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[87.92.251.137]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-39c6631e1ebsm965691fa.42.2026.07.06.15.39.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jul 2026 15:39:38 -0700 (PDT) From: Md Shofiqul Islam To: jic23@kernel.org, lars@metafoo.de Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, robh@kernel.org, krzysztof.kozlowski+dt@linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 v7 2/3] iio: health: add MAX86150 ECG and PPG biosensor driver Date: Tue, 7 Jul 2026 01:39:29 +0300 Message-ID: <20260706223930.1807714-3-shofiqtest@gmail.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260706223930.1807714-1-shofiqtest@gmail.com> References: <20260706223930.1807714-1-shofiqtest@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a new IIO driver for the Analog Devices MAX86150 integrated biosensor, which combines two PPG optical channels (Red/IR LED) and one ECG biopotential channel in a single I2C device. The device has a 32-entry hardware FIFO with a configurable almost-full interrupt. Because all samples arrive via the FIFO, the driver uses a kfifo buffer (like the sibling MAX30100 and MAX30102 drivers) rather than the triggered-buffer framework. The interrupt handler drains the FIFO on each A_FULL event and timestamps samples back-calculated from the interrupt arrival time by one sample_period_ns per step. Key implementation details: - FIFO draining via iio_buffer_setup_ops postenable/predisable - DMA-safe FIFO read buffer aligned to IIO_DMA_MINALIGN - IIO_DECLARE_BUFFER_WITH_TS for the push buffer - 24-bit FIFO words decoded via get_unaligned_be24() - regmap_set_bits() / regmap_clear_bits() for single-direction writes - Overflow drops all samples; timestamps are unreliable after overflow - Device remains in shutdown between captures to suppress LED current - vdd and vled regulators required per datasheet; vref is not a supply Signed-off-by: Md Shofiqul Islam --- drivers/iio/health/Kconfig | 18 ++ drivers/iio/health/Makefile | 1 + drivers/iio/health/max86150.c | 533 ++++++++++++++++++++++++++++++++++ 3 files changed, 552 insertions(+) create mode 100644 drivers/iio/health/max86150.c diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig index a89f3abf11f4a..e5b8b6bb9351e 100644 --- a/drivers/iio/health/Kconfig +++ b/drivers/iio/health/Kconfig @@ -62,4 +62,22 @@ config MAX30102 endmenu + +config MAX86150 + tristate "MAX86150 ECG and PPG biosensor" + depends on I2C + select IIO_BUFFER + select IIO_KFIFO_BUF + select REGMAP_I2C + help + Say Y here to enable support for the Maxim MAX86150 combined + ECG and photoplethysmography (PPG) biosensor. + + The driver exposes three IIO channels: two PPG optical channels + (Red and IR LED) for heart rate and SpO2 monitoring, and one + ECG channel for biopotential recording. + + This driver can also be built as a module. If so, the module + will be called max86150. + endmenu diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile index 9108171122588..04fc73c584449 100644 --- a/drivers/iio/health/Makefile +++ b/drivers/iio/health/Makefile @@ -9,3 +9,4 @@ obj-$(CONFIG_AFE4403) += afe4403.o obj-$(CONFIG_AFE4404) += afe4404.o obj-$(CONFIG_MAX30100) += max30100.o obj-$(CONFIG_MAX30102) += max30102.o +obj-$(CONFIG_MAX86150) += max86150.o diff --git a/drivers/iio/health/max86150.c b/drivers/iio/health/max86150.c new file mode 100644 index 0000000000000..1e3d28cb41b70 --- /dev/null +++ b/drivers/iio/health/max86150.c @@ -0,0 +1,533 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * MAX86150 combined ECG and PPG biosensor driver + * + * Copyright (C) 2026 Md Shofiqul Islam + * + * The MAX86150 integrates two PPG optical channels (Red/IR LED) and one + * ECG biopotential channel in a single I2C device. Data is captured + * through a 32-entry hardware FIFO with a configurable almost-full + * interrupt, making it well-suited for continuous monitoring with a + * low-power host. + * + * Datasheet: + * https://www.analog.com/media/en/technical-documentation/data-sheets/MAX86150.pdf + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* Register addresses */ +#define MAX86150_REG_INT_STATUS1 0x00 +#define MAX86150_REG_INT_STATUS2 0x01 +#define MAX86150_REG_INT_ENABLE1 0x02 +#define MAX86150_REG_INT_ENABLE2 0x03 +#define MAX86150_REG_FIFO_WR_PTR 0x04 +#define MAX86150_REG_OVF_COUNTER 0x05 +#define MAX86150_REG_FIFO_RD_PTR 0x06 +#define MAX86150_REG_FIFO_DATA 0x07 +#define MAX86150_REG_FIFO_CONFIG 0x08 +#define MAX86150_REG_FIFO_DCTRL1 0x09 +#define MAX86150_REG_FIFO_DCTRL2 0x0A +#define MAX86150_REG_SYS_CTRL 0x0D +#define MAX86150_REG_PPG_CONFIG1 0x10 +#define MAX86150_REG_PPG_CONFIG2 0x11 +#define MAX86150_REG_LED1_PA 0x14 +#define MAX86150_REG_LED2_PA 0x15 +#define MAX86150_REG_ECG_CONFIG1 0x3C +#define MAX86150_REG_ECG_CONFIG3 0x3E +#define MAX86150_REG_PART_ID 0xFF + +#define MAX86150_PART_ID_VAL 0x1E + +/* INT_STATUS1 / INT_ENABLE1 */ +#define MAX86150_INT_A_FULL BIT(7) +#define MAX86150_INT_PPG_RDY BIT(6) + +/* SYS_CTRL */ +#define MAX86150_SYS_CTRL_SHDN BIT(1) +#define MAX86150_SYS_CTRL_RESET BIT(0) + +/* FIFO_CONFIG */ +#define MAX86150_FIFO_CONFIG_SMP_AVE_MASK GENMASK(7, 5) +#define MAX86150_FIFO_CONFIG_ROLLOVER_EN BIT(4) +#define MAX86150_FIFO_CONFIG_A_FULL_MASK GENMASK(3, 0) + +/* FIFO slot data-type codes */ +#define MAX86150_FD_NONE 0x0 +#define MAX86150_FD_LED1 0x1 +#define MAX86150_FD_LED2 0x2 +#define MAX86150_FD_ECG 0x9 + +/* FIFO_DCTRL1 / FIFO_DCTRL2 */ +#define MAX86150_FIFO_DCTRL_FD_LO_MASK GENMASK(3, 0) +#define MAX86150_FIFO_DCTRL_FD_HI_MASK GENMASK(7, 4) + +/* PPG_CONFIG1 */ +#define MAX86150_PPG_CONFIG1_ADC_RGE_MASK GENMASK(7, 6) +#define MAX86150_PPG_CONFIG1_SR_MASK GENMASK(5, 1) + +#define MAX86150_FIFO_DEPTH 32 +#define MAX86150_BYTES_PER_SLOT 3 +#define MAX86150_NUM_SLOTS 3 +#define MAX86150_SAMPLE_BYTES (MAX86150_NUM_SLOTS * MAX86150_BYTES_PER_SLOT) + +/* Fire A_FULL when 17 slots are available (32 - 15 = 17) */ +#define MAX86150_FIFO_A_FULL_VAL 15 + +#define MAX86150_LED_PA_50MA 0x3F +#define MAX86150_PPG_SR_100HZ 4 +#define MAX86150_PPG_ADC_RGE_16384 2 + +enum max86150_scan_idx { + MAX86150_IDX_PPG_RED = 0, + MAX86150_IDX_PPG_IR = 1, + MAX86150_IDX_ECG = 2, + MAX86150_IDX_TS, +}; + +struct max86150_data { + struct regmap *regmap; + u32 sample_period_ns; + u8 fifo_raw[ALIGN(MAX86150_SAMPLE_BYTES, IIO_DMA_MINALIGN)] + __aligned(IIO_DMA_MINALIGN); + IIO_DECLARE_BUFFER_WITH_TS(s32, buf, 3); +}; + +static const struct iio_chan_spec max86150_channels[] = { + { + .type = IIO_INTENSITY, + .modified = 1, + .channel2 = IIO_MOD_LIGHT_RED, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .scan_index = MAX86150_IDX_PPG_RED, + .scan_type = { + .sign = 'u', + .realbits = 19, + .storagebits = 32, + .endianness = IIO_CPU, + }, + }, + { + .type = IIO_INTENSITY, + .modified = 1, + .channel2 = IIO_MOD_LIGHT_IR, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .scan_index = MAX86150_IDX_PPG_IR, + .scan_type = { + .sign = 'u', + .realbits = 19, + .storagebits = 32, + .endianness = IIO_CPU, + }, + }, + { + .type = IIO_VOLTAGE, + .channel = 0, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .scan_index = MAX86150_IDX_ECG, + .scan_type = { + .sign = 's', + .realbits = 18, + .storagebits = 32, + .endianness = IIO_CPU, + }, + }, + IIO_CHAN_SOFT_TIMESTAMP(MAX86150_IDX_TS), +}; + +static const struct regmap_config max86150_regmap_config = { + .reg_bits = 8, + .val_bits = 8, + .max_register = MAX86150_REG_PART_ID, +}; + +static int max86150_read_one_sample(struct max86150_data *data, + u32 *ppg_red, u32 *ppg_ir, s32 *ecg) +{ + int ret; + + ret = regmap_noinc_read(data->regmap, MAX86150_REG_FIFO_DATA, + data->fifo_raw, MAX86150_SAMPLE_BYTES); + if (ret) + return ret; + + *ppg_red = get_unaligned_be24(&data->fifo_raw[0]) & GENMASK(18, 0); + *ppg_ir = get_unaligned_be24(&data->fifo_raw[3]) & GENMASK(18, 0); + *ecg = sign_extend32(get_unaligned_be24(&data->fifo_raw[6]) & + GENMASK(17, 0), 17); + + return 0; +} + +static int max86150_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct max86150_data *data = iio_priv(indio_dev); + unsigned int ppg_rdy_status; + u32 ppg_red, ppg_ir; + s32 ecg; + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + if (!iio_device_claim_direct(indio_dev)) + return -EBUSY; + + ret = regmap_clear_bits(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); + if (ret) + goto out_shutdown; + + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0); + if (ret) + goto out_shutdown; + ret = regmap_write(data->regmap, MAX86150_REG_OVF_COUNTER, 0); + if (ret) + goto out_shutdown; + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_RD_PTR, 0); + if (ret) + goto out_shutdown; + + /* + * Poll PPG_RDY rather than sleeping a fixed interval -- the + * internal oscillator may start slower than nominal, leaving + * the FIFO empty if we read too early. + */ + ret = regmap_read_poll_timeout(data->regmap, + MAX86150_REG_INT_STATUS1, + ppg_rdy_status, + ppg_rdy_status & MAX86150_INT_PPG_RDY, + 1000, 25000); + if (ret) + goto out_shutdown; + + ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg); + +out_shutdown: + regmap_set_bits(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); + iio_device_release_direct(indio_dev); + + if (ret) + return ret; + + switch (chan->scan_index) { + case MAX86150_IDX_PPG_RED: + *val = ppg_red; + break; + case MAX86150_IDX_PPG_IR: + *val = ppg_ir; + break; + case MAX86150_IDX_ECG: + *val = ecg; + break; + default: + return -EINVAL; + } + return IIO_VAL_INT; + + default: + return -EINVAL; + } +} + +static const struct iio_info max86150_iio_info = { + .read_raw = max86150_read_raw, +}; + +static int max86150_buffer_postenable(struct iio_dev *indio_dev) +{ + struct max86150_data *data = iio_priv(indio_dev); + int ret; + + ret = regmap_clear_bits(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); + if (ret) + return ret; + + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0); + if (ret) + goto err_shutdown; + ret = regmap_write(data->regmap, MAX86150_REG_OVF_COUNTER, 0); + if (ret) + goto err_shutdown; + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_RD_PTR, 0); + if (ret) + goto err_shutdown; + ret = regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, + MAX86150_INT_A_FULL); + if (ret) + goto err_shutdown; + return 0; + +err_shutdown: + regmap_set_bits(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); + return ret; +} + +static int max86150_buffer_predisable(struct iio_dev *indio_dev) +{ + struct max86150_data *data = iio_priv(indio_dev); + + regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, 0); + regmap_set_bits(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); + return 0; +} + +static const struct iio_buffer_setup_ops max86150_buffer_setup_ops = { + .postenable = max86150_buffer_postenable, + .predisable = max86150_buffer_predisable, +}; + +static irqreturn_t max86150_interrupt_handler(int irq, void *private) +{ + struct iio_dev *indio_dev = private; + struct max86150_data *data = iio_priv(indio_dev); + unsigned int status, wr_ptr, rd_ptr, ovf; + u32 ppg_red, ppg_ir; + s32 ecg; + s64 ts; + int ret, n_avail, i, j; + + ret = regmap_read(data->regmap, MAX86150_REG_INT_STATUS1, &status); + if (ret) + return IRQ_HANDLED; + + if (!(status & MAX86150_INT_A_FULL)) + return IRQ_NONE; + + ret = regmap_read(data->regmap, MAX86150_REG_OVF_COUNTER, &ovf); + if (ret) + return IRQ_HANDLED; + + if (ovf > 0) { + /* FIFO overflowed; timestamps are unreliable - flush and discard */ + regmap_write(data->regmap, MAX86150_REG_FIFO_WR_PTR, 0); + regmap_write(data->regmap, MAX86150_REG_OVF_COUNTER, 0); + regmap_write(data->regmap, MAX86150_REG_FIFO_RD_PTR, 0); + return IRQ_HANDLED; + } + + ret = regmap_read(data->regmap, MAX86150_REG_FIFO_WR_PTR, &wr_ptr); + if (ret) + return IRQ_HANDLED; + ret = regmap_read(data->regmap, MAX86150_REG_FIFO_RD_PTR, &rd_ptr); + if (ret) + return IRQ_HANDLED; + + n_avail = (wr_ptr - rd_ptr) & (MAX86150_FIFO_DEPTH - 1); + if (!n_avail) + return IRQ_HANDLED; + + /* + * Anchor timestamps to the interrupt time: sample (n_avail - 1) is + * the newest and corresponds to ts; earlier samples are back-calculated + * by one sample_period_ns per step. + */ + ts = ktime_get_ns(); + + for (i = 0; i < n_avail; i++) { + s64 sample_ts = ts - + (s64)(n_avail - 1 - i) * data->sample_period_ns; + + ret = max86150_read_one_sample(data, &ppg_red, &ppg_ir, &ecg); + if (ret) + break; + + j = 0; + if (test_bit(MAX86150_IDX_PPG_RED, indio_dev->active_scan_mask)) + data->buf[j++] = ppg_red; + if (test_bit(MAX86150_IDX_PPG_IR, indio_dev->active_scan_mask)) + data->buf[j++] = ppg_ir; + if (test_bit(MAX86150_IDX_ECG, indio_dev->active_scan_mask)) + data->buf[j++] = ecg; + + iio_push_to_buffers_with_ts(indio_dev, data->buf, + sizeof(data->buf), sample_ts); + } + + return IRQ_HANDLED; +} + +static void max86150_powerdown(void *arg) +{ + struct max86150_data *data = arg; + + regmap_write(data->regmap, MAX86150_REG_INT_ENABLE1, 0); + regmap_set_bits(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); +} + +static int max86150_chip_init(struct max86150_data *data) +{ + int ret; + + /* Software reset; the bit self-clears within 1 ms */ + ret = regmap_write(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_RESET); + if (ret) + return ret; + fsleep(1000); + + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_CONFIG, + MAX86150_FIFO_CONFIG_ROLLOVER_EN | + FIELD_PREP(MAX86150_FIFO_CONFIG_A_FULL_MASK, + MAX86150_FIFO_A_FULL_VAL)); + if (ret) + return ret; + + /* Slot 1 = PPG Red (LED1), Slot 2 = PPG IR (LED2) */ + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL1, + FIELD_PREP(MAX86150_FIFO_DCTRL_FD_LO_MASK, + MAX86150_FD_LED1) | + FIELD_PREP(MAX86150_FIFO_DCTRL_FD_HI_MASK, + MAX86150_FD_LED2)); + if (ret) + return ret; + + /* Slot 3 = ECG, Slot 4 = disabled */ + ret = regmap_write(data->regmap, MAX86150_REG_FIFO_DCTRL2, + FIELD_PREP(MAX86150_FIFO_DCTRL_FD_LO_MASK, + MAX86150_FD_ECG) | + FIELD_PREP(MAX86150_FIFO_DCTRL_FD_HI_MASK, + MAX86150_FD_NONE)); + if (ret) + return ret; + + /* PPG: 100 Hz sample rate, 16384 nA ADC full-scale range */ + ret = regmap_write(data->regmap, MAX86150_REG_PPG_CONFIG1, + FIELD_PREP(MAX86150_PPG_CONFIG1_ADC_RGE_MASK, + MAX86150_PPG_ADC_RGE_16384) | + FIELD_PREP(MAX86150_PPG_CONFIG1_SR_MASK, + MAX86150_PPG_SR_100HZ)); + if (ret) + return ret; + + ret = regmap_write(data->regmap, MAX86150_REG_LED1_PA, MAX86150_LED_PA_50MA); + if (ret) + return ret; + + ret = regmap_write(data->regmap, MAX86150_REG_LED2_PA, MAX86150_LED_PA_50MA); + if (ret) + return ret; + + data->sample_period_ns = 10 * NSEC_PER_MSEC; + + return regmap_write(data->regmap, MAX86150_REG_SYS_CTRL, + MAX86150_SYS_CTRL_SHDN); +} + +static int max86150_probe(struct i2c_client *client) +{ + struct iio_dev *indio_dev; + struct max86150_data *data; + unsigned int part_id; + int ret; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + + ret = devm_regulator_get_enable(&client->dev, "vdd"); + if (ret) + return dev_err_probe(&client->dev, ret, + "Failed to get/enable vdd supply\n"); + + ret = devm_regulator_get_enable(&client->dev, "vled"); + if (ret) + return dev_err_probe(&client->dev, ret, + "Failed to get/enable vled supply\n"); + + data->regmap = devm_regmap_init_i2c(client, &max86150_regmap_config); + if (IS_ERR(data->regmap)) + return dev_err_probe(&client->dev, PTR_ERR(data->regmap), + "Failed to initialise regmap\n"); + + ret = regmap_read(data->regmap, MAX86150_REG_PART_ID, &part_id); + if (ret) + return dev_err_probe(&client->dev, ret, + "Cannot read part ID\n"); + + if (part_id != MAX86150_PART_ID_VAL) + dev_warn(&client->dev, + "Unexpected part ID 0x%02x (expected 0x%02x)\n", + part_id, MAX86150_PART_ID_VAL); + + ret = max86150_chip_init(data); + if (ret) + return dev_err_probe(&client->dev, ret, + "Chip initialisation failed\n"); + + ret = devm_add_action_or_reset(&client->dev, max86150_powerdown, data); + if (ret) + return ret; + + indio_dev->name = "max86150"; + indio_dev->channels = max86150_channels; + indio_dev->num_channels = ARRAY_SIZE(max86150_channels); + indio_dev->info = &max86150_iio_info; + indio_dev->modes = INDIO_DIRECT_MODE; + + if (client->irq > 0) { + unsigned long irq_trig = irq_get_trigger_type(client->irq); + + ret = devm_iio_kfifo_buffer_setup(&client->dev, indio_dev, + &max86150_buffer_setup_ops); + if (ret) + return dev_err_probe(&client->dev, ret, + "Cannot setup kfifo buffer\n"); + + ret = devm_request_threaded_irq(&client->dev, client->irq, + NULL, + max86150_interrupt_handler, + irq_trig | IRQF_ONESHOT, + "max86150", indio_dev); + if (ret) + return dev_err_probe(&client->dev, ret, + "Cannot request IRQ %d\n", + client->irq); + } + + return devm_iio_device_register(&client->dev, indio_dev); +} + +static const struct i2c_device_id max86150_id[] = { + { "max86150" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max86150_id); + +static const struct of_device_id max86150_of_match[] = { + { .compatible = "adi,max86150" }, + { } +}; +MODULE_DEVICE_TABLE(of, max86150_of_match); + +static struct i2c_driver max86150_driver = { + .driver = { + .name = "max86150", + .of_match_table = max86150_of_match, + }, + .probe = max86150_probe, + .id_table = max86150_id, +}; +module_i2c_driver(max86150_driver); + +MODULE_AUTHOR("Md Shofiqul Islam "); +MODULE_DESCRIPTION("MAX86150 ECG and PPG biosensor driver"); +MODULE_LICENSE("GPL"); -- 2.51.1