staging:iio:adc: Add AD7791 driver

This patch adds support for the Analog Devices AD7787, AD7788, AD7789, AD7790
and AD7791 Sigma Delta Analog-to-Digital converters.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 473 insertions, 0 deletions

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a2c50713b0b6..d0ae71ec2aa0 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -18,6 +18,18 @@ config AD7266
           Say yes here to build support for Analog Devices AD7265 and AD7266
           ADCs.
 
+config AD7791
+        tristate "Analog Devices AD7791 ADC driver"
+        depends on SPI
+        select AD_SIGMA_DELTA
+        help
+          Say yes here to build support for Analog Devices AD7787, AD7788, AD7789,
+          AD7790 and AD7791 SPI analog to digital converters (ADC). If unsure, say
+          N (but it is safe to say "Y").
+
+          To compile this driver as a module, choose M here: the module will be
+          called ad7791.
+
 config AT91_ADC
         tristate "Atmel AT91 ADC"
         depends on ARCH_AT91
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 5989356c5735..f187ff6c2a16 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -4,4 +4,5 @@
 
 obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o
 obj-$(CONFIG_AD7266) += ad7266.o
+obj-$(CONFIG_AD7791) += ad7791.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
diff --git a/drivers/iio/adc/ad7791.c b/drivers/iio/adc/ad7791.c
new file mode 100644
index 000000000000..e93740843b2b
--- /dev/null
+++ b/drivers/iio/adc/ad7791.c
@@ -0,0 +1,460 @@
+/*
+ * AD7787/AD7788/AD7789/AD7790/AD7791 SPI ADC driver
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <lars@metafoo.de>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/spi/spi.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/adc/ad_sigma_delta.h>
+
+#include <linux/platform_data/ad7791.h>
+
+#define AD7791_REG_COMM                 0x0 /* For writes */
+#define AD7791_REG_STATUS               0x0 /* For reads */
+#define AD7791_REG_MODE                 0x1
+#define AD7791_REG_FILTER               0x2
+#define AD7791_REG_DATA                 0x3
+
+#define AD7791_MODE_CONTINUOUS          0x00
+#define AD7791_MODE_SINGLE              0x02
+#define AD7791_MODE_POWERDOWN           0x03
+
+#define AD7791_CH_AIN1P_AIN1N           0x00
+#define AD7791_CH_AIN2                  0x01
+#define AD7791_CH_AIN1N_AIN1N           0x02
+#define AD7791_CH_AVDD_MONITOR          0x03
+
+#define AD7791_FILTER_CLK_DIV_1         (0x0 << 4)
+#define AD7791_FILTER_CLK_DIV_2         (0x1 << 4)
+#define AD7791_FILTER_CLK_DIV_4         (0x2 << 4)
+#define AD7791_FILTER_CLK_DIV_8         (0x3 << 4)
+#define AD7791_FILTER_CLK_MASK          (0x3 << 4)
+#define AD7791_FILTER_RATE_120          0x0
+#define AD7791_FILTER_RATE_100          0x1
+#define AD7791_FILTER_RATE_33_3         0x2
+#define AD7791_FILTER_RATE_20           0x3
+#define AD7791_FILTER_RATE_16_6         0x4
+#define AD7791_FILTER_RATE_16_7         0x5
+#define AD7791_FILTER_RATE_13_3         0x6
+#define AD7791_FILTER_RATE_9_5          0x7
+#define AD7791_FILTER_RATE_MASK         0x7
+
+#define AD7791_MODE_BUFFER              BIT(1)
+#define AD7791_MODE_UNIPOLAR            BIT(2)
+#define AD7791_MODE_BURNOUT             BIT(3)
+#define AD7791_MODE_SEL_MASK            (0x3 << 6)
+#define AD7791_MODE_SEL(x)              ((x) << 6)
+
+#define DECLARE_AD7787_CHANNELS(name, bits, storagebits) \
+const struct iio_chan_spec name[] = { \
+        AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
+                (bits), (storagebits), 0), \
+        AD_SD_CHANNEL(1, 1, AD7791_CH_AIN2, (bits), (storagebits), 0), \
+        AD_SD_SHORTED_CHANNEL(2, 0, AD7791_CH_AIN1N_AIN1N, \
+                (bits), (storagebits), 0), \
+        AD_SD_SUPPLY_CHANNEL(3, 2, AD7791_CH_AVDD_MONITOR,  \
+                (bits), (storagebits), 0), \
+        IIO_CHAN_SOFT_TIMESTAMP(4), \
+}
+
+#define DECLARE_AD7791_CHANNELS(name, bits, storagebits) \
+const struct iio_chan_spec name[] = { \
+        AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
+                (bits), (storagebits), 0), \
+        AD_SD_SHORTED_CHANNEL(1, 0, AD7791_CH_AIN1N_AIN1N, \
+                (bits), (storagebits), 0), \
+        AD_SD_SUPPLY_CHANNEL(2, 1, AD7791_CH_AVDD_MONITOR, \
+                (bits), (storagebits), 0), \
+        IIO_CHAN_SOFT_TIMESTAMP(3), \
+}
+
+static DECLARE_AD7787_CHANNELS(ad7787_channels, 24, 32);
+static DECLARE_AD7791_CHANNELS(ad7790_channels, 16, 16);
+static DECLARE_AD7791_CHANNELS(ad7791_channels, 24, 32);
+
+enum {
+        AD7787,
+        AD7788,
+        AD7789,
+        AD7790,
+        AD7791,
+};
+
+enum ad7791_chip_info_flags {
+        AD7791_FLAG_HAS_FILTER          = (1 << 0),
+        AD7791_FLAG_HAS_BUFFER          = (1 << 1),
+        AD7791_FLAG_HAS_UNIPOLAR        = (1 << 2),
+        AD7791_FLAG_HAS_BURNOUT         = (1 << 3),
+};
+
+struct ad7791_chip_info {
+        const struct iio_chan_spec *channels;
+        unsigned int num_channels;
+        enum ad7791_chip_info_flags flags;
+};
+
+static const struct ad7791_chip_info ad7791_chip_infos[] = {
+        [AD7787] = {
+                .channels = ad7787_channels,
+                .num_channels = ARRAY_SIZE(ad7787_channels),
+                .flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
+                        AD7791_FLAG_HAS_UNIPOLAR | AD7791_FLAG_HAS_BURNOUT,
+        },
+        [AD7788] = {
+                .channels = ad7790_channels,
+                .num_channels = ARRAY_SIZE(ad7790_channels),
+                .flags = AD7791_FLAG_HAS_UNIPOLAR,
+        },
+        [AD7789] = {
+                .channels = ad7791_channels,
+                .num_channels = ARRAY_SIZE(ad7791_channels),
+                .flags = AD7791_FLAG_HAS_UNIPOLAR,
+        },
+        [AD7790] = {
+                .channels = ad7790_channels,
+                .num_channels = ARRAY_SIZE(ad7790_channels),
+                .flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
+                        AD7791_FLAG_HAS_BURNOUT,
+        },
+        [AD7791] = {
+                .channels = ad7791_channels,
+                .num_channels = ARRAY_SIZE(ad7791_channels),
+                .flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
+                        AD7791_FLAG_HAS_UNIPOLAR | AD7791_FLAG_HAS_BURNOUT,
+        },
+};
+
+struct ad7791_state {
+        struct ad_sigma_delta sd;
+        uint8_t mode;
+        uint8_t filter;
+
+        struct regulator *reg;
+        const struct ad7791_chip_info *info;
+};
+
+static struct ad7791_state *ad_sigma_delta_to_ad7791(struct ad_sigma_delta *sd)
+{
+        return container_of(sd, struct ad7791_state, sd);
+}
+
+static int ad7791_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
+{
+        ad_sd_set_comm(sd, channel);
+
+        return 0;
+}
+
+static int ad7791_set_mode(struct ad_sigma_delta *sd,
+        enum ad_sigma_delta_mode mode)
+{
+        struct ad7791_state *st = ad_sigma_delta_to_ad7791(sd);
+
+        switch (mode) {
+        case AD_SD_MODE_CONTINUOUS:
+                mode = AD7791_MODE_CONTINUOUS;
+                break;
+        case AD_SD_MODE_SINGLE:
+                mode = AD7791_MODE_SINGLE;
+                break;
+        case AD_SD_MODE_IDLE:
+        case AD_SD_MODE_POWERDOWN:
+                mode = AD7791_MODE_POWERDOWN;
+                break;
+        }
+
+        st->mode &= ~AD7791_MODE_SEL_MASK;
+        st->mode |= AD7791_MODE_SEL(mode);
+
+        return ad_sd_write_reg(sd, AD7791_REG_MODE, sizeof(st->mode), st->mode);
+}
+
+static const struct ad_sigma_delta_info ad7791_sigma_delta_info = {
+        .set_channel = ad7791_set_channel,
+        .set_mode = ad7791_set_mode,
+        .has_registers = true,
+        .addr_shift = 4,
+        .read_mask = BIT(3),
+};
+
+static int ad7791_read_raw(struct iio_dev *indio_dev,
+        const struct iio_chan_spec *chan, int *val, int *val2, long info)
+{
+        struct ad7791_state *st = iio_priv(indio_dev);
+        bool unipolar = !!(st->mode & AD7791_MODE_UNIPOLAR);
+        unsigned long long scale_pv;
+
+        switch (info) {
+        case IIO_CHAN_INFO_RAW:
+                return ad_sigma_delta_single_conversion(indio_dev, chan, val);
+        case IIO_CHAN_INFO_OFFSET:
+                /**
+                 * Unipolar: 0 to VREF
+                 * Bipolar -VREF to VREF
+                 **/
+                if (unipolar)
+                        *val = 0;
+                else
+                        *val = -(1 << (chan->scan_type.realbits - 1));
+                return IIO_VAL_INT;
+        case IIO_CHAN_INFO_SCALE:
+                /* The monitor channel uses an internal reference. */
+                if (chan->address == AD7791_CH_AVDD_MONITOR) {
+                        scale_pv = 5850000000000ULL;
+                } else {
+                        int voltage_uv;
+
+                        voltage_uv = regulator_get_voltage(st->reg);
+                        if (voltage_uv < 0)
+                                return voltage_uv;
+                        scale_pv = (unsigned long long)voltage_uv * 1000000;
+                }
+                if (unipolar)
+                        scale_pv >>= chan->scan_type.realbits;
+                else
+                        scale_pv >>= chan->scan_type.realbits - 1;
+                *val2 = do_div(scale_pv, 1000000000);
+                *val = scale_pv;
+
+                return IIO_VAL_INT_PLUS_NANO;
+        }
+
+        return -EINVAL;
+}
+
+static const char * const ad7791_sample_freq_avail[] = {
+        [AD7791_FILTER_RATE_120] = "120",
+        [AD7791_FILTER_RATE_100] = "100",
+        [AD7791_FILTER_RATE_33_3] = "33.3",
+        [AD7791_FILTER_RATE_20] = "20",
+        [AD7791_FILTER_RATE_16_6] = "16.6",
+        [AD7791_FILTER_RATE_16_7] = "16.7",
+        [AD7791_FILTER_RATE_13_3] = "13.3",
+        [AD7791_FILTER_RATE_9_5] = "9.5",
+};
+
+static ssize_t ad7791_read_frequency(struct device *dev,
+        struct device_attribute *attr, char *buf)
+{
+        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+        struct ad7791_state *st = iio_priv(indio_dev);
+        unsigned int rate = st->filter & AD7791_FILTER_RATE_MASK;
+
+        return sprintf(buf, "%s\n", ad7791_sample_freq_avail[rate]);
+}
+
+static ssize_t ad7791_write_frequency(struct device *dev,
+        struct device_attribute *attr, const char *buf, size_t len)
+{
+        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+        struct ad7791_state *st = iio_priv(indio_dev);
+        int i, ret;
+
+        mutex_lock(&indio_dev->mlock);
+        if (iio_buffer_enabled(indio_dev)) {
+                mutex_unlock(&indio_dev->mlock);
+                return -EBUSY;
+        }
+        mutex_unlock(&indio_dev->mlock);
+
+        ret = -EINVAL;
+
+        for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++) {
+                if (sysfs_streq(ad7791_sample_freq_avail[i], buf)) {
+
+                        mutex_lock(&indio_dev->mlock);
+                        st->filter &= ~AD7791_FILTER_RATE_MASK;
+                        st->filter |= i;
+                        ad_sd_write_reg(&st->sd, AD7791_REG_FILTER,
+                                         sizeof(st->filter), st->filter);
+                        mutex_unlock(&indio_dev->mlock);
+                        ret = 0;
+                        break;
+                }
+        }
+
+        return ret ? ret : len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
+                ad7791_read_frequency,
+                ad7791_write_frequency);
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("120 100 33.3 20 16.7 16.6 13.3 9.5");
+
+static struct attribute *ad7791_attributes[] = {
+        &iio_dev_attr_sampling_frequency.dev_attr.attr,
+        &iio_const_attr_sampling_frequency_available.dev_attr.attr,
+        NULL
+};
+
+static const struct attribute_group ad7791_attribute_group = {
+        .attrs = ad7791_attributes,
+};
+
+static const struct iio_info ad7791_info = {
+        .read_raw = &ad7791_read_raw,
+        .attrs = &ad7791_attribute_group,
+        .validate_trigger = ad_sd_validate_trigger,
+        .driver_module = THIS_MODULE,
+};
+
+static const struct iio_info ad7791_no_filter_info = {
+        .read_raw = &ad7791_read_raw,
+        .validate_trigger = ad_sd_validate_trigger,
+        .driver_module = THIS_MODULE,
+};
+
+static int __devinit ad7791_setup(struct ad7791_state *st,
+        struct ad7791_platform_data *pdata)
+{
+        /* Set to poweron-reset default values */
+        st->mode = AD7791_MODE_BUFFER;
+        st->filter = AD7791_FILTER_RATE_16_6;
+
+        if (!pdata)
+                return 0;
+
+        if ((st->info->flags & AD7791_FLAG_HAS_BUFFER) && !pdata->buffered)
+                st->mode &= ~AD7791_MODE_BUFFER;
+
+        if ((st->info->flags & AD7791_FLAG_HAS_BURNOUT) &&
+                pdata->burnout_current)
+                st->mode |= AD7791_MODE_BURNOUT;
+
+        if ((st->info->flags & AD7791_FLAG_HAS_UNIPOLAR) && pdata->unipolar)
+                st->mode |= AD7791_MODE_UNIPOLAR;
+
+        return ad_sd_write_reg(&st->sd, AD7791_REG_MODE, sizeof(st->mode),
+                st->mode);
+}
+
+static int __devinit ad7791_probe(struct spi_device *spi)
+{
+        struct ad7791_platform_data *pdata = spi->dev.platform_data;
+        struct iio_dev *indio_dev;
+        struct ad7791_state *st;
+        int ret;
+
+        if (!spi->irq) {
+                dev_err(&spi->dev, "Missing IRQ.\n");
+                return -ENXIO;
+        }
+
+        indio_dev = iio_device_alloc(sizeof(*st));
+        if (!indio_dev)
+                return -ENOMEM;
+
+        st = iio_priv(indio_dev);
+
+        st->reg = regulator_get(&spi->dev, "refin");
+        if (IS_ERR(st->reg)) {
+                ret = PTR_ERR(st->reg);
+                goto err_iio_free;
+        }
+
+        ret = regulator_enable(st->reg);
+        if (ret)
+                goto error_put_reg;
+
+        st->info = &ad7791_chip_infos[spi_get_device_id(spi)->driver_data];
+        ad_sd_init(&st->sd, indio_dev, spi, &ad7791_sigma_delta_info);
+
+        spi_set_drvdata(spi, indio_dev);
+
+        indio_dev->dev.parent = &spi->dev;
+        indio_dev->name = spi_get_device_id(spi)->name;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+        indio_dev->channels = st->info->channels;
+        indio_dev->num_channels = st->info->num_channels;
+        if (st->info->flags & AD7791_FLAG_HAS_FILTER)
+                indio_dev->info = &ad7791_info;
+        else
+                indio_dev->info = &ad7791_no_filter_info;
+
+        ret = ad_sd_setup_buffer_and_trigger(indio_dev);
+        if (ret)
+                goto error_disable_reg;
+
+        ret = ad7791_setup(st, pdata);
+        if (ret)
+                goto error_remove_trigger;
+
+        ret = iio_device_register(indio_dev);
+        if (ret)
+                goto error_remove_trigger;
+
+        return 0;
+
+error_remove_trigger:
+        ad_sd_cleanup_buffer_and_trigger(indio_dev);
+error_disable_reg:
+        regulator_disable(st->reg);
+error_put_reg:
+        regulator_put(st->reg);
+err_iio_free:
+        iio_device_free(indio_dev);
+
+        return ret;
+}
+
+static int __devexit ad7791_remove(struct spi_device *spi)
+{
+        struct iio_dev *indio_dev = spi_get_drvdata(spi);
+        struct ad7791_state *st = iio_priv(indio_dev);
+
+        iio_device_unregister(indio_dev);
+        ad_sd_cleanup_buffer_and_trigger(indio_dev);
+
+        regulator_disable(st->reg);
+        regulator_put(st->reg);
+
+        iio_device_free(indio_dev);
+
+        return 0;
+}
+
+static const struct spi_device_id ad7791_spi_ids[] = {
+        { "ad7787", AD7787 },
+        { "ad7788", AD7788 },
+        { "ad7789", AD7789 },
+        { "ad7790", AD7790 },
+        { "ad7791", AD7791 },
+        {}
+};
+MODULE_DEVICE_TABLE(spi, ad7791_spi_ids);
+
+static struct spi_driver ad7791_driver = {
+        .driver = {
+                .name   = "ad7791",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = ad7791_probe,
+        .remove         = __devexit_p(ad7791_remove),
+        .id_table       = ad7791_spi_ids,
+};
+module_spi_driver(ad7791_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("Analog Device AD7787/AD7788/AD7789/AD7790/AD7791 ADC driver");
+MODULE_LICENSE("GPL v2");