[PATCH] misc: mcp4xxx_dpot: Driver for Microchip digital potentiometers
From: peda
Date: Mon Aug 31 2015 - 16:18:24 EST
From: Peter Rosin <peda@xxxxxxxxxx>
Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>
---
Documentation/misc-devices/mcp4xxx_dpot.txt | 47 +++++
MAINTAINERS | 5 +
drivers/misc/Kconfig | 15 ++
drivers/misc/Makefile | 1 +
drivers/misc/mcp4xxx_dpot.c | 269 +++++++++++++++++++++++++++
drivers/misc/mcp4xxx_dpot.h | 44 +++++
6 files changed, 381 insertions(+)
create mode 100644 Documentation/misc-devices/mcp4xxx_dpot.txt
create mode 100644 drivers/misc/mcp4xxx_dpot.c
create mode 100644 drivers/misc/mcp4xxx_dpot.h
This patch has two checkpatch errors but I really don't know how to fix them.
The offending code was copied from drivers/misc/ad525x_dpot.c and the errors
are:
ERROR: Macros with complex values should be enclosed in parentheses
#266: FILE: drivers/misc/mcp4xxx_dpot.c:129:
+#define MCP4XXX_DPOT_DEVICE_SHOW_SET(name, reg) \
+MCP4XXX_DPOT_DEVICE_SHOW(name, reg) \
+MCP4XXX_DPOT_DEVICE_SET(name, reg) \
+static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, show_##name, set_##name)
ERROR: Macros with complex values should be enclosed in parentheses
#271: FILE: drivers/misc/mcp4xxx_dpot.c:134:
+#define MCP4XXX_DPOT_DEVICE_SHOW_ONLY(name, reg) \
+MCP4XXX_DPOT_DEVICE_SHOW(name, reg) \
+static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, show_##name, NULL)
I have tried to add various parentheses, but no luck.
I am also unsure if I have modelled this on deprecated stuff. Is
there a better place to add a digital potentiometer driver?
Industrial IO perhaps? In any case, this is a sufficient implementation
for my needs, and a more complex user-space api is only going to be a
burden.
Cheers,
Peter
diff --git a/Documentation/misc-devices/mcp4xxx_dpot.txt b/Documentation/misc-devices/mcp4xxx_dpot.txt
new file mode 100644
index 000000000000..10ed02958775
--- /dev/null
+++ b/Documentation/misc-devices/mcp4xxx_dpot.txt
@@ -0,0 +1,47 @@
+---------------------------------
+ MCP4XXX Digital Potentiometers
+---------------------------------
+
+The mcp4xxx_dpot driver exports a simple sysfs interface. This allows you to
+work with the immediate resistance settings.
+
+---------
+ Files
+---------
+
+Each dpot device will have its own rdac files. How many depends on the actual
+part you have, as will the range of allowed values.
+
+This rdac file is used to program the immediate value of the device.
+
+-----------
+ Example
+-----------
+
+Locate the device in your sysfs tree. This is probably easiest by going into
+the common i2c directory and locating the device by the i2c slave address.
+
+ # ls /sys/bus/i2c/devices/
+ 0-0028 0-0050
+
+So assuming the device in question is on the first i2c bus and has the slave
+address of 0x28, we descend (unrelated sysfs entries have been trimmed).
+
+ # ls /sys/bus/i2c/devices/0-0028/
+ rdac0 rdac1
+
+You can use simple reads/writes to access these files:
+
+ # cd /sys/bus/i2c/devices/0-0028/
+
+ # cat rdac0
+ 0
+ # echo 128 > rdac0
+ # cat rdac0
+ 128
+
+ # cat rdac1
+ 5
+ # echo 35 > rdac1
+ # cat rdac1
+ 35
diff --git a/MAINTAINERS b/MAINTAINERS
index b60e2b2369d2..c7bc2cc8051d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6600,6 +6600,11 @@ W: http://linuxtv.org
S: Maintained
F: drivers/media/radio/radio-maxiradio*
+MPC4XXX MICROCHIP DIGITAL POTENTIOMETERS DRIVER
+M: Peter Rosin <peda@xxxxxxxxxx>
+S: Maintained
+F: drivers/misc/mcp4xxx_dpot.*
+
MEDIA DRIVERS FOR RENESAS - VSP1
M: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
L: linux-media@xxxxxxxxxxxxxxx
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 42c38525904b..a4e5e42b6b92 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -51,6 +51,21 @@ config AD525X_DPOT_SPI
To compile this driver as a module, choose M here: the
module will be called ad525x_dpot-spi.
+config MCP4XXX_DPOT
+ tristate "Microchip Digital Potentiometer"
+ depends on I2C && SYSFS
+ help
+ If you say yes here, you get support for the Microchip
+ MCP4531, MCP4532, MCP4551, MCP4552,
+ MCP4631, MCP4632, MCP4651, MCP4652,
+ digital potentiometer chips.
+
+ See Documentation/misc-devices/mcp4xxx_dpot.txt for the
+ userspace interface.
+
+ This driver can also be built as a module. If so, the module
+ will be called mcp4xxx_dpot.
+
config ATMEL_TCLIB
bool "Atmel AT32/AT91 Timer/Counter Library"
depends on (AVR32 || ARCH_AT91)
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index d056fb7186fe..bb8c2994fd98 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_BMP085_SPI) += bmp085-spi.o
obj-$(CONFIG_DUMMY_IRQ) += dummy-irq.o
obj-$(CONFIG_ICS932S401) += ics932s401.o
obj-$(CONFIG_LKDTM) += lkdtm.o
+obj-$(CONFIG_MCP4XXX_DPOT) += mcp4xxx_dpot.o
obj-$(CONFIG_TIFM_CORE) += tifm_core.o
obj-$(CONFIG_TIFM_7XX1) += tifm_7xx1.o
obj-$(CONFIG_PHANTOM) += phantom.o
diff --git a/drivers/misc/mcp4xxx_dpot.c b/drivers/misc/mcp4xxx_dpot.c
new file mode 100644
index 000000000000..abacae99ae42
--- /dev/null
+++ b/drivers/misc/mcp4xxx_dpot.c
@@ -0,0 +1,269 @@
+/*
+ * mcp4xxx_dpot: Driver for Microchip digital potentiometers
+ * Copyright (c) 2015 Axentia Technologies AB
+ * Author: Peter Rosin <peda@xxxxxxxxxx>
+ *
+ * DEVID #Wipers #Positions Resistor Options (kOhm)
+ * mcp4531 1 129 5, 10, 50, 100
+ * mcp4532 1 129 5, 10, 50, 100
+ * mcp4551 1 257 5, 10, 50, 100
+ * mcp4552 1 257 5, 10, 50, 100
+ * mcp4631 2 129 5, 10, 50, 100
+ * mcp4632 2 129 5, 10, 50, 100
+ * mcp4651 2 257 5, 10, 50, 100
+ * mcp4652 2 257 5, 10, 50, 100
+ *
+ * See Documentation/misc-devices/mcp4xxx_dpot.txt for more info.
+ *
+ * derived from ad525x.c
+ * Copyright (c) 2009-2010 Analog Devices, Inc.
+ * Author: Michael Hennerich <hennerich@xxxxxxxxxxxxxxxxxxxx>
+ *
+ * derived from ad5258.c
+ * Copyright (c) 2009 Cyber Switching, Inc.
+ * Author: Chris Verges <chrisv@xxxxxxxxxxxxxxxxxx>
+ *
+ * derived from ad5252.c
+ * Copyright (c) 2006-2011 Michael Hennerich <hennerich@xxxxxxxxxxxxxxxxxxxx>
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "mcp4xxx_dpot.h"
+
+/*
+ * Client data (each client gets its own)
+ */
+
+struct mcp4xxx_dpot_data {
+ struct i2c_client *client;
+ struct mutex update_lock;
+ unsigned max_pos;
+ unsigned long devid;
+ unsigned uid;
+ unsigned wipers;
+};
+
+static s32 mcp4xxx_dpot_read(struct mcp4xxx_dpot_data *dpot, u8 reg)
+{
+ s32 value;
+
+ value = i2c_smbus_read_word_data(dpot->client, (reg << 4) | 0xc);
+ if (value < 0)
+ return value;
+ return ((value >> 8) & 0xff) | ((value & 0xff) << 8);
+}
+
+static s32 mcp4xxx_dpot_write(struct mcp4xxx_dpot_data *dpot,
+ u8 reg, u16 value)
+{
+ return i2c_smbus_write_byte_data(dpot->client,
+ (reg << 4) | value >> 8,
+ value & 0xff);
+}
+
+/* sysfs functions */
+
+static ssize_t mcp4xxx_sysfs_show_reg(struct device *dev,
+ struct device_attribute *attr,
+ char *buf, u32 reg)
+{
+ struct mcp4xxx_dpot_data *data = dev_get_drvdata(dev);
+ s32 value;
+
+ mutex_lock(&data->update_lock);
+ value = mcp4xxx_dpot_read(data, reg);
+ mutex_unlock(&data->update_lock);
+
+ if (value < 0)
+ return -EINVAL;
+
+ return sprintf(buf, "%u\n", value);
+}
+
+static ssize_t mcp4xxx_sysfs_set_reg(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count, u32 reg)
+{
+ struct mcp4xxx_dpot_data *data = dev_get_drvdata(dev);
+ unsigned long value;
+ int err;
+
+ err = kstrtoul(buf, 10, &value);
+ if (err)
+ return err;
+
+ if (value >= data->max_pos)
+ value = data->max_pos - 1;
+
+ mutex_lock(&data->update_lock);
+ mcp4xxx_dpot_write(data, reg, value);
+ mutex_unlock(&data->update_lock);
+
+ return count;
+}
+
+/* ------------------------------------------------------------------------- */
+
+#define MCP4XXX_DPOT_DEVICE_SHOW(_name, _reg) \
+static ssize_t show_##_name(struct device *dev, \
+ struct device_attribute *attr, char *buf) \
+{ \
+ return mcp4xxx_sysfs_show_reg(dev, attr, buf, _reg); \
+}
+
+#define MCP4XXX_DPOT_DEVICE_SET(_name, _reg) \
+static ssize_t set_##_name(struct device *dev, \
+ struct device_attribute *attr, \
+ const char *buf, size_t count) \
+{ \
+ return mcp4xxx_sysfs_set_reg(dev, attr, buf, count, _reg); \
+}
+
+#define MCP4XXX_DPOT_DEVICE_SHOW_SET(name, reg) \
+MCP4XXX_DPOT_DEVICE_SHOW(name, reg) \
+MCP4XXX_DPOT_DEVICE_SET(name, reg) \
+static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, show_##name, set_##name)
+
+#define MCP4XXX_DPOT_DEVICE_SHOW_ONLY(name, reg) \
+MCP4XXX_DPOT_DEVICE_SHOW(name, reg) \
+static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, show_##name, NULL)
+
+MCP4XXX_DPOT_DEVICE_SHOW_SET(rdac0, DPOT_ADDR_RDAC | DPOT_RDAC0);
+MCP4XXX_DPOT_DEVICE_SHOW_SET(rdac1, DPOT_ADDR_RDAC | DPOT_RDAC1);
+
+static const struct attribute *mcp4xxx_dpot_attrib_wipers[] = {
+ &dev_attr_rdac0.attr,
+ &dev_attr_rdac1.attr,
+ NULL
+};
+
+/* ------------------------------------------------------------------------- */
+
+static int mcp4xxx_dpot_add_files(struct device *dev, unsigned rdac)
+{
+ int err = sysfs_create_file(&dev->kobj,
+ mcp4xxx_dpot_attrib_wipers[rdac]);
+
+ if (err)
+ dev_err(dev, "failed to register sysfs hooks for RDAC%d\n",
+ rdac);
+
+ return err;
+}
+
+static inline void mcp4xxx_dpot_remove_files(struct device *dev, unsigned rdac)
+{
+ sysfs_remove_file(&dev->kobj,
+ mcp4xxx_dpot_attrib_wipers[rdac]);
+}
+
+static int mcp4xxx_dpot_i2c_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ unsigned long devid = id->driver_data;
+ const char *name = id->name;
+ struct mcp4xxx_dpot_data *data;
+ int i, err = 0;
+
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_WORD_DATA)) {
+ dev_err(&client->dev, "SMBUS Word Data not Supported\n");
+ return -EIO;
+ }
+
+ data = kzalloc(sizeof(struct mcp4xxx_dpot_data), GFP_KERNEL);
+ if (!data) {
+ err = -ENOMEM;
+ goto exit;
+ }
+
+ dev_set_drvdata(dev, data);
+ mutex_init(&data->update_lock);
+
+ data->client = client;
+ data->devid = devid;
+
+ data->max_pos = (1 << DPOT_MAX_POS(devid)) + 1;
+ data->uid = DPOT_UID(devid);
+ data->wipers = DPOT_WIPERS(devid);
+
+ for (i = DPOT_RDAC0; i < MAX_RDACS; i++) {
+ if (!(data->wipers & (1 << i)))
+ continue;
+ if (mcp4xxx_dpot_add_files(dev, i))
+ goto exit_remove_files;
+ }
+
+ dev_info(dev, "%s %d-Position Digital Potentiometer registered\n",
+ name, data->max_pos);
+
+ return 0;
+
+exit_remove_files:
+ for (i = DPOT_RDAC0; i < MAX_RDACS; i++) {
+ if (!(data->wipers & (1 << i)))
+ continue;
+ mcp4xxx_dpot_remove_files(dev, i);
+ }
+
+ kfree(data);
+ dev_set_drvdata(dev, NULL);
+exit:
+ dev_err(dev, "failed to create client for %s ID 0x%lX\n",
+ name, devid);
+ return err;
+}
+
+static int mcp4xxx_dpot_i2c_remove(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct mcp4xxx_dpot_data *data = dev_get_drvdata(dev);
+ int i;
+
+ for (i = DPOT_RDAC0; i < MAX_RDACS; i++) {
+ if (!(data->wipers & (1 << i)))
+ continue;
+ mcp4xxx_dpot_remove_files(dev, i);
+ }
+
+ kfree(data);
+
+ return 0;
+}
+
+static const struct i2c_device_id mcp4xxx_dpot_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, mcp4xxx_dpot_id);
+
+static struct i2c_driver mcp4xxx_dpot_i2c_driver = {
+ .driver = {
+ .name = "mcp4xxx_dpot",
+ .owner = THIS_MODULE,
+ },
+ .probe = mcp4xxx_dpot_i2c_probe,
+ .remove = mcp4xxx_dpot_i2c_remove,
+ .id_table = mcp4xxx_dpot_id,
+};
+
+module_i2c_driver(mcp4xxx_dpot_i2c_driver);
+
+MODULE_AUTHOR("Peter Rosin <peda@xxxxxxxxxx>");
+MODULE_DESCRIPTION("MCP4XXX digital potentiometer I2C bus driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/misc/mcp4xxx_dpot.h b/drivers/misc/mcp4xxx_dpot.h
new file mode 100644
index 000000000000..34cf077b67ad
--- /dev/null
+++ b/drivers/misc/mcp4xxx_dpot.h
@@ -0,0 +1,44 @@
+/*
+ * Driver for the Microchip digital potentiometers
+ *
+ * Copyright (C) 2015 Peter Rosin, Axentia Technologies AB
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef _MCP4XXX_DPOT_H_
+#define _MCP4XXX_DPOT_H_
+
+#include <linux/types.h>
+
+#define DPOT_CONF(wipers, max_pos, uid) \
+ ((((wipers) & 0xff) << 10) | \
+ ((max_pos & 0xf) << 6) | (uid & 0x3f))
+
+#define DPOT_UID(conf) (conf & 0x3f)
+#define DPOT_MAX_POS(conf) ((conf >> 6) & 0xf)
+#define DPOT_WIPERS(conf) ((conf >> 10) & 0xff)
+
+#define BRDAC0 (1 << 0)
+#define BRDAC1 (1 << 1)
+#define MAX_RDACS 2
+
+enum mcp4xxx_dpot_devid {
+ MCP4531_ID = DPOT_CONF(BRDAC0, 7, 0),
+ MCP4532_ID = DPOT_CONF(BRDAC0, 7, 1),
+ MCP4551_ID = DPOT_CONF(BRDAC0, 8, 2),
+ MCP4552_ID = DPOT_CONF(BRDAC0, 8, 3),
+ MCP4631_ID = DPOT_CONF(BRDAC0 | BRDAC1, 7, 4),
+ MCP4632_ID = DPOT_CONF(BRDAC0 | BRDAC1, 7, 5),
+ MCP4651_ID = DPOT_CONF(BRDAC0 | BRDAC1, 8, 6),
+ MCP4652_ID = DPOT_CONF(BRDAC0 | BRDAC1, 8, 7),
+};
+
+#define DPOT_RDAC0 0
+#define DPOT_RDAC1 1
+
+#define DPOT_RDAC_MASK 0x1F
+
+#define DPOT_ADDR_RDAC 0
+
+#endif
--
1.7.10.4
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