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>
---
Changes in v5:
Derive the name from the chip ID register
Fail probe if the ID is unknown
Interpret the number of channels (only tested the "8")
Changes in v4:
Explain rdata_xfer_busy better and remove post-decrement
Reset assert explanation and add cansleep
Additional style changes
Changes in v3:
Indentation fixups
Remove unused headers
Remove #define leftovers
Use devm_get_clk_optional_enabled
Use ilog2 instead of fls()-1
Magic "23" replaced
Explain the extra "0" in read/write register
use guard() from cleanup.h
use REGCACHE_MAPLE
Changes in v2:
Remove accidental "default y" in Kconfig
Indentation and similar cosmetic fixes
Magic numbers into constants
Short return paths in read_raw and write_raw
DMA buffer alignment
Bounce buffer is u32 instead of u8
Avoid races using claim_direct_mode
Check errors on all register accesses
Immediate SPI restart to reduce underruns
"name" is chip name, not unique
drivers/iio/adc/Kconfig | 11 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-ads1298.c | 768 +++++++++++++++++++++++++++++++++++
3 files changed, 780 insertions(+)
create mode 100644 drivers/iio/adc/ti-ads1298.c
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 35f9867da12c..1d2d2eff15da 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1318,6 +1318,17 @@ 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
+ 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..b50e88bddcea
--- /dev/null
+++ b/drivers/iio/adc/ti-ads1298.c
@@ -0,0 +1,768 @@
+// SPDX-License-Identifier: GPL-2.0
+/* TI ADS1298 chip family driver
+ * Copyright (C) 2023 - 2024 Topic Embedded Products
+ */
+
+#include <linux/bitfield.h>
+#include <linux/cleanup.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/log2.h>
+#include <linux/math.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/units.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+
+#include <asm/unaligned.h>
+
+/* 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_MASK_ID_FAMILY GENMASK(7, 3)
+#define ADS1298_MASK_ID_CHANNELS GENMASK(2, 0)
+#define ADS1298_ID_FAMILY_ADS129X 0x90
+#define ADS1298_ID_FAMILY_ADS129XR 0xd0
+
+#define ADS1298_REG_CONFIG1 0x01
+#define ADS1298_MASK_CONFIG1_HR BIT(7)
+#define ADS1298_MASK_CONFIG1_DR GENMASK(2, 0)
+#define ADS1298_SHIFT_DR_HR 6
+#define ADS1298_SHIFT_DR_LP 7
+#define ADS1298_LOWEST_DR 0x06
+
+#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_BITS_PER_SAMPLE 24
+#define ADS1298_CLK_RATE_HZ 2048000
+#define ADS1298_CLOCKS_TO_USECS(x) \
+ (DIV_ROUND_UP((x) * MICROHZ_PER_HZ, ADS1298_CLK_RATE_HZ))
+/*
+ * 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_HZ
+/* For reading and writing registers, we need a 3-byte buffer */
+#define ADS1298_SPI_CMD_BUFFER_SIZE 3
+/* Outputs status word and 'n' 24-bit samples, plus the command byte */
+#define ADS1298_SPI_RDATA_BUFFER_SIZE(n) (((n) + 1) * 3 + 1)
+#define ADS1298_SPI_RDATA_BUFFER_SIZE_MAX \
+ ADS1298_SPI_RDATA_BUFFER_SIZE(ADS1298_MAX_CHANNELS)
+
+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 */
+ /*
+ * rdata_xfer_busy increments when a DRDY occurs and decrements when SPI
+ * completion is reported. Hence its meaning is:
+ * 0 = Waiting for DRDY interrupt
+ * 1 = SPI transfer in progress
+ * 2 = DRDY during SPI transfer, start another transfer on completion
+ * >2 = Multiple DRDY during transfer, lost rdata_xfer_busy - 2 samples
+ */
+ unsigned int rdata_xfer_busy;
+
+ /* Temporary storage for demuxing data after SPI transfer */
+ u32 bounce_buffer[ADS1298_MAX_CHANNELS];
+
+ /* For synchronous SPI exchanges (read/write registers) */
+ u8 cmd_buffer[ADS1298_SPI_CMD_BUFFER_SIZE] __aligned(IIO_DMA_MINALIGN);
+
+ /* Buffer used for incoming SPI data */
+ u8 rx_buffer[ADS1298_SPI_RDATA_BUFFER_SIZE_MAX];
+ /* Contains the RDATA command and zeroes to clock out */
+ u8 tx_buffer[ADS1298_SPI_RDATA_BUFFER_SIZE_MAX];
+};
+
+/* Three bytes per sample in RX buffer, starting at offset 4 */
+#define ADS1298_OFFSET_IN_RX_BUFFER(index) (3 * (index) + 4)
+
+#define ADS1298_CHAN(index) \
+{ \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = index, \
+ .address = ADS1298_OFFSET_IN_RX_BUFFER(index), \
+ .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 = ADS1298_BITS_PER_SAMPLE, \
+ .storagebits = 32, \
+ .endianness = IIO_CPU, \
+ }, \
+}
+
+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 xfer = {
+ .tx_buf = priv->cmd_buffer,
+ .rx_buf = priv->cmd_buffer,
+ .len = 1,
+ .speed_hz = ADS1298_SPI_BUS_SPEED_SLOW,
+ .delay = {
+ .value = 2,
+ .unit = SPI_DELAY_UNIT_USECS,
+ },
+ };
+
+ priv->cmd_buffer[0] = command;
+
+ return spi_sync_transfer(priv->spi, &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;
+ unsigned int cfg;
+ int ret;
+
+ 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_HZ;
+ if (!rate)
+ return -EINVAL;
+
+ /* Data rate shift depends on HR/LP mode */
+ if (cfg & ADS1298_MASK_CONFIG1_HR)
+ rate >>= ADS1298_SHIFT_DR_HR;
+ else
+ rate >>= ADS1298_SHIFT_DR_LP;
+
+ *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_HZ;
+ if (!rate)
+ return -EINVAL;
+
+ factor = (rate >> ADS1298_SHIFT_DR_HR) / val;
+ if (factor >= BIT(ADS1298_SHIFT_DR_LP))
+ cfg = ADS1298_LOWEST_DR;
+ else if (factor)
+ cfg = ADS1298_MASK_CONFIG1_HR | ilog2(factor); /* Use HR mode */
+ else
+ cfg = ADS1298_MASK_CONFIG1_HR; /* Fastest possible */
+
+ 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 / MILLI; /* Convert to millivolts */
+ } else {
+ ret = regmap_read(priv->regmap, ADS1298_REG_CONFIG3, ®val);
+ 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), ®val);
+ if (ret)
+ return ret;
+
+ gain = ads1298_pga_settings[FIELD_GET(ADS1298_MASK_CH_PGA, regval)];
+ *val /= gain; /* Full scale is VREF / gain */
+
+ *val2 = ADS1298_BITS_PER_SAMPLE - 1; /* Signed, hence the -1 */
+
+ 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:
+ ret = iio_device_claim_direct_mode(indio_dev);
+ if (ret)
+ return ret;
+
+ ret = ads1298_read_one(priv, chan->scan_index);
+
+ iio_device_release_direct_mode(indio_dev);
+
+ if (ret)
+ return ret;
+
+ *val = sign_extend32(get_unaligned_be24(priv->rx_buffer + chan->address),
+ ADS1298_BITS_PER_SAMPLE - 1);
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ return ads1298_get_scale(priv, chan->channel, val, val2);
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ return ads1298_get_samp_freq(priv, val);
+ case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+ ret = regmap_read(priv->regmap, ADS1298_REG_CONFIG1, val);
+ if (ret)
+ return ret;
+
+ *val = 16 << (*val & ADS1298_MASK_CONFIG1_DR);
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+}
+
+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);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ return ads1298_set_samp_freq(priv, val);
+ default:
+ return -EINVAL;
+ }
+}
+
+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,
+ .unit = SPI_DELAY_UNIT_USECS,
+ },
+ };
+
+ priv->cmd_buffer[0] = ADS1298_CMD_WREG | reg;
+ priv->cmd_buffer[1] = 0; /* Number of registers to be written - 1 */
+ priv->cmd_buffer[2] = val;
+
+ return spi_sync_transfer(priv->spi, ®_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,
+ .unit = SPI_DELAY_UNIT_USECS,
+ },
+ };
+ int ret;
+
+ priv->cmd_buffer[0] = ADS1298_CMD_RREG | reg;
+ priv->cmd_buffer[1] = 0; /* Number of registers to be read - 1 */
+ priv->cmd_buffer[2] = 0;
+
+ ret = spi_sync_transfer(priv->spi, ®_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_read(priv->regmap, reg, readval);
+
+ return regmap_write(priv->regmap, reg, writeval);
+}
+
+static void ads1298_rdata_unmark_busy(struct ads1298_private *priv)
+{
+ /* Notify we're no longer waiting for the SPI transfer to complete */
+ guard(spinlock_irqsave)(&priv->irq_busy_lock);
+ priv->rdata_xfer_busy = 0;
+}
+
+static int ads1298_update_scan_mode(struct iio_dev *indio_dev,
+ const unsigned long *scan_mask)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ unsigned int val;
+ int ret;
+ int i;
+
+ /* Make the interrupt routines start with a clean slate */
+ ads1298_rdata_unmark_busy(priv);
+
+ /* Configure power-down bits to match scan mask */
+ for (i = 0; i < indio_dev->num_channels; i++) {
+ val = test_bit(i, scan_mask) ? 0 : ADS1298_MASK_CH_PD;
+ ret = regmap_update_bits(priv->regmap, ADS1298_REG_CHnSET(i),
+ ADS1298_MASK_CH_PD, val);
+ if (ret)
+ return ret;
+ }
+
+ 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_release_busy_or_restart(struct ads1298_private *priv)
+{
+ guard(spinlock_irqsave)(&priv->irq_busy_lock);
+
+ if (priv->rdata_xfer_busy > 1) {
+ /*
+ * DRDY interrupt occurred before SPI completion. Start a new
+ * SPI transaction now to retrieve the data that wasn't latched
+ * into the ADS1298 chip's transfer buffer yet.
+ */
+ spi_async(priv->spi, &priv->rdata_msg);
+ /*
+ * If more than one DRDY took place, there was an overrun. Since
+ * the sample is already lost, reset the counter to 1 so that
+ * we will wait for a DRDY interrupt after this SPI transaction.
+ */
+ priv->rdata_xfer_busy = 1;
+ } else {
+ /* No pending data, wait for DRDY */
+ priv->rdata_xfer_busy = 0;
+ }
+}
+
+/* Called from SPI completion interrupt handler */
+static void ads1298_rdata_complete(void *context)
+{
+ struct iio_dev *indio_dev = context;
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ int scan_index;
+ u32 *bounce = priv->bounce_buffer;
+
+ if (!iio_buffer_enabled(indio_dev)) {
+ /*
+ * for a single transfer mode we're kept in direct_mode until
+ * completion, avoiding a race with buffered IO.
+ */
+ 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;
+
+ *bounce++ = get_unaligned_be24(data);
+ }
+
+ /* rx_buffer can be overwritten from this point on */
+ ads1298_rdata_release_busy_or_restart(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 int wasbusy;
+
+ guard(spinlock_irqsave)(&priv->irq_busy_lock);
+
+ wasbusy = priv->rdata_xfer_busy++;
+ /* When no SPI transfer in transit, start one now */
+ 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_MAPLE,
+};
+
+static int ads1298_init(struct iio_dev *indio_dev)
+{
+ struct ads1298_private *priv = iio_priv(indio_dev);
+ struct device *dev = &priv->spi->dev;
+ const char *suffix;
+ unsigned int val;
+ int ret;
+
+ /* 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;
+
+ /* Fill in name and channel count based on what the chip told us */
+ indio_dev->num_channels = 4 + 2 * (val & ADS1298_MASK_ID_CHANNELS);
+ switch (val & ADS1298_MASK_ID_FAMILY) {
+ case ADS1298_ID_FAMILY_ADS129X:
+ suffix = "";
+ break;
+ case ADS1298_ID_FAMILY_ADS129XR:
+ suffix = "r";
+ break;
+ default:
+ return dev_err_probe(dev, -ENODEV, "Unknown ID: 0x%x\n", val);
+ }
+ indio_dev->name = devm_kasprintf(dev, GFP_KERNEL, "ads129%u%s",
+ indio_dev->num_channels, suffix);
+
+ /* Enable internal test signal, double amplitude, double frequency */
+ ret = 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);
+ if (ret)
+ return ret;
+
+ 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;
+ }
+ return regmap_write(priv->regmap, ADS1298_REG_CONFIG3, val);
+}
+
+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)
+ return -ENOMEM;
+
+ priv = iio_priv(indio_dev);
+
+ /* Reset to be asserted before enabling clock and power */
+ 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");
+
+ /* 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)
+ return dev_err_probe(dev, PTR_ERR(priv->reg_avdd),
+ "Failed to get vref regulator\n");
+
+ priv->reg_vref = NULL;
+ } 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_optional_enabled(dev, "clk");
+ if (IS_ERR(priv->clk))
+ return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clk\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");
+
+ 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);
+
+ indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
+ indio_dev->channels = ads1298_channels;
+ indio_dev->info = &ads1298_info;
+
+ if (reset_gpio) {
+ /*
+ * Deassert reset now that clock and power are active.
+ * Minimum reset pulsewidth is 2 clock cycles.
+ */
+ udelay(ADS1298_CLOCKS_TO_USECS(2));
+ gpiod_set_value_cansleep(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(ADS1298_CLOCKS_TO_USECS(18));
+
+ ret = ads1298_init(indio_dev);
+ if (ret)
+ return dev_err_probe(dev, ret, "Init failed\n");
+
+ 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(indio_dev->num_channels);
+ /* 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;
+
+ ret = devm_request_irq(dev, spi->irq, &ads1298_interrupt,
+ IRQF_TRIGGER_FALLING, indio_dev->name,
+ indio_dev);
+ if (ret)
+ return ret;
+
+ ret = devm_iio_kfifo_buffer_setup(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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