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* [PATCH] misc: mcp4xxx_dpot: Driver for Microchip digital potentiometers
@ 2015-08-31 20:08 peda
  2015-09-21  5:35 ` Greg Kroah-Hartman
  0 siblings, 1 reply; 3+ messages in thread
From: peda @ 2015-08-31 20:08 UTC (permalink / raw)
  To: linux-kernel
  Cc: Peter Rosin, Jonathan Corbet, Arnd Bergmann, Greg Kroah-Hartman,
	linux-doc

From: Peter Rosin <peda@axentia.se>

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 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@axentia.se>
+S:	Maintained
+F:	drivers/misc/mcp4xxx_dpot.*
+
 MEDIA DRIVERS FOR RENESAS - VSP1
 M:	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 L:	linux-media@vger.kernel.org
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@axentia.se>
+ *
+ * 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@blackfin.uclinux.org>
+ *
+ * derived from ad5258.c
+ * Copyright (c) 2009 Cyber Switching, Inc.
+ * Author: Chris Verges <chrisv@cyberswitching.com>
+ *
+ * derived from ad5252.c
+ * Copyright (c) 2006-2011 Michael Hennerich <hennerich@blackfin.uclinux.org>
+ *
+ * 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@axentia.se>");
+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


^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-09-21 17:41 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-08-31 20:08 [PATCH] misc: mcp4xxx_dpot: Driver for Microchip digital potentiometers peda
2015-09-21  5:35 ` Greg Kroah-Hartman
2015-09-21 17:40   ` Peter Rosin

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