iio: add support of the max1027

This driver add partial support of the
maxim 1027/1029/1031. Differential mode is not
supported.

It was tested on armadeus apf27 board.

Signed-off-by: Philippe Reynes <tremyfr@yahoo.fr>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/adc/max1027-adc.txt

@@ -0,0 +1,22 @@
+* Maxim 1027/1029/1031 Analog to Digital Converter (ADC)
+
+Required properties:
+  - compatible: Should be "maxim,max1027" or "maxim,max1029" or "maxim,max1031"
+  - reg: SPI chip select number for the device
+  - interrupt-parent: phandle to the parent interrupt controller
+  see: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+  - interrupts: IRQ line for the ADC
+  see: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
+
+Recommended properties:
+- spi-max-frequency: Definition as per
+                     Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+adc@0 {
+	compatible = "maxim,max1027";
+	reg = <0>;
+	interrupt-parent = <&gpio5>;
+	interrupts = <15 IRQ_TYPE_EDGE_RISING>;
+	spi-max-frequency = <1000000>;
+};

drivers/iio/adc/Kconfig

@@ -131,6 +131,15 @@ config LP8788_ADC
 	help
 	  Say yes here to build support for TI LP8788 ADC.
 
+config MAX1027
+	tristate "Maxim max1027 ADC driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Maxim SPI ADC models
+	  max1027, max1029 and max1031.
+
 config MAX1363
 	tristate "Maxim max1363 ADC driver"
 	depends on I2C

drivers/iio/adc/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_AD799X) += ad799x.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
 obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
 obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
+obj-$(CONFIG_MAX1027) += max1027.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o

drivers/iio/adc/max1027.c

@@ -0,0 +1,521 @@
+ /*
+  * iio/adc/max1027.c
+  * Copyright (C) 2014 Philippe Reynes
+  *
+  * based on linux/drivers/iio/ad7923.c
+  * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
+  * Copyright 2012 CS Systemes d'Information
+  *
+  * 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.
+  *
+  * max1027.c
+  *
+  * Partial support for max1027 and similar chips.
+  */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/delay.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define MAX1027_CONV_REG  BIT(7)
+#define MAX1027_SETUP_REG BIT(6)
+#define MAX1027_AVG_REG   BIT(5)
+#define MAX1027_RST_REG   BIT(4)
+
+/* conversion register */
+#define MAX1027_TEMP      BIT(0)
+#define MAX1027_SCAN_0_N  (0x00 << 1)
+#define MAX1027_SCAN_N_M  (0x01 << 1)
+#define MAX1027_SCAN_N    (0x02 << 1)
+#define MAX1027_NOSCAN    (0x03 << 1)
+#define MAX1027_CHAN(n)   ((n) << 3)
+
+/* setup register */
+#define MAX1027_UNIPOLAR  0x02
+#define MAX1027_BIPOLAR   0x03
+#define MAX1027_REF_MODE0 (0x00 << 2)
+#define MAX1027_REF_MODE1 (0x01 << 2)
+#define MAX1027_REF_MODE2 (0x02 << 2)
+#define MAX1027_REF_MODE3 (0x03 << 2)
+#define MAX1027_CKS_MODE0 (0x00 << 4)
+#define MAX1027_CKS_MODE1 (0x01 << 4)
+#define MAX1027_CKS_MODE2 (0x02 << 4)
+#define MAX1027_CKS_MODE3 (0x03 << 4)
+
+/* averaging register */
+#define MAX1027_NSCAN_4   0x00
+#define MAX1027_NSCAN_8   0x01
+#define MAX1027_NSCAN_12  0x02
+#define MAX1027_NSCAN_16  0x03
+#define MAX1027_NAVG_4    (0x00 << 2)
+#define MAX1027_NAVG_8    (0x01 << 2)
+#define MAX1027_NAVG_16   (0x02 << 2)
+#define MAX1027_NAVG_32   (0x03 << 2)
+#define MAX1027_AVG_EN    BIT(4)
+
+enum max1027_id {
+	max1027,
+	max1029,
+	max1031,
+};
+
+static const struct spi_device_id max1027_id[] = {
+	{"max1027", max1027},
+	{"max1029", max1029},
+	{"max1031", max1031},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, max1027_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id max1027_adc_dt_ids[] = {
+	{ .compatible = "maxim,max1027" },
+	{ .compatible = "maxim,max1029" },
+	{ .compatible = "maxim,max1031" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);
+#endif
+
+#define MAX1027_V_CHAN(index)						\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.indexed = 1,						\
+		.channel = index,					\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.scan_index = index + 1,				\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 10,					\
+			.storagebits = 16,				\
+			.shift = 2,					\
+			.endianness = IIO_BE,				\
+		},							\
+	}
+
+#define MAX1027_T_CHAN							\
+	{								\
+		.type = IIO_TEMP,					\
+		.channel = 0,						\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.scan_index = 0,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+			.endianness = IIO_BE,				\
+		},							\
+	}
+
+static const struct iio_chan_spec max1027_channels[] = {
+	MAX1027_T_CHAN,
+	MAX1027_V_CHAN(0),
+	MAX1027_V_CHAN(1),
+	MAX1027_V_CHAN(2),
+	MAX1027_V_CHAN(3),
+	MAX1027_V_CHAN(4),
+	MAX1027_V_CHAN(5),
+	MAX1027_V_CHAN(6),
+	MAX1027_V_CHAN(7)
+};
+
+static const struct iio_chan_spec max1029_channels[] = {
+	MAX1027_T_CHAN,
+	MAX1027_V_CHAN(0),
+	MAX1027_V_CHAN(1),
+	MAX1027_V_CHAN(2),
+	MAX1027_V_CHAN(3),
+	MAX1027_V_CHAN(4),
+	MAX1027_V_CHAN(5),
+	MAX1027_V_CHAN(6),
+	MAX1027_V_CHAN(7),
+	MAX1027_V_CHAN(8),
+	MAX1027_V_CHAN(9),
+	MAX1027_V_CHAN(10),
+	MAX1027_V_CHAN(11)
+};
+
+static const struct iio_chan_spec max1031_channels[] = {
+	MAX1027_T_CHAN,
+	MAX1027_V_CHAN(0),
+	MAX1027_V_CHAN(1),
+	MAX1027_V_CHAN(2),
+	MAX1027_V_CHAN(3),
+	MAX1027_V_CHAN(4),
+	MAX1027_V_CHAN(5),
+	MAX1027_V_CHAN(6),
+	MAX1027_V_CHAN(7),
+	MAX1027_V_CHAN(8),
+	MAX1027_V_CHAN(9),
+	MAX1027_V_CHAN(10),
+	MAX1027_V_CHAN(11),
+	MAX1027_V_CHAN(12),
+	MAX1027_V_CHAN(13),
+	MAX1027_V_CHAN(14),
+	MAX1027_V_CHAN(15)
+};
+
+static const unsigned long max1027_available_scan_masks[] = {
+	0x000001ff,
+	0x00000000,
+};
+
+static const unsigned long max1029_available_scan_masks[] = {
+	0x00001fff,
+	0x00000000,
+};
+
+static const unsigned long max1031_available_scan_masks[] = {
+	0x0001ffff,
+	0x00000000,
+};
+
+struct max1027_chip_info {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+	const unsigned long *available_scan_masks;
+};
+
+static const struct max1027_chip_info max1027_chip_info_tbl[] = {
+	[max1027] = {
+		.channels = max1027_channels,
+		.num_channels = ARRAY_SIZE(max1027_channels),
+		.available_scan_masks = max1027_available_scan_masks,
+	},
+	[max1029] = {
+		.channels = max1029_channels,
+		.num_channels = ARRAY_SIZE(max1029_channels),
+		.available_scan_masks = max1029_available_scan_masks,
+	},
+	[max1031] = {
+		.channels = max1031_channels,
+		.num_channels = ARRAY_SIZE(max1031_channels),
+		.available_scan_masks = max1031_available_scan_masks,
+	},
+};
+
+struct max1027_state {
+	const struct max1027_chip_info	*info;
+	struct spi_device		*spi;
+	struct iio_trigger		*trig;
+	__be16				*buffer;
+	struct mutex			lock;
+
+	u8				reg ____cacheline_aligned;
+};
+
+static int max1027_read_single_value(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *chan,
+				     int *val)
+{
+	int ret;
+	struct max1027_state *st = iio_priv(indio_dev);
+
+	if (iio_buffer_enabled(indio_dev)) {
+		dev_warn(&indio_dev->dev, "trigger mode already enabled");
+		return -EBUSY;
+	}
+
+	/* Start acquisition on conversion register write */
+	st->reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2 | MAX1027_CKS_MODE2;
+	ret = spi_write(st->spi, &st->reg, 1);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev,
+			"Failed to configure setup register\n");
+		return ret;
+	}
+
+	/* Configure conversion register with the requested chan */
+	st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) |
+		  MAX1027_NOSCAN | !!(chan->type == IIO_TEMP);
+	ret = spi_write(st->spi, &st->reg, 1);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev,
+			"Failed to configure conversion register\n");
+		return ret;
+	}
+
+	/*
+	 * For an unknown reason, when we use the mode "10" (write
+	 * conversion register), the interrupt doesn't occur every time.
+	 * So we just wait 1 ms.
+	 */
+	mdelay(1);
+
+	/* Read result */
+	ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ? 4 : 2);
+	if (ret < 0)
+		return ret;
+
+	*val = be16_to_cpu(st->buffer[0]);
+
+	return IIO_VAL_INT;
+}
+
+static int max1027_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	int ret = 0;
+	struct max1027_state *st = iio_priv(indio_dev);
+
+	mutex_lock(&st->lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = max1027_read_single_value(indio_dev, chan, val);
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_TEMP:
+			*val = 1;
+			*val2 = 8;
+			ret = IIO_VAL_FRACTIONAL;
+			break;
+		case IIO_VOLTAGE:
+			*val = 2500;
+			*val2 = 10;
+			ret = IIO_VAL_FRACTIONAL_LOG2;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
+				      unsigned reg, unsigned writeval,
+				      unsigned *readval)
+{
+	struct max1027_state *st = iio_priv(indio_dev);
+	u8 *val = (u8 *)st->buffer;
+
+	if (readval != NULL)
+		return -EINVAL;
+
+	*val = (u8)writeval;
+	return spi_write(st->spi, val, 1);
+}
+
+static int max1027_validate_trigger(struct iio_dev *indio_dev,
+				    struct iio_trigger *trig)
+{
+	struct max1027_state *st = iio_priv(indio_dev);
+
+	if (st->trig != trig)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int max1027_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct max1027_state *st = iio_priv(indio_dev);
+	int ret;
+
+	if (state) {
+		/* Start acquisition on cnvst */
+		st->reg = MAX1027_SETUP_REG | MAX1027_CKS_MODE0 |
+			  MAX1027_REF_MODE2;
+		ret = spi_write(st->spi, &st->reg, 1);
+		if (ret < 0)
+			return ret;
+
+		/* Scan from 0 to max */
+		st->reg = MAX1027_CONV_REG | MAX1027_CHAN(0) |
+			  MAX1027_SCAN_N_M | MAX1027_TEMP;
+		ret = spi_write(st->spi, &st->reg, 1);
+		if (ret < 0)
+			return ret;
+	} else {
+		/* Start acquisition on conversion register write */
+		st->reg = MAX1027_SETUP_REG | MAX1027_CKS_MODE2	|
+			  MAX1027_REF_MODE2;
+		ret = spi_write(st->spi, &st->reg, 1);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int max1027_validate_device(struct iio_trigger *trig,
+				   struct iio_dev *indio_dev)
+{
+	struct iio_dev *indio = iio_trigger_get_drvdata(trig);
+
+	if (indio != indio_dev)
+		return -EINVAL;
+
+	return 0;
+}
+
+static irqreturn_t max1027_trigger_handler(int irq, void *private)
+{
+	struct iio_poll_func *pf = (struct iio_poll_func *)private;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct max1027_state *st = iio_priv(indio_dev);
+
+	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
+
+	/* fill buffer with all channel */
+	spi_read(st->spi, st->buffer, indio_dev->masklength * 2);
+
+	iio_push_to_buffers(indio_dev, st->buffer);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_trigger_ops max1027_trigger_ops = {
+	.owner = THIS_MODULE,
+	.validate_device = &max1027_validate_device,
+	.set_trigger_state = &max1027_set_trigger_state,
+};
+
+static const struct iio_info max1027_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = &max1027_read_raw,
+	.validate_trigger = &max1027_validate_trigger,
+	.debugfs_reg_access = &max1027_debugfs_reg_access,
+};
+
+static int max1027_probe(struct spi_device *spi)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct max1027_state *st;
+
+	pr_debug("%s: probe(spi = 0x%p)\n", __func__, spi);
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (indio_dev == NULL) {
+		pr_err("Can't allocate iio device\n");
+		return -ENOMEM;
+	}
+
+	spi_set_drvdata(spi, indio_dev);
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+	st->info = &max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];
+
+	mutex_init(&st->lock);
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->info = &max1027_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = st->info->channels;
+	indio_dev->num_channels = st->info->num_channels;
+	indio_dev->available_scan_masks = st->info->available_scan_masks;
+
+	st->buffer = devm_kmalloc(&indio_dev->dev,
+				  indio_dev->num_channels * 2,
+				  GFP_KERNEL);
+	if (st->buffer == NULL) {
+		dev_err(&indio_dev->dev, "Can't allocate bufffer\n");
+		return -ENOMEM;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
+					 &max1027_trigger_handler, NULL);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "Failed to setup buffer\n");
+		return ret;
+	}
+
+	st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
+							indio_dev->name);
+	if (st->trig == NULL) {
+		ret = -ENOMEM;
+		dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n");
+		goto fail_trigger_alloc;
+	}
+
+	st->trig->ops = &max1027_trigger_ops;
+	st->trig->dev.parent = &spi->dev;
+	iio_trigger_set_drvdata(st->trig, indio_dev);
+	iio_trigger_register(st->trig);
+
+	ret = devm_request_threaded_irq(&spi->dev, spi->irq,
+					iio_trigger_generic_data_rdy_poll,
+					NULL,
+					IRQF_TRIGGER_FALLING,
+					spi->dev.driver->name, st->trig);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
+		goto fail_dev_register;
+	}
+
+	/* Disable averaging */
+	st->reg = MAX1027_AVG_REG;
+	ret = spi_write(st->spi, &st->reg, 1);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "Failed to configure averaging register\n");
+		goto fail_dev_register;
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&indio_dev->dev, "Failed to register iio device\n");
+		goto fail_dev_register;
+	}
+
+	return 0;
+
+fail_dev_register:
+fail_trigger_alloc:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return ret;
+}
+
+static int max1027_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+
+	pr_debug("%s: remove(spi = 0x%p)\n", __func__, spi);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return 0;
+}
+
+static struct spi_driver max1027_driver = {
+	.driver = {
+		.name	= "max1027",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= max1027_probe,
+	.remove		= max1027_remove,
+	.id_table	= max1027_id,
+};
+module_spi_driver(max1027_driver);
+
+MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
+MODULE_DESCRIPTION("MAX1027/MAX1029/MAX1031 ADC");
+MODULE_LICENSE("GPL v2");