iio: Add IIO support for the DAC on the Apex Embedded Systems STX104 (97a445da) · Commits · e / devices / android_kernel_fairphone_FP5

MAINTAINERS

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		@@ -778,6 +778,12 @@ L: alsa-devel@alsa-project.org (moderated for non-subscribers)
		S: Maintained
		F: sound/aoa/

		APEX EMBEDDED SYSTEMS STX104 DAC DRIVER
		M: William Breathitt Gray <vilhelm.gray@gmail.com>
		L: linux-iio@vger.kernel.org
		S: Maintained
		F: drivers/iio/dac/stx104.c

		APM DRIVER
		M: Jiri Kosina <jikos@kernel.org>
		S: Odd fixes

drivers/iio/dac/Kconfig

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		@@ -208,4 +208,13 @@ config MCP4922
		To compile this driver as a module, choose M here: the module
		will be called mcp4922.

		config STX104
		tristate "Apex Embedded Systems STX104 DAC driver"
		depends on ISA
		help
		Say yes here to build support for the 2-channel DAC on the Apex
		Embedded Systems STX104 integrated analog PC/104 card. The base port
		addresses for the devices may be configured via the "base" module
		parameter array.

		endmenu

drivers/iio/dac/Makefile

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		@@ -22,3 +22,4 @@ obj-$(CONFIG_MAX517) += max517.o
		obj-$(CONFIG_MAX5821) += max5821.o
		obj-$(CONFIG_MCP4725) += mcp4725.o
		obj-$(CONFIG_MCP4922) += mcp4922.o
		obj-$(CONFIG_STX104) += stx104.o

drivers/iio/dac/stx104.c

0 → 100644

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		/*
		* DAC driver for the Apex Embedded Systems STX104
		* Copyright (C) 2016 William Breathitt Gray
		*
		* 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.
		*
		* This program is distributed in the hope that it will be useful, but
		* WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
		* General Public License for more details.
		*/
		#include <linux/bitops.h>
		#include <linux/device.h>
		#include <linux/errno.h>
		#include <linux/iio/iio.h>
		#include <linux/iio/types.h>
		#include <linux/io.h>
		#include <linux/ioport.h>
		#include <linux/isa.h>
		#include <linux/module.h>
		#include <linux/moduleparam.h>

		#define STX104_NUM_CHAN 2

		#define STX104_CHAN(chan) { \
		.type = IIO_VOLTAGE, \
		.channel = chan, \
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
		.indexed = 1, \
		.output = 1 \
		}

		#define STX104_EXTENT 16
		/**
		* The highest base address possible for an ISA device is 0x3FF; this results in
		* 1024 possible base addresses. Dividing the number of possible base addresses
		* by the address extent taken by each device results in the maximum number of
		* devices on a system.
		*/
		#define MAX_NUM_STX104 (1024 / STX104_EXTENT)

		static unsigned base[MAX_NUM_STX104];
		static unsigned num_stx104;
		module_param_array(base, uint, &num_stx104, 0);
		MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");

		/**
		* struct stx104_iio - IIO device private data structure
		* @chan_out_states: channels' output states
		* @base: base port address of the IIO device
		*/
		struct stx104_iio {
		unsigned chan_out_states[STX104_NUM_CHAN];
		unsigned base;
		};

		static int stx104_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const chan, int val, int *val2, long mask)
		{
		struct stx104_iio *const priv = iio_priv(indio_dev);

		if (mask != IIO_CHAN_INFO_RAW)
		return -EINVAL;

		*val = priv->chan_out_states[chan->channel];

		return IIO_VAL_INT;
		}

		static int stx104_write_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan, int val, int val2, long mask)
		{
		struct stx104_iio *const priv = iio_priv(indio_dev);
		const unsigned chan_addr_offset = 2 * chan->channel;

		if (mask != IIO_CHAN_INFO_RAW)
		return -EINVAL;

		priv->chan_out_states[chan->channel] = val;
		outw(val, priv->base + 4 + chan_addr_offset);

		return 0;
		}

		static const struct iio_info stx104_info = {
		.driver_module = THIS_MODULE,
		.read_raw = stx104_read_raw,
		.write_raw = stx104_write_raw
		};

		static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
		STX104_CHAN(0),
		STX104_CHAN(1)
		};

		static int stx104_probe(struct device *dev, unsigned int id)
		{
		struct iio_dev *indio_dev;
		struct stx104_iio *priv;

		indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
		if (!indio_dev)
		return -ENOMEM;

		if (!devm_request_region(dev, base[id], STX104_EXTENT,
		dev_name(dev))) {
		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
		base[id], base[id] + STX104_EXTENT);
		return -EBUSY;
		}

		indio_dev->info = &stx104_info;
		indio_dev->modes = INDIO_DIRECT_MODE;
		indio_dev->channels = stx104_channels;
		indio_dev->num_channels = STX104_NUM_CHAN;
		indio_dev->name = dev_name(dev);

		priv = iio_priv(indio_dev);
		priv->base = base[id];

		/* initialize DAC output to 0V */
		outw(0, base[id] + 4);
		outw(0, base[id] + 6);

		return devm_iio_device_register(dev, indio_dev);
		}

		static struct isa_driver stx104_driver = {
		.probe = stx104_probe,
		.driver = {
		.name = "stx104"
		}
		};

		static void __exit stx104_exit(void)
		{
		isa_unregister_driver(&stx104_driver);
		}

		static int __init stx104_init(void)
		{
		return isa_register_driver(&stx104_driver, num_stx104);
		}

		module_init(stx104_init);
		module_exit(stx104_exit);

		MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
		MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
		MODULE_LICENSE("GPL v2");