IIO : ADC: tiadc: Add support of TI's ADC driver

This patch adds support for TI's ADC driver.
This is a multifunctional device.
Analog input lines are provided on which
voltage measurements can be carried out.
You can have upto 8 input lines.

Signed-off-by: Patil, Rachna <rachna@ti.com>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 260 insertions, 0 deletions

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
new file mode 100644
index 00000000000..02a43c87a8a
--- /dev/null
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -0,0 +1,260 @@
+/*
+ * TI ADC MFD driver
+ *
+ * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/iio/iio.h>
+
+#include <linux/mfd/ti_am335x_tscadc.h>
+#include <linux/platform_data/ti_am335x_adc.h>
+
+struct tiadc_device {
+	struct ti_tscadc_dev *mfd_tscadc;
+	int channels;
+};
+
+static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
+{
+	return readl(adc->mfd_tscadc->tscadc_base + reg);
+}
+
+static void tiadc_writel(struct tiadc_device *adc, unsigned int reg,
+					unsigned int val)
+{
+	writel(val, adc->mfd_tscadc->tscadc_base + reg);
+}
+
+static void tiadc_step_config(struct tiadc_device *adc_dev)
+{
+	unsigned int stepconfig;
+	int i, channels = 0, steps;
+
+	/*
+	 * There are 16 configurable steps and 8 analog input
+	 * lines available which are shared between Touchscreen and ADC.
+	 *
+	 * Steps backwards i.e. from 16 towards 0 are used by ADC
+	 * depending on number of input lines needed.
+	 * Channel would represent which analog input
+	 * needs to be given to ADC to digitalize data.
+	 */
+
+	steps = TOTAL_STEPS - adc_dev->channels;
+	channels = TOTAL_CHANNELS - adc_dev->channels;
+
+	stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
+
+	for (i = (steps + 1); i <= TOTAL_STEPS; i++) {
+		tiadc_writel(adc_dev, REG_STEPCONFIG(i),
+				stepconfig | STEPCONFIG_INP(channels));
+		tiadc_writel(adc_dev, REG_STEPDELAY(i),
+				STEPCONFIG_OPENDLY);
+		channels++;
+	}
+	tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB);
+}
+
+static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
+{
+	struct iio_chan_spec *chan_array;
+	int i;
+
+	indio_dev->num_channels = channels;
+	chan_array = kcalloc(indio_dev->num_channels,
+			sizeof(struct iio_chan_spec), GFP_KERNEL);
+
+	if (chan_array == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < (indio_dev->num_channels); i++) {
+		struct iio_chan_spec *chan = chan_array + i;
+		chan->type = IIO_VOLTAGE;
+		chan->indexed = 1;
+		chan->channel = i;
+		chan->info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT;
+	}
+
+	indio_dev->channels = chan_array;
+
+	return indio_dev->num_channels;
+}
+
+static void tiadc_channels_remove(struct iio_dev *indio_dev)
+{
+	kfree(indio_dev->channels);
+}
+
+static int tiadc_read_raw(struct iio_dev *indio_dev,
+		struct iio_chan_spec const *chan,
+		int *val, int *val2, long mask)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	int i;
+	unsigned int fifo1count, readx1;
+
+	/*
+	 * When the sub-system is first enabled,
+	 * the sequencer will always start with the
+	 * lowest step (1) and continue until step (16).
+	 * For ex: If we have enabled 4 ADC channels and
+	 * currently use only 1 out of them, the
+	 * sequencer still configures all the 4 steps,
+	 * leading to 3 unwanted data.
+	 * Hence we need to flush out this data.
+	 */
+
+	fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+	for (i = 0; i < fifo1count; i++) {
+		readx1 = tiadc_readl(adc_dev, REG_FIFO1);
+		if (i == chan->channel)
+			*val = readx1 & 0xfff;
+	}
+	tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB);
+
+	return IIO_VAL_INT;
+}
+
+static const struct iio_info tiadc_info = {
+	.read_raw = &tiadc_read_raw,
+};
+
+static int __devinit tiadc_probe(struct platform_device *pdev)
+{
+	struct iio_dev		*indio_dev;
+	struct tiadc_device	*adc_dev;
+	struct ti_tscadc_dev	*tscadc_dev = pdev->dev.platform_data;
+	struct mfd_tscadc_board	*pdata;
+	int			err;
+
+	pdata = tscadc_dev->dev->platform_data;
+	if (!pdata || !pdata->adc_init) {
+		dev_err(&pdev->dev, "Could not find platform data\n");
+		return -EINVAL;
+	}
+
+	indio_dev = iio_device_alloc(sizeof(struct tiadc_device));
+	if (indio_dev == NULL) {
+		dev_err(&pdev->dev, "failed to allocate iio device\n");
+		err = -ENOMEM;
+		goto err_ret;
+	}
+	adc_dev = iio_priv(indio_dev);
+
+	adc_dev->mfd_tscadc = tscadc_dev;
+	adc_dev->channels = pdata->adc_init->adc_channels;
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &tiadc_info;
+
+	tiadc_step_config(adc_dev);
+
+	err = tiadc_channel_init(indio_dev, adc_dev->channels);
+	if (err < 0)
+		goto err_free_device;
+
+	err = iio_device_register(indio_dev);
+	if (err)
+		goto err_free_channels;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	return 0;
+
+err_free_channels:
+	tiadc_channels_remove(indio_dev);
+err_free_device:
+	iio_device_free(indio_dev);
+err_ret:
+	return err;
+}
+
+static int __devexit tiadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+
+	iio_device_unregister(indio_dev);
+	tiadc_channels_remove(indio_dev);
+
+	iio_device_free(indio_dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int tiadc_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct ti_tscadc_dev *tscadc_dev = dev->platform_data;
+	unsigned int idle;
+
+	if (!device_may_wakeup(tscadc_dev->dev)) {
+		idle = tiadc_readl(adc_dev, REG_CTRL);
+		idle &= ~(CNTRLREG_TSCSSENB);
+		tiadc_writel(adc_dev, REG_CTRL, (idle |
+				CNTRLREG_POWERDOWN));
+	}
+
+	return 0;
+}
+
+static int tiadc_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	unsigned int restore;
+
+	/* Make sure ADC is powered up */
+	restore = tiadc_readl(adc_dev, REG_CTRL);
+	restore &= ~(CNTRLREG_POWERDOWN);
+	tiadc_writel(adc_dev, REG_CTRL, restore);
+
+	tiadc_step_config(adc_dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops tiadc_pm_ops = {
+	.suspend = tiadc_suspend,
+	.resume = tiadc_resume,
+};
+#define TIADC_PM_OPS (&tiadc_pm_ops)
+#else
+#define TIADC_PM_OPS NULL
+#endif
+
+static struct platform_driver tiadc_driver = {
+	.driver = {
+		.name   = "tiadc",
+		.owner	= THIS_MODULE,
+		.pm	= TIADC_PM_OPS,
+	},
+	.probe	= tiadc_probe,
+	.remove	= __devexit_p(tiadc_remove),
+};
+
+module_platform_driver(tiadc_driver);
+
+MODULE_DESCRIPTION("TI ADC controller driver");
+MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
+MODULE_LICENSE("GPL");