[PATCH v4 2/2] iio: mcp4531: Driver for Microchip digital potentiometers

From: Peter Rosin
Date: Tue Sep 22 2015 - 11:38:52 EST

From: Peter Rosin <peda@xxxxxxxxxx>

Add support for Microchip digital potentiometers and rheostats
MCP4531, MCP4532, MCP4551, MCP4552
MCP4631, MCP4632, MCP4651, MCP4652

These are either single (45xx) or dual (46xx) wipers with either
129 (4x3x) or 257 (4x5x) steps, and configured either as
potentiometers (4xx1) or rheostats (4xx2). They all use i2c
client addresses of the 0101xxx form.

Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22096b.pdf

Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>
---
MAINTAINERS | 6 ++
drivers/iio/Kconfig | 1 +
drivers/iio/Makefile | 1 +
drivers/iio/potentiometer/Kconfig | 20 ++++
drivers/iio/potentiometer/Makefile | 6 ++
drivers/iio/potentiometer/mcp4531.c | 196 +++++++++++++++++++++++++++++++++++
6 files changed, 230 insertions(+)
create mode 100644 drivers/iio/potentiometer/Kconfig
create mode 100644 drivers/iio/potentiometer/Makefile
create mode 100644 drivers/iio/potentiometer/mcp4531.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b60e2b2369d2..27862156c7a7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6600,6 +6600,12 @@ W: http://linuxtv.org
S: Maintained
F: drivers/media/radio/radio-maxiradio*

+MCP4531 MICROCHIP DIGITAL POTENTIOMETER DRIVER
+M: Peter Rosin <peda@xxxxxxxxxx>
+L: linux-iio@xxxxxxxxxxxxxxx
+S: Maintained
+F: drivers/iio/potentiometer/mcp4531.c
+
MEDIA DRIVERS FOR RENESAS - VSP1
M: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
L: linux-media@xxxxxxxxxxxxxxx
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 4011effe4c05..7cc87f322655 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -73,6 +73,7 @@ source "drivers/iio/orientation/Kconfig"
if IIO_TRIGGER
source "drivers/iio/trigger/Kconfig"
endif #IIO_TRIGGER
+source "drivers/iio/potentiometer/Kconfig"
source "drivers/iio/pressure/Kconfig"
source "drivers/iio/proximity/Kconfig"
source "drivers/iio/temperature/Kconfig"
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 698afc2d17ce..121c814e366b 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -23,6 +23,7 @@ obj-y += imu/
obj-y += light/
obj-y += magnetometer/
obj-y += orientation/
+obj-y += potentiometer/
obj-y += pressure/
obj-y += proximity/
obj-y += temperature/
diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
new file mode 100644
index 000000000000..fd75db73e582
--- /dev/null
+++ b/drivers/iio/potentiometer/Kconfig
@@ -0,0 +1,20 @@
+#
+# Potentiometer drivers
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Digital potentiometers"
+
+config MCP4531
+ tristate "Microchip MCP45xx/MCP46xx Digital Potentiometer driver"
+ depends on I2C
+ help
+ Say yes here to build support for the Microchip
+ MCP4531, MCP4532, MCP4551, MCP4552,
+ MCP4631, MCP4632, MCP4651, MCP4652
+ digital potentiomenter chips.
+
+ To compile this driver as a module, choose M here: the
+ module will be called mcp4531.
+
+endmenu
diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
new file mode 100644
index 000000000000..8afe49227012
--- /dev/null
+++ b/drivers/iio/potentiometer/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for industrial I/O potentiometer drivers
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_MCP4531) += mcp4531.o
diff --git a/drivers/iio/potentiometer/mcp4531.c b/drivers/iio/potentiometer/mcp4531.c
new file mode 100644
index 000000000000..04faf56dabe0
--- /dev/null
+++ b/drivers/iio/potentiometer/mcp4531.c
@@ -0,0 +1,196 @@
+/*
+ * Industrial I/O driver for Microchip digital potentiometers
+ * Copyright (c) 2015 Axentia Technologies AB
+ * Author: Peter Rosin <peda@xxxxxxxxxx>
+ *
+ * Datasheet: http://www.microchip.com/downloads/en/DeviceDoc/22096b.pdf
+ *
+ * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address
+ * mcp4531 1 129 5, 10, 50, 100 010111x
+ * mcp4532 1 129 5, 10, 50, 100 01011xx
+ * mcp4551 1 257 5, 10, 50, 100 010111x
+ * mcp4552 1 257 5, 10, 50, 100 01011xx
+ * mcp4631 2 129 5, 10, 50, 100 0101xxx
+ * mcp4632 2 129 5, 10, 50, 100 01011xx
+ * mcp4651 2 257 5, 10, 50, 100 0101xxx
+ * mcp4652 2 257 5, 10, 50, 100 01011xx
+ *
+ * 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/i2c.h>
+#include <linux/err.h>
+
+#include <linux/iio/iio.h>
+
+#define MCP4531_CONF(wipers, max_pos, uid) \
+ ((((wipers) & 0xf) << 10) | \
+ (((max_pos) & 0xf) << 6) | \
+ ((uid) & 0x3f))
+
+#define MCP4531_UID(conf) ((conf) & 0x3f)
+#define MCP4531_MAX_POS(conf) (((conf) >> 6) & 0xf)
+#define MCP4531_WIPERS(conf) (((conf) >> 10) & 0xf)
+
+#define MCP4531_WRITE (0 << 2)
+#define MCP4531_INCR (1 << 2)
+#define MCP4531_DECR (2 << 2)
+#define MCP4531_READ (3 << 2)
+
+#define MCP4531_WIPER_SHIFT (4)
+
+enum mcp4531_devid {
+ MCP4531_ID = MCP4531_CONF(1, 7, 0),
+ MCP4532_ID = MCP4531_CONF(1, 7, 1),
+ MCP4551_ID = MCP4531_CONF(1, 8, 2),
+ MCP4552_ID = MCP4531_CONF(1, 8, 3),
+ MCP4631_ID = MCP4531_CONF(2, 7, 4),
+ MCP4632_ID = MCP4531_CONF(2, 7, 5),
+ MCP4651_ID = MCP4531_CONF(2, 8, 6),
+ MCP4652_ID = MCP4531_CONF(2, 8, 7),
+};
+
+struct mcp4531_data {
+ struct i2c_client *client;
+ unsigned int max_pos;
+ unsigned long devid;
+};
+
+#define MCP4531_CHANNEL(ch) { \
+ .type = IIO_RESISTANCE, \
+ .indexed = 1, \
+ .output = 1, \
+ .channel = (ch), \
+ .address = (ch) << MCP4531_WIPER_SHIFT, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+}
+
+static const struct iio_chan_spec mcp4531_channels[] = {
+ MCP4531_CHANNEL(0),
+ MCP4531_CHANNEL(1),
+};
+
+static int mcp4531_get_value(struct iio_dev *indio_dev,
+ int address, int *val)
+{
+ struct mcp4531_data *data = iio_priv(indio_dev);
+ s32 ret;
+
+ ret = i2c_smbus_read_word_swapped(data->client,
+ MCP4531_READ | address);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ return 0;
+}
+
+static int mcp4531_set_value(struct iio_dev *indio_dev,
+ int address, int val)
+{
+ struct mcp4531_data *data = iio_priv(indio_dev);
+
+ if (val >= data->max_pos || val < 0)
+ return -EINVAL;
+
+ return i2c_smbus_write_byte_data(data->client,
+ MCP4531_WRITE | address | (val >> 8),
+ val & 0xff);
+}
+
+static int mcp4531_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ int err;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ err = mcp4531_get_value(indio_dev, chan->address, val);
+ if (err < 0)
+ return err;
+ return IIO_VAL_INT;
+ }
+
+ return -EINVAL;
+}
+
+static int mcp4531_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ return mcp4531_set_value(indio_dev, chan->address, val);
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info mcp4531_info = {
+ .read_raw = mcp4531_read_raw,
+ .write_raw = mcp4531_write_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int mcp4531_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ unsigned long devid = id->driver_data;
+ struct mcp4531_data *data;
+ struct iio_dev *indio_dev;
+
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_WORD_DATA)) {
+ dev_err(dev, "SMBUS Word Data not supported\n");
+ return -EIO;
+ }
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+ data = iio_priv(indio_dev);
+ i2c_set_clientdata(client, indio_dev);
+ data->client = client;
+ data->devid = devid;
+
+ data->max_pos = (1 << MCP4531_MAX_POS(devid)) + 1;
+
+ indio_dev->dev.parent = dev;
+ indio_dev->info = &mcp4531_info;
+ indio_dev->channels = mcp4531_channels;
+ indio_dev->num_channels = MCP4531_WIPERS(devid);
+ indio_dev->name = client->name;
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct i2c_device_id mcp4531_id[] = {
+ { "mcp4531", MCP4531_ID },
+ { "mcp4532", MCP4532_ID },
+ { "mcp4551", MCP4551_ID },
+ { "mcp4552", MCP4552_ID },
+ { "mcp4631", MCP4631_ID },
+ { "mcp4632", MCP4632_ID },
+ { "mcp4651", MCP4651_ID },
+ { "mcp4652", MCP4652_ID },
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, mcp4531_id);
+
+static struct i2c_driver mcp4531_driver = {
+ .driver = {
+ .name = "mcp4531",
+ },
+ .probe = mcp4531_probe,
+ .id_table = mcp4531_id,
+};
+
+module_i2c_driver(mcp4531_driver);
+
+MODULE_AUTHOR("Peter Rosin <peda@xxxxxxxxxx>");
+MODULE_DESCRIPTION("MCP4531 digital potentiometer");
+MODULE_LICENSE("GPL");
--
1.7.10.4

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