[PATCH] iio: max5487: Add support for Maxim digital potentiometers
From: Cristina Moraru
Date: Thu Mar 24 2016 - 07:23:06 EST
Add implementation for Maxim MAX5487, MAX5488, MAX5489
digital potentiometers.
Signed-off-by: Cristina Moraru <cristina.moraru09@xxxxxxxxx>
CC: Daniel Baluta <daniel.baluta@xxxxxxxxx>
---
drivers/iio/potentiometer/Kconfig | 11 +++
drivers/iio/potentiometer/Makefile | 1 +
drivers/iio/potentiometer/max5487.c | 185 ++++++++++++++++++++++++++++++++++++
3 files changed, 197 insertions(+)
create mode 100644 drivers/iio/potentiometer/max5487.c
diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index ffc735c..3046c79 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -5,6 +5,17 @@
menu "Digital potentiometers"
+config MAX5487
+ tristate "Maxim MAX5487/MAX5488/MAX5489 Digital Potentiometer driver"
+ depends on SPI
+ help
+ Say yes here to build support for the Maxim
+ MAX5487, MAX5488, MAX5489 digital potentiomenter
+ chips.
+
+ To compile this driver as a module, choose M here: the
+ module will be called max5487.
+
config MCP4531
tristate "Microchip MCP45xx/MCP46xx Digital Potentiometer driver"
depends on I2C
diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
index b563b49..dcc791a 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -3,5 +3,6 @@
#
# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_MAX5487) += max5487.o
obj-$(CONFIG_MCP4531) += mcp4531.o
obj-$(CONFIG_TPL0102) += tpl0102.o
diff --git a/drivers/iio/potentiometer/max5487.c b/drivers/iio/potentiometer/max5487.c
new file mode 100644
index 0000000..69db979
--- /dev/null
+++ b/drivers/iio/potentiometer/max5487.c
@@ -0,0 +1,185 @@
+/*
+ * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
+ *
+ * Copyright (C) Cristina-Gabriela Moraru <cristina.moraru09@xxxxxxxxx>
+ *
+ * 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/module.h>
+#include <linux/spi/spi.h>
+#include <linux/acpi.h>
+#include <linux/regmap.h>
+
+#include <linux/iio/sysfs.h>
+#include <linux/iio/iio.h>
+
+#define MAX5487_DRV_NAME "max5487"
+
+#define MAX5487_WRITE_WIPER_A 0x01
+#define MAX5487_WRITE_WIPER_B 0x02
+
+/* copy both wiper regs to NV regs */
+#define MAX5487_COPY_AB_TO_NV 0x23
+/* copy both NV regs to wiper regs */
+#define MAX5487_COPY_NV_TO_AB 0x33
+
+enum {
+ MAX5487,
+ MAX5488,
+ MAX5489,
+};
+
+struct max5487_cfg {
+ int wipers;
+ int max_pos;
+ int kohms;
+};
+
+static const struct max5487_cfg max5487_cfg[] = {
+ [MAX5487] = { .wipers = 2, .max_pos = 256, .kohms = 10,},
+ [MAX5488] = { .wipers = 2, .max_pos = 256, .kohms = 50,},
+ [MAX5489] = { .wipers = 2, .max_pos = 256, .kohms = 100,}
+};
+
+struct max5487_data {
+ struct regmap *regmap;
+ int chip_id;
+};
+
+#define MAX5487_CHANNEL(ch, addr) { \
+ .type = IIO_RESISTANCE, \
+ .indexed = 1, \
+ .output = 1, \
+ .channel = ch, \
+ .address = addr, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+}
+
+static const struct iio_chan_spec max5487_channels[] = {
+ MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
+ MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
+};
+
+static int max5487_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct max5487_data *data = iio_priv(indio_dev);
+
+ if (mask != IIO_CHAN_INFO_SCALE)
+ return -EINVAL;
+
+ *val = 1000 * max5487_cfg[data->chip_id].kohms;
+ *val2 = max5487_cfg[data->chip_id].max_pos;
+ return IIO_VAL_FRACTIONAL;
+}
+
+static int max5487_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct max5487_data *data = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val < 0 || val >= max5487_cfg[data->chip_id].max_pos)
+ return -EINVAL;
+ return regmap_write(data->regmap, chan->address, val);
+ default:
+ return -EINVAL;
+ }
+ return -EINVAL;
+}
+
+static const struct iio_info max5487_info = {
+ .read_raw = &max5487_read_raw,
+ .write_raw = &max5487_write_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static const struct regmap_config max5487_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+
+ .max_register = MAX5487_COPY_NV_TO_AB,
+};
+
+static int max5487_spi_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct max5487_data *data;
+ const struct spi_device_id *id = spi_get_device_id(spi);
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ dev_set_drvdata(&spi->dev, indio_dev);
+ data = iio_priv(indio_dev);
+
+ data->regmap = devm_regmap_init_spi(spi, &max5487_regmap_config);
+ if (IS_ERR(data->regmap))
+ return PTR_ERR(data->regmap);
+
+ data->chip_id = id->driver_data;
+
+ indio_dev->info = &max5487_info;
+ indio_dev->name = id->name;
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = max5487_channels;
+ indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
+
+ /* restore both wiper regs from NV regs */
+ ret = regmap_write(data->regmap, MAX5487_COPY_NV_TO_AB, 0);
+ if (ret < 0)
+ return ret;
+
+ return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static int max5487_spi_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
+ struct max5487_data *data = iio_priv(indio_dev);
+
+ /* save both wiper regs to NV regs */
+ return regmap_write(data->regmap, MAX5487_COPY_AB_TO_NV, 0);
+}
+
+static const struct spi_device_id max5487_id[] = {
+ { "MAX5487", MAX5487 },
+ { "MAX5488", MAX5488 },
+ { "MAX5489", MAX5489 },
+ { }
+};
+MODULE_DEVICE_TABLE(spi, max5487_id);
+
+static const struct acpi_device_id max5487_acpi_match[] = {
+ { "MAX5487", MAX5487 },
+ { "MAX5488", MAX5488 },
+ { "MAX5489", MAX5489 },
+ { },
+};
+MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
+
+static struct spi_driver max5487_driver = {
+ .driver = {
+ .name = MAX5487_DRV_NAME,
+ .owner = THIS_MODULE,
+ .acpi_match_table = ACPI_PTR(max5487_acpi_match),
+ },
+ .id_table = max5487_id,
+ .probe = max5487_spi_probe,
+ .remove = max5487_spi_remove
+};
+module_spi_driver(max5487_driver);
+
+MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@xxxxxxxxx>");
+MODULE_DESCRIPTION("max5487 SPI driver");
+MODULE_LICENSE("GPL v2");
--
2.5.0