This patch adds a 3-channel ADC driver for the LPC32xx ARM SoC
Signed-off-by: Roland Stigge <stigge@xxxxxxxxx>
Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx>
---
drivers/staging/iio/adc/Kconfig | 9 +
drivers/staging/iio/adc/Makefile | 1
drivers/staging/iio/adc/lpc32xx_adc.c | 237 ++++++++++++++++++++++++++++++++++
3 files changed, 247 insertions(+)
--- linux-2.6.orig/drivers/staging/iio/adc/Kconfig
+++ linux-2.6/drivers/staging/iio/adc/Kconfig
@@ -193,4 +193,13 @@ config MAX1363_RING_BUFFER
Say yes here to include ring buffer support in the MAX1363
ADC driver.
+config LPC32XX_ADC
+ tristate "NXP LPC32XX ADC"
+ depends on ARCH_LPC32XX && !TOUCHSCREEN_LPC32XX
+ help
+ Say yes here to build support for the integrated ADC inside the
+ LPC32XX SoC. Note that this feature uses the same hardware as the
+ touchscreen driver, so you can only select one of the two drivers
+ (lpc32xx_adc or lpc32xx_ts). Provides direct access via sysfs.
+
endmenu
--- linux-2.6.orig/drivers/staging/iio/adc/Makefile
+++ linux-2.6/drivers/staging/iio/adc/Makefile
@@ -37,3 +37,4 @@ obj-$(CONFIG_AD7192) += ad7192.o
obj-$(CONFIG_ADT7310) += adt7310.o
obj-$(CONFIG_ADT7410) += adt7410.o
obj-$(CONFIG_AD7280) += ad7280a.o
+obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
--- /dev/null
+++ linux-2.6/drivers/staging/iio/adc/lpc32xx_adc.c
@@ -0,0 +1,237 @@
+/*
+ * lpc32xx_adc.c - Support for ADC in LPC32XX
+ *
+ * 3-channel, 10-bit ADC
+ *
+ * Copyright (C) 2011, 2012 Roland Stigge <stigge@xxxxxxxxx>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/completion.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+
+/*
+ * LPC32XX registers definitions
+ */
+#define LPC32XX_ADC_SELECT(x) ((x) + 0x04)
+#define LPC32XX_ADC_CTRL(x) ((x) + 0x08)
+#define LPC32XX_ADC_VALUE(x) ((x) + 0x48)
+
+/* Bit definitions for LPC32XX_ADC_SELECT: */
+#define AD_REFm 0x00000200 /* constant, always write this value! */
+#define AD_REFp 0x00000080 /* constant, always write this value! */
+#define AD_IN 0x00000010 /* multiple of this is the */
+ /* channel number: 0, 1, 2 */
+#define AD_INTERNAL 0x00000004 /* constant, always write this value! */
+
+/* Bit definitions for LPC32XX_ADC_CTRL: */
+#define AD_STROBE 0x00000002
+#define AD_PDN_CTRL 0x00000004
+
+/* Bit definitions for LPC32XX_ADC_VALUE: */
+#define ADC_VALUE_MASK 0x000003FF
+
+#define MOD_NAME "lpc32xx-adc"
+
+struct lpc32xx_adc_info {
+ void __iomem *adc_base;
+ struct clk *clk;
+ struct completion completion;
+
+ u32 value;
+};
+
+static int lpc32xx_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct lpc32xx_adc_info *info = iio_priv(indio_dev);
+
+ if (mask == 0) {
+ mutex_lock(&indio_dev->mlock);
+ clk_enable(info->clk);
+ /* Measurement setup */
+ __raw_writel(AD_INTERNAL | (chan->address) | AD_REFp | AD_REFm,
+ LPC32XX_ADC_SELECT(info->adc_base));
+ /* Trigger conversion */
+ __raw_writel(AD_PDN_CTRL | AD_STROBE,
+ LPC32XX_ADC_CTRL(info->adc_base));
+ wait_for_completion(&info->completion); /* set by ISR */
+ clk_disable(info->clk);
+ *val = info->value;
+ mutex_unlock(&indio_dev->mlock);
+
+ return IIO_VAL_INT;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info lpc32xx_adc_iio_info = {
+ .read_raw = &lpc32xx_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+#define LPC32XX_ADC_CHANNEL(_index) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = _index, \
+ .address = AD_IN * _index, \
+ .scan_index = _index, \
+}
+
+static struct iio_chan_spec lpc32xx_adc_iio_channels[] = {
+ LPC32XX_ADC_CHANNEL(0),
+ LPC32XX_ADC_CHANNEL(1),
+ LPC32XX_ADC_CHANNEL(2),
+};
+
+static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id)
+{
+ struct lpc32xx_adc_info *info = (struct lpc32xx_adc_info *) dev_id;
+
+ /* Read value and clear irq */
+ info->value = __raw_readl(LPC32XX_ADC_VALUE(info->adc_base)) &
+ ADC_VALUE_MASK;
+ complete(&info->completion);
+
+ return IRQ_HANDLED;
+}
+
+static int __devinit lpc32xx_adc_probe(struct platform_device *pdev)
+{
+ struct lpc32xx_adc_info *info = NULL;
+ struct resource *res;
+ int retval = -ENODEV;
+ struct iio_dev *iodev = NULL;
+ int irq;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "failed to get platform I/O memory\n");
+ retval = -EBUSY;
+ goto errout1;
+ }
+
+ iodev = iio_allocate_device(sizeof(struct lpc32xx_adc_info));
+ if (!iodev) {
+ dev_err(&pdev->dev, "failed allocating iio device\n");
+ retval = -ENOMEM;
+ goto errout1;
+ }
+
+ info = iio_priv(iodev);
+
+ info->adc_base = ioremap(res->start, res->end - res->start + 1);
+ if (!info->adc_base) {
+ dev_err(&pdev->dev, "failed mapping memory\n");
+ retval = -EBUSY;
+ goto errout2;
+ }
+
+ info->clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(info->clk)) {
+ dev_err(&pdev->dev, "failed getting clock\n");
+ goto errout3;
+ }
+
+ irq = platform_get_irq(pdev, 0);
+ if ((irq < 0) || (irq >= NR_IRQS)) {
+ dev_err(&pdev->dev, "failed getting interrupt resource\n");
+ retval = -EINVAL;
+ goto errout4;
+ }
+
+ retval = request_irq(irq, lpc32xx_adc_isr, 0, MOD_NAME, info);
+ if (retval < 0) {
+ dev_err(&pdev->dev, "failed requesting interrupt\n");
+ goto errout4;
+ }
+
+ platform_set_drvdata(pdev, iodev);
+
+ init_completion(&info->completion);
+
+ iodev->name = MOD_NAME;
+ iodev->dev.parent = &pdev->dev;
+ iodev->info = &lpc32xx_adc_iio_info;
+ iodev->modes = INDIO_DIRECT_MODE;
+ iodev->channels = lpc32xx_adc_iio_channels;
+ iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels);
+
+ retval = iio_device_register(iodev);
+ if (retval)
+ goto errout5;
+
+ dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq);
+
+ return 0;
+
+errout5:
+ free_irq(irq, iodev);
+errout4:
+ clk_put(info->clk);
+errout3:
+ iounmap(info->adc_base);
+errout2:
+ iio_free_device(iodev);
+errout1:
+ return retval;
+}
+
+static int __devexit lpc32xx_adc_remove(struct platform_device *pdev)
+{
+ struct iio_dev *iodev = platform_get_drvdata(pdev);
+ struct lpc32xx_adc_info *info = iio_priv(iodev);
+ int irq = platform_get_irq(pdev, 0);
+
+ iio_device_unregister(iodev);
+ free_irq(irq, iodev);
+ platform_set_drvdata(pdev, NULL);
+ clk_put(info->clk);
+ iounmap(info->adc_base);
+ iio_free_device(iodev);
+
+ return 0;
+}
+
+static struct platform_driver lpc32xx_adc_driver = {
+ .probe = lpc32xx_adc_probe,
+ .remove = __devexit_p(lpc32xx_adc_remove),
+ .driver = {
+ .name = MOD_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+module_platform_driver(lpc32xx_adc_driver);
+
+MODULE_AUTHOR("Roland Stigge <stigge@xxxxxxxxx>");
+MODULE_DESCRIPTION("LPC32XX ADC driver");
+MODULE_LICENSE("GPL");
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