iio: max5487: Add support for Maxim digital potentiometers

Add implementation for Maxim MAX5487, MAX5488, MAX5489
digital potentiometers.

Datasheet:
http://datasheets.maximintegrated.com/en/ds/MAX5487-MAX5489.pdf

Signed-off-by: Cristina Moraru <cristina.moraru09@gmail.com>
CC: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index 6acb23810bb46e4ba645bddf06e3f600d0f87685..0941c8d490a0a19efe909497802bf82fad03f029 100644 (file)
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -15,6 +15,17 @@ config DS1803
          To compile this driver as a module, choose M here: the
          module will be called ds1803.
 
+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 potentiometer
+          chips.
+
+          To compile this driver as a module, choose M here: the
+          module will be called max5487.
+
 config MCP4131
        tristate "Microchip MCP413X/414X/415X/416X/423X/424X/425X/426X Digital Potentiometer driver"
        depends on SPI

diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
index 6007faa2fb0279dc2a338aa985acf6b3a09abb25..8adb58f38c0b8498f5e5638943f1cb8de3685334 100644 (file)
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -4,6 +4,7 @@
 
 # When adding new entries keep the list in alphabetical order
 obj-$(CONFIG_DS1803) += ds1803.o
+obj-$(CONFIG_MAX5487) += max5487.o
 obj-$(CONFIG_MCP4131) += mcp4131.o
 obj-$(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 (file)
index 0000000..6c50939
--- /dev/null
+++ b/drivers/iio/potentiometer/max5487.c
@@ -0,0 +1,161 @@
+/*
+ * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
+ *
+ * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
+ *
+ * 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/iio/sysfs.h>
+#include <linux/iio/iio.h>
+
+#define MAX5487_WRITE_WIPER_A  (0x01 << 8)
+#define MAX5487_WRITE_WIPER_B  (0x02 << 8)
+
+/* copy both wiper regs to NV regs */
+#define MAX5487_COPY_AB_TO_NV  (0x23 << 8)
+/* copy both NV regs to wiper regs */
+#define MAX5487_COPY_NV_TO_AB  (0x33 << 8)
+
+#define MAX5487_MAX_POS                255
+
+struct max5487_data {
+       struct spi_device *spi;
+       int kohms;
+};
+
+#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_write_cmd(struct spi_device *spi, u16 cmd)
+{
+       return spi_write(spi, (const void *) &cmd, sizeof(u16));
+}
+
+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 * data->kohms;
+       *val2 = MAX5487_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);
+
+       if (mask != IIO_CHAN_INFO_RAW)
+               return -EINVAL;
+
+       if (val < 0 || val > MAX5487_MAX_POS)
+               return -EINVAL;
+
+       return max5487_write_cmd(data->spi, chan->address | val);
+}
+
+static const struct iio_info max5487_info = {
+       .read_raw = max5487_read_raw,
+       .write_raw = max5487_write_raw,
+       .driver_module = THIS_MODULE,
+};
+
+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->spi = spi;
+       data->kohms = 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 = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
+       if (ret < 0)
+               return ret;
+
+       return iio_device_register(indio_dev);
+}
+
+static int max5487_spi_remove(struct spi_device *spi)
+{
+       struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
+
+       iio_device_unregister(indio_dev);
+
+       /* save both wiper regs to NV regs */
+       return max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
+}
+
+static const struct spi_device_id max5487_id[] = {
+       { "MAX5487", 10 },
+       { "MAX5488", 50 },
+       { "MAX5489", 100 },
+       { }
+};
+MODULE_DEVICE_TABLE(spi, max5487_id);
+
+static const struct acpi_device_id max5487_acpi_match[] = {
+       { "MAX5487", 10 },
+       { "MAX5488", 50 },
+       { "MAX5489", 100 },
+       { },
+};
+MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
+
+static struct spi_driver max5487_driver = {
+       .driver = {
+               .name = "max5487",
+               .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@gmail.com>");
+MODULE_DESCRIPTION("max5487 SPI driver");
+MODULE_LICENSE("GPL v2");