* [PATCH v4 2/2] iio: temperature: add support for Analog Devices MAX30210
2026-10-15 1:21 [PATCH v4 0/2] Add support for Analog Devices MAX30210 John Erasmus Mari Geronimo
2026-10-15 1:21 ` [PATCH v4 1/2] dt-bindings: iio: temperature: add ADI MAX30210 John Erasmus Mari Geronimo
@ 2026-10-15 1:21 ` John Erasmus Mari Geronimo
2026-10-15 1:32 ` sashiko-bot
1 sibling, 1 reply; 5+ messages in thread
From: John Erasmus Mari Geronimo @ 2026-10-15 1:21 UTC (permalink / raw)
To: linux-iio, devicetree
Cc: krzk+dt, jic23, dlechner, nuno.sa, Michael.Hennerich, andy, robh,
conor+dt
Add support for the Analog Devices MAX30210 I2C temperature
sensor.
The driver uses regmap for register access and integrates with
the IIO framework. It supports:
- Direct mode temperature conversion
- Configurable sampling frequency
- Threshold events
- FIFO operation with IIO kfifo buffer support
- Optional interrupt-driven data ready signaling
The device provides 16-bit signed temperature data and a
64-sample FIFO.
Signed-off-by: John Erasmus Mari Geronimo <johnerasmusmari.geronimo@analog.com>
---
MAINTAINERS | 1 +
drivers/iio/temperature/Kconfig | 13 +
drivers/iio/temperature/Makefile | 1 +
drivers/iio/temperature/max30210.c | 788 +++++++++++++++++++++++++++++
4 files changed, 803 insertions(+)
create mode 100644 drivers/iio/temperature/max30210.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 6eb3cf66f431c..e479c64a284e0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1659,6 +1659,7 @@ L: linux-iio@vger.kernel.org
S: Supported
W: https://ez.analog.com/linux-software-drivers
F: Documentation/devicetree/bindings/iio/temperature/adi,max30210.yaml
+F: drivers/iio/temperature/max30210.c
ANALOG DEVICES INC ADA4250 DRIVER
M: Antoniu Miclaus <antoniu.miclaus@analog.com>
diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index 9328b2250aced..05b3af6872b31 100644
--- a/drivers/iio/temperature/Kconfig
+++ b/drivers/iio/temperature/Kconfig
@@ -152,6 +152,19 @@ config MAX30208
This driver can also be built as a module. If so, the module
will be called max30208.
+config MAX30210
+ tristate "Analog Devices MAX30210 temperature sensor"
+ depends on I2C
+ select REGMAP_I2C
+ select IIO_BUFFER
+ select IIO_KFIFO_BUF
+ help
+ If you say yes here you get support for MAX30210 low-power digital
+ temperature sensor chip connected via I2C.
+
+ This driver can also be built as a module. If so, the module
+ will be called max30210.
+
config MAX31856
tristate "MAX31856 thermocouple sensor"
depends on SPI
diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
index 07d6e65709f7f..e5aad14dc09b9 100644
--- a/drivers/iio/temperature/Makefile
+++ b/drivers/iio/temperature/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_LTC2983) += ltc2983.o
obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
obj-$(CONFIG_MAX30208) += max30208.o
+obj-$(CONFIG_MAX30210) += max30210.o
obj-$(CONFIG_MAX31856) += max31856.o
obj-$(CONFIG_MAX31865) += max31865.o
obj-$(CONFIG_MCP9600) += mcp9600.o
diff --git a/drivers/iio/temperature/max30210.c b/drivers/iio/temperature/max30210.c
new file mode 100644
index 0000000000000..04123d51c6da4
--- /dev/null
+++ b/drivers/iio/temperature/max30210.c
@@ -0,0 +1,788 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices MAX30210 I2C Temperature Sensor driver
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/events.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/iio/sysfs.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/time.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+#include <linux/units.h>
+
+#define MAX30210_STATUS_REG 0x00
+#define MAX30210_STATUS_A_FULL_MASK BIT(7)
+#define MAX30210_STATUS_TEMP_RDY_MASK BIT(6)
+#define MAX30210_STATUS_TEMP_DEC_MASK BIT(5)
+#define MAX30210_STATUS_TEMP_INC_MASK BIT(4)
+#define MAX30210_STATUS_TEMP_LO_MASK BIT(3)
+#define MAX30210_STATUS_TEMP_HI_MASK BIT(2)
+#define MAX30210_STATUS_PWR_RDY BIT(0)
+#define MAX30210_INT_EN_REG 0x02
+#define MAX30210_FIFO_DATA_REG 0x08
+#define MAX30210_FIFO_CONF_1_REG 0x09
+#define MAX30210_FIFOCONF1_A_FULL_MASK GENMASK(5, 0)
+#define MAX30210_FIFO_CONF_2_REG 0x0A
+#define MAX30210_FIFOCONF2_FLUSH_FIFO BIT(4)
+#define MAX30210_SYS_CONF_REG 0x11
+#define MAX30210_SYSCONF_RESET BIT(0)
+#define MAX30210_PIN_CONF_REG 0x12
+#define MAX30210_PINCONF_EXT_CNV_EN BIT(7)
+#define MAX30210_PINCONF_EXT_CVT_ICFG BIT(6)
+#define MAX30210_PINCONF_INT_FCFG_MASK GENMASK(3, 2)
+#define MAX30210_PINCONF_INT_OCFG_MASK GENMASK(1, 0)
+#define MAX30210_TEMP_ALM_HI_REG 0x22
+#define MAX30210_TEMP_ALM_LO_REG 0x24
+#define MAX30210_TEMP_INC_THRESH_REG 0x26
+#define MAX30210_TEMP_DEC_THRESH_REG 0x27
+#define MAX30210_TEMP_CONF_1_REG 0x28
+#define MAX30210_TEMPCONF1_CHG_DET_EN BIT(3)
+#define MAX30210_TEMPCONF1_RATE_CHG_FILTER_MASK GENMASK(2, 0)
+#define MAX30210_TEMP_CONF_2_REG 0x29
+#define MAX30210_TEMPCONF2_TEMP_PERIOD_MASK GENMASK(3, 0)
+#define MAX30210_TEMPCONF2_ALERT_MODE BIT(7)
+#define MAX30210_TEMP_CONV_REG 0x2A
+#define MAX30210_TEMPCONV_CONV_T BIT(0)
+#define MAX30210_TEMPCONV_AUTO BIT(1)
+#define MAX30210_TEMP_DATA_REG 0x2B
+#define MAX30210_TEMP_SLOPE_REG 0x2D
+#define MAX30210_UNIQUE_ID_REG 0x30
+#define MAX30210_PART_ID_REG 0xFF
+
+#define MAX30210_PART_ID 0x45
+#define MAX30210_FIFO_SIZE 64
+#define MAX30210_FIFO_BYTES_PER_SAMPLE 3
+#define MAX30210_FIFO_TEMP_MASK GENMASK(15, 0)
+#define MAX30210_FIFO_INVAL_DATA GENMASK(23, 0)
+#define MAX30210_WATERMARK_DEFAULT (0x40 - 0x1F)
+
+#define MAX30210_UNIQUE_ID_LEN 6
+#define MAX30210_EXT_CVT_FREQ_MIN 1
+#define MAX30210_EXT_CVT_FREQ_MAX 20
+
+struct max30210_state {
+ struct regmap *regmap;
+ /* Raw FIFO byte buffer */
+ u8 fifo_buf[MAX30210_FIFO_BYTES_PER_SAMPLE * MAX30210_FIFO_SIZE];
+ /* Protects autoconv_users and the autonomous-conversion enable bit */
+ struct mutex lock;
+ unsigned int autoconv_users;
+ u8 watermark;
+};
+
+static const int max30210_samp_freq_avail[][2] = {
+ { 0, 15625 },
+ { 0, 31250 },
+ { 0, 62500 },
+ { 0, 125000 },
+ { 0, 250000 },
+ { 0, 500000 },
+ { 1, 0 },
+ { 2, 0 },
+ { 4, 0 },
+ { 8, 0 },
+};
+
+static bool max30210_volatile_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MAX30210_STATUS_REG:
+ case MAX30210_FIFO_DATA_REG:
+ case MAX30210_FIFO_CONF_2_REG:
+ case MAX30210_TEMP_CONV_REG:
+ /*
+ * TEMP_DATA_REG is a 16-bit value spanning two byte registers;
+ * both must be volatile or regmap_bulk_read()'s range check falls
+ * back to caching the second byte forever (see max30210_read_temp()).
+ */
+ case MAX30210_TEMP_DATA_REG:
+ case MAX30210_TEMP_DATA_REG + 1:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static const struct regmap_config max30210_regmap = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = MAX30210_PART_ID_REG,
+ .volatile_reg = max30210_volatile_reg,
+ .cache_type = REGCACHE_MAPLE,
+};
+
+static int max30210_read_temp(struct regmap *regmap, unsigned int reg,
+ int *temp)
+{
+ __be16 val;
+ int ret;
+
+ ret = regmap_bulk_read(regmap, reg, &val, sizeof(val));
+ if (ret)
+ return ret;
+
+ *temp = sign_extend32(be16_to_cpu(val), 15);
+
+ return IIO_VAL_INT;
+}
+
+static int max30210_write_temp(struct regmap *regmap, unsigned int reg,
+ int temp)
+{
+ __be16 val;
+
+ val = cpu_to_be16(temp);
+
+ return regmap_bulk_write(regmap, reg, &val, sizeof(val));
+}
+
+/* Keeps the device sampling autonomously while buffer and/or events need it. */
+static int max30210_autoconv_get(struct max30210_state *st)
+{
+ int ret = 0;
+
+ guard(mutex)(&st->lock);
+
+ if (st->autoconv_users == 0)
+ ret = regmap_write(st->regmap, MAX30210_TEMP_CONV_REG,
+ MAX30210_TEMPCONV_AUTO | MAX30210_TEMPCONV_CONV_T);
+ if (!ret)
+ st->autoconv_users++;
+
+ return ret;
+}
+
+static int max30210_autoconv_put(struct max30210_state *st)
+{
+ int ret = 0;
+
+ guard(mutex)(&st->lock);
+
+ if (st->autoconv_users == 1)
+ ret = regmap_write(st->regmap, MAX30210_TEMP_CONV_REG, 0);
+ if (st->autoconv_users)
+ st->autoconv_users--;
+
+ return ret;
+}
+
+static void max30210_fifo_read(struct iio_dev *indio_dev)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ int ret;
+
+ /*
+ * FIFO_DATA_REG auto-increments in hardware; bulk_read would treat
+ * each subsequent byte as a separate cacheable register.
+ */
+ ret = regmap_noinc_read(st->regmap, MAX30210_FIFO_DATA_REG,
+ st->fifo_buf,
+ MAX30210_FIFO_BYTES_PER_SAMPLE * st->watermark);
+ if (ret) {
+ dev_err(&indio_dev->dev, "Failed to read from fifo.\n");
+ return;
+ }
+
+ for (unsigned int i = 0; i < st->watermark; i++) {
+ u32 raw = get_unaligned_be24(&st->fifo_buf[MAX30210_FIFO_BYTES_PER_SAMPLE * i]);
+ s16 temp;
+
+ if (raw == MAX30210_FIFO_INVAL_DATA) {
+ dev_err_ratelimited(&indio_dev->dev, "Invalid data\n");
+ continue;
+ }
+
+ temp = sign_extend32(FIELD_GET(MAX30210_FIFO_TEMP_MASK, raw), 15);
+
+ iio_push_to_buffers(indio_dev, &temp);
+ }
+}
+
+static irqreturn_t max30210_irq_handler(int irq, void *dev_id)
+{
+ struct iio_dev *indio_dev = dev_id;
+ struct max30210_state *st = iio_priv(indio_dev);
+ unsigned int status;
+ int ret;
+
+ ret = regmap_read(st->regmap, MAX30210_STATUS_REG, &status);
+ if (ret) {
+ dev_err(&indio_dev->dev, "Status read failed\n");
+ return IRQ_NONE;
+ }
+
+ if (status & MAX30210_STATUS_A_FULL_MASK)
+ max30210_fifo_read(indio_dev);
+
+ if (status & MAX30210_STATUS_TEMP_HI_MASK)
+ iio_push_event(indio_dev,
+ IIO_UNMOD_EVENT_CODE(IIO_TEMP, 0,
+ IIO_EV_TYPE_THRESH,
+ IIO_EV_DIR_RISING),
+ iio_get_time_ns(indio_dev));
+
+ if (status & MAX30210_STATUS_TEMP_LO_MASK)
+ iio_push_event(indio_dev,
+ IIO_UNMOD_EVENT_CODE(IIO_TEMP, 0,
+ IIO_EV_TYPE_THRESH,
+ IIO_EV_DIR_FALLING),
+ iio_get_time_ns(indio_dev));
+
+ return IRQ_HANDLED;
+}
+
+static int max30210_reg_access(struct iio_dev *indio_dev, unsigned int reg,
+ unsigned int writeval, unsigned int *readval)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+
+ if (readval)
+ return regmap_read(st->regmap, reg, readval);
+
+ return regmap_write(st->regmap, reg, writeval);
+}
+
+static int max30210_read_event(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ enum iio_event_type type,
+ enum iio_event_direction dir,
+ enum iio_event_info info, int *val, int *val2)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+
+ if (info != IIO_EV_INFO_VALUE)
+ return -EINVAL;
+
+ switch (dir) {
+ case IIO_EV_DIR_RISING:
+ switch (type) {
+ case IIO_EV_TYPE_THRESH:
+ return max30210_read_temp(st->regmap, MAX30210_TEMP_ALM_HI_REG, val);
+ default:
+ return -EINVAL;
+ }
+ case IIO_EV_DIR_FALLING:
+ switch (type) {
+ case IIO_EV_TYPE_THRESH:
+ return max30210_read_temp(st->regmap, MAX30210_TEMP_ALM_LO_REG, val);
+ default:
+ return -EINVAL;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max30210_write_event(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ enum iio_event_type type,
+ enum iio_event_direction dir,
+ enum iio_event_info info, int val, int val2)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+
+ if (info != IIO_EV_INFO_VALUE)
+ return -EINVAL;
+
+ if (val < S16_MIN || val > S16_MAX)
+ return -EINVAL;
+
+ switch (dir) {
+ case IIO_EV_DIR_RISING:
+ switch (type) {
+ case IIO_EV_TYPE_THRESH:
+ return max30210_write_temp(st->regmap, MAX30210_TEMP_ALM_HI_REG, val);
+ default:
+ return -EINVAL;
+ }
+ case IIO_EV_DIR_FALLING:
+ switch (type) {
+ case IIO_EV_TYPE_THRESH:
+ return max30210_write_temp(st->regmap, MAX30210_TEMP_ALM_LO_REG, val);
+ default:
+ return -EINVAL;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max30210_read_event_config(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ enum iio_event_type type,
+ enum iio_event_direction dir)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ unsigned int val;
+ int ret;
+
+ ret = regmap_read(st->regmap, MAX30210_INT_EN_REG, &val);
+ if (ret)
+ return ret;
+
+ switch (dir) {
+ case IIO_EV_DIR_RISING:
+ switch (type) {
+ case IIO_EV_TYPE_THRESH:
+ return FIELD_GET(MAX30210_STATUS_TEMP_HI_MASK, val);
+ default:
+ return -EINVAL;
+ }
+ case IIO_EV_DIR_FALLING:
+ switch (type) {
+ case IIO_EV_TYPE_THRESH:
+ return FIELD_GET(MAX30210_STATUS_TEMP_LO_MASK, val);
+ default:
+ return -EINVAL;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max30210_write_event_config(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ enum iio_event_type type,
+ enum iio_event_direction dir, bool state)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ unsigned int mask;
+ int ret;
+
+ if (type != IIO_EV_TYPE_THRESH)
+ return -EINVAL;
+
+ switch (dir) {
+ case IIO_EV_DIR_RISING:
+ mask = MAX30210_STATUS_TEMP_HI_MASK;
+ break;
+ case IIO_EV_DIR_FALLING:
+ mask = MAX30210_STATUS_TEMP_LO_MASK;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /*
+ * Threshold events need the device sampling autonomously, independent
+ * of whether the FIFO buffer is also enabled.
+ */
+ if (state) {
+ ret = max30210_autoconv_get(st);
+ if (ret)
+ return ret;
+ }
+
+ ret = regmap_assign_bits(st->regmap, MAX30210_INT_EN_REG, mask, state);
+ if (ret) {
+ if (state)
+ max30210_autoconv_put(st);
+ return ret;
+ }
+
+ return state ? 0 : max30210_autoconv_put(st);
+}
+
+static int max30210_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long mask)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ unsigned int uval;
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SCALE:
+ *val = 5;
+ *val2 = MILLI;
+
+ return IIO_VAL_FRACTIONAL;
+ case IIO_CHAN_INFO_SAMP_FREQ: {
+ unsigned int period;
+
+ ret = regmap_read(st->regmap, MAX30210_TEMP_CONF_2_REG, &uval);
+ if (ret)
+ return ret;
+
+ period = FIELD_GET(MAX30210_TEMPCONF2_TEMP_PERIOD_MASK, uval);
+
+ /*
+ * TEMP_PERIOD is an index into the sampling frequency lookup
+ * table. Clamp in case the register holds a reserved value.
+ */
+ if (period >= ARRAY_SIZE(max30210_samp_freq_avail))
+ period = ARRAY_SIZE(max30210_samp_freq_avail) - 1;
+
+ *val = max30210_samp_freq_avail[period][0];
+ *val2 = max30210_samp_freq_avail[period][1];
+
+ return IIO_VAL_INT_PLUS_MICRO;
+ }
+ case IIO_CHAN_INFO_RAW: {
+ IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+ if (IIO_DEV_ACQUIRE_FAILED(claim))
+ return -EBUSY;
+
+ guard(mutex)(&st->lock);
+
+ /*
+ * TEMP_DATA_REG is only refreshed by a single-shot
+ * conversion; the buffer/FIFO path is the only thing that
+ * gets updated during AUTO mode. If AUTO is already running
+ * for the buffer and/or events, triggering a one-off
+ * conversion here would stomp the AUTO bit out from under
+ * whoever enabled it, and there is no way to get a fresh
+ * single-shot value without doing so -- refuse instead of
+ * returning stale data.
+ */
+ if (st->autoconv_users > 0)
+ return -EBUSY;
+
+ ret = regmap_write(st->regmap, MAX30210_TEMP_CONV_REG,
+ MAX30210_TEMPCONV_CONV_T);
+ if (ret)
+ return ret;
+
+ /*
+ * Wait until CONVERT_T auto-clears.
+ * Datasheet:
+ * tBIAS_WU = 260 µs
+ * tINT = 8 ms
+ *
+ * Worst-case conversion ≈ 8.26 ms.
+ * Use 10 ms timeout for margin.
+ */
+ ret = regmap_read_poll_timeout(st->regmap, MAX30210_TEMP_CONV_REG, uval,
+ !(uval & MAX30210_TEMPCONV_CONV_T),
+ 500, 10 * USEC_PER_MSEC);
+ if (ret)
+ return ret;
+
+ return max30210_read_temp(st->regmap, MAX30210_TEMP_DATA_REG, val);
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max30210_read_avail(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int **vals, int *type, int *length,
+ long mask)
+{
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ *vals = &max30210_samp_freq_avail[0][0];
+ *type = IIO_VAL_INT_PLUS_MICRO;
+ *length = ARRAY_SIZE(max30210_samp_freq_avail) * 2;
+
+ return IIO_AVAIL_LIST;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max30210_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_SAMP_FREQ: {
+ if (val < 0 || val2 < 0)
+ return -EINVAL;
+
+ IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+ if (IIO_DEV_ACQUIRE_FAILED(claim))
+ return -EBUSY;
+
+ for (unsigned int i = 0; i < ARRAY_SIZE(max30210_samp_freq_avail); i++) {
+ if (val != max30210_samp_freq_avail[i][0] ||
+ val2 != max30210_samp_freq_avail[i][1])
+ continue;
+
+ return regmap_update_bits(st->regmap, MAX30210_TEMP_CONF_2_REG,
+ MAX30210_TEMPCONF2_TEMP_PERIOD_MASK,
+ FIELD_PREP(MAX30210_TEMPCONF2_TEMP_PERIOD_MASK, i));
+ }
+
+ return -EINVAL;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int max30210_set_watermark(struct iio_dev *indio_dev, unsigned int val)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ int ret;
+
+ if (val < 1 || val > MAX30210_FIFO_SIZE)
+ return -EINVAL;
+
+ /*
+ * FIFO_A_FULL sets the number of empty FIFO slots remaining when the
+ * A_FULL interrupt fires. For a watermark of N samples, set
+ * FIFO_A_FULL = FIFO_SIZE - N.
+ */
+ ret = regmap_write(st->regmap, MAX30210_FIFO_CONF_1_REG,
+ FIELD_PREP(MAX30210_FIFOCONF1_A_FULL_MASK,
+ MAX30210_FIFO_SIZE - val));
+ if (ret)
+ return ret;
+
+ st->watermark = val;
+
+ return 0;
+}
+
+static ssize_t hwfifo_watermark_show(struct device *dev,
+ struct device_attribute *devattr,
+ char *buf)
+{
+ struct max30210_state *st = iio_priv(dev_to_iio_dev(dev));
+
+ return sysfs_emit(buf, "%d\n", st->watermark);
+}
+
+IIO_STATIC_CONST_DEVICE_ATTR(hwfifo_watermark_min, "1");
+IIO_STATIC_CONST_DEVICE_ATTR(hwfifo_watermark_max, __stringify(MAX30210_FIFO_SIZE));
+static IIO_DEVICE_ATTR_RO(hwfifo_watermark, 0);
+
+static const struct iio_dev_attr *max30210_fifo_attributes[] = {
+ &iio_dev_attr_hwfifo_watermark_min,
+ &iio_dev_attr_hwfifo_watermark_max,
+ &iio_dev_attr_hwfifo_watermark,
+ NULL
+};
+
+static int max30210_buffer_preenable(struct iio_dev *indio_dev)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ int ret;
+
+ /* Enable FIFO-full interrupt */
+ ret = regmap_set_bits(st->regmap, MAX30210_INT_EN_REG,
+ MAX30210_STATUS_A_FULL_MASK);
+ if (ret)
+ return ret;
+
+ /* Flush FIFO before starting autonomous conversions */
+ ret = regmap_set_bits(st->regmap, MAX30210_FIFO_CONF_2_REG,
+ MAX30210_FIFOCONF2_FLUSH_FIFO);
+ if (ret)
+ return ret;
+
+ return max30210_autoconv_get(st);
+}
+
+static int max30210_buffer_postdisable(struct iio_dev *indio_dev)
+{
+ struct max30210_state *st = iio_priv(indio_dev);
+ int ret;
+
+ ret = max30210_autoconv_put(st);
+ if (ret)
+ return ret;
+
+ /* Flush FIFO */
+ ret = regmap_set_bits(st->regmap, MAX30210_FIFO_CONF_2_REG,
+ MAX30210_FIFOCONF2_FLUSH_FIFO);
+ if (ret)
+ return ret;
+
+ /* Disable FIFO-full interrupt */
+ return regmap_clear_bits(st->regmap, MAX30210_INT_EN_REG,
+ MAX30210_STATUS_A_FULL_MASK);
+}
+
+static const struct iio_buffer_setup_ops max30210_buffer_ops = {
+ .preenable = max30210_buffer_preenable,
+ .postdisable = max30210_buffer_postdisable,
+};
+
+static const struct iio_info max30210_info = {
+ .read_raw = max30210_read_raw,
+ .read_avail = max30210_read_avail,
+ .write_raw = max30210_write_raw,
+ .hwfifo_set_watermark = max30210_set_watermark,
+ .debugfs_reg_access = max30210_reg_access,
+ .read_event_value = max30210_read_event,
+ .write_event_value = max30210_write_event,
+ .write_event_config = max30210_write_event_config,
+ .read_event_config = max30210_read_event_config,
+};
+
+static const struct iio_event_spec max30210_events[] = {
+ {
+ .type = IIO_EV_TYPE_THRESH,
+ .dir = IIO_EV_DIR_RISING,
+ .mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
+ }, {
+ .type = IIO_EV_TYPE_THRESH,
+ .dir = IIO_EV_DIR_FALLING,
+ .mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
+ },
+};
+
+static const struct iio_chan_spec max30210_channel = {
+ .type = IIO_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE) |
+ BIT(IIO_CHAN_INFO_SAMP_FREQ),
+ .info_mask_separate_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+ .scan_index = 0,
+ .event_spec = max30210_events,
+ .num_event_specs = ARRAY_SIZE(max30210_events),
+ .scan_type = {
+ .sign = 's',
+ .realbits = 16,
+ .storagebits = 16,
+ .endianness = IIO_CPU,
+ },
+};
+
+static void max30210_powerdown(void *data)
+{
+ struct gpio_desc *powerdown_gpio = data;
+
+ gpiod_set_value(powerdown_gpio, 1);
+}
+
+static int max30210_setup(struct max30210_state *st, struct device *dev)
+{
+ struct gpio_desc *powerdown_gpio;
+ unsigned int val;
+ int ret;
+
+ powerdown_gpio = devm_gpiod_get_optional(dev, "powerdown",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(powerdown_gpio))
+ return dev_err_probe(dev, PTR_ERR(powerdown_gpio),
+ "failed to request powerdown GPIO\n");
+
+ if (powerdown_gpio) {
+ /* Deassert powerdown to power up device */
+ gpiod_set_value(powerdown_gpio, 0);
+
+ ret = devm_add_action_or_reset(dev, max30210_powerdown, powerdown_gpio);
+ if (ret)
+ return ret;
+ } else {
+ ret = regmap_set_bits(st->regmap, MAX30210_SYS_CONF_REG,
+ MAX30210_SYSCONF_RESET);
+ if (ret)
+ return ret;
+ }
+
+ /*
+ * Datasheet Figure 6:
+ * tPU max = 700 µs after power-up or reset before device is ready.
+ */
+ fsleep(700);
+
+ /* Clear status byte */
+ return regmap_read(st->regmap, MAX30210_STATUS_REG, &val);
+}
+
+static int max30210_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct iio_dev *indio_dev;
+ struct max30210_state *st;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ mutex_init(&st->lock);
+
+ ret = devm_regulator_get_enable(dev, "vdd");
+ if (ret)
+ return dev_err_probe(dev, ret,
+ "Failed to enable vdd regulator.\n");
+
+ st->regmap = devm_regmap_init_i2c(client, &max30210_regmap);
+ if (IS_ERR(st->regmap))
+ return dev_err_probe(dev, PTR_ERR(st->regmap),
+ "Failed to allocate regmap.\n");
+
+ st->watermark = MAX30210_WATERMARK_DEFAULT;
+
+ ret = max30210_setup(st, dev);
+ if (ret)
+ return ret;
+
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = &max30210_channel;
+ indio_dev->num_channels = 1;
+ indio_dev->name = "max30210";
+ indio_dev->info = &max30210_info;
+
+ /* Without an interrupt there is no way to drain the FIFO into the buffer */
+ if (client->irq) {
+ ret = devm_iio_kfifo_buffer_setup_ext(dev, indio_dev, &max30210_buffer_ops,
+ max30210_fifo_attributes);
+ if (ret)
+ return ret;
+ }
+
+ ret = devm_iio_device_register(dev, indio_dev);
+ if (ret)
+ return ret;
+
+ if (!client->irq)
+ return 0;
+
+ /*
+ * Request the IRQ after registering the IIO device so devm tears it
+ * down first on removal, before the event interface is freed.
+ */
+ return devm_request_threaded_irq(dev, client->irq, NULL,
+ max30210_irq_handler, IRQF_ONESHOT,
+ indio_dev->name, indio_dev);
+}
+
+static const struct i2c_device_id max30210_id[] = {
+ { "max30210" },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, max30210_id);
+
+static const struct of_device_id max30210_of_match[] = {
+ { .compatible = "adi,max30210" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, max30210_of_match);
+
+static struct i2c_driver max30210_driver = {
+ .driver = {
+ .name = "max30210",
+ .of_match_table = max30210_of_match,
+ },
+ .probe = max30210_probe,
+ .id_table = max30210_id,
+};
+module_i2c_driver(max30210_driver);
+
+MODULE_AUTHOR("John Erasmus Mari Geronimo <johnerasmusmari.geronimo@analog.com>");
+MODULE_DESCRIPTION("MAX30210 low-power digital temperature sensor");
+MODULE_LICENSE("GPL");
--
2.34.1
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