staging: iio: dds: new driver for AD5930/2 devices

This is the initial driver in the new Direct Digital Synthesis section.
Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Kconfig

@@ -44,6 +44,7 @@ source "drivers/staging/iio/accel/Kconfig"
 source "drivers/staging/iio/adc/Kconfig"
 source "drivers/staging/iio/addac/Kconfig"
 source "drivers/staging/iio/dac/Kconfig"
+source "drivers/staging/iio/dds/Kconfig"
 source "drivers/staging/iio/gyro/Kconfig"
 source "drivers/staging/iio/imu/Kconfig"
 source "drivers/staging/iio/light/Kconfig"

drivers/staging/iio/Makefile

@@ -13,6 +13,7 @@ obj-y += accel/
 obj-y += adc/
 obj-y += addac/
 obj-y += dac/
+obj-y += dds/
 obj-y += gyro/
 obj-y += imu/
 obj-y += light/

drivers/staging/iio/dds/Kconfig

+#
+# Direct Digital Synthesis drivers
+#
+comment "Direct Digital Synthesis"
+
+config AD5930
+	tristate "Analog Devices ad5930/5932 driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices DDS chip
+	  ad5930/ad5932, provides direct access via sysfs.

drivers/staging/iio/dds/Makefile

+#
+# Makefile for Direct Digital Synthesis drivers
+#
+
+obj-$(CONFIG_AD5930) += ad5930.o

drivers/staging/iio/dds/ad5930.c

+/*
+ * Driver for ADI Direct Digital Synthesis ad5930
+ *
+ * Copyright (c) 2010-2010 Analog Devices Inc.
+ *
+ * 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/types.h>
+#include <linux/mutex.h>
+#include <linux/device.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+
+#define DRV_NAME "ad5930"
+
+#define value_mask (u16)0xf000
+#define addr_shift 12
+
+/* Register format: 4 bits addr + 12 bits value */
+struct ad5903_config {
+	u16 control;
+	u16 incnum;
+	u16 frqdelt[2];
+	u16 incitvl;
+	u16 buritvl;
+	u16 strtfrq[2];
+};
+
+struct ad5930_state {
+	struct mutex lock;
+	struct iio_dev *idev;
+	struct spi_device *sdev;
+};
+
+static ssize_t ad5930_set_parameter(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf,
+					size_t len)
+{
+	struct spi_message msg;
+	struct spi_transfer xfer;
+	int ret;
+	struct ad5903_config *config = (struct ad5903_config *)buf;
+	struct iio_dev *idev = dev_get_drvdata(dev);
+	struct ad5930_state *st = idev->dev_data;
+
+	config->control = (config->control & ~value_mask);
+	config->incnum = (config->control & ~value_mask) | (1 << addr_shift);
+	config->frqdelt[0] = (config->control & ~value_mask) | (2 << addr_shift);
+	config->frqdelt[1] = (config->control & ~value_mask) | 3 << addr_shift;
+	config->incitvl = (config->control & ~value_mask) | 4 << addr_shift;
+	config->buritvl = (config->control & ~value_mask) | 8 << addr_shift;
+	config->strtfrq[0] = (config->control & ~value_mask) | 0xc << addr_shift;
+	config->strtfrq[1] = (config->control & ~value_mask) | 0xd << addr_shift;
+
+	xfer.len = len;
+	xfer.tx_buf = config;
+	mutex_lock(&st->lock);
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+	ret = spi_sync(st->sdev, &msg);
+	if (ret)
+		goto error_ret;
+error_ret:
+	mutex_unlock(&st->lock);
+
+	return ret ? ret : len;
+}
+
+static IIO_DEVICE_ATTR(dds, S_IWUSR, NULL, ad5930_set_parameter, 0);
+
+static struct attribute *ad5930_attributes[] = {
+	&iio_dev_attr_dds.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ad5930_attribute_group = {
+	.name = DRV_NAME,
+	.attrs = ad5930_attributes,
+};
+
+static int __devinit ad5930_probe(struct spi_device *spi)
+{
+	struct ad5930_state *st;
+	int ret = 0;
+
+	st = kzalloc(sizeof(*st), GFP_KERNEL);
+	if (st == NULL) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+	spi_set_drvdata(spi, st);
+
+	mutex_init(&st->lock);
+	st->sdev = spi;
+
+	st->idev = iio_allocate_device();
+	if (st->idev == NULL) {
+		ret = -ENOMEM;
+		goto error_free_st;
+	}
+	st->idev->dev.parent = &spi->dev;
+	st->idev->num_interrupt_lines = 0;
+	st->idev->event_attrs = NULL;
+
+	st->idev->attrs = &ad5930_attribute_group;
+	st->idev->dev_data = (void *)(st);
+	st->idev->driver_module = THIS_MODULE;
+	st->idev->modes = INDIO_DIRECT_MODE;
+
+	ret = iio_device_register(st->idev);
+	if (ret)
+		goto error_free_dev;
+	spi->max_speed_hz = 2000000;
+	spi->mode = SPI_MODE_3;
+	spi->bits_per_word = 16;
+	spi_setup(spi);
+
+	return 0;
+
+error_free_dev:
+	iio_free_device(st->idev);
+error_free_st:
+	kfree(st);
+error_ret:
+	return ret;
+}
+
+static int __devexit ad5930_remove(struct spi_device *spi)
+{
+	struct ad5930_state *st = spi_get_drvdata(spi);
+
+	iio_device_unregister(st->idev);
+	kfree(st);
+
+	return 0;
+}
+
+static struct spi_driver ad5930_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+	},
+	.probe = ad5930_probe,
+	.remove = __devexit_p(ad5930_remove),
+};
+
+static __init int ad5930_spi_init(void)
+{
+	return spi_register_driver(&ad5930_driver);
+}
+module_init(ad5930_spi_init);
+
+static __exit void ad5930_spi_exit(void)
+{
+	spi_unregister_driver(&ad5930_driver);
+}
+module_exit(ad5930_spi_exit);
+
+MODULE_AUTHOR("Cliff Cai");
+MODULE_DESCRIPTION("Analog Devices ad5930 driver");
+MODULE_LICENSE("GPL v2");