Add support for reading conversion results from the ADC and provide them
through a single IIO channel. A proper scaling factor is also exported
based on the reference voltage provided by a regulator.
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>
---
Changes in v2:
- use the more common IIO_VAL_FRACTIONAL_LOG2 instead of IIO_VAL_INT_PLUS_MICRO
for the ADC scale factor
- make the channel specification static const since it is the same for
all devices
- convert the scale factor such that the result of multiplying the raw
value with the scale factor yields a voltage in millivolts
drivers/iio/adc/Kconfig | 10 +++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-adc081c.c | 161 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 172 insertions(+)
create mode 100644 drivers/iio/adc/ti-adc081c.c
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index b719f3b..e8be025 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -91,6 +91,16 @@ config MAX1363
max11646, max11647) Provides direct access via sysfs and buffered
data via the iio dev interface.
+config TI_ADC081C
+ tristate "Texas Instruments ADC081C021/027"
+ depends on I2C
+ help
+ If you say yes here you get support for Texas Instruments ADC081C021
+ and ADC081C027 ADC chips.
+
+ This driver can also be built as a module. If so, the module will be
+ called ti-adc081c.
+
config TI_AM335X_ADC
tristate "TI's ADC driver"
depends on MFD_TI_AM335X_TSCADC
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 19d709c..6ad20aa 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -10,4 +10,5 @@ obj-$(CONFIG_AD7887) += ad7887.o
obj-$(CONFIG_AT91_ADC) += at91_adc.o
obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
obj-$(CONFIG_MAX1363) += max1363.o
+obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
diff --git a/drivers/iio/adc/ti-adc081c.c b/drivers/iio/adc/ti-adc081c.c
new file mode 100644
index 0000000..f4a46dd
--- /dev/null
+++ b/drivers/iio/adc/ti-adc081c.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2012 Avionic Design GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/regulator/consumer.h>
+
+struct adc081c {
+ struct i2c_client *i2c;
+ struct regulator *ref;
+};
+
+#define REG_CONV_RES 0x00
+
+static int adc081c_read_raw(struct iio_dev *iio,
+ struct iio_chan_spec const *channel, int *value,
+ int *shift, long mask)
+{
+ struct adc081c *adc = iio_priv(iio);
+ int err;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ err = i2c_smbus_read_word_swapped(adc->i2c, REG_CONV_RES);
+ if (err < 0)
+ return err;
+
+ *value = (err >> 4) & 0xff;
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ err = regulator_get_voltage(adc->ref);
+ if (err < 0)
+ return err;
+
+ *value = err / 1000;
+ *shift = 8;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+
+ default:
+ break;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_chan_spec adc081c_channel = {
+ .type = IIO_VOLTAGE,
+ .info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT |
+ IIO_CHAN_INFO_RAW_SEPARATE_BIT,
+};
+
+static const struct iio_info adc081c_info = {
+ .read_raw = adc081c_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int adc081c_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct iio_dev *iio;
+ struct adc081c *adc;
+ int err;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
+ return -ENODEV;
+
+ iio = iio_device_alloc(sizeof(*adc));
+ if (!iio)
+ return -ENOMEM;
+
+ adc = iio_priv(iio);
+ adc->i2c = client;
+
+ adc->ref = regulator_get(&client->dev, "vref");
+ if (IS_ERR(adc->ref)) {
+ err = PTR_ERR(adc->ref);
+ goto iio_free;
+ }
+
+ err = regulator_enable(adc->ref);
+ if (err < 0)
+ goto regulator_put;
+
+ iio->dev.parent = &client->dev;
+ iio->name = dev_name(&client->dev);
+ iio->modes = INDIO_DIRECT_MODE;
+ iio->info = &adc081c_info;
+
+ iio->channels = &adc081c_channel;
+ iio->num_channels = 1;
+
+ err = iio_device_register(iio);
+ if (err < 0)
+ goto regulator_disable;
+
+ i2c_set_clientdata(client, iio);
+
+ return 0;
+
+regulator_disable:
+ regulator_disable(adc->ref);
+regulator_put:
+ regulator_put(adc->ref);
+iio_free:
+ iio_device_free(iio);
+
+ return err;
+}
+
+static int adc081c_remove(struct i2c_client *client)
+{
+ struct iio_dev *iio = i2c_get_clientdata(client);
+ struct adc081c *adc = iio_priv(iio);
+
+ iio_device_unregister(iio);
+ regulator_disable(adc->ref);
+ regulator_put(adc->ref);
+ iio_device_free(iio);
+
+ return 0;
+}
+
+static const struct i2c_device_id adc081c_id[] = {
+ { "adc081c", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, adc081c_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id adc081c_of_match[] = {
+ { .compatible = "ti,adc081c" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, adc081c_of_match);
+#endif
+
+static struct i2c_driver adc081c_driver = {
+ .driver = {
+ .name = "adc081c",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(adc081c_of_match),
+ },
+ .probe = adc081c_probe,
+ .remove = adc081c_remove,
+ .id_table = adc081c_id,
+};
+module_i2c_driver(adc081c_driver);
+
+MODULE_AUTHOR("Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Texas Instruments ADC081C021/027 driver");
+MODULE_LICENSE("GPL v2");
--
1.8.0
--
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