iio:adc: Add AD7265/AD7266 support

This patch adds support for the Analog Devices AD7265 and AD7266
Analog-to-Digital converters.

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

3 files changed, 547 insertions, 0 deletions

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 4f7f584cfd61..8a78b4f3ef58 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -3,6 +3,16 @@
 #
 menu "Analog to digital converters"
 
+config AD7266
+        tristate "Analog Devices AD7265/AD7266 ADC driver"
+        depends on SPI_MASTER
+        select IIO_BUFFER
+        select IIO_TRIGGER
+        select IIO_TRIGGERED_BUFFER
+        help
+          Say yes here to build support for Analog Devices AD7265 and AD7266
+          ADCs.
+
 config AT91_ADC
         tristate "Atmel AT91 ADC"
         depends on ARCH_AT91
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 175c8d41ea99..52eec254c38c 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -2,4 +2,5 @@
 # Makefile for IIO ADC drivers
 #
 
+obj-$(CONFIG_AD7266) += ad7266.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
diff --git a/drivers/iio/adc/ad7266.c b/drivers/iio/adc/ad7266.c
new file mode 100644
index 000000000000..5c3f1ba5a06d
--- /dev/null
+++ b/drivers/iio/adc/ad7266.c
@@ -0,0 +1,536 @@
+/*
+ * AD7266/65 SPI ADC driver
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+
+#include <linux/interrupt.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#include <linux/platform_data/ad7266.h>
+
+struct ad7266_state {
+        struct spi_device       *spi;
+        struct regulator        *reg;
+        unsigned long           vref_uv;
+
+        struct spi_transfer     single_xfer[3];
+        struct spi_message      single_msg;
+
+        enum ad7266_range       range;
+        enum ad7266_mode        mode;
+        bool                    fixed_addr;
+        struct gpio             gpios[3];
+
+        /*
+         * DMA (thus cache coherency maintenance) requires the
+         * transfer buffers to live in their own cache lines.
+         * The buffer needs to be large enough to hold two samples (4 bytes) and
+         * the naturally aligned timestamp (8 bytes).
+         */
+        uint8_t data[ALIGN(4, sizeof(s64)) + sizeof(s64)] ____cacheline_aligned;
+};
+
+static int ad7266_wakeup(struct ad7266_state *st)
+{
+        /* Any read with >= 2 bytes will wake the device */
+        return spi_read(st->spi, st->data, 2);
+}
+
+static int ad7266_powerdown(struct ad7266_state *st)
+{
+        /* Any read with < 2 bytes will powerdown the device */
+        return spi_read(st->spi, st->data, 1);
+}
+
+static int ad7266_preenable(struct iio_dev *indio_dev)
+{
+        struct ad7266_state *st = iio_priv(indio_dev);
+        int ret;
+
+        ret = ad7266_wakeup(st);
+        if (ret)
+                return ret;
+
+        ret = iio_sw_buffer_preenable(indio_dev);
+        if (ret)
+                ad7266_powerdown(st);
+
+        return ret;
+}
+
+static int ad7266_postdisable(struct iio_dev *indio_dev)
+{
+        struct ad7266_state *st = iio_priv(indio_dev);
+        return ad7266_powerdown(st);
+}
+
+static const struct iio_buffer_setup_ops iio_triggered_buffer_setup_ops = {
+        .preenable = &ad7266_preenable,
+        .postenable = &iio_triggered_buffer_postenable,
+        .predisable = &iio_triggered_buffer_predisable,
+        .postdisable = &ad7266_postdisable,
+};
+
+static irqreturn_t ad7266_trigger_handler(int irq, void *p)
+{
+        struct iio_poll_func *pf = p;
+        struct iio_dev *indio_dev = pf->indio_dev;
+        struct iio_buffer *buffer = indio_dev->buffer;
+        struct ad7266_state *st = iio_priv(indio_dev);
+        int ret;
+
+        ret = spi_read(st->spi, st->data, 4);
+        if (ret == 0) {
+                if (indio_dev->scan_timestamp)
+                        ((s64 *)st->data)[1] = pf->timestamp;
+                iio_push_to_buffer(buffer, (u8 *)st->data, pf->timestamp);
+        }
+
+        iio_trigger_notify_done(indio_dev->trig);
+
+        return IRQ_HANDLED;
+}
+
+static void ad7266_select_input(struct ad7266_state *st, unsigned int nr)
+{
+        unsigned int i;
+
+        if (st->fixed_addr)
+                return;
+
+        switch (st->mode) {
+        case AD7266_MODE_SINGLE_ENDED:
+                nr >>= 1;
+                break;
+        case AD7266_MODE_PSEUDO_DIFF:
+                nr |= 1;
+                break;
+        case AD7266_MODE_DIFF:
+                nr &= ~1;
+                break;
+        }
+
+        for (i = 0; i < 3; ++i)
+                gpio_set_value(st->gpios[i].gpio, (bool)(nr & BIT(i)));
+}
+
+static int ad7266_update_scan_mode(struct iio_dev *indio_dev,
+        const unsigned long *scan_mask)
+{
+        struct ad7266_state *st = iio_priv(indio_dev);
+        unsigned int nr = find_first_bit(scan_mask, indio_dev->masklength);
+
+        ad7266_select_input(st, nr);
+
+        return 0;
+}
+
+static int ad7266_read_single(struct ad7266_state *st, int *val,
+        unsigned int address)
+{
+        int ret;
+
+        ad7266_select_input(st, address);
+
+        ret = spi_sync(st->spi, &st->single_msg);
+        *val = be16_to_cpu(st->data[address % 2]);
+
+        return ret;
+}
+
+static int ad7266_read_raw(struct iio_dev *indio_dev,
+        struct iio_chan_spec const *chan, int *val, int *val2, long m)
+{
+        struct ad7266_state *st = iio_priv(indio_dev);
+        unsigned long scale_uv;
+        int ret;
+
+        switch (m) {
+        case IIO_CHAN_INFO_RAW:
+                if (iio_buffer_enabled(indio_dev))
+                        return -EBUSY;
+
+                ret = ad7266_read_single(st, val, chan->address);
+                if (ret)
+                        return ret;
+
+                *val = (*val >> 2) & 0xfff;
+                if (chan->scan_type.sign == 's')
+                        *val = sign_extend32(*val, 11);
+
+                return IIO_VAL_INT;
+        case IIO_CHAN_INFO_SCALE:
+                scale_uv = (st->vref_uv * 100);
+                if (st->mode == AD7266_MODE_DIFF)
+                        scale_uv *= 2;
+                if (st->range == AD7266_RANGE_2VREF)
+                        scale_uv *= 2;
+
+                scale_uv >>= chan->scan_type.realbits;
+                *val =  scale_uv / 100000;
+                *val2 = (scale_uv % 100000) * 10;
+                return IIO_VAL_INT_PLUS_MICRO;
+        case IIO_CHAN_INFO_OFFSET:
+                if (st->range == AD7266_RANGE_2VREF &&
+                        st->mode != AD7266_MODE_DIFF)
+                        *val = 2048;
+                else
+                        *val = 0;
+                return IIO_VAL_INT;
+        }
+        return -EINVAL;
+}
+
+#define AD7266_CHAN(_chan, _sign) {                     \
+        .type = IIO_VOLTAGE,                            \
+        .indexed = 1,                                   \
+        .channel = (_chan),                             \
+        .address = (_chan),                             \
+        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT     \
+                | IIO_CHAN_INFO_SCALE_SHARED_BIT        \
+                | IIO_CHAN_INFO_OFFSET_SHARED_BIT,      \
+        .scan_index = (_chan),                          \
+        .scan_type = {                                  \
+                .sign = (_sign),                        \
+                .realbits = 12,                         \
+                .storagebits = 16,                      \
+                .shift = 2,                             \
+                .endianness = IIO_BE,                   \
+        },                                              \
+}
+
+#define AD7266_DECLARE_SINGLE_ENDED_CHANNELS(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_##_name[] = { \
+        AD7266_CHAN(0, (_sign)), \
+        AD7266_CHAN(1, (_sign)), \
+        AD7266_CHAN(2, (_sign)), \
+        AD7266_CHAN(3, (_sign)), \
+        AD7266_CHAN(4, (_sign)), \
+        AD7266_CHAN(5, (_sign)), \
+        AD7266_CHAN(6, (_sign)), \
+        AD7266_CHAN(7, (_sign)), \
+        AD7266_CHAN(8, (_sign)), \
+        AD7266_CHAN(9, (_sign)), \
+        AD7266_CHAN(10, (_sign)), \
+        AD7266_CHAN(11, (_sign)), \
+        IIO_CHAN_SOFT_TIMESTAMP(13), \
+}
+
+#define AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_##_name##_fixed[] = { \
+        AD7266_CHAN(0, (_sign)), \
+        AD7266_CHAN(1, (_sign)), \
+        IIO_CHAN_SOFT_TIMESTAMP(2), \
+}
+
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS(u, 'u');
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS(s, 's');
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(u, 'u');
+static AD7266_DECLARE_SINGLE_ENDED_CHANNELS_FIXED(s, 's');
+
+#define AD7266_CHAN_DIFF(_chan, _sign) {                        \
+        .type = IIO_VOLTAGE,                            \
+        .indexed = 1,                                   \
+        .channel = (_chan) * 2,                         \
+        .channel2 = (_chan) * 2 + 1,                    \
+        .address = (_chan),                             \
+        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT     \
+                | IIO_CHAN_INFO_SCALE_SHARED_BIT        \
+                | IIO_CHAN_INFO_OFFSET_SHARED_BIT,      \
+        .scan_index = (_chan),                          \
+        .scan_type = {                                  \
+                .sign = _sign,                  \
+                .realbits = 12,                         \
+                .storagebits = 16,                      \
+                .shift = 2,                             \
+                .endianness = IIO_BE,                   \
+        },                                              \
+        .differential = 1,                              \
+}
+
+#define AD7266_DECLARE_DIFF_CHANNELS(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_diff_##_name[] = { \
+        AD7266_CHAN_DIFF(0, (_sign)), \
+        AD7266_CHAN_DIFF(1, (_sign)), \
+        AD7266_CHAN_DIFF(2, (_sign)), \
+        AD7266_CHAN_DIFF(3, (_sign)), \
+        AD7266_CHAN_DIFF(4, (_sign)), \
+        AD7266_CHAN_DIFF(5, (_sign)), \
+        IIO_CHAN_SOFT_TIMESTAMP(6), \
+}
+
+static AD7266_DECLARE_DIFF_CHANNELS(s, 's');
+static AD7266_DECLARE_DIFF_CHANNELS(u, 'u');
+
+#define AD7266_DECLARE_DIFF_CHANNELS_FIXED(_name, _sign) \
+const struct iio_chan_spec ad7266_channels_diff_fixed_##_name[] = { \
+        AD7266_CHAN_DIFF(0, (_sign)), \
+        AD7266_CHAN_DIFF(1, (_sign)), \
+        IIO_CHAN_SOFT_TIMESTAMP(2), \
+}
+
+static AD7266_DECLARE_DIFF_CHANNELS_FIXED(s, 's');
+static AD7266_DECLARE_DIFF_CHANNELS_FIXED(u, 'u');
+
+static const struct iio_info ad7266_info = {
+        .read_raw = &ad7266_read_raw,
+        .update_scan_mode = &ad7266_update_scan_mode,
+        .driver_module = THIS_MODULE,
+};
+
+static unsigned long ad7266_available_scan_masks[] = {
+        0x003,
+        0x00c,
+        0x030,
+        0x0c0,
+        0x300,
+        0xc00,
+        0x000,
+};
+
+static unsigned long ad7266_available_scan_masks_diff[] = {
+        0x003,
+        0x00c,
+        0x030,
+        0x000,
+};
+
+static unsigned long ad7266_available_scan_masks_fixed[] = {
+        0x003,
+        0x000,
+};
+
+struct ad7266_chan_info {
+        const struct iio_chan_spec *channels;
+        unsigned int num_channels;
+        unsigned long *scan_masks;
+};
+
+#define AD7266_CHAN_INFO_INDEX(_differential, _signed, _fixed) \
+        (((_differential) << 2) | ((_signed) << 1) | ((_fixed) << 0))
+
+static const struct ad7266_chan_info ad7266_chan_infos[] = {
+        [AD7266_CHAN_INFO_INDEX(0, 0, 0)] = {
+                .channels = ad7266_channels_u,
+                .num_channels = ARRAY_SIZE(ad7266_channels_u),
+                .scan_masks = ad7266_available_scan_masks,
+        },
+        [AD7266_CHAN_INFO_INDEX(0, 0, 1)] = {
+                .channels = ad7266_channels_u_fixed,
+                .num_channels = ARRAY_SIZE(ad7266_channels_u_fixed),
+                .scan_masks = ad7266_available_scan_masks_fixed,
+        },
+        [AD7266_CHAN_INFO_INDEX(0, 1, 0)] = {
+                .channels = ad7266_channels_s,
+                .num_channels = ARRAY_SIZE(ad7266_channels_s),
+                .scan_masks = ad7266_available_scan_masks,
+        },
+        [AD7266_CHAN_INFO_INDEX(0, 1, 1)] = {
+                .channels = ad7266_channels_s_fixed,
+                .num_channels = ARRAY_SIZE(ad7266_channels_s_fixed),
+                .scan_masks = ad7266_available_scan_masks_fixed,
+        },
+        [AD7266_CHAN_INFO_INDEX(1, 0, 0)] = {
+                .channels = ad7266_channels_diff_u,
+                .num_channels = ARRAY_SIZE(ad7266_channels_diff_u),
+                .scan_masks = ad7266_available_scan_masks_diff,
+        },
+        [AD7266_CHAN_INFO_INDEX(1, 0, 1)] = {
+                .channels = ad7266_channels_diff_fixed_u,
+                .num_channels = ARRAY_SIZE(ad7266_channels_diff_fixed_u),
+                .scan_masks = ad7266_available_scan_masks_fixed,
+        },
+        [AD7266_CHAN_INFO_INDEX(1, 1, 0)] = {
+                .channels = ad7266_channels_diff_s,
+                .num_channels = ARRAY_SIZE(ad7266_channels_diff_s),
+                .scan_masks = ad7266_available_scan_masks_diff,
+        },
+        [AD7266_CHAN_INFO_INDEX(1, 1, 1)] = {
+                .channels = ad7266_channels_diff_fixed_s,
+                .num_channels = ARRAY_SIZE(ad7266_channels_diff_fixed_s),
+                .scan_masks = ad7266_available_scan_masks_fixed,
+        },
+};
+
+static void __devinit ad7266_init_channels(struct iio_dev *indio_dev)
+{
+        struct ad7266_state *st = iio_priv(indio_dev);
+        bool is_differential, is_signed;
+        const struct ad7266_chan_info *chan_info;
+        int i;
+
+        is_differential = st->mode != AD7266_MODE_SINGLE_ENDED;
+        is_signed = (st->range == AD7266_RANGE_2VREF) |
+                    (st->mode == AD7266_MODE_DIFF);
+
+        i = AD7266_CHAN_INFO_INDEX(is_differential, is_signed, st->fixed_addr);
+        chan_info = &ad7266_chan_infos[i];
+
+        indio_dev->channels = chan_info->channels;
+        indio_dev->num_channels = chan_info->num_channels;
+        indio_dev->available_scan_masks = chan_info->scan_masks;
+        indio_dev->masklength = chan_info->num_channels - 1;
+}
+
+static const char * const ad7266_gpio_labels[] = {
+        "AD0", "AD1", "AD2",
+};
+
+static int __devinit ad7266_probe(struct spi_device *spi)
+{
+        struct ad7266_platform_data *pdata = spi->dev.platform_data;
+        struct iio_dev *indio_dev;
+        struct ad7266_state *st;
+        unsigned int i;
+        int ret;
+
+        indio_dev = iio_device_alloc(sizeof(*st));
+        if (indio_dev == NULL)
+                return -ENOMEM;
+
+        st = iio_priv(indio_dev);
+
+        st->reg = regulator_get(&spi->dev, "vref");
+        if (!IS_ERR_OR_NULL(st->reg)) {
+                ret = regulator_enable(st->reg);
+                if (ret)
+                        goto error_put_reg;
+
+                st->vref_uv = regulator_get_voltage(st->reg);
+        } else {
+                /* Use internal reference */
+                st->vref_uv = 2500000;
+        }
+
+        if (pdata) {
+                st->fixed_addr = pdata->fixed_addr;
+                st->mode = pdata->mode;
+                st->range = pdata->range;
+
+                if (!st->fixed_addr) {
+                        for (i = 0; i < ARRAY_SIZE(st->gpios); ++i) {
+                                st->gpios[i].gpio = pdata->addr_gpios[i];
+                                st->gpios[i].flags = GPIOF_OUT_INIT_LOW;
+                                st->gpios[i].label = ad7266_gpio_labels[i];
+                        }
+                        ret = gpio_request_array(st->gpios,
+                                ARRAY_SIZE(st->gpios));
+                        if (ret)
+                                goto error_disable_reg;
+                }
+        } else {
+                st->fixed_addr = true;
+                st->range = AD7266_RANGE_VREF;
+                st->mode = AD7266_MODE_DIFF;
+        }
+
+        spi_set_drvdata(spi, indio_dev);
+        st->spi = spi;
+
+        indio_dev->dev.parent = &spi->dev;
+        indio_dev->name = spi_get_device_id(spi)->name;
+        indio_dev->modes = INDIO_DIRECT_MODE;
+        indio_dev->info = &ad7266_info;
+
+        ad7266_init_channels(indio_dev);
+
+        /* wakeup */
+        st->single_xfer[0].rx_buf = &st->data;
+        st->single_xfer[0].len = 2;
+        st->single_xfer[0].cs_change = 1;
+        /* conversion */
+        st->single_xfer[1].rx_buf = &st->data;
+        st->single_xfer[1].len = 4;
+        st->single_xfer[1].cs_change = 1;
+        /* powerdown */
+        st->single_xfer[2].tx_buf = &st->data;
+        st->single_xfer[2].len = 1;
+
+        spi_message_init(&st->single_msg);
+        spi_message_add_tail(&st->single_xfer[0], &st->single_msg);
+        spi_message_add_tail(&st->single_xfer[1], &st->single_msg);
+        spi_message_add_tail(&st->single_xfer[2], &st->single_msg);
+
+        ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,
+                &ad7266_trigger_handler, &iio_triggered_buffer_setup_ops);
+        if (ret)
+                goto error_free_gpios;
+
+        ret = iio_device_register(indio_dev);
+        if (ret)
+                goto error_buffer_cleanup;
+
+        return 0;
+
+error_buffer_cleanup:
+        iio_triggered_buffer_cleanup(indio_dev);
+error_free_gpios:
+        if (!st->fixed_addr)
+                gpio_free_array(st->gpios, ARRAY_SIZE(st->gpios));
+error_disable_reg:
+        if (!IS_ERR_OR_NULL(st->reg))
+                regulator_disable(st->reg);
+error_put_reg:
+        if (!IS_ERR_OR_NULL(st->reg))
+                regulator_put(st->reg);
+
+        iio_device_free(indio_dev);
+
+        return ret;
+}
+
+static int __devexit ad7266_remove(struct spi_device *spi)
+{
+        struct iio_dev *indio_dev = spi_get_drvdata(spi);
+        struct ad7266_state *st = iio_priv(indio_dev);
+
+        iio_device_unregister(indio_dev);
+        iio_triggered_buffer_cleanup(indio_dev);
+        if (!st->fixed_addr)
+                gpio_free_array(st->gpios, ARRAY_SIZE(st->gpios));
+        if (!IS_ERR_OR_NULL(st->reg)) {
+                regulator_disable(st->reg);
+                regulator_put(st->reg);
+        }
+        iio_device_free(indio_dev);
+
+        return 0;
+}
+
+static const struct spi_device_id ad7266_id[] = {
+        {"ad7265", 0},
+        {"ad7266", 0},
+        { }
+};
+MODULE_DEVICE_TABLE(spi, ad7266_id);
+
+static struct spi_driver ad7266_driver = {
+        .driver = {
+                .name   = "ad7266",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = ad7266_probe,
+        .remove         = __devexit_p(ad7266_remove),
+        .id_table       = ad7266_id,
+};
+module_spi_driver(ad7266_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("Analog Devices AD7266/65 ADC");
+MODULE_LICENSE("GPL v2");