* [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
* Re: [PATCH] misc: mcp4xxx_dpot: Driver for Microchip digital potentiometers
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
0 siblings, 1 reply; 3+ messages in thread
From: Greg Kroah-Hartman @ 2015-09-21 5:35 UTC (permalink / raw)
To: peda; +Cc: linux-kernel, Peter Rosin, Jonathan Corbet, Arnd Bergmann, linux-doc
On Mon, Aug 31, 2015 at 10:08:08PM +0200, peda@lysator.liu.se wrote:
> From: Peter Rosin <peda@axentia.se>
>
> Signed-off-by: Peter Rosin <peda@axentia.se>
A whole new driver with exactly no changelog description at all? I
can't take that :(
> ---
> 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.
sysfs files all need to be documented in Documentation/ABI/ not in
random Documentation files :)
Also, why isn't this just an IIO driver? Creating one-off sysfs files
for each driver is a path to madness, please work on using standard
interfaces if at all possible.
> +---------
> + 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
You never say what the contents of these files really are. Nor what the
units are, if any, or what this driver even does or is used for. For
all I know it just is a sysfs file value storage driver :)
> 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)
DEVICE_ATTR_RW()?
> +
> +#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)
DEVICE_ATTR_RW()?
> +
> +MCP4XXX_DPOT_DEVICE_SHOW_SET(rdac0, DPOT_ADDR_RDAC | DPOT_RDAC0);
> +MCP4XXX_DPOT_DEVICE_SHOW_SET(rdac1, DPOT_ADDR_RDAC | DPOT_RDAC1);
That's a bunch of macros for just 2 files, you could just spell them out
which would make things easier...
> +
> +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]);
> +
Oops, you just raced with userspace and it never saw your sysfs file
created :(
You need to use an attribute group instead.
Or better yet, the IIO interface please.
> + 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);
Don't be "noisy", if a driver is working properly, nothing should show
up in the kernel log. Otherwise it's a total mess.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] misc: mcp4xxx_dpot: Driver for Microchip digital potentiometers
2015-09-21 5:35 ` Greg Kroah-Hartman
@ 2015-09-21 17:40 ` Peter Rosin
0 siblings, 0 replies; 3+ messages in thread
From: Peter Rosin @ 2015-09-21 17:40 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: linux-kernel, Peter Rosin, Jonathan Corbet, Arnd Bergmann, linux-doc
Hi Greg!
Thanks for having a look!
On 2015-09-21 07:35, Greg Kroah-Hartman wrote:
> On Mon, Aug 31, 2015 at 10:08:08PM +0200, peda@lysator.liu.se wrote:
>> From: Peter Rosin <peda@axentia.se>
>>
>> Signed-off-by: Peter Rosin <peda@axentia.se>
>
> A whole new driver with exactly no changelog description at all? I
> can't take that :(
I didn't really expect anyone to take it even with a decent changelog, it was
more of a "let's see in how many ways it's wrong"-thing. I modeled the driver
after the only potentiometer driver I could find, but it didn't feel right,
which I hint at below...
>> ---
>> 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?
...around here, but you seem to have missed that completely?
>> 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.
>
> sysfs files all need to be documented in Documentation/ABI/ not in
> random Documentation files :)
>
> Also, why isn't this just an IIO driver? Creating one-off sysfs files
> for each driver is a path to madness, please work on using standard
> interfaces if at all possible.
I suspected IIO might be the right place, but when I looked at IIO I
only noticed drivers for things with a real-world connection, e.g.
movement or temperature. And a potentiometer seemed like a more general
thing, more like a component that you build some real-world thing from.
So, since I couldn't find an existing pot in IIO, I did a dirty driver
based on the only pot-driver I could find, more or less just to see
what I should have been doing. After having a closer look at IIO I
also notice DACs and ADCs, which are kind of low-level like pots. Oh
well, it's not always easy to know where a new driver should go, and
it's also not easy to knew where one should ask...
I apologize for not being more clear about the nature of the patch,
and I hope I didn't waste too much of your time.
Anyway, let's scrap that attempt. I'll come back with an IIO driver in
a bit. I haven't previously worked with IIO, so I'm bound to fall into
some trap, please bear with me...
Cheers,
Peter
^ 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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