On 03/22/2012 10:10 AM, Jonathan Cameron wrote:
On 3/22/2012 8:52 AM, Michael Hennerich wrote:
On 03/21/2012 08:34 PM, Jonathan Cameron wrote:
On 02/22/2012 12:36 PM, michael.hennerich@xxxxxxxxxx wrote:
From: Michael Hennerich<michael.hennerich@xxxxxxxxxx>
Sorry for the slow response on this one. Been off sick...
Anyhow, I'm still not sure what the right interface for this type
of device is.
The obvious options are:
1) Make gain an IIO type (doesn't make much sense as gain is only going
to be of one particular existing type).
2) Have it as an IIO_ALTVOLTAGE channel as you have here and use extend
name. Any real reason for picking altvoltage rather than voltage?
I'm open for advice. Since I made the amplifier being an OUT type device
I chose IIO_ALTVOLTAGE analogous to our DDS/PLL drivers.
Some VGAs/PGAs work from DC, but typically VGAs are HF devices.
Hmm.. Don't suppose it really matters but we ought to aim for consistency
(by review) at least. This particular part is DC through to 600MHz.
Clearly gain has the same meaning in either case (assuming it's linear).
3) Make a change to core to allow a channel to have elements in
info_mask but not actually to have a raw access. Not entirely sure
how we will do that cleanly. Also it's not clear whether the gain
would be an IN or an OUT channel type!
Well - having the ability for channels without raw access element
would be of interest.
True enough. Cleanest way to do this that I can think of is to make a tree
wide change to add the raw element to the info_mask. We could allow for
a zero info_mask value actually being the equivalent of having only a raw
channel. It's invasive but if we agreee it should be done now is
probably the
best time to do it (just post merge window etc).
Hi Jonathan,
Thanks for getting this in place.
Whilst here, we clearly need way of destinguishing values in DB from linear
gains. Could add a new return type for read_raw callbacks?
Does something like this work for you?
Also wondering if we should introduce IIO_CHAN_INFO_GAIN
for amplifier type devices?
From e62f3a3de86f2edde2137237531732cdf5fc2ed8 Mon Sep 17 00:00:00 2001
From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
Date: Mon, 7 May 2012 16:53:45 +0200
Subject: [PATCH] iio: core: introduce dB scle: IIO_VAL_INT_PLUS_MICRO_DB
Signed-off-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
---
drivers/iio/industrialio-core.c | 19 +++++++++++++------
include/linux/iio/types.h | 1 +
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/iio/industrialio-core.c
b/drivers/iio/industrialio-core.c
index 72e33b8..e436f6f 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -306,26 +306,33 @@ static ssize_t iio_read_channel_info(struct device
*dev,
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
int val, val2;
+ bool scale_db = false;
int ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
&val, &val2, this_attr->address);
if (ret < 0)
return ret;
- if (ret == IIO_VAL_INT)
+ switch (ret) {
+ case IIO_VAL_INT:
return sprintf(buf, "%d\n", val);
- else if (ret == IIO_VAL_INT_PLUS_MICRO) {
+ case IIO_VAL_INT_PLUS_MICRO_DB:
+ scale_db = true;
+ case IIO_VAL_INT_PLUS_MICRO:
if (val2 < 0)
- return sprintf(buf, "-%d.%06u\n", val, -val2);
+ return sprintf(buf, "-%d.%06u%s\n", val, -val2,
+ scale_db ? " db" : "");
else
- return sprintf(buf, "%d.%06u\n", val, val2);
- } else if (ret == IIO_VAL_INT_PLUS_NANO) {
+ return sprintf(buf, "%d.%06u%s\n", val, val2,
+ scale_db ? " db" : "");
+ case IIO_VAL_INT_PLUS_NANO:
if (val2 < 0)
return sprintf(buf, "-%d.%09u\n", val, -val2);
else
return sprintf(buf, "%d.%09u\n", val, val2);
- } else
+ default:
return 0;
+ }
}
static ssize_t iio_write_channel_info(struct device *dev,
diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h
index a471fd5..1b073b1 100644
--- a/include/linux/iio/types.h
+++ b/include/linux/iio/types.h
@@ -50,5 +50,6 @@ enum iio_modifier {
#define IIO_VAL_INT 1
#define IIO_VAL_INT_PLUS_MICRO 2
#define IIO_VAL_INT_PLUS_NANO 3
+#define IIO_VAL_INT_PLUS_MICRO_DB 4
#endif /* _IIO_TYPES_H_ */
--
1.7.0.4
All thoughts on this welcome. Maybe we have to decide to leave it
for now and get back to the question at a later date?
The driver is clean and short so it's only really the above question of
approach that needs answering to my mind... I guess you feel that
what you have here is the best plan but I'd like a few more views on
this before we set the precedence....
I've pulled Mark into the cc as he might have come across similar
devices from the audio side of things and hence have some experience
around this question...
Signed-off-by: Michael Hennerich<michael.hennerich@xxxxxxxxxx>
---
drivers/staging/iio/Kconfig | 1 +
drivers/staging/iio/Makefile | 1 +
drivers/staging/iio/amplifiers/Kconfig | 17 +++
drivers/staging/iio/amplifiers/Makefile | 5 +
drivers/staging/iio/amplifiers/ad8366.c | 228
+++++++++++++++++++++++++++++++
5 files changed, 252 insertions(+), 0 deletions(-)
create mode 100644 drivers/staging/iio/amplifiers/Kconfig
create mode 100644 drivers/staging/iio/amplifiers/Makefile
create mode 100644 drivers/staging/iio/amplifiers/ad8366.c
diff --git a/drivers/staging/iio/Kconfig b/drivers/staging/iio/Kconfig
index 2b56823..fd7a164 100644
--- a/drivers/staging/iio/Kconfig
+++ b/drivers/staging/iio/Kconfig
@@ -59,6 +59,7 @@ config IIO_CONSUMERS_PER_TRIGGER
source "drivers/staging/iio/accel/Kconfig"
source "drivers/staging/iio/adc/Kconfig"
source "drivers/staging/iio/addac/Kconfig"
+source "drivers/staging/iio/amplifiers/Kconfig"
source "drivers/staging/iio/cdc/Kconfig"
source "drivers/staging/iio/dac/Kconfig"
source "drivers/staging/iio/frequency/Kconfig"
diff --git a/drivers/staging/iio/Makefile
b/drivers/staging/iio/Makefile
index 0161095..c52cde3 100644
--- a/drivers/staging/iio/Makefile
+++ b/drivers/staging/iio/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_IIO_DUMMY_EVGEN) += iio_dummy_evgen.o
obj-y += accel/
obj-y += adc/
obj-y += addac/
+obj-y += amplifiers/
obj-y += cdc/
obj-y += dac/
obj-y += frequency/
diff --git a/drivers/staging/iio/amplifiers/Kconfig
b/drivers/staging/iio/amplifiers/Kconfig
new file mode 100644
index 0000000..05d707e
--- /dev/null
+++ b/drivers/staging/iio/amplifiers/Kconfig
@@ -0,0 +1,17 @@
+#
+# Gain Amplifiers, etc.
+#
+menu "Amplifiers"
+
+config AD8366
+ tristate "Analog Devices AD8366 VGA"
+ depends on SPI
+ select BITREVERSE
+ help
+ Say yes here to build support for Analog Devices AD8366
+ SPI Dual-Digital Variable Gain Amplifier (VGA).
Hmm.. interesting choice of acronym! Just for the unknowledgable
amongst us, what's the difference between a vga and a pga?
PGA = Programmable Gain Amplifier
VGA = Variable Gain Amplifier.
That's a good question.IMHO VGA is the more widely
use acronym. But I guess it depends who ever decided the title
of the datasheet.
Fair enough. I've curiously hit a lot of PGAs but VGA was a new one
to me ;)
+
+ To compile this driver as a module, choose M here: the
+ module will be called ad8366.
+
+endmenu
diff --git a/drivers/staging/iio/amplifiers/Makefile
b/drivers/staging/iio/amplifiers/Makefile
new file mode 100644
index 0000000..a6ca366
--- /dev/null
+++ b/drivers/staging/iio/amplifiers/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile iio/amplifiers
+#
+
+obj-$(CONFIG_AD8366) += ad8366.o
diff --git a/drivers/staging/iio/amplifiers/ad8366.c
b/drivers/staging/iio/amplifiers/ad8366.c
new file mode 100644
index 0000000..187606f
--- /dev/null
+++ b/drivers/staging/iio/amplifiers/ad8366.c
@@ -0,0 +1,228 @@
+/*
+ * AD8366 SPI Dual-Digital Variable Gain Amplifier (VGA)
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include<linux/device.h>
+#include<linux/kernel.h>
+#include<linux/slab.h>
+#include<linux/sysfs.h>
+#include<linux/spi/spi.h>
+#include<linux/regulator/consumer.h>
+#include<linux/err.h>
+#include<linux/module.h>
+#include<linux/bitrev.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+
+struct ad8366_state {
+ struct spi_device *spi;
+ struct regulator *reg;
+ unsigned char ch_a;
+ unsigned char ch_b;
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ unsigned char data[2] ____cacheline_aligned;
+};
+
+static int ad8366_write(struct iio_dev *indio_dev,
+ unsigned char ch_a, char unsigned ch_b)
+{
+ struct ad8366_state *st = iio_priv(indio_dev);
+ int ret;
+
+ ch_a = bitrev8(ch_a& 0x3F);
+ ch_b = bitrev8(ch_b& 0x3F);
+
+ st->data[0] = ch_b>> 4;
+ st->data[1] = (ch_b<< 4) | (ch_a>> 2);
+
+ ret = spi_write(st->spi, st->data, ARRAY_SIZE(st->data));
+ if (ret< 0)
+ dev_err(&indio_dev->dev, "write failed (%d)", ret);
+
+ return ret;
+}
+
+static int ad8366_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long m)
+{
+ struct ad8366_state *st = iio_priv(indio_dev);
+ int ret;
+ unsigned code;
+
+ mutex_lock(&indio_dev->mlock);
+ switch (m) {
+ case 0:
+ if (chan->channel == 0)
+ code = st->ch_a;
+ else
+ code = st->ch_b;
+
+ /* Values in dB */
+ code = code * 253 + 4500;
+ *val = code / 1000;
+ *val2 = (code % 1000) * 1000;
+
+ ret = IIO_VAL_INT_PLUS_MICRO;
+ break;
+ default:
+ ret = -EINVAL;
+ }
+ mutex_unlock(&indio_dev->mlock);
+
+ return ret;
+};
+
+static int ad8366_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val,
+ int val2,
+ long mask)
+{
+ struct ad8366_state *st = iio_priv(indio_dev);
+ unsigned code;
+ int ret;
+
+ /* Values in dB */
+ code = (((u8)val * 1000) + ((u32)val2 / 1000));
+
+ if (code> 20500 || code< 4500)
+ return -EINVAL;
+
+ code = (code - 4500) / 253;
+
+ mutex_lock(&indio_dev->mlock);
+ switch (mask) {
+ case 0:
+ if (chan->channel == 0)
+ st->ch_a = code;
+ else
+ st->ch_b = code;
+
+ ret = ad8366_write(indio_dev, st->ch_a, st->ch_b);
+ break;
+ default:
+ ret = -EINVAL;
+ }
+ mutex_unlock(&indio_dev->mlock);
+
+ return ret;
+}
+
+static const struct iio_info ad8366_info = {
+ .read_raw =&ad8366_read_raw,
+ .write_raw =&ad8366_write_raw,
+ .driver_module = THIS_MODULE,
+};
+
+#define AD8366_CHAN(_channel, _name) { \
+ .type = IIO_ALTVOLTAGE, \
+ .output = 1, \
+ .indexed = 1, \
+ .processed_val = 1, \
+ .channel = _channel, \
+ .extend_name = _name, \
+}
+
+static const struct iio_chan_spec ad8366_channels[] = {
+ AD8366_CHAN(0, "gain"),
+ AD8366_CHAN(1, "gain"),
+};
+
+static int __devinit ad8366_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct ad8366_state *st;
+ int ret;
+
+ indio_dev = iio_allocate_device(sizeof(*st));
+ if (indio_dev == NULL)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+
+ st->reg = regulator_get(&spi->dev, "vcc");
+ if (!IS_ERR(st->reg)) {
+ ret = regulator_enable(st->reg);
+ if (ret)
+ goto error_put_reg;
+ }
+
+ spi_set_drvdata(spi, indio_dev);
+ st->spi = spi;
+
+ indio_dev->dev.parent =&spi->dev;
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->info =&ad8366_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = ad8366_channels;
+ indio_dev->num_channels = ARRAY_SIZE(ad8366_channels);
+
+ ret = iio_device_register(indio_dev);
+ if (ret)
+ goto error_disable_reg;
+
+ ad8366_write(indio_dev, 0 , 0);
+
+ return 0;
+
+error_disable_reg:
+ if (!IS_ERR(st->reg))
+ regulator_disable(st->reg);
+error_put_reg:
+ if (!IS_ERR(st->reg))
+ regulator_put(st->reg);
+
+ iio_free_device(indio_dev);
+
+ return ret;
+}
+
+static int __devexit ad8366_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct ad8366_state *st = iio_priv(indio_dev);
+ struct regulator *reg = st->reg;
+
+ iio_device_unregister(indio_dev);
+
+ if (!IS_ERR(reg)) {
+ regulator_disable(reg);
+ regulator_put(reg);
+ }
+
+ iio_free_device(indio_dev);
+
+ return 0;
+}
+
+static const struct spi_device_id ad8366_id[] = {
+ {"ad8366", 0},
+ {}
+};
+
+static struct spi_driver ad8366_driver = {
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .owner = THIS_MODULE,
+ },
+ .probe = ad8366_probe,
+ .remove = __devexit_p(ad8366_remove),
+ .id_table = ad8366_id,
+};
+
+module_spi_driver(ad8366_driver);
+
+MODULE_AUTHOR("Michael Hennerich<hennerich@xxxxxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Analog Devices AD8366 VGA");
+MODULE_LICENSE("GPL v2");
--
1.7.0.4
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--
Greetings,
Michael
--
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