From 4aa91223fd6c9b9e6c73f9dc6ffb55cbf04df4ac Mon Sep 17 00:00:00 2001 From: David Jander Date: Tue, 18 Nov 2025 15:18:21 +0100 Subject: [PATCH] iio: adc: Add TI ADS131M0x ADC driver Add a new IIO ADC driver for Texas Instruments ADS131M0x devices (ADS131M02/03/04/06/08). These are 24-bit, up to 64 kSPS, simultaneous- sampling delta-sigma ADCs accessed via SPI. Highlights: - Supports 2/3/4/6/8-channel variants with per-channel RAW and SCALE. - Implements device-required full-duplex fixed-frame transfers. - Handles both input and output CRC Note: Despite the almost identical name, this hardware is not compatible with the ADS131E0x series handled by drivers/iio/adc/ti-ads131e08.c. Signed-off-by: David Jander Co-developed-by: Oleksij Rempel Signed-off-by: Oleksij Rempel Reviewed-by: David Lechner Signed-off-by: Jonathan Cameron --- drivers/iio/adc/Kconfig | 11 + drivers/iio/adc/Makefile | 1 + drivers/iio/adc/ti-ads131m02.c | 968 +++++++++++++++++++++++++++++++++ 3 files changed, 980 insertions(+) create mode 100644 drivers/iio/adc/ti-ads131m02.c diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index 58da8255525e4..9c4c1e23090aa 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -1722,6 +1722,17 @@ config TI_ADS131E08 This driver can also be built as a module. If so, the module will be called ti-ads131e08. +config TI_ADS131M02 + tristate "Texas Instruments ADS131M02" + depends on SPI && REGULATOR + select CRC_ITU_T + help + Say yes here to get support for Texas Instruments ADS131M02, ADS131M03, + ADS131M04, ADS131M06 and ADS131M08 chips. + + This driver can also be built as a module. If so, the module will be + called ti-ads131m02. + config TI_ADS7138 tristate "Texas Instruments ADS7128 and ADS7138 ADC driver" depends on I2C diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile index 7cc8f9a12f763..ca3f875103310 100644 --- a/drivers/iio/adc/Makefile +++ b/drivers/iio/adc/Makefile @@ -150,6 +150,7 @@ obj-$(CONFIG_TI_ADS1119) += ti-ads1119.o obj-$(CONFIG_TI_ADS124S08) += ti-ads124s08.o obj-$(CONFIG_TI_ADS1298) += ti-ads1298.o obj-$(CONFIG_TI_ADS131E08) += ti-ads131e08.o +obj-$(CONFIG_TI_ADS131M02) += ti-ads131m02.o obj-$(CONFIG_TI_ADS7138) += ti-ads7138.o obj-$(CONFIG_TI_ADS7924) += ti-ads7924.o obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o diff --git a/drivers/iio/adc/ti-ads131m02.c b/drivers/iio/adc/ti-ads131m02.c new file mode 100644 index 0000000000000..07d63bf62c5f2 --- /dev/null +++ b/drivers/iio/adc/ti-ads131m02.c @@ -0,0 +1,968 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Driver for Texas Instruments ADS131M02 family ADC chips. + * + * Copyright (C) 2024 Protonic Holland + * Copyright (C) 2025 Oleksij Rempel , Pengutronix + * + * Primary Datasheet Reference (used for citations): + * ADS131M08 8-Channel, Simultaneously-Sampling, 24-Bit, Delta-Sigma ADC + * Document SBAS950B, Revised February 2021 + * https://www.ti.com/lit/ds/symlink/ads131m08.pdf + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* Max channels supported by the largest variant in the family (ADS131M08) */ +#define ADS131M_MAX_CHANNELS 8 + +/* Section 6.7, t_REGACQ (min time after reset) is 5us */ +#define ADS131M_RESET_DELAY_US 5 + +#define ADS131M_WORD_SIZE_BYTES 3 +#define ADS131M_RESPONSE_WORDS 1 +#define ADS131M_CRC_WORDS 1 + +/* + * SPI Frame word count calculation. + * Frame = N channel words + 1 response word + 1 CRC word. + * Word size depends on WLENGTH bits in MODE register (Default 24-bit). + */ +#define ADS131M_FRAME_WORDS(nch) \ + ((nch) + ADS131M_RESPONSE_WORDS + ADS131M_CRC_WORDS) + +/* + * SPI Frame byte size calculation. + * Assumes default word size of 24 bits (3 bytes). + */ +#define ADS131M_FRAME_BYTES(nch) \ + (ADS131M_FRAME_WORDS(nch) * ADS131M_WORD_SIZE_BYTES) + +/* + * Index calculation for the start byte of channel 'x' data within the RX buffer. + * Assumes 24-bit words (3 bytes per word). + * The received frame starts with the response word (e.g., STATUS register + * content when NULL command was sent), followed by data for channels 0 to N-1, + * and finally the output CRC word. + * Response = index 0..2, Chan0 = index 3..5, Chan1 = index 6..8, ... + * Index for ChanX = 3 (response) + x * 3 (channel data size). + */ +#define ADS131M_CHANNEL_INDEX(x) \ + ((x) * ADS131M_WORD_SIZE_BYTES + ADS131M_WORD_SIZE_BYTES) + +#define ADS131M_CMD_NULL 0x0000 +#define ADS131M_CMD_RESET 0x0011 + +#define ADS131M_CMD_ADDR_MASK GENMASK(11, 7) +#define ADS131M_CMD_NUM_MASK GENMASK(6, 0) + +#define ADS131M_CMD_RREG_OP 0xa000 +#define ADS131M_CMD_WREG_OP 0x6000 + +#define ADS131M_CMD_RREG(a, n) \ + (ADS131M_CMD_RREG_OP | \ + FIELD_PREP(ADS131M_CMD_ADDR_MASK, a) | \ + FIELD_PREP(ADS131M_CMD_NUM_MASK, n)) +#define ADS131M_CMD_WREG(a, n) \ + (ADS131M_CMD_WREG_OP | \ + FIELD_PREP(ADS131M_CMD_ADDR_MASK, a) | \ + FIELD_PREP(ADS131M_CMD_NUM_MASK, n)) + +/* STATUS Register (0x01h) bit definitions */ +#define ADS131M_STATUS_CRC_ERR BIT(12) /* Input CRC error */ + +#define ADS131M_REG_MODE 0x02 +#define ADS131M_MODE_RX_CRC_EN BIT(12) /* Enable Input CRC */ +#define ADS131M_MODE_CRC_TYPE_ANSI BIT(11) /* 0 = CCITT, 1 = ANSI */ +#define ADS131M_MODE_RESET_FLAG BIT(10) + +#define ADS131M_REG_CLOCK 0x03 +#define ADS131M_CLOCK_XTAL_DIS BIT(7) +#define ADS131M_CLOCK_EXTREF_EN BIT(6) + +/* 1.2V internal reference, in millivolts, for IIO_VAL_FRACTIONAL_LOG2 */ +#define ADS131M_VREF_INTERNAL_mV 1200 +/* 24-bit resolution */ +#define ADS131M_RESOLUTION_BITS 24 +/* Signed data uses (RESOLUTION_BITS - 1) magnitude bits */ +#define ADS131M_CODE_BITS (ADS131M_RESOLUTION_BITS - 1) + +/* External ref FSR = Vref * 0.96 */ +#define ADS131M_EXTREF_SCALE_NUM 96 +#define ADS131M_EXTREF_SCALE_DEN 100 + +struct ads131m_configuration { + const struct iio_chan_spec *channels; + const char *name; + u16 reset_ack; + u8 num_channels; + u8 supports_extref:1; + u8 supports_xtal:1; +}; + +struct ads131m_priv { + struct iio_dev *indio_dev; + struct spi_device *spi; + const struct ads131m_configuration *config; + + bool use_external_ref; + int scale_val; + int scale_val2; + + struct spi_transfer xfer; + struct spi_message msg; + + /* + * Protects the shared tx_buffer and rx_buffer. More importantly, + * this serializes all SPI communication to ensure the atomicity + * of multi-cycle command sequences (like WREG, RREG, or RESET). + */ + struct mutex lock; + + /* DMA-safe buffers should be placed at the end of the struct. */ + u8 tx_buffer[ADS131M_FRAME_BYTES(ADS131M_MAX_CHANNELS)] + __aligned(IIO_DMA_MINALIGN); + u8 rx_buffer[ADS131M_FRAME_BYTES(ADS131M_MAX_CHANNELS)]; +}; + +/** + * ads131m_tx_frame_unlocked - Sends a command frame with Input CRC + * @priv: Device private data structure. + * @command: The 16-bit command to send (e.g., NULL, RREG, RESET). + * + * This function sends a command in Word 0, and its calculated 16-bit + * CRC in Word 1, as required when Input CRC is enabled. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_tx_frame_unlocked(struct ads131m_priv *priv, u32 command) +{ + struct iio_dev *indio_dev = priv->indio_dev; + u16 crc; + + lockdep_assert_held(&priv->lock); + + memset(priv->tx_buffer, 0, ADS131M_FRAME_BYTES(indio_dev->num_channels)); + + /* Word 0: 16-bit command, MSB-aligned in 24-bit word */ + put_unaligned_be16(command, &priv->tx_buffer[0]); + + /* Word 1: Input CRC. Calculated over the 3 bytes of Word 0. */ + crc = crc_itu_t(0xffff, priv->tx_buffer, 3); + put_unaligned_be16(crc, &priv->tx_buffer[3]); + + return spi_sync(priv->spi, &priv->msg); +} + +/** + * ads131m_rx_frame_unlocked - Receives a full SPI data frame. + * @priv: Device private data structure. + * + * This function sends a NULL command (with its CRC) to clock out a + * full SPI frame from the device (e.g., response + channel data + CRC). + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_rx_frame_unlocked(struct ads131m_priv *priv) +{ + return ads131m_tx_frame_unlocked(priv, ADS131M_CMD_NULL); +} + +/** + * ads131m_check_status_crc_err - Checks for an Input CRC error. + * @priv: Device private data structure. + * + * Sends a NULL command to fetch the STATUS register and checks the + * CRC_ERR bit. This is used to verify the integrity of the previous + * command (like RREG or WREG). + * + * Return: 0 on success, -EIO if CRC_ERR bit is set. + */ +static int ads131m_check_status_crc_err(struct ads131m_priv *priv) +{ + struct device *dev = &priv->spi->dev; + u16 status; + int ret; + + lockdep_assert_held(&priv->lock); + + ret = ads131m_rx_frame_unlocked(priv); + if (ret < 0) { + dev_err_ratelimited(dev, + "SPI error on STATUS read for CRC check\n"); + return ret; + } + + status = get_unaligned_be16(&priv->rx_buffer[0]); + if (status & ADS131M_STATUS_CRC_ERR) { + dev_err_ratelimited(dev, + "Input CRC error reported in STATUS = 0x%04x\n", + status); + return -EIO; + } + + return 0; +} + +/** + * ads131m_write_reg_unlocked - Writes a single register and verifies the ACK. + * @priv: Device private data structure. + * @reg: The 8-bit register address. + * @val: The 16-bit value to write. + * + * This function performs the full 3-cycle WREG operation with Input CRC: + * 1. (Cycle 1) Sends WREG command, data, and its calculated CRC. + * 2. (Cycle 2) Sends NULL+CRC to retrieve the response from Cycle 1. + * 3. Verifies the response is the correct ACK for the WREG. + * 4. (Cycle 3) Sends NULL+CRC to retrieve STATUS and check for CRC_ERR. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_write_reg_unlocked(struct ads131m_priv *priv, u8 reg, u16 val) +{ + struct iio_dev *indio_dev = priv->indio_dev; + u16 command, expected_ack, response, crc; + struct device *dev = &priv->spi->dev; + int ret_crc_err = 0; + int ret; + + lockdep_assert_held(&priv->lock); + + command = ADS131M_CMD_WREG(reg, 0); /* n = 0 for 1 register */ + /* + * Per Table 8-11, WREG response is: 010a aaaa ammm mmmm + * For 1 reg (n = 0 -> m = 0): 010a aaaa a000 0000 = 0x4000 | (reg << 7) + */ + expected_ack = 0x4000 | (reg << 7); + + /* Cycle 1: Send WREG Command + Data + Input CRC */ + + memset(priv->tx_buffer, 0, ADS131M_FRAME_BYTES(indio_dev->num_channels)); + + /* Word 0: WREG command, 1 reg (n = 0), MSB-aligned */ + put_unaligned_be16(command, &priv->tx_buffer[0]); + + /* Word 1: Data, MSB-aligned */ + put_unaligned_be16(val, &priv->tx_buffer[3]); + + /* Word 2: Input CRC. Calculated over Word 0 (Cmd) and Word 1 (Data). */ + crc = crc_itu_t(0xffff, priv->tx_buffer, 6); + put_unaligned_be16(crc, &priv->tx_buffer[6]); + + /* Ignore the RX buffer (it's from the previous command) */ + ret = spi_sync(priv->spi, &priv->msg); + if (ret < 0) { + dev_err_ratelimited(dev, "SPI error on WREG (cycle 1)\n"); + return ret; + } + + /* Cycle 2: Send NULL Command to get the WREG response */ + ret = ads131m_rx_frame_unlocked(priv); + if (ret < 0) { + dev_err_ratelimited(dev, "SPI error on WREG ACK (cycle 2)\n"); + return ret; + } + + /* + * Response is in the first 2 bytes of the RX buffer + * (MSB-aligned 16-bit response) + */ + response = get_unaligned_be16(&priv->rx_buffer[0]); + if (response != expected_ack) { + dev_err_ratelimited(dev, "WREG(0x%02x) failed, expected ACK 0x%04x, got 0x%04x\n", + reg, expected_ack, response); + ret_crc_err = -EIO; + /* + * Don't return yet, still need to do Cycle 3 to clear + * any potential CRC_ERR flag from this failed command. + */ + } + + /* + * Cycle 3: Check STATUS for Input CRC error. + * This is necessary even if ACK was wrong, to clear the CRC_ERR flag. + */ + ret = ads131m_check_status_crc_err(priv); + if (ret < 0) + return ret; + + return ret_crc_err; +} + +/** + * ads131m_read_reg_unlocked - Reads a single register from the device. + * @priv: Device private data structure. + * @reg: The 8-bit register address. + * @val: Pointer to store the 16-bit register value. + * + * This function performs the full 3-cycle RREG operation with Input CRC: + * 1. (Cycle 1) Sends the RREG command + Input CRC. + * 2. (Cycle 2) Sends NULL+CRC to retrieve the register data. + * 3. (Cycle 3) Sends NULL+CRC to retrieve STATUS and check for CRC_ERR. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_read_reg_unlocked(struct ads131m_priv *priv, u8 reg, u16 *val) +{ + struct device *dev = &priv->spi->dev; + u16 command; + int ret; + + lockdep_assert_held(&priv->lock); + + command = ADS131M_CMD_RREG(reg, 0); /* n=0 for 1 register */ + + /* + * Cycle 1: Send RREG Command + Input CRC + * Ignore the RX buffer (it's from the previous command) + */ + ret = ads131m_tx_frame_unlocked(priv, command); + if (ret < 0) { + dev_err_ratelimited(dev, "SPI error on RREG (cycle 1)\n"); + return ret; + } + + /* Cycle 2: Send NULL Command to get the register data */ + ret = ads131m_rx_frame_unlocked(priv); + if (ret < 0) { + dev_err_ratelimited(dev, "SPI error on RREG data (cycle 2)\n"); + return ret; + } + + /* + * Per datasheet, for a single reg read, the response is the data. + * It's in the first 2 bytes of the RX buffer (MSB-aligned 16-bit). + */ + *val = get_unaligned_be16(&priv->rx_buffer[0]); + + /* + * Cycle 3: Check STATUS for Input CRC error. + * The RREG command does not execute if CRC is bad, but we read + * STATUS anyway to clear the flag in case it was set. + */ + return ads131m_check_status_crc_err(priv); +} + +/** + * ads131m_rmw_reg - Reads, modifies, and writes a single register. + * @priv: Device private data structure. + * @reg: The 8-bit register address. + * @clear: Bitmask of bits to clear. + * @set: Bitmask of bits to set. + * + * This function performs an atomic read-modify-write operation on a register. + * It reads the register, applies the clear and set masks, and writes + * the new value back if it has changed. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_rmw_reg(struct ads131m_priv *priv, u8 reg, u16 clear, u16 set) +{ + u16 old_val, new_val; + int ret; + + guard(mutex)(&priv->lock); + + ret = ads131m_read_reg_unlocked(priv, reg, &old_val); + if (ret < 0) + return ret; + + new_val = (old_val & ~clear) | set; + if (new_val == old_val) + return 0; + + return ads131m_write_reg_unlocked(priv, reg, new_val); +} + +/** + * ads131m_verify_output_crc - Verifies the CRC of the received SPI frame. + * @priv: Device private data structure. + * + * This function calculates the CRC-16-CCITT (Poly 0x1021, Seed 0xFFFF) over + * the received response and channel data, and compares it to the CRC word + * received at the end of the SPI frame. + * + * Return: 0 on success, -EIO on CRC mismatch. + */ +static int ads131m_verify_output_crc(struct ads131m_priv *priv) +{ + struct iio_dev *indio_dev = priv->indio_dev; + struct device *dev = &priv->spi->dev; + u16 calculated_crc, received_crc; + size_t data_len; + + lockdep_assert_held(&priv->lock); + + /* + * Frame: [Response][Chan 0]...[Chan N-1][CRC Word] + * Data for CRC: [Response][Chan 0]...[Chan N-1] + * Data length = (N_channels + 1) * 3 bytes (at 24-bit word size) + */ + data_len = ADS131M_FRAME_BYTES(indio_dev->num_channels) - 3; + calculated_crc = crc_itu_t(0xffff, priv->rx_buffer, data_len); + + /* + * The received 16-bit CRC is MSB-aligned in the last 24-bit word. + * We extract it from the first 2 bytes (BE) of that word. + */ + received_crc = get_unaligned_be16(&priv->rx_buffer[data_len]); + if (calculated_crc != received_crc) { + dev_err_ratelimited(dev, "Output CRC error. Got %04x, expected %04x\n", + received_crc, calculated_crc); + return -EIO; + } + + return 0; +} + +/** + * ads131m_adc_read - Reads channel data, checks input and output CRCs. + * @priv: Device private data structure. + * @channel: The channel number to read. + * @val: Pointer to store the raw 24-bit value. + * + * This function sends a NULL command (with Input CRC) to retrieve data. + * It checks the received STATUS word for any Input CRC errors from the + * previous command, and then verifies the Output CRC of the current + * data frame. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_adc_read(struct ads131m_priv *priv, u8 channel, s32 *val) +{ + struct device *dev = &priv->spi->dev; + u16 status; + int ret; + u8 *buf; + + guard(mutex)(&priv->lock); + + /* Send NULL command + Input CRC, and receive data frame */ + ret = ads131m_rx_frame_unlocked(priv); + if (ret < 0) + return ret; + + /* + * Check STATUS for Input CRC error from the previous command frame. + * Note: the STATUS word belongs to the frame before this NULL command. + */ + status = get_unaligned_be16(&priv->rx_buffer[0]); + if (status & ADS131M_STATUS_CRC_ERR) { + dev_err_ratelimited(dev, + "Previous input CRC error reported in STATUS (0x%04x)\n", + status); + } + + ret = ads131m_verify_output_crc(priv); + if (ret < 0) + return ret; + + buf = &priv->rx_buffer[ADS131M_CHANNEL_INDEX(channel)]; + *val = sign_extend32(get_unaligned_be24(buf), ADS131M_CODE_BITS); + + return 0; +} + +static int ads131m_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *channel, + int *val, int *val2, long mask) +{ + struct ads131m_priv *priv = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + ret = ads131m_adc_read(priv, channel->channel, val); + if (ret) + return ret; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + *val = priv->scale_val; + *val2 = priv->scale_val2; + + return IIO_VAL_FRACTIONAL; + default: + return -EINVAL; + } +} + +#define ADS131M_VOLTAGE_CHANNEL(num) \ + { \ + .type = IIO_VOLTAGE, \ + .differential = 1, \ + .indexed = 1, \ + .channel = (num), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ + } + +static const struct iio_chan_spec ads131m02_channels[] = { + ADS131M_VOLTAGE_CHANNEL(0), + ADS131M_VOLTAGE_CHANNEL(1), +}; + +static const struct iio_chan_spec ads131m03_channels[] = { + ADS131M_VOLTAGE_CHANNEL(0), + ADS131M_VOLTAGE_CHANNEL(1), + ADS131M_VOLTAGE_CHANNEL(2), +}; + +static const struct iio_chan_spec ads131m04_channels[] = { + ADS131M_VOLTAGE_CHANNEL(0), + ADS131M_VOLTAGE_CHANNEL(1), + ADS131M_VOLTAGE_CHANNEL(2), + ADS131M_VOLTAGE_CHANNEL(3), +}; + +static const struct iio_chan_spec ads131m06_channels[] = { + ADS131M_VOLTAGE_CHANNEL(0), + ADS131M_VOLTAGE_CHANNEL(1), + ADS131M_VOLTAGE_CHANNEL(2), + ADS131M_VOLTAGE_CHANNEL(3), + ADS131M_VOLTAGE_CHANNEL(4), + ADS131M_VOLTAGE_CHANNEL(5), +}; + +static const struct iio_chan_spec ads131m08_channels[] = { + ADS131M_VOLTAGE_CHANNEL(0), + ADS131M_VOLTAGE_CHANNEL(1), + ADS131M_VOLTAGE_CHANNEL(2), + ADS131M_VOLTAGE_CHANNEL(3), + ADS131M_VOLTAGE_CHANNEL(4), + ADS131M_VOLTAGE_CHANNEL(5), + ADS131M_VOLTAGE_CHANNEL(6), + ADS131M_VOLTAGE_CHANNEL(7), +}; + +static const struct ads131m_configuration ads131m02_config = { + .channels = ads131m02_channels, + .num_channels = ARRAY_SIZE(ads131m02_channels), + .reset_ack = 0xff22, + .name = "ads131m02", +}; + +static const struct ads131m_configuration ads131m03_config = { + .channels = ads131m03_channels, + .num_channels = ARRAY_SIZE(ads131m03_channels), + .reset_ack = 0xff23, + .name = "ads131m03", +}; + +static const struct ads131m_configuration ads131m04_config = { + .channels = ads131m04_channels, + .num_channels = ARRAY_SIZE(ads131m04_channels), + .reset_ack = 0xff24, + .name = "ads131m04", +}; + +static const struct ads131m_configuration ads131m06_config = { + .channels = ads131m06_channels, + .num_channels = ARRAY_SIZE(ads131m06_channels), + .reset_ack = 0xff26, + .supports_extref = true, + .supports_xtal = true, + .name = "ads131m06", +}; + +static const struct ads131m_configuration ads131m08_config = { + .channels = ads131m08_channels, + .num_channels = ARRAY_SIZE(ads131m08_channels), + .reset_ack = 0xff28, + .supports_extref = true, + .supports_xtal = true, + .name = "ads131m08", +}; + +static const struct iio_info ads131m_info = { + .read_raw = ads131m_read_raw, +}; + +/* + * Prepares the reusable SPI message structure for a full-duplex transfer. + * The ADS131M requires sending a command frame while simultaneously + * receiving the response/data frame from the previous command cycle. + * + * This message is optimized for the primary data acquisition workflow: + * sending a single-word command (like NULL) and receiving a full data + * frame (Response + N*Channels + CRC). + * + * This message is sized for a full data frame and is reused for all + * command/data cycles. The driver does not implement variable-length SPI + * messages. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_prepare_message(struct ads131m_priv *priv) +{ + struct iio_dev *indio_dev = priv->indio_dev; + struct device *dev = &priv->spi->dev; + int ret; + + priv->xfer.tx_buf = priv->tx_buffer; + priv->xfer.rx_buf = priv->rx_buffer; + priv->xfer.len = ADS131M_FRAME_BYTES(indio_dev->num_channels); + spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1); + + ret = devm_spi_optimize_message(dev, priv->spi, &priv->msg); + if (ret) + return dev_err_probe(dev, ret, "failed to optimize SPI message\n"); + + return 0; +} + +/** + * ads131m_hw_reset - Pulses the optional hardware reset. + * @priv: Device private data structure. + * @rstc: Reset control for the /RESET line. + * + * Pulses the /RESET line to perform a hardware reset and waits the + * required t_REGACQ time for the device to be ready. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_hw_reset(struct ads131m_priv *priv, + struct reset_control *rstc) +{ + struct device *dev = &priv->spi->dev; + int ret; + + /* + * Manually pulse the reset line using the framework. + * The reset-gpio provider does not implement the .reset op, + * so we must use .assert and .deassert. + */ + ret = reset_control_assert(rstc); + if (ret) + return dev_err_probe(dev, ret, "Failed to assert reset\n"); + + /* Datasheet: Hold /RESET low for > 2 f_CLKIN cycles. 1us is ample. */ + fsleep(1); + + ret = reset_control_deassert(rstc); + if (ret < 0) + return dev_err_probe(dev, ret, "Failed to deassert reset\n"); + + /* Wait t_REGACQ (5us) for registers to be accessible */ + fsleep(ADS131M_RESET_DELAY_US); + + return 0; +} + +/** + * ads131m_sw_reset - Issues a software RESET and verifies ACK. + * @priv: Device private data structure. + * + * This function sends a RESET command (with Input CRC), waits t_REGACQ, + * reads back the RESET ACK, and then sends a final NULL to check for + * any input CRC errors. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_sw_reset(struct ads131m_priv *priv) +{ + u16 expected_ack = priv->config->reset_ack; + struct device *dev = &priv->spi->dev; + u16 response; + int ret; + + guard(mutex)(&priv->lock); + + ret = ads131m_tx_frame_unlocked(priv, ADS131M_CMD_RESET); + if (ret < 0) + return dev_err_probe(dev, ret, "Failed to send RESET command\n"); + + /* Wait t_REGACQ (5us) for device to be ready after reset */ + fsleep(ADS131M_RESET_DELAY_US); + + /* Cycle 2: Send NULL + CRC to retrieve the response to the RESET */ + ret = ads131m_rx_frame_unlocked(priv); + if (ret < 0) + return dev_err_probe(dev, ret, "Failed to read RESET ACK\n"); + + response = get_unaligned_be16(&priv->rx_buffer[0]); + + /* Check against the device-specific ACK value */ + if (response != expected_ack) + return dev_err_probe(dev, -EIO, + "RESET ACK mismatch, got 0x%04x, expected 0x%04x\n", + response, expected_ack); + + /* Cycle 3: Check STATUS for Input CRC error on the RESET command. */ + return ads131m_check_status_crc_err(priv); +} + +/** + * ads131m_reset - Resets the device using hardware or software. + * @priv: Device private data structure. + * @rstc: Optional reset control, or NULL for software reset. + * + * This function performs a hardware reset if supported (rstc provided), + * otherwise it issues a software RESET command via SPI. + * + * Note: The software reset path also validates the device's reset + * acknowledgment against the expected ID for the compatible string. + * The hardware reset path bypasses this ID check. + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_reset(struct ads131m_priv *priv, struct reset_control *rstc) +{ + if (rstc) + return ads131m_hw_reset(priv, rstc); + + return ads131m_sw_reset(priv); +} + +static int ads131m_power_init(struct ads131m_priv *priv) +{ + static const char * const supply_ids[] = { "avdd", "dvdd" }; + struct device *dev = &priv->spi->dev; + int vref_uV; + int ret; + + ret = devm_regulator_bulk_get_enable(dev, ARRAY_SIZE(supply_ids), supply_ids); + if (ret < 0) + return dev_err_probe(dev, ret, "failed to enable regulators\n"); + + /* Default to Internal 1.2V reference: 1200mV / 2^23 */ + priv->scale_val = ADS131M_VREF_INTERNAL_mV; + priv->scale_val2 = BIT(ADS131M_CODE_BITS); + + if (!priv->config->supports_extref) + return 0; + + ret = devm_regulator_get_enable_read_voltage(dev, "refin"); + if (ret < 0 && ret != -ENODEV) + return dev_err_probe(dev, ret, "failed to get refin supply\n"); + + if (ret == 0) + return dev_err_probe(dev, -EINVAL, "refin supply reports 0V\n"); + + if (ret == -ENODEV) + return 0; + + vref_uV = ret; + + /* + * External reference found: Scale(mV) = (vref_uV * 0.96) / 1000 + * The denominator is 100 * 2^23 because of the 0.96 factor (96/100). + */ + priv->scale_val = div_s64((s64)vref_uV * ADS131M_EXTREF_SCALE_NUM, 1000); + priv->scale_val2 = ADS131M_EXTREF_SCALE_DEN * BIT(ADS131M_CODE_BITS); + priv->use_external_ref = true; + + return 0; +} + +/** + * ads131m_hw_init - Initialize the ADC hardware. + * @priv: Device private data structure. + * @rstc: Optional reset control, or NULL for software reset. + * @is_xtal: True if 'clock-names' is "xtal", false if "clkin". + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_hw_init(struct ads131m_priv *priv, + struct reset_control *rstc, bool is_xtal) +{ + struct device *dev = &priv->spi->dev; + u16 mode_clear, mode_set; + int ret; + + ret = ads131m_reset(priv, rstc); + if (ret < 0) + return ret; + + /* + * Configure CLOCK register (0x03) based on DT properties. + * This register only needs configuration for 32-pin (M06/M08) + * variants, as the configurable bits (XTAL_DIS, EXTREF_EN) + * are reserved on 20-pin (M02/M03/M04) variants. + */ + if (priv->config->supports_xtal || priv->config->supports_extref) { + u16 clk_set = 0; + + if (priv->config->supports_xtal && !is_xtal) + clk_set |= ADS131M_CLOCK_XTAL_DIS; + + if (priv->config->supports_extref && priv->use_external_ref) + clk_set |= ADS131M_CLOCK_EXTREF_EN; + + ret = ads131m_rmw_reg(priv, ADS131M_REG_CLOCK, + ADS131M_CLOCK_EXTREF_EN | ADS131M_CLOCK_XTAL_DIS, + clk_set); + if (ret < 0) + return dev_err_probe(dev, ret, "Failed to configure CLOCK register\n"); + } + + /* + * The RESET command sets all registers to default, which means: + * 1. The RESET bit (Bit 10) in MODE is set to '1'. + * 2. The CRC_TYPE bit (Bit 11) in MODE is '0' (CCITT). + * 3. The RX_CRC_EN bit (Bit 12) in MODE is '0' (Disabled). + * + * We must: + * 1. Clear the RESET bit. + * 2. Enable Input CRC (RX_CRC_EN). + * 3. Explicitly clear the ANSI CRC bit (for certainty). + */ + mode_clear = ADS131M_MODE_CRC_TYPE_ANSI | ADS131M_MODE_RESET_FLAG; + mode_set = ADS131M_MODE_RX_CRC_EN; + + ret = ads131m_rmw_reg(priv, ADS131M_REG_MODE, mode_clear, mode_set); + if (ret < 0) + return dev_err_probe(dev, ret, "Failed to configure MODE register\n"); + + return 0; +} + +/** + * ads131m_parse_clock - enable clock and detect "xtal" selection + * @priv: Device private data structure. + * @is_xtal: result flag (true if "xtal", false if default "clkin") + * + * Return: 0 on success, or a negative error code. + */ +static int ads131m_parse_clock(struct ads131m_priv *priv, bool *is_xtal) +{ + struct device *dev = &priv->spi->dev; + struct clk *clk; + int ret; + + clk = devm_clk_get_enabled(dev, NULL); + if (IS_ERR_OR_NULL(clk)) { + if (IS_ERR(clk)) + ret = PTR_ERR(clk); + else + ret = -ENODEV; + + return dev_err_probe(dev, ret, "clk get enabled failed\n"); + } + + ret = device_property_match_string(dev, "clock-names", "xtal"); + if (ret > 0) + return dev_err_probe(dev, -EINVAL, + "'xtal' must be the only or first clock name"); + + if (ret < 0 && ret != -ENODATA) + return dev_err_probe(dev, ret, + "failed to read 'clock-names' property"); + + if (ret == 0 && !priv->config->supports_xtal) + return dev_err_probe(dev, -EINVAL, + "'xtal' clock not supported on this device"); + + *is_xtal = !ret; + + return 0; +} + +static int ads131m_probe(struct spi_device *spi) +{ + const struct ads131m_configuration *config; + struct device *dev = &spi->dev; + struct reset_control *rstc; + struct iio_dev *indio_dev; + struct ads131m_priv *priv; + bool is_xtal; + int ret; + + indio_dev = devm_iio_device_alloc(dev, sizeof(*priv)); + if (!indio_dev) + return -ENOMEM; + + priv = iio_priv(indio_dev); + priv->indio_dev = indio_dev; + priv->spi = spi; + + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &ads131m_info; + + config = spi_get_device_match_data(spi); + + priv->config = config; + indio_dev->name = config->name; + indio_dev->channels = config->channels; + indio_dev->num_channels = config->num_channels; + + rstc = devm_reset_control_get_optional_exclusive(dev, NULL); + if (IS_ERR(rstc)) + return dev_err_probe(dev, PTR_ERR(rstc), + "Failed to get reset controller\n"); + + ret = devm_mutex_init(dev, &priv->lock); + if (ret < 0) + return ret; + + ret = ads131m_prepare_message(priv); + if (ret < 0) + return ret; + + ret = ads131m_power_init(priv); + if (ret < 0) + return ret; + + /* Power must be applied and stable before the clock is enabled. */ + ret = ads131m_parse_clock(priv, &is_xtal); + if (ret < 0) + return ret; + + ret = ads131m_hw_init(priv, rstc, is_xtal); + if (ret < 0) + return ret; + + return devm_iio_device_register(dev, indio_dev); +} + +static const struct of_device_id ads131m_of_match[] = { + { .compatible = "ti,ads131m02", .data = &ads131m02_config }, + { .compatible = "ti,ads131m03", .data = &ads131m03_config }, + { .compatible = "ti,ads131m04", .data = &ads131m04_config }, + { .compatible = "ti,ads131m06", .data = &ads131m06_config }, + { .compatible = "ti,ads131m08", .data = &ads131m08_config }, + { } +}; +MODULE_DEVICE_TABLE(of, ads131m_of_match); + +static const struct spi_device_id ads131m_id[] = { + { "ads131m02", (kernel_ulong_t)&ads131m02_config }, + { "ads131m03", (kernel_ulong_t)&ads131m03_config }, + { "ads131m04", (kernel_ulong_t)&ads131m04_config }, + { "ads131m06", (kernel_ulong_t)&ads131m06_config }, + { "ads131m08", (kernel_ulong_t)&ads131m08_config }, + { } +}; +MODULE_DEVICE_TABLE(spi, ads131m_id); + +static struct spi_driver ads131m_driver = { + .driver = { + .name = "ads131m02", + .of_match_table = ads131m_of_match, + }, + .probe = ads131m_probe, + .id_table = ads131m_id, +}; +module_spi_driver(ads131m_driver); + +MODULE_AUTHOR("David Jander "); +MODULE_DESCRIPTION("Texas Instruments ADS131M02 ADC driver"); +MODULE_LICENSE("GPL"); -- 2.47.3