[PATCH 2/2] iio: adc: ti-ads1298: Add driver

From: Mike Looijmans
Date: Wed Dec 13 2023 - 04:47:51 EST

Skeleton driver for the TI ADS1298 medical ADC. This device is
typically used for ECG and similar measurements. Supports data
acquisition at configurable scale and sampling frequency.

Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx>

---

drivers/iio/adc/Kconfig | 12 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-ads1298.c | 740 +++++++++++++++++++++++++++++++++++
3 files changed, 753 insertions(+)
create mode 100644 drivers/iio/adc/ti-ads1298.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 35f9867da12c..57ccbf347828 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1318,6 +1318,18 @@ config TI_ADS8688
This driver can also be built as a module. If so, the module will be
called ti-ads8688.

+config TI_ADS1298
+ tristate "Texas Instruments ADS1298"
+ depends on SPI
+ select IIO_BUFFER
+ default y
+ help
+ If you say yes here you get support for Texas Instruments ADS1298
+ medical ADC chips
+
+ This driver can also be built as a module. If so, the module will be
+ called ti-ads1298.
+
config TI_ADS124S08
tristate "Texas Instruments ADS124S08"
depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index bee11d442af4..ff0e3633eded 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -117,6 +117,7 @@ obj-$(CONFIG_TI_ADS7924) += ti-ads7924.o
obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
+obj-$(CONFIG_TI_ADS1298) += ti-ads1298.o
obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o
obj-$(CONFIG_TI_ADS131E08) += ti-ads131e08.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
diff --git a/drivers/iio/adc/ti-ads1298.c b/drivers/iio/adc/ti-ads1298.c
new file mode 100644
index 000000000000..54466285063f
--- /dev/null
+++ b/drivers/iio/adc/ti-ads1298.c
@@ -0,0 +1,740 @@
+// SPDX-License-Identifier: GPL-2.0
+/* TI ADS1298 chip family driver
+ * Copyright (C) 2023 Topic Embedded Products
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/iio/sysfs.h>
+
+#include <asm/unaligned.h>
+
+#define ADS1298_WAKEUP 0x02
+#define ADS1298_STANDBY 0x04
+#define ADS1298_RESET 0x06
+#define ADS1298_START 0x08
+#define ADS1298_STOP 0x0A
+#define ADS1298_RDATAC 0x10
+#define ADS1298_SDATAC 0x11
+#define ADS1298_RDATA 0x12
+
+/* Commands */
+#define ADS1298_CMD_WAKEUP 0x02
+#define ADS1298_CMD_STANDBY 0x04
+#define ADS1298_CMD_RESET 0x06
+#define ADS1298_CMD_START 0x08
+#define ADS1298_CMD_STOP 0x0a
+#define ADS1298_CMD_RDATAC 0x10
+#define ADS1298_CMD_SDATAC 0x11
+#define ADS1298_CMD_RDATA 0x12
+#define ADS1298_CMD_RREG 0x20
+#define ADS1298_CMD_WREG 0x40
+
+/* Registers */
+#define ADS1298_REG_ID 0x00
+#define ADS1298_REG_CONFIG1 0x01
+#define ADS1298_MASK_CONFIG1_HR BIT(7)
+#define ADS1298_MASK_CONFIG1_DR 0x07
+#define ADS1298_REG_CONFIG2 0x02
+#define ADS1298_MASK_CONFIG2_RESERVED BIT(6)
+#define ADS1298_MASK_CONFIG2_WCT_CHOP BIT(5)
+#define ADS1298_MASK_CONFIG2_INT_TEST BIT(4)
+#define ADS1298_MASK_CONFIG2_TEST_AMP BIT(2)
+#define ADS1298_MASK_CONFIG2_TEST_FREQ_DC GENMASK(1, 0)
+#define ADS1298_MASK_CONFIG2_TEST_FREQ_SLOW 0
+#define ADS1298_MASK_CONFIG2_TEST_FREQ_FAST BIT(0)
+#define ADS1298_REG_CONFIG3 0x03
+#define ADS1298_MASK_CONFIG3_PWR_REFBUF BIT(7)
+#define ADS1298_MASK_CONFIG3_RESERVED BIT(6)
+#define ADS1298_MASK_CONFIG3_VREF_4V BIT(5)
+#define ADS1298_REG_LOFF 0x04
+#define ADS1298_REG_CHnSET(n) (0x05 + n)
+#define ADS1298_MASK_CH_PD BIT(7)
+#define ADS1298_MASK_CH_PGA GENMASK(6, 4)
+#define ADS1298_MASK_CH_MUX GENMASK(2, 0)
+#define ADS1298_REG_LOFF_STATP 0x12
+#define ADS1298_REG_LOFF_STATN 0x13
+
+#define ADS1298_REG_CONFIG4 0x17
+#define ADS1298_MASK_CONFIG4_SINGLE_SHOT BIT(3)
+#define ADS1298_REG_WCT1 0x18
+#define ADS1298_REG_WCT2 0x19
+
+#define ADS1298_MAX_CHANNELS 8
+#define ADS1298_CLK_RATE 2048000
+/*
+ * Read/write register commands require 4 clocks to decode, for speeds above
+ * 2x the clock rate, this would require extra time between the command byte and
+ * the data. Much simpler is to just limit the SPI transfer speed while doing
+ * register access.
+ */
+#define ADS1298_SPI_BUS_SPEED_SLOW ADS1298_CLK_RATE
+/* For reading and writing registers, we need a 3-byte buffer */
+#define ADS1298_SPI_CMD_BUFFER_SIZE 3
+/* Outputs status word and 8 samples of 24 bits each, plus the command byte */
+#define ADS1298_SPI_RDATA_BUFFER_SIZE ((ADS1298_MAX_CHANNELS + 1) * 3 + 1)
+
+struct ads1298_private {
+ const struct ads1298_chip_info *chip_info;
+ struct spi_device *spi;
+ struct regulator *reg_avdd;
+ struct regulator *reg_vref;
+ struct clk *clk;
+ struct regmap *regmap;
+ struct completion completion;
+ struct iio_trigger *trig;
+ struct spi_transfer rdata_xfer;
+ struct spi_message rdata_msg;
+ spinlock_t irq_busy_lock; /* Handshake between SPI and DRDY irqs */
+ bool rdata_xfer_busy;
+
+ /* Temporary storage for demuxing data after SPI transfer */
+ u8 bounce_buffer[ADS1298_MAX_CHANNELS * 4];
+
+ /* For synchronous SPI exchanges (read/write registers) */
+ u8 cmd_buffer[ADS1298_SPI_CMD_BUFFER_SIZE] ____cacheline_aligned;
+
+ /* Buffer used for incoming SPI data */
+ u8 rx_buffer[ADS1298_SPI_RDATA_BUFFER_SIZE] ____cacheline_aligned;
+ /* Contains the RDATA command and zeroes to clock out */
+ u8 tx_buffer[ADS1298_SPI_RDATA_BUFFER_SIZE] ____cacheline_aligned;
+};
+
+#define ADS1298_CHAN(index) \
+{ \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = index, \
+ .address = 3 * index + 4, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_SCALE), \
+ .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+ BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
+ .scan_index = index, \
+ .scan_type = { \
+ .sign = 's', \
+ .realbits = 24, \
+ .storagebits = 32, \
+ .endianness = IIO_BE, \
+ }, \
+}
+
+static const struct iio_chan_spec ads1298_channels[] = {
+ ADS1298_CHAN(0),
+ ADS1298_CHAN(1),
+ ADS1298_CHAN(2),
+ ADS1298_CHAN(3),
+ ADS1298_CHAN(4),
+ ADS1298_CHAN(5),
+ ADS1298_CHAN(6),
+ ADS1298_CHAN(7),
+};
+
+static int ads1298_write_cmd(struct ads1298_private *priv, u8 command)
+{
+ struct spi_transfer cmd_xfer = {
+ .tx_buf = priv->cmd_buffer,
+ .rx_buf = priv->cmd_buffer,
+ .len = 1,
+ .speed_hz = ADS1298_SPI_BUS_SPEED_SLOW,
+ .delay.value = 2,
+ .delay.unit = SPI_DELAY_UNIT_USECS,
+ };
+
+ priv->cmd_buffer[0] = command;
+
+ return spi_sync_transfer(priv->spi, &cmd_xfer, 1);
+}
+
+static int ads1298_read_one(struct ads1298_private *priv, int chan_index)
+{
+ int ret;
+
+ /* Enable the channel */
+ ret = regmap_update_bits(priv->regmap, ADS1298_REG_CHnSET(chan_index),
+ ADS1298_MASK_CH_PD, 0);
+ if (ret)
+ return ret;
+
+ /* Enable single-shot mode, so we don't need to send a STOP */
+ ret = regmap_update_bits(priv->regmap, ADS1298_REG_CONFIG4,
+ ADS1298_MASK_CONFIG4_SINGLE_SHOT,
+ ADS1298_MASK_CONFIG4_SINGLE_SHOT);
+ if (ret)
+ return ret;
+
+ reinit_completion(&priv->completion);
+
+ ret = ads1298_write_cmd(priv, ADS1298_CMD_START);
+ if (ret < 0) {
+ dev_err(&priv->spi->dev, "CMD_START error: %d\n", ret);
+ return ret;
+ }
+
+ /* Cannot take longer than 40ms (250Hz) */
+ ret = wait_for_completion_timeout(&priv->completion,
+ msecs_to_jiffies(50));
+ if (!ret)
+ return -ETIMEDOUT;
+
+ return 0;
+}
+
+static int ads1298_get_samp_freq(struct ads1298_private *priv, int *val)
+{
+ unsigned long rate;
+ int ret;
+ unsigned int cfg;
+
+ ret = regmap_read(priv->regmap, ADS1298_REG_CONFIG1, &cfg);
+ if (ret)
+ return ret;
+
+ if (priv->clk)
+ rate = clk_get_rate(priv->clk);
+ else
+ rate = ADS1298_CLK_RATE;
+ if (!rate)
+ return -EINVAL;
+
+ if (cfg & ADS1298_MASK_CONFIG1_HR)
+ rate >>= 6; /* HR mode */
+ else
+ rate >>= 7; /* LP mode */
+
+ *val = rate >> (cfg & ADS1298_MASK_CONFIG1_DR);
+
+ return IIO_VAL_INT;
+}
+
+static int ads1298_set_samp_freq(struct ads1298_private *priv, int val)
+{
+ unsigned long rate;
+ unsigned int factor;
+ unsigned int cfg;
+
+ if (priv->clk)
+ rate = clk_get_rate(priv->clk);
+ else
+ rate = ADS1298_CLK_RATE;
+ if (!rate)
+ return -EINVAL;
+
+ factor = (rate >> 6) / val;
+ if (factor >= 128) {
+ cfg = 0x06; /* Lowest frequency possible, must use LR mode */
+ } else if (factor <= 1) {
+ cfg = ADS1298_MASK_CONFIG1_HR; /* Fastest possible */
+ } else {
+ cfg = fls(factor) - 1;
+ cfg |= ADS1298_MASK_CONFIG1_HR; /* Use HR mode */
+ }
+
+ return regmap_update_bits(priv->regmap, ADS1298_REG_CONFIG1,
+ ADS1298_MASK_CONFIG1_HR | ADS1298_MASK_CONFIG1_DR,
+ cfg);
+}
+
+static const u8 ads1298_pga_settings[] = { 6, 1, 2, 3, 4, 8, 12 };
+
+static int ads1298_get_scale(struct ads1298_private *priv,
+ int channel, int *val, int *val2)
+{
+ int ret;
+ unsigned int regval;
+ u8 gain;
+
+ if (priv->reg_vref) {
+ ret = regulator_get_voltage(priv->reg_vref);
+ if (ret < 0)
+ return ret;
+
+ *val = ret / 1000; /* Convert to millivolts */
+ } else {
+ ret = regmap_read(priv->regmap, ADS1298_REG_CONFIG3, &regval);
+ if (ret)
+ return ret;
+
+ /* Refererence in millivolts */
+ *val = regval & ADS1298_MASK_CONFIG3_VREF_4V ? 4000 : 2400;
+ }
+
+ ret = regmap_read(priv->regmap, ADS1298_REG_CHnSET(channel), &regval);
+ if (ret)
+ return ret;
+
+ gain = ads1298_pga_settings[FIELD_GET(ADS1298_MASK_CH_PGA, regval)];
+ *val /= gain; /* Full scale is VREF / gain */
+
+ *val2 = 23; /* Signed 24-bit, max amplitude is 2^23 */
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+}
+
+
+static int ads1298_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ /* When busy, just peek in the buffer */
+ if (!iio_buffer_enabled(indio_dev)) {
+ ret = ads1298_read_one(priv, chan->scan_index);
+ if (ret)
+ return ret;
+ }
+ *val = sign_extend32(get_unaligned_be24(
+ priv->rx_buffer + chan->address), 23);
+ ret = IIO_VAL_INT;
+ break;
+ case IIO_CHAN_INFO_SCALE:
+ ret = ads1298_get_scale(priv, chan->channel, val, val2);
+ break;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ ret = ads1298_get_samp_freq(priv, val);
+ break;
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ ret = regmap_read(priv->regmap, ADS1298_REG_CONFIG1, val);
+ if (!ret) {
+ ret = IIO_VAL_INT;
+ *val = (16 << (*val & ADS1298_MASK_CONFIG1_DR));
+ }
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+static int ads1298_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ ret = ads1298_set_samp_freq(priv, val);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+static int ads1298_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+ struct ads1298_private *priv = context;
+ struct spi_transfer reg_write_xfer = {
+ .tx_buf = priv->cmd_buffer,
+ .rx_buf = priv->cmd_buffer,
+ .len = 3,
+ .speed_hz = ADS1298_SPI_BUS_SPEED_SLOW,
+ .delay.value = 2,
+ .delay.unit = SPI_DELAY_UNIT_USECS,
+ };
+
+ priv->cmd_buffer[0] = ADS1298_CMD_WREG | reg;
+ priv->cmd_buffer[1] = 0x0;
+ priv->cmd_buffer[2] = val;
+
+ return spi_sync_transfer(priv->spi, &reg_write_xfer, 1);
+}
+
+static int ads1298_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+ struct ads1298_private *priv = context;
+ struct spi_transfer reg_read_xfer = {
+ .tx_buf = priv->cmd_buffer,
+ .rx_buf = priv->cmd_buffer,
+ .len = 3,
+ .speed_hz = ADS1298_SPI_BUS_SPEED_SLOW,
+ .delay.value = 2,
+ .delay.unit = SPI_DELAY_UNIT_USECS,
+ };
+ int ret;
+
+ priv->cmd_buffer[0] = ADS1298_CMD_RREG | reg;
+ priv->cmd_buffer[1] = 0x0;
+ priv->cmd_buffer[2] = 0;
+
+ ret = spi_sync_transfer(priv->spi, &reg_read_xfer, 1);
+ if (ret)
+ return ret;
+
+ *val = priv->cmd_buffer[2];
+
+ return 0;
+}
+
+static int ads1298_reg_access(struct iio_dev *indio_dev, unsigned int reg,
+ unsigned int writeval, unsigned int *readval)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+
+ if (!readval)
+ return regmap_write(priv->regmap, reg, writeval);
+
+ return regmap_read(priv->regmap, reg, readval);
+}
+
+static int ads1298_update_scan_mode(struct iio_dev *indio_dev,
+ const unsigned long *scan_mask)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ int i;
+
+ /* Power down channels that aren't in use */
+ for (i = 0; i < ADS1298_MAX_CHANNELS; i++) {
+ regmap_update_bits(priv->regmap, ADS1298_REG_CHnSET(i),
+ ADS1298_MASK_CH_PD,
+ test_bit(i, scan_mask) ?
+ 0 : ADS1298_MASK_CH_PD);
+ }
+
+ return 0;
+}
+
+static const struct iio_info ads1298_info = {
+ .read_raw = &ads1298_read_raw,
+ .write_raw = &ads1298_write_raw,
+ .update_scan_mode = &ads1298_update_scan_mode,
+ .debugfs_reg_access = &ads1298_reg_access,
+};
+
+static void ads1298_rdata_unmark_busy(struct ads1298_private *priv)
+{
+ unsigned long flags;
+
+ /* Notify we're no longer waiting for the SPI transfer to complete */
+ spin_lock_irqsave(&priv->irq_busy_lock, flags);
+ priv->rdata_xfer_busy = false;
+ spin_unlock_irqrestore(&priv->irq_busy_lock, flags);
+}
+
+static void ads1298_rdata_complete(void *context)
+{
+ struct iio_dev *indio_dev = context;
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ int scan_index;
+ u8 *bounce = priv->bounce_buffer;
+
+ if (!iio_buffer_enabled(indio_dev)) {
+ /* Happens when running in single transfer mode */
+ ads1298_rdata_unmark_busy(priv);
+ complete(&priv->completion);
+ return;
+ }
+
+ /* Demux the channel data into our bounce buffer */
+ for_each_set_bit(scan_index, indio_dev->active_scan_mask,
+ indio_dev->masklength) {
+ const struct iio_chan_spec *scan_chan =
+ &indio_dev->channels[scan_index];
+ const u8 *data = priv->rx_buffer + scan_chan->address;
+
+ /* Transfer 24-bit value into 32-bit array */
+ memcpy(bounce + 1, data, 3);
+ bounce += 4;
+ }
+
+ /* rx_buffer can be overwritten from this point on */
+ ads1298_rdata_unmark_busy(priv);
+
+ iio_push_to_buffers(indio_dev, priv->bounce_buffer);
+}
+
+static irqreturn_t ads1298_interrupt(int irq, void *dev_id)
+{
+ struct iio_dev *indio_dev = dev_id;
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ unsigned long flags;
+ bool wasbusy;
+
+ /* Prevent that we submit a message that was still in progress */
+ spin_lock_irqsave(&priv->irq_busy_lock, flags);
+ wasbusy = priv->rdata_xfer_busy;
+ priv->rdata_xfer_busy = true;
+ spin_unlock_irqrestore(&priv->irq_busy_lock, flags);
+
+ if (!wasbusy)
+ spi_async(priv->spi, &priv->rdata_msg);
+
+ return IRQ_HANDLED;
+};
+
+static int ads1298_buffer_postenable(struct iio_dev *indio_dev)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ int ret;
+
+ /* Disable single-shot mode */
+ ret = regmap_update_bits(priv->regmap, ADS1298_REG_CONFIG4,
+ ADS1298_MASK_CONFIG4_SINGLE_SHOT, 0);
+ if (ret)
+ return ret;
+
+ return ads1298_write_cmd(priv, ADS1298_CMD_START);
+}
+
+static int ads1298_buffer_predisable(struct iio_dev *indio_dev)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+
+ return ads1298_write_cmd(priv, ADS1298_CMD_STOP);
+}
+
+static const struct iio_buffer_setup_ops ads1298_setup_ops = {
+ .postenable = &ads1298_buffer_postenable,
+ .predisable = &ads1298_buffer_predisable,
+};
+
+static void ads1298_reg_disable(void *reg)
+{
+ regulator_disable(reg);
+}
+
+static const struct regmap_range ads1298_regmap_volatile_range[] = {
+ regmap_reg_range(ADS1298_REG_LOFF_STATP, ADS1298_REG_LOFF_STATN),
+};
+
+static const struct regmap_access_table ads1298_regmap_volatile = {
+ .yes_ranges = ads1298_regmap_volatile_range,
+ .n_yes_ranges = ARRAY_SIZE(ads1298_regmap_volatile_range),
+};
+
+static const struct regmap_config ads1298_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .reg_read = ads1298_reg_read,
+ .reg_write = ads1298_reg_write,
+ .max_register = ADS1298_REG_WCT2,
+ .volatile_table = &ads1298_regmap_volatile,
+ .cache_type = REGCACHE_RBTREE,
+};
+
+static const char *ads1298_family_name(unsigned int id)
+{
+ switch (id & 0xe0) {
+ case 0x80:
+ return "ADS129x";
+ case 0xc0:
+ return "ADS129xR";
+ default:
+ return "(unknown)";
+ }
+}
+
+static int ads1298_init(struct ads1298_private *priv)
+{
+ struct device *dev = &priv->spi->dev;
+ int ret;
+ unsigned int val;
+
+ /* Device initializes into RDATAC mode, which we don't want. */
+ ret = ads1298_write_cmd(priv, ADS1298_CMD_SDATAC);
+ if (ret)
+ return ret;
+
+ ret = regmap_read(priv->regmap, ADS1298_REG_ID, &val);
+ if (ret)
+ return ret;
+
+ if ((val & 0x18) == 0x10) {
+ dev_info(dev, "Found %s, %d channels\n",
+ ads1298_family_name(val),
+ 4 + 2 * (val & 0x07));
+ } else {
+ dev_err(dev, "Unknown ID: 0x%x\n", val);
+ return -ENODEV;
+ }
+
+ /* Enable internal test signal, double amplitude, double frequency */
+ regmap_write(priv->regmap, ADS1298_REG_CONFIG2,
+ ADS1298_MASK_CONFIG2_RESERVED |
+ ADS1298_MASK_CONFIG2_INT_TEST |
+ ADS1298_MASK_CONFIG2_TEST_AMP |
+ ADS1298_MASK_CONFIG2_TEST_FREQ_FAST);
+
+ val = ADS1298_MASK_CONFIG3_RESERVED; /* Must write 1 always */
+ if (!priv->reg_vref) {
+ /* Enable internal reference */
+ val |= ADS1298_MASK_CONFIG3_PWR_REFBUF;
+ /* Use 4V VREF when power supply is at least 4.4V */
+ if (regulator_get_voltage(priv->reg_avdd) >= 4400000)
+ val |= ADS1298_MASK_CONFIG3_VREF_4V;
+ }
+ regmap_write(priv->regmap, ADS1298_REG_CONFIG3, val);
+
+ for (val = 0; val < ADS1298_MAX_CHANNELS; val++) {
+ /* Set mux to analog input, PGA = 6x */
+ regmap_write(priv->regmap, ADS1298_REG_CHnSET(val), 0x00);
+ }
+
+ return 0;
+}
+
+static int ads1298_probe(struct spi_device *spi)
+{
+ struct ads1298_private *priv;
+ struct iio_dev *indio_dev;
+ struct device *dev = &spi->dev;
+ struct gpio_desc *reset_gpio;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
+ if (indio_dev == NULL)
+ return -ENOMEM;
+
+ priv = iio_priv(indio_dev);
+
+ reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(reset_gpio))
+ return dev_err_probe(dev, ret, "Cannot get reset GPIO\n");
+
+ priv->reg_avdd = devm_regulator_get(dev, "avdd");
+ if (IS_ERR(priv->reg_avdd))
+ return dev_err_probe(dev, PTR_ERR(priv->reg_avdd),
+ "Failed to get avdd regulator\n");
+
+ /* VREF can be supplied externally. Otherwise use internal reference */
+ priv->reg_vref = devm_regulator_get_optional(dev, "vref");
+ if (IS_ERR(priv->reg_vref)) {
+ if (PTR_ERR(priv->reg_vref) == -ENODEV)
+ priv->reg_vref = NULL;
+ else
+ return dev_err_probe(dev, PTR_ERR(priv->reg_avdd),
+ "Failed to get vref regulator\n");
+ } else {
+ ret = regulator_enable(priv->reg_vref);
+ if (ret)
+ return ret;
+
+ ret = devm_add_action_or_reset(dev, ads1298_reg_disable,
+ priv->reg_vref);
+ if (ret)
+ return ret;
+ }
+
+ priv->clk = devm_clk_get_enabled(dev, "clk");
+ if (IS_ERR(priv->clk))
+ return dev_err_probe(dev, PTR_ERR(priv->clk),
+ "Failed to get clk\n");
+
+ ret = regulator_enable(priv->reg_avdd);
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to enable avdd regulator\n");
+
+ ret = devm_add_action_or_reset(dev, ads1298_reg_disable,
+ priv->reg_avdd);
+ if (ret)
+ return ret;
+
+ priv->spi = spi;
+ init_completion(&priv->completion);
+ spin_lock_init(&priv->irq_busy_lock);
+ priv->regmap = devm_regmap_init(dev, NULL, priv,
+ &ads1298_regmap_config);
+ if (IS_ERR(priv->regmap))
+ return PTR_ERR(priv->regmap);
+
+ priv->tx_buffer[0] = ADS1298_CMD_RDATA;
+ priv->rdata_xfer.tx_buf = priv->tx_buffer;
+ priv->rdata_xfer.rx_buf = priv->rx_buffer;
+ priv->rdata_xfer.len = ADS1298_SPI_RDATA_BUFFER_SIZE;
+ /* Must keep CS low for 4 clocks */
+ priv->rdata_xfer.delay.value = 2;
+ priv->rdata_xfer.delay.unit = SPI_DELAY_UNIT_USECS;
+ spi_message_init_with_transfers(&priv->rdata_msg, &priv->rdata_xfer, 1);
+ priv->rdata_msg.complete = &ads1298_rdata_complete;
+ priv->rdata_msg.context = indio_dev;
+
+ /* Avoid giving all the same name, iio scope doesn't handle that well */
+ indio_dev->name = devm_kasprintf(dev, GFP_KERNEL, "%s@%s",
+ spi_get_device_id(spi)->name,
+ dev_name(dev));
+ indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
+ indio_dev->channels = ads1298_channels;
+ indio_dev->num_channels = ADS1298_MAX_CHANNELS;
+ indio_dev->info = &ads1298_info;
+
+ if (reset_gpio) {
+ udelay(1); /* Minimum pulse width is 2 clocks at 2MHz */
+ gpiod_set_value(reset_gpio, 0);
+ } else {
+ ret = ads1298_write_cmd(priv, ADS1298_CMD_RESET);
+ if (ret)
+ return dev_err_probe(dev, ret, "RESET failed\n");
+ }
+ /* Wait 18 clock cycles for reset command to complete */
+ udelay(9);
+
+ ret = ads1298_init(priv);
+ if (ret)
+ return dev_err_probe(dev, ret, "Init failed\n");
+
+ ret = devm_request_irq(&spi->dev, spi->irq, &ads1298_interrupt,
+ IRQF_TRIGGER_FALLING, indio_dev->name,
+ indio_dev);
+ if (ret)
+ return ret;
+
+ ret = devm_iio_kfifo_buffer_setup(&spi->dev, indio_dev,
+ &ads1298_setup_ops);
+ if (ret)
+ return ret;
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct spi_device_id ads1298_id[] = {
+ { "ads1298", },
+ { }
+};
+MODULE_DEVICE_TABLE(spi, ads1298_id);
+
+static const struct of_device_id ads1298_of_table[] = {
+ { .compatible = "ti,ads1298" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, ads1298_of_table);
+
+static struct spi_driver ads1298_driver = {
+ .driver = {
+ .name = "ads1298",
+ .of_match_table = ads1298_of_table,
+ },
+ .probe = ads1298_probe,
+ .id_table = ads1298_id,
+};
+module_spi_driver(ads1298_driver);
+
+MODULE_AUTHOR("Mike Looijmans <mike.looijmans@xxxxxxxx>");
+MODULE_DESCRIPTION("TI ADS1298 ADC");
+MODULE_LICENSE("GPL");
--
2.34.1


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@xxxxxxxx
W: www.topic.nl

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