ARM: AT91: IIO: Add AT91 ADC driver. (0e589d5f) · Commits · e / devices / android_kernel_fairphone_FP4

drivers/iio/Kconfig

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Original line number	Diff line number	Diff line
		@@ -48,6 +48,7 @@ config IIO_CONSUMERS_PER_TRIGGER
		This value controls the maximum number of consumers that a
		given trigger may handle. Default is 2.

		source "drivers/iio/adc/Kconfig"
		source "drivers/iio/amplifiers/Kconfig"

		endif # IIO

drivers/iio/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -9,4 +9,5 @@ industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o

		obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o

		obj-y += adc/
		obj-y += amplifiers/

drivers/iio/adc/Kconfig

0 → 100644

+16 −0

Original line number	Diff line number	Diff line
		#
		# ADC drivers
		#
		menu "Analog to digital converters"

		config AT91_ADC
		tristate "Atmel AT91 ADC"
		depends on ARCH_AT91
		select IIO_BUFFER
		select IIO_KFIFO_BUF
		select IIO_TRIGGER
		select SYSFS
		help
		Say yes here to build support for Atmel AT91 ADC.

		endmenu

drivers/iio/adc/Makefile

0 → 100644

+5 −0

Original line number	Diff line number	Diff line
		#
		# Makefile for IIO ADC drivers
		#

		obj-$(CONFIG_AT91_ADC) += at91_adc.o

drivers/iio/adc/at91_adc.c

0 → 100644

+672 −0

Original line number	Diff line number	Diff line
		/*
		* Driver for the ADC present in the Atmel AT91 evaluation boards.
		*
		* Copyright 2011 Free Electrons
		*
		* Licensed under the GPLv2 or later.
		*/

		#include <linux/bitmap.h>
		#include <linux/bitops.h>
		#include <linux/clk.h>
		#include <linux/err.h>
		#include <linux/io.h>
		#include <linux/interrupt.h>
		#include <linux/jiffies.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/platform_device.h>
		#include <linux/sched.h>
		#include <linux/slab.h>
		#include <linux/wait.h>

		#include <linux/platform_data/at91_adc.h>

		#include <linux/iio/iio.h>
		#include <linux/iio/buffer.h>
		#include <linux/iio/kfifo_buf.h>
		#include <linux/iio/trigger.h>
		#include <linux/iio/trigger_consumer.h>

		#include <mach/at91_adc.h>

		#define AT91_ADC_CHAN(st, ch) \
		(st->registers->channel_base + (ch * 4))
		#define at91_adc_readl(st, reg) \
		(readl_relaxed(st->reg_base + reg))
		#define at91_adc_writel(st, reg, val) \
		(writel_relaxed(val, st->reg_base + reg))

		struct at91_adc_state {
		struct clk *adc_clk;
		u16 *buffer;
		unsigned long channels_mask;
		struct clk *clk;
		bool done;
		int irq;
		bool irq_enabled;
		u16 last_value;
		struct mutex lock;
		u8 num_channels;
		void __iomem *reg_base;
		struct at91_adc_reg_desc *registers;
		u8 startup_time;
		struct iio_trigger **trig;
		struct at91_adc_trigger *trigger_list;
		u32 trigger_number;
		bool use_external;
		u32 vref_mv;
		wait_queue_head_t wq_data_avail;
		};

		static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
		{
		struct iio_poll_func *pf = p;
		struct iio_dev *idev = pf->indio_dev;
		struct at91_adc_state *st = iio_priv(idev);
		struct iio_buffer *buffer = idev->buffer;
		int i, j = 0;

		for (i = 0; i < idev->masklength; i++) {
		if (!test_bit(i, idev->active_scan_mask))
		continue;
		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
		j++;
		}

		if (idev->scan_timestamp) {
		s64 timestamp = (s64 )((u8 *)st->buffer +
		ALIGN(j, sizeof(s64)));
		*timestamp = pf->timestamp;
		}

		buffer->access->store_to(buffer, (u8 *)st->buffer, pf->timestamp);

		iio_trigger_notify_done(idev->trig);
		st->irq_enabled = true;

		/* Needed to ACK the DRDY interruption */
		at91_adc_readl(st, AT91_ADC_LCDR);

		enable_irq(st->irq);

		return IRQ_HANDLED;
		}

		static irqreturn_t at91_adc_eoc_trigger(int irq, void *private)
		{
		struct iio_dev *idev = private;
		struct at91_adc_state *st = iio_priv(idev);
		u32 status = at91_adc_readl(st, st->registers->status_register);

		if (!(status & st->registers->drdy_mask))
		return IRQ_HANDLED;

		if (iio_buffer_enabled(idev)) {
		disable_irq_nosync(irq);
		st->irq_enabled = false;
		iio_trigger_poll(idev->trig, iio_get_time_ns());
		} else {
		st->last_value = at91_adc_readl(st, AT91_ADC_LCDR);
		st->done = true;
		wake_up_interruptible(&st->wq_data_avail);
		}

		return IRQ_HANDLED;
		}

		static int at91_adc_channel_init(struct iio_dev *idev)
		{
		struct at91_adc_state *st = iio_priv(idev);
		struct iio_chan_spec chan_array, timestamp;
		int bit, idx = 0;

		idev->num_channels = bitmap_weight(&st->channels_mask,
		st->num_channels) + 1;

		chan_array = devm_kzalloc(&idev->dev,
		((idev->num_channels + 1) *
		sizeof(struct iio_chan_spec)),
		GFP_KERNEL);

		if (!chan_array)
		return -ENOMEM;

		for_each_set_bit(bit, &st->channels_mask, st->num_channels) {
		struct iio_chan_spec *chan = chan_array + idx;

		chan->type = IIO_VOLTAGE;
		chan->indexed = 1;
		chan->channel = bit;
		chan->scan_index = idx;
		chan->scan_type.sign = 'u';
		chan->scan_type.realbits = 10;
		chan->scan_type.storagebits = 16;
		chan->info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT \|
		IIO_CHAN_INFO_RAW_SEPARATE_BIT;
		idx++;
		}
		timestamp = chan_array + idx;

		timestamp->type = IIO_TIMESTAMP;
		timestamp->channel = -1;
		timestamp->scan_index = idx;
		timestamp->scan_type.sign = 's';
		timestamp->scan_type.realbits = 64;
		timestamp->scan_type.storagebits = 64;

		idev->channels = chan_array;
		return idev->num_channels;
		}

		static u8 at91_adc_get_trigger_value_by_name(struct iio_dev *idev,
		struct at91_adc_trigger *triggers,
		const char *trigger_name)
		{
		struct at91_adc_state *st = iio_priv(idev);
		u8 value = 0;
		int i;

		for (i = 0; i < st->trigger_number; i++) {
		char *name = kasprintf(GFP_KERNEL,
		"%s-dev%d-%s",
		idev->name,
		idev->id,
		triggers[i].name);
		if (!name)
		return -ENOMEM;

		if (strcmp(trigger_name, name) == 0) {
		value = triggers[i].value;
		kfree(name);
		break;
		}

		kfree(name);
		}

		return value;
		}

		static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
		{
		struct iio_dev *idev = trig->private_data;
		struct at91_adc_state *st = iio_priv(idev);
		struct iio_buffer *buffer = idev->buffer;
		struct at91_adc_reg_desc *reg = st->registers;
		u32 status = at91_adc_readl(st, reg->trigger_register);
		u8 value;
		u8 bit;

		value = at91_adc_get_trigger_value_by_name(idev,
		st->trigger_list,
		idev->trig->name);
		if (value == 0)
		return -EINVAL;

		if (state) {
		st->buffer = kmalloc(idev->scan_bytes, GFP_KERNEL);
		if (st->buffer == NULL)
		return -ENOMEM;

		at91_adc_writel(st, reg->trigger_register,
		status \| value);

		for_each_set_bit(bit, buffer->scan_mask,
		st->num_channels) {
		struct iio_chan_spec const *chan = idev->channels + bit;
		at91_adc_writel(st, AT91_ADC_CHER,
		AT91_ADC_CH(chan->channel));
		}

		at91_adc_writel(st, AT91_ADC_IER, reg->drdy_mask);

		} else {
		at91_adc_writel(st, AT91_ADC_IDR, reg->drdy_mask);

		at91_adc_writel(st, reg->trigger_register,
		status & ~value);

		for_each_set_bit(bit, buffer->scan_mask,
		st->num_channels) {
		struct iio_chan_spec const *chan = idev->channels + bit;
		at91_adc_writel(st, AT91_ADC_CHDR,
		AT91_ADC_CH(chan->channel));
		}
		kfree(st->buffer);
		}

		return 0;
		}

		static const struct iio_trigger_ops at91_adc_trigger_ops = {
		.owner = THIS_MODULE,
		.set_trigger_state = &at91_adc_configure_trigger,
		};

		static struct iio_trigger at91_adc_allocate_trigger(struct iio_dev idev,
		struct at91_adc_trigger *trigger)
		{
		struct iio_trigger *trig;
		int ret;

		trig = iio_trigger_alloc("%s-dev%d-%s", idev->name,
		idev->id, trigger->name);
		if (trig == NULL)
		return NULL;

		trig->dev.parent = idev->dev.parent;
		trig->private_data = idev;
		trig->ops = &at91_adc_trigger_ops;

		ret = iio_trigger_register(trig);
		if (ret)
		return NULL;

		return trig;
		}

		static int at91_adc_trigger_init(struct iio_dev *idev)
		{
		struct at91_adc_state *st = iio_priv(idev);
		int i, ret;

		st->trig = devm_kzalloc(&idev->dev,
		st->trigger_number * sizeof(st->trig),
		GFP_KERNEL);

		if (st->trig == NULL) {
		ret = -ENOMEM;
		goto error_ret;
		}

		for (i = 0; i < st->trigger_number; i++) {
		if (st->trigger_list[i].is_external && !(st->use_external))
		continue;

		st->trig[i] = at91_adc_allocate_trigger(idev,
		st->trigger_list + i);
		if (st->trig[i] == NULL) {
		dev_err(&idev->dev,
		"Could not allocate trigger %d\n", i);
		ret = -ENOMEM;
		goto error_trigger;
		}
		}

		return 0;

		error_trigger:
		for (i--; i >= 0; i--) {
		iio_trigger_unregister(st->trig[i]);
		iio_trigger_free(st->trig[i]);
		}
		error_ret:
		return ret;
		}

		static void at91_adc_trigger_remove(struct iio_dev *idev)
		{
		struct at91_adc_state *st = iio_priv(idev);
		int i;

		for (i = 0; i < st->trigger_number; i++) {
		iio_trigger_unregister(st->trig[i]);
		iio_trigger_free(st->trig[i]);
		}
		}

		static const struct iio_buffer_setup_ops at91_adc_buffer_ops = {
		.preenable = &iio_sw_buffer_preenable,
		.postenable = &iio_triggered_buffer_postenable,
		.predisable = &iio_triggered_buffer_predisable,
		};

		static int at91_adc_buffer_init(struct iio_dev *idev)
		{
		int ret;

		idev->buffer = iio_kfifo_allocate(idev);
		if (!idev->buffer) {
		ret = -ENOMEM;
		goto error_ret;
		}

		idev->pollfunc = iio_alloc_pollfunc(&iio_pollfunc_store_time,
		&at91_adc_trigger_handler,
		IRQF_ONESHOT,
		idev,
		"%s-consumer%d",
		idev->name,
		idev->id);
		if (idev->pollfunc == NULL) {
		ret = -ENOMEM;
		goto error_pollfunc;
		}

		idev->setup_ops = &at91_adc_buffer_ops;
		idev->modes \|= INDIO_BUFFER_TRIGGERED;

		ret = iio_buffer_register(idev,
		idev->channels,
		idev->num_channels);
		if (ret)
		goto error_register;

		return 0;

		error_register:
		iio_dealloc_pollfunc(idev->pollfunc);
		error_pollfunc:
		iio_kfifo_free(idev->buffer);
		error_ret:
		return ret;
		}

		static void at91_adc_buffer_remove(struct iio_dev *idev)
		{
		iio_buffer_unregister(idev);
		iio_dealloc_pollfunc(idev->pollfunc);
		iio_kfifo_free(idev->buffer);
		}

		static int at91_adc_read_raw(struct iio_dev *idev,
		struct iio_chan_spec const *chan,
		int val, int val2, long mask)
		{
		struct at91_adc_state *st = iio_priv(idev);
		int ret;

		switch (mask) {
		case IIO_CHAN_INFO_RAW:
		mutex_lock(&st->lock);

		at91_adc_writel(st, AT91_ADC_CHER,
		AT91_ADC_CH(chan->channel));
		at91_adc_writel(st, AT91_ADC_IER, st->registers->drdy_mask);
		at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_START);

		ret = wait_event_interruptible_timeout(st->wq_data_avail,
		st->done,
		msecs_to_jiffies(1000));
		if (ret == 0)
		return -ETIMEDOUT;
		else if (ret < 0)
		return ret;

		*val = st->last_value;

		at91_adc_writel(st, AT91_ADC_CHDR,
		AT91_ADC_CH(chan->channel));
		at91_adc_writel(st, AT91_ADC_IDR, st->registers->drdy_mask);

		st->last_value = 0;
		st->done = false;
		mutex_unlock(&st->lock);
		return IIO_VAL_INT;

		case IIO_CHAN_INFO_SCALE:
		val = (st->vref_mv 1000) >> chan->scan_type.realbits;
		*val2 = 0;
		return IIO_VAL_INT_PLUS_MICRO;
		default:
		break;
		}
		return -EINVAL;
		}

		static int at91_adc_probe_pdata(struct at91_adc_state *st,
		struct platform_device *pdev)
		{
		struct at91_adc_data *pdata = pdev->dev.platform_data;

		if (!pdata)
		return -EINVAL;

		st->use_external = pdata->use_external_triggers;
		st->vref_mv = pdata->vref;
		st->channels_mask = pdata->channels_used;
		st->num_channels = pdata->num_channels;
		st->startup_time = pdata->startup_time;
		st->trigger_number = pdata->trigger_number;
		st->trigger_list = pdata->trigger_list;
		st->registers = pdata->registers;

		return 0;
		}

		static const struct iio_info at91_adc_info = {
		.driver_module = THIS_MODULE,
		.read_raw = &at91_adc_read_raw,
		};

		static int __devinit at91_adc_probe(struct platform_device *pdev)
		{
		unsigned int prsc, mstrclk, ticks, adc_clk;
		int ret;
		struct iio_dev *idev;
		struct at91_adc_state *st;
		struct resource *res;

		idev = iio_device_alloc(sizeof(struct at91_adc_state));
		if (idev == NULL) {
		ret = -ENOMEM;
		goto error_ret;
		}

		st = iio_priv(idev);

		ret = at91_adc_probe_pdata(st, pdev);
		if (ret) {
		dev_err(&pdev->dev, "No platform data available.\n");
		ret = -EINVAL;
		goto error_free_device;
		}

		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
		if (!res) {
		dev_err(&pdev->dev, "No resource defined\n");
		ret = -ENXIO;
		goto error_ret;
		}

		platform_set_drvdata(pdev, idev);

		idev->dev.parent = &pdev->dev;
		idev->name = dev_name(&pdev->dev);
		idev->modes = INDIO_DIRECT_MODE;
		idev->info = &at91_adc_info;

		st->irq = platform_get_irq(pdev, 0);
		if (st->irq < 0) {
		dev_err(&pdev->dev, "No IRQ ID is designated\n");
		ret = -ENODEV;
		goto error_free_device;
		}

		if (!request_mem_region(res->start, resource_size(res),
		"AT91 adc registers")) {
		dev_err(&pdev->dev, "Resources are unavailable.\n");
		ret = -EBUSY;
		goto error_free_device;
		}

		st->reg_base = ioremap(res->start, resource_size(res));
		if (!st->reg_base) {
		dev_err(&pdev->dev, "Failed to map registers.\n");
		ret = -ENOMEM;
		goto error_release_mem;
		}

		/*
		* Disable all IRQs before setting up the handler
		*/
		at91_adc_writel(st, AT91_ADC_CR, AT91_ADC_SWRST);
		at91_adc_writel(st, AT91_ADC_IDR, 0xFFFFFFFF);
		ret = request_irq(st->irq,
		at91_adc_eoc_trigger,
		0,
		pdev->dev.driver->name,
		idev);
		if (ret) {
		dev_err(&pdev->dev, "Failed to allocate IRQ.\n");
		goto error_unmap_reg;
		}

		st->clk = clk_get(&pdev->dev, "adc_clk");
		if (IS_ERR(st->clk)) {
		dev_err(&pdev->dev, "Failed to get the clock.\n");
		ret = PTR_ERR(st->clk);
		goto error_free_irq;
		}

		ret = clk_prepare(st->clk);
		if (ret) {
		dev_err(&pdev->dev, "Could not prepare the clock.\n");
		goto error_free_clk;
		}

		ret = clk_enable(st->clk);
		if (ret) {
		dev_err(&pdev->dev, "Could not enable the clock.\n");
		goto error_unprepare_clk;
		}

		st->adc_clk = clk_get(&pdev->dev, "adc_op_clk");
		if (IS_ERR(st->adc_clk)) {
		dev_err(&pdev->dev, "Failed to get the ADC clock.\n");
		ret = PTR_ERR(st->clk);
		goto error_disable_clk;
		}

		ret = clk_prepare(st->adc_clk);
		if (ret) {
		dev_err(&pdev->dev, "Could not prepare the ADC clock.\n");
		goto error_free_adc_clk;
		}

		ret = clk_enable(st->adc_clk);
		if (ret) {
		dev_err(&pdev->dev, "Could not enable the ADC clock.\n");
		goto error_unprepare_adc_clk;
		}

		/*
		* Prescaler rate computation using the formula from the Atmel's
		* datasheet : ADC Clock = MCK / ((Prescaler + 1) * 2), ADC Clock being
		* specified by the electrical characteristics of the board.
		*/
		mstrclk = clk_get_rate(st->clk);
		adc_clk = clk_get_rate(st->adc_clk);
		prsc = (mstrclk / (2 * adc_clk)) - 1;

		if (!st->startup_time) {
		dev_err(&pdev->dev, "No startup time available.\n");
		ret = -EINVAL;
		goto error_disable_adc_clk;
		}

		/*
		* Number of ticks needed to cover the startup time of the ADC as
		* defined in the electrical characteristics of the board, divided by 8.
		* The formula thus is : Startup Time = (ticks + 1) * 8 / ADC Clock
		*/
		ticks = round_up((st->startup_time * adc_clk /
		1000000) - 1, 8) / 8;
		at91_adc_writel(st, AT91_ADC_MR,
		(AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) \|
		(AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));

		/* Setup the ADC channels available on the board */
		ret = at91_adc_channel_init(idev);
		if (ret < 0) {
		dev_err(&pdev->dev, "Couldn't initialize the channels.\n");
		goto error_disable_adc_clk;
		}

		init_waitqueue_head(&st->wq_data_avail);
		mutex_init(&st->lock);

		ret = at91_adc_buffer_init(idev);
		if (ret < 0) {
		dev_err(&pdev->dev, "Couldn't initialize the buffer.\n");
		goto error_disable_adc_clk;
		}

		ret = at91_adc_trigger_init(idev);
		if (ret < 0) {
		dev_err(&pdev->dev, "Couldn't setup the triggers.\n");
		goto error_unregister_buffer;
		}

		ret = iio_device_register(idev);
		if (ret < 0) {
		dev_err(&pdev->dev, "Couldn't register the device.\n");
		goto error_remove_triggers;
		}

		return 0;

		error_remove_triggers:
		at91_adc_trigger_remove(idev);
		error_unregister_buffer:
		at91_adc_buffer_remove(idev);
		error_disable_adc_clk:
		clk_disable(st->adc_clk);
		error_unprepare_adc_clk:
		clk_unprepare(st->adc_clk);
		error_free_adc_clk:
		clk_put(st->adc_clk);
		error_disable_clk:
		clk_disable(st->clk);
		error_unprepare_clk:
		clk_unprepare(st->clk);
		error_free_clk:
		clk_put(st->clk);
		error_free_irq:
		free_irq(st->irq, idev);
		error_unmap_reg:
		iounmap(st->reg_base);
		error_release_mem:
		release_mem_region(res->start, resource_size(res));
		error_free_device:
		iio_device_free(idev);
		error_ret:
		return ret;
		}

		static int __devexit at91_adc_remove(struct platform_device *pdev)
		{
		struct iio_dev *idev = platform_get_drvdata(pdev);
		struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
		struct at91_adc_state *st = iio_priv(idev);

		iio_device_unregister(idev);
		at91_adc_trigger_remove(idev);
		at91_adc_buffer_remove(idev);
		clk_disable_unprepare(st->adc_clk);
		clk_put(st->adc_clk);
		clk_disable(st->clk);
		clk_unprepare(st->clk);
		clk_put(st->clk);
		free_irq(st->irq, idev);
		iounmap(st->reg_base);
		release_mem_region(res->start, resource_size(res));
		iio_device_free(idev);

		return 0;
		}

		static struct platform_driver at91_adc_driver = {
		.probe = at91_adc_probe,
		.remove = __devexit_p(at91_adc_remove),
		.driver = {
		.name = "at91_adc",
		},
		};

		module_platform_driver(at91_adc_driver);

		MODULE_LICENSE("GPL");
		MODULE_DESCRIPTION("Atmel AT91 ADC Driver");
		MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");