[PATCH v7 2/7] iio: adc: ad7380: new driver for AD7380 ADCs

Julien Stephan
2024-05-28T14:20:41Z

From: David Lechner <dlechner@baylibre.com>

This adds a new driver for the AD7380 family ADCs.

The driver currently implements basic support for the AD7380, AD7381,
2-channel differential ADCs. Support for additional single-ended,
pseudo-differential and 4-channel chips that use the same register map
as well as additional features of the chip will be added in future patches.

Co-developed-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
[Julien Stephan: add datasheet links of supported parts]
[Julien Stephan: fix rx/tx buffer for regmap access]
[Julien Stephan: fix scale issue]
[Julien Stephan: use the new iio_device_claim_direct_scoped
instead of iio_device_claim_direct_mode]
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
---
MAINTAINERS | 1 +
drivers/iio/adc/Kconfig | 16 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ad7380.c | 438 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 456 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 4f162600e982..315b3060946f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -435,6 +435,7 @@ S: Supported
W: https://wiki.analog.com/resources/tools-software/linux-drivers/iio-adc/ad738x
W: https://ez.analog.com/linux-software-drivers
F: Documentation/devicetree/bindings/iio/adc/adi,ad7380.yaml
+F: drivers/iio/adc/ad7380.c

AD7877 TOUCHSCREEN DRIVER
M: Michael Hennerich <michael.hennerich@analog.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 8db68b80b391..631386b037ae 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -155,6 +155,22 @@ config AD7298
To compile this driver as a module, choose M here: the
module will be called ad7298.

+config AD7380
+ tristate "Analog Devices AD7380 ADC driver"
+ depends on SPI_MASTER
+ select IIO_BUFFER
+ select IIO_TRIGGER
+ select IIO_TRIGGERED_BUFFER
+ help
+ AD7380 is a family of simultaneous sampling ADCs that share the same
+ SPI register map and have similar pinouts.
+
+ Say yes here to build support for Analog Devices AD7380 ADC and
+ similar chips.
+
+ To compile this driver as a module, choose M here: the module will be
+ called ad7380.
+
config AD7476
tristate "Analog Devices AD7476 1-channel ADCs driver and other similar devices from AD and TI"
depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index edb32ce2af02..bd3cbbb178fa 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_AD7291) += ad7291.o
obj-$(CONFIG_AD7292) += ad7292.o
obj-$(CONFIG_AD7298) += ad7298.o
obj-$(CONFIG_AD7923) += ad7923.o
+obj-$(CONFIG_AD7380) += ad7380.o
obj-$(CONFIG_AD7476) += ad7476.o
obj-$(CONFIG_AD7606_IFACE_PARALLEL) += ad7606_par.o
obj-$(CONFIG_AD7606_IFACE_SPI) += ad7606_spi.o
diff --git a/drivers/iio/adc/ad7380.c b/drivers/iio/adc/ad7380.c
new file mode 100644
index 000000000000..dac7e11755ff
--- /dev/null
+++ b/drivers/iio/adc/ad7380.c
@@ -0,0 +1,438 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices AD738x Simultaneous Sampling SAR ADCs
+ *
+ * Copyright 2017 Analog Devices Inc.
+ * Copyright 2024 BayLibre, SAS
+ *
+ * Datasheets of supported parts:
+ * ad7380/1 : https://www.analog.com/media/en/technical-documentation/data-sheets/AD7380-7381.pdf
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+/* 2.5V internal reference voltage */
+#define AD7380_INTERNAL_REF_MV 2500
+
+/* reading and writing registers is more reliable at lower than max speed */
+#define AD7380_REG_WR_SPEED_HZ 10000000
+
+#define AD7380_REG_WR BIT(15)
+#define AD7380_REG_REGADDR GENMASK(14, 12)
+#define AD7380_REG_DATA GENMASK(11, 0)
+
+#define AD7380_REG_ADDR_NOP 0x0
+#define AD7380_REG_ADDR_CONFIG1 0x1
+#define AD7380_REG_ADDR_CONFIG2 0x2
+#define AD7380_REG_ADDR_ALERT 0x3
+#define AD7380_REG_ADDR_ALERT_LOW_TH 0x4
+#define AD7380_REG_ADDR_ALERT_HIGH_TH 0x5
+
+#define AD7380_CONFIG1_OS_MODE BIT(9)
+#define AD7380_CONFIG1_OSR GENMASK(8, 6)
+#define AD7380_CONFIG1_CRC_W BIT(5)
+#define AD7380_CONFIG1_CRC_R BIT(4)
+#define AD7380_CONFIG1_ALERTEN BIT(3)
+#define AD7380_CONFIG1_RES BIT(2)
+#define AD7380_CONFIG1_REFSEL BIT(1)
+#define AD7380_CONFIG1_PMODE BIT(0)
+
+#define AD7380_CONFIG2_SDO2 GENMASK(9, 8)
+#define AD7380_CONFIG2_SDO BIT(8)
+#define AD7380_CONFIG2_RESET GENMASK(7, 0)
+
+#define AD7380_CONFIG2_RESET_SOFT 0x3C
+#define AD7380_CONFIG2_RESET_HARD 0xFF
+
+#define AD7380_ALERT_LOW_TH GENMASK(11, 0)
+#define AD7380_ALERT_HIGH_TH GENMASK(11, 0)
+
+struct ad7380_chip_info {
+ const char *name;
+ const struct iio_chan_spec *channels;
+ unsigned int num_channels;
+};
+
+#define AD7380_CHANNEL(index, bits) { \
+ .type = IIO_VOLTAGE, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .indexed = 1, \
+ .differential = 1, \
+ .channel = 2 * (index), \
+ .channel2 = 2 * (index) + 1, \
+ .scan_index = (index), \
+ .scan_type = { \
+ .sign = 's', \
+ .realbits = (bits), \
+ .storagebits = 16, \
+ .endianness = IIO_CPU, \
+ }, \
+}
+
+#define DEFINE_AD7380_2_CHANNEL(name, bits) \
+static const struct iio_chan_spec name[] = { \
+ AD7380_CHANNEL(0, bits), \
+ AD7380_CHANNEL(1, bits), \
+ IIO_CHAN_SOFT_TIMESTAMP(2), \
+}
+
+DEFINE_AD7380_2_CHANNEL(ad7380_channels, 16);
+DEFINE_AD7380_2_CHANNEL(ad7381_channels, 14);
+
+/* Since this is simultaneous sampling, we don't allow individual channels. */
+static const unsigned long ad7380_2_channel_scan_masks[] = {
+ GENMASK(1, 0),
+ 0
+};
+
+static const struct ad7380_chip_info ad7380_chip_info = {
+ .name = "ad7380",
+ .channels = ad7380_channels,
+ .num_channels = ARRAY_SIZE(ad7380_channels),
+};
+
+static const struct ad7380_chip_info ad7381_chip_info = {
+ .name = "ad7381",
+ .channels = ad7381_channels,
+ .num_channels = ARRAY_SIZE(ad7381_channels),
+};
+
+struct ad7380_state {
+ const struct ad7380_chip_info *chip_info;
+ struct spi_device *spi;
+ struct regmap *regmap;
+ unsigned int vref_mv;
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ * Make the buffer large enough for 2 16-bit samples and one 64-bit
+ * aligned 64 bit timestamp.
+ */
+ struct {
+ u16 raw[2];
+
+ s64 ts __aligned(8);
+ } scan_data __aligned(IIO_DMA_MINALIGN);
+ u16 tx;
+ u16 rx;
+};
+
+static int ad7380_regmap_reg_write(void *context, unsigned int reg,
+ unsigned int val)
+{
+ struct ad7380_state *st = context;
+ struct spi_transfer xfer = {
+ .speed_hz = AD7380_REG_WR_SPEED_HZ,
+ .bits_per_word = 16,
+ .len = 2,
+ .tx_buf = &st->tx,
+ };
+
+ st->tx = FIELD_PREP(AD7380_REG_WR, 1) |
+ FIELD_PREP(AD7380_REG_REGADDR, reg) |
+ FIELD_PREP(AD7380_REG_DATA, val);
+
+ return spi_sync_transfer(st->spi, &xfer, 1);
+}
+
+static int ad7380_regmap_reg_read(void *context, unsigned int reg,
+ unsigned int *val)
+{
+ struct ad7380_state *st = context;
+ struct spi_transfer xfers[] = {
+ {
+ .speed_hz = AD7380_REG_WR_SPEED_HZ,
+ .bits_per_word = 16,
+ .len = 2,
+ .tx_buf = &st->tx,
+ .cs_change = 1,
+ .cs_change_delay = {
+ .value = 10, /* t[CSH] */
+ .unit = SPI_DELAY_UNIT_NSECS,
+ },
+ }, {
+ .speed_hz = AD7380_REG_WR_SPEED_HZ,
+ .bits_per_word = 16,
+ .len = 2,
+ .rx_buf = &st->rx,
+ },
+ };
+ int ret;
+
+ st->tx = FIELD_PREP(AD7380_REG_WR, 0) |
+ FIELD_PREP(AD7380_REG_REGADDR, reg) |
+ FIELD_PREP(AD7380_REG_DATA, 0);
+
+ ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
+ if (ret < 0)
+ return ret;
+
+ *val = FIELD_GET(AD7380_REG_DATA, st->rx);
+
+ return 0;
+}
+
+static const struct regmap_config ad7380_regmap_config = {
+ .reg_bits = 3,
+ .val_bits = 12,
+ .reg_read = ad7380_regmap_reg_read,
+ .reg_write = ad7380_regmap_reg_write,
+ .max_register = AD7380_REG_ADDR_ALERT_HIGH_TH,
+ .can_sleep = true,
+};
+
+static int ad7380_debugfs_reg_access(struct iio_dev *indio_dev, u32 reg,
+ u32 writeval, u32 *readval)
+{
+ iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
+ struct ad7380_state *st = iio_priv(indio_dev);
+
+ if (readval)
+ return regmap_read(st->regmap, reg, readval);
+ else
+ return regmap_write(st->regmap, reg, writeval);
+ }
+ unreachable();
+}
+
+static irqreturn_t ad7380_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct ad7380_state *st = iio_priv(indio_dev);
+ struct spi_transfer xfer = {
+ .bits_per_word = st->chip_info->channels[0].scan_type.realbits,
+ .len = 4,
+ .rx_buf = st->scan_data.raw,
+ };
+ int ret;
+
+ ret = spi_sync_transfer(st->spi, &xfer, 1);
+ if (ret)
+ goto out;
+
+ iio_push_to_buffers_with_timestamp(indio_dev, &st->scan_data,
+ pf->timestamp);
+
+out:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static int ad7380_read_direct(struct ad7380_state *st,
+ struct iio_chan_spec const *chan, int *val)
+{
+ struct spi_transfer xfers[] = {
+ /* toggle CS (no data xfer) to trigger a conversion */
+ {
+ .speed_hz = AD7380_REG_WR_SPEED_HZ,
+ .bits_per_word = chan->scan_type.realbits,
+ .delay = {
+ .value = 190, /* t[CONVERT] */
+ .unit = SPI_DELAY_UNIT_NSECS,
+ },
+ .cs_change = 1,
+ .cs_change_delay = {
+ .value = 10, /* t[CSH] */
+ .unit = SPI_DELAY_UNIT_NSECS,
+ },
+ },
+ /* then read both channels */
+ {
+ .speed_hz = AD7380_REG_WR_SPEED_HZ,
+ .bits_per_word = chan->scan_type.realbits,
+ .rx_buf = st->scan_data.raw,
+ .len = 4,
+ },
+ };
+ int ret;
+
+ ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
+ if (ret < 0)
+ return ret;
+
+ *val = sign_extend32(st->scan_data.raw[chan->scan_index],
+ chan->scan_type.realbits - 1);
+
+ return IIO_VAL_INT;
+}
+
+static int ad7380_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long info)
+{
+ struct ad7380_state *st = iio_priv(indio_dev);
+
+ switch (info) {
+ case IIO_CHAN_INFO_RAW:
+ iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
+ return ad7380_read_direct(st, chan, val);
+ }
+ unreachable();
+ case IIO_CHAN_INFO_SCALE:
+ /*
+ * According to the datasheet, the LSB size for fully differential ADC is
+ * (2 × VREF) / 2^N, where N is the ADC resolution (i.e realbits)
+ */
+ *val = st->vref_mv;
+ *val2 = chan->scan_type.realbits - 1;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info ad7380_info = {
+ .read_raw = &ad7380_read_raw,
+ .debugfs_reg_access = &ad7380_debugfs_reg_access,
+};
+
+static int ad7380_init(struct ad7380_state *st, struct regulator *vref)
+{
+ int ret;
+
+ /* perform hard reset */
+ ret = regmap_update_bits(st->regmap, AD7380_REG_ADDR_CONFIG2,
+ AD7380_CONFIG2_RESET,
+ FIELD_PREP(AD7380_CONFIG2_RESET,
+ AD7380_CONFIG2_RESET_HARD));
+ if (ret < 0)
+ return ret;
+
+ /* select internal or external reference voltage */
+ ret = regmap_update_bits(st->regmap, AD7380_REG_ADDR_CONFIG1,
+ AD7380_CONFIG1_REFSEL,
+ FIELD_PREP(AD7380_CONFIG1_REFSEL,
+ vref ? 1 : 0));
+ if (ret < 0)
+ return ret;
+
+ /* SPI 1-wire mode */
+ return regmap_update_bits(st->regmap, AD7380_REG_ADDR_CONFIG2,
+ AD7380_CONFIG2_SDO,
+ FIELD_PREP(AD7380_CONFIG2_SDO, 1));
+}
+
+static void ad7380_regulator_disable(void *p)
+{
+ regulator_disable(p);
+}
+
+static int ad7380_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct ad7380_state *st;
+ struct regulator *vref;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ st->spi = spi;
+ st->chip_info = spi_get_device_match_data(spi);
+ if (!st->chip_info)
+ return dev_err_probe(&spi->dev, -EINVAL, "missing match data\n");
+
+ vref = devm_regulator_get_optional(&spi->dev, "refio");
+ if (IS_ERR(vref)) {
+ if (PTR_ERR(vref) != -ENODEV)
+ return dev_err_probe(&spi->dev, PTR_ERR(vref),
+ "Failed to get refio regulator\n");
+
+ vref = NULL;
+ }
+
+ /*
+ * If there is no REFIO supply, then it means that we are using
+ * the internal 2.5V reference, otherwise REFIO is reference voltage.
+ */
+ if (vref) {
+ ret = regulator_enable(vref);
+ if (ret)
+ return ret;
+
+ ret = devm_add_action_or_reset(&spi->dev,
+ ad7380_regulator_disable, vref);
+ if (ret)
+ return ret;
+
+ ret = regulator_get_voltage(vref);
+ if (ret < 0)
+ return ret;
+
+ st->vref_mv = ret / 1000;
+ } else {
+ st->vref_mv = AD7380_INTERNAL_REF_MV;
+ }
+
+ st->regmap = devm_regmap_init(&spi->dev, NULL, st, &ad7380_regmap_config);
+ if (IS_ERR(st->regmap))
+ return dev_err_probe(&spi->dev, PTR_ERR(st->regmap),
+ "failed to allocate register map\n");
+
+ indio_dev->channels = st->chip_info->channels;
+ indio_dev->num_channels = st->chip_info->num_channels;
+ indio_dev->name = st->chip_info->name;
+ indio_dev->info = &ad7380_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->available_scan_masks = ad7380_2_channel_scan_masks;
+
+ ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
+ iio_pollfunc_store_time,
+ ad7380_trigger_handler, NULL);
+ if (ret)
+ return ret;
+
+ ret = ad7380_init(st, vref);
+ if (ret)
+ return ret;
+
+ return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static const struct of_device_id ad7380_of_match_table[] = {
+ { .compatible = "adi,ad7380", .data = &ad7380_chip_info },
+ { .compatible = "adi,ad7381", .data = &ad7381_chip_info },
+ { }
+};
+
+static const struct spi_device_id ad7380_id_table[] = {
+ { "ad7380", (kernel_ulong_t)&ad7380_chip_info },
+ { "ad7381", (kernel_ulong_t)&ad7381_chip_info },
+ { }
+};
+MODULE_DEVICE_TABLE(spi, ad7380_id_table);
+
+static struct spi_driver ad7380_driver = {
+ .driver = {
+ .name = "ad7380",
+ .of_match_table = ad7380_of_match_table,
+ },
+ .probe = ad7380_probe,
+ .id_table = ad7380_id_table,
+};
+module_spi_driver(ad7380_driver);
+
+MODULE_AUTHOR("Stefan Popa <stefan.popa@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD738x ADC driver");
+MODULE_LICENSE("GPL");

--
2.44.0