A_WIN_FAC * 100;
+ div = data->als_gain_fac * data->int_time_fac * 100;
+
+ return div_u64(lux, div);
+}
+
+static int ltrf216a_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long mask)
+{
+ struct ltrf216a_data *data = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_PROCESSED:
+ mutex_lock(&data->lock);
+ ret = ltrf216a_get_lux(data);
+ mutex_unlock(&data->lock);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_INT_TIME:
+ mutex_lock(&data->lock);
+ ret = ltrf216a_get_int_time(data, val, val2);
+ mutex_unlock(&data->lock);
+ return ret;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltrf216a_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ struct ltrf216a_data *data = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_INT_TIME:
+ if (val != 0)
+ return -EINVAL;
+ mutex_lock(&data->lock);
+ ret = ltrf216a_set_int_time(data, val2);
+ mutex_unlock(&data->lock);
+ return ret;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltrf216a_read_available(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int **vals, int *type, int *length,
+ long mask)
+{
+ switch (mask) {
+ case IIO_CHAN_INFO_INT_TIME:
+ *length = ARRAY_SIZE(ltrf216a_int_time_available) * 2;
+ *vals = (const int *)ltrf216a_int_time_available;
+ *type = IIO_VAL_INT_PLUS_MICRO;
+ return IIO_AVAIL_LIST;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info ltrf216a_info = {
+ .read_raw = ltrf216a_read_raw,
+ .write_raw = ltrf216a_write_raw,
+ .read_avail = ltrf216a_read_available,
+};
+
+static const struct regmap_config ltrf216a_regmap_config = {
+ .name = LTRF216A_DRV_NAME,
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = LTRF216A_MAX_REG,
+};
+
+static int ltrf216a_probe(struct i2c_client *client)
+{
+ struct ltrf216a_data *data;
+ struct iio_dev *indio_dev;
+ int ret;
+
+ 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, &ltrf216a_regmap_config);
+ if (IS_ERR(data->regmap)) {
+ dev_err(&client->dev, "Regmap initialization failed.\n");
+ return PTR_ERR(data->regmap);
+ }
+
+ i2c_set_clientdata(client, indio_dev);
+ data->client = client;
+
+ mutex_init(&data->lock);
+
+ indio_dev->info = &ltrf216a_info;
+ indio_dev->name = LTRF216A_DRV_NAME;
+ indio_dev->channels = ltrf216a_channels;
+ indio_dev->num_channels = ARRAY_SIZE(ltrf216a_channels);
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ /* reset sensor, chip fails to respond to this, so ignore any errors */
+ ltrf216a_reset(indio_dev);
+
+ ret = devm_pm_runtime_enable(&client->dev);
+ if (ret < 0) {
+ dev_err_probe(&client->dev, ret, "Failed to enable runtime PM\n");
+ return ret;
+ }
+ pm_runtime_set_autosuspend_delay(&client->dev, 1000);
+ pm_runtime_use_autosuspend(&client->dev);
+
+ if (!IS_ENABLED(CONFIG_PM)) {
+ ret = ltrf216a_init(indio_dev);
+ if (ret) {
+ dev_err_probe(&client->dev, ret, "Failed to enable the sensor\n");
+ return ret;
+ }
+ }
+
+ data->int_time = 100000;
+ data->int_time_fac = 100;
+ data->als_gain_fac = 3;
+
+ ret = devm_add_action_or_reset(&client->dev, als_ltrf216a_disable, indio_dev);
+ if (ret < 0)
+ return ret;
+
+ return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static int ltrf216a_runtime_suspend(struct device *dev)
+{
+ struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+
+ return ltrf216a_disable(indio_dev);
+}
+
+static int ltrf216a_runtime_resume(struct device *dev)
+{
+ struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+ int ret;
+
+ ret = ltrf216a_init(indio_dev);
+
+ /* Sleep for one integration cycle after resuming the device. */
+ msleep(ltrf216a_int_time_reg[0][0]);
+
+ return ret;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(ltrf216a_pm_ops, ltrf216a_runtime_suspend,
+ ltrf216a_runtime_resume, NULL);
+
+static const struct i2c_device_id ltrf216a_id[] = {
+ { LTRF216A_DRV_NAME, 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, ltrf216a_id);
+
+static const struct of_device_id ltrf216a_of_match[] = {
+ { .compatible = "liteon,ltrf216a", },
+ { .compatible = "ltr,ltrf216a", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, ltrf216a_of_match);
+
+static struct i2c_driver ltrf216a_driver = {
+ .driver = {
+ .name = LTRF216A_DRV_NAME,
+ .pm = pm_ptr(&ltrf216a_pm_ops),
+ .of_match_table = ltrf216a_of_match,
+ },
+ .probe_new = ltrf216a_probe,
+ .id_table = ltrf216a_id,
+};
+module_i2c_driver(ltrf216a_driver);
+
+MODULE_AUTHOR("Shi Zhigang <Zhigang.Shi@xxxxxxxxxx>");
+MODULE_AUTHOR("Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("LTRF216A ambient light sensor driver");
+MODULE_LICENSE("GPL");
--
2.30.2