diff options
Diffstat (limited to 'drivers/iio/adc/ad7944.c')
| -rw-r--r-- | drivers/iio/adc/ad7944.c | 690 |
1 files changed, 690 insertions, 0 deletions
diff --git a/drivers/iio/adc/ad7944.c b/drivers/iio/adc/ad7944.c new file mode 100644 index 0000000000..4602ab5ed2 --- /dev/null +++ b/drivers/iio/adc/ad7944.c @@ -0,0 +1,690 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Analog Devices AD7944/85/86 PulSAR ADC family driver. + * + * Copyright 2024 Analog Devices, Inc. + * Copyright 2024 BayLibre, SAS + */ + +#include <linux/align.h> +#include <linux/bitfield.h> +#include <linux/bitops.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/gpio/consumer.h> +#include <linux/module.h> +#include <linux/property.h> +#include <linux/regulator/consumer.h> +#include <linux/spi/spi.h> +#include <linux/string_helpers.h> + +#include <linux/iio/iio.h> +#include <linux/iio/sysfs.h> +#include <linux/iio/trigger_consumer.h> +#include <linux/iio/triggered_buffer.h> + +#define AD7944_INTERNAL_REF_MV 4096 + +struct ad7944_timing_spec { + /* Normal mode max conversion time (t_{CONV}). */ + unsigned int conv_ns; + /* TURBO mode max conversion time (t_{CONV}). */ + unsigned int turbo_conv_ns; +}; + +enum ad7944_spi_mode { + /* datasheet calls this "4-wire mode" */ + AD7944_SPI_MODE_DEFAULT, + /* datasheet calls this "3-wire mode" (not related to SPI_3WIRE!) */ + AD7944_SPI_MODE_SINGLE, + /* datasheet calls this "chain mode" */ + AD7944_SPI_MODE_CHAIN, +}; + +/* maps adi,spi-mode property value to enum */ +static const char * const ad7944_spi_modes[] = { + [AD7944_SPI_MODE_DEFAULT] = "", + [AD7944_SPI_MODE_SINGLE] = "single", + [AD7944_SPI_MODE_CHAIN] = "chain", +}; + +struct ad7944_adc { + struct spi_device *spi; + enum ad7944_spi_mode spi_mode; + struct spi_transfer xfers[3]; + struct spi_message msg; + void *chain_mode_buf; + /* Chip-specific timing specifications. */ + const struct ad7944_timing_spec *timing_spec; + /* GPIO connected to CNV pin. */ + struct gpio_desc *cnv; + /* Optional GPIO to enable turbo mode. */ + struct gpio_desc *turbo; + /* Indicates TURBO is hard-wired to be always enabled. */ + bool always_turbo; + /* Reference voltage (millivolts). */ + unsigned int ref_mv; + + /* + * DMA (thus cache coherency maintenance) requires the + * transfer buffers to live in their own cache lines. + */ + struct { + union { + u16 u16; + u32 u32; + } raw; + u64 timestamp __aligned(8); + } sample __aligned(IIO_DMA_MINALIGN); +}; + +/* quite time before CNV rising edge */ +#define T_QUIET_NS 20 + +static const struct ad7944_timing_spec ad7944_timing_spec = { + .conv_ns = 420, + .turbo_conv_ns = 320, +}; + +static const struct ad7944_timing_spec ad7986_timing_spec = { + .conv_ns = 500, + .turbo_conv_ns = 400, +}; + +struct ad7944_chip_info { + const char *name; + const struct ad7944_timing_spec *timing_spec; + const struct iio_chan_spec channels[2]; +}; + +/* + * AD7944_DEFINE_CHIP_INFO - Define a chip info structure for a specific chip + * @_name: The name of the chip + * @_ts: The timing specification for the chip + * @_bits: The number of bits in the conversion result + * @_diff: Whether the chip is true differential or not + */ +#define AD7944_DEFINE_CHIP_INFO(_name, _ts, _bits, _diff) \ +static const struct ad7944_chip_info _name##_chip_info = { \ + .name = #_name, \ + .timing_spec = &_ts##_timing_spec, \ + .channels = { \ + { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .differential = _diff, \ + .channel = 0, \ + .channel2 = _diff ? 1 : 0, \ + .scan_index = 0, \ + .scan_type.sign = _diff ? 's' : 'u', \ + .scan_type.realbits = _bits, \ + .scan_type.storagebits = _bits > 16 ? 32 : 16, \ + .scan_type.endianness = IIO_CPU, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \ + | BIT(IIO_CHAN_INFO_SCALE), \ + }, \ + IIO_CHAN_SOFT_TIMESTAMP(1), \ + }, \ +} + +/* pseudo-differential with ground sense */ +AD7944_DEFINE_CHIP_INFO(ad7944, ad7944, 14, 0); +AD7944_DEFINE_CHIP_INFO(ad7985, ad7944, 16, 0); +/* fully differential */ +AD7944_DEFINE_CHIP_INFO(ad7986, ad7986, 18, 1); + +static void ad7944_unoptimize_msg(void *msg) +{ + spi_unoptimize_message(msg); +} + +static int ad7944_3wire_cs_mode_init_msg(struct device *dev, struct ad7944_adc *adc, + const struct iio_chan_spec *chan) +{ + unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns + : adc->timing_spec->conv_ns; + struct spi_transfer *xfers = adc->xfers; + int ret; + + /* + * NB: can get better performance from some SPI controllers if we use + * the same bits_per_word in every transfer. + */ + xfers[0].bits_per_word = chan->scan_type.realbits; + /* + * CS is tied to CNV and we need a low to high transition to start the + * conversion, so place CNV low for t_QUIET to prepare for this. + */ + xfers[0].delay.value = T_QUIET_NS; + xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS; + + /* + * CS has to be high for full conversion time to avoid triggering the + * busy indication. + */ + xfers[1].cs_off = 1; + xfers[1].delay.value = t_conv_ns; + xfers[1].delay.unit = SPI_DELAY_UNIT_NSECS; + xfers[1].bits_per_word = chan->scan_type.realbits; + + /* Then we can read the data during the acquisition phase */ + xfers[2].rx_buf = &adc->sample.raw; + xfers[2].len = BITS_TO_BYTES(chan->scan_type.storagebits); + xfers[2].bits_per_word = chan->scan_type.realbits; + + spi_message_init_with_transfers(&adc->msg, xfers, 3); + + ret = spi_optimize_message(adc->spi, &adc->msg); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg); +} + +static int ad7944_4wire_mode_init_msg(struct device *dev, struct ad7944_adc *adc, + const struct iio_chan_spec *chan) +{ + unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns + : adc->timing_spec->conv_ns; + struct spi_transfer *xfers = adc->xfers; + int ret; + + /* + * NB: can get better performance from some SPI controllers if we use + * the same bits_per_word in every transfer. + */ + xfers[0].bits_per_word = chan->scan_type.realbits; + /* + * CS has to be high for full conversion time to avoid triggering the + * busy indication. + */ + xfers[0].cs_off = 1; + xfers[0].delay.value = t_conv_ns; + xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS; + + xfers[1].rx_buf = &adc->sample.raw; + xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits); + xfers[1].bits_per_word = chan->scan_type.realbits; + + spi_message_init_with_transfers(&adc->msg, xfers, 2); + + ret = spi_optimize_message(adc->spi, &adc->msg); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg); +} + +static int ad7944_chain_mode_init_msg(struct device *dev, struct ad7944_adc *adc, + const struct iio_chan_spec *chan, + u32 n_chain_dev) +{ + struct spi_transfer *xfers = adc->xfers; + int ret; + + /* + * NB: SCLK has to be low before we toggle CS to avoid triggering the + * busy indication. + */ + if (adc->spi->mode & SPI_CPOL) + return dev_err_probe(dev, -EINVAL, + "chain mode requires ~SPI_CPOL\n"); + + /* + * We only support CNV connected to CS in chain mode and we need CNV + * to be high during the transfer to trigger the conversion. + */ + if (!(adc->spi->mode & SPI_CS_HIGH)) + return dev_err_probe(dev, -EINVAL, + "chain mode requires SPI_CS_HIGH\n"); + + /* CNV has to be high for full conversion time before reading data. */ + xfers[0].delay.value = adc->timing_spec->conv_ns; + xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS; + + xfers[1].rx_buf = adc->chain_mode_buf; + xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits) * n_chain_dev; + xfers[1].bits_per_word = chan->scan_type.realbits; + + spi_message_init_with_transfers(&adc->msg, xfers, 2); + + ret = spi_optimize_message(adc->spi, &adc->msg); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg); +} + +/** + * ad7944_convert_and_acquire - Perform a single conversion and acquisition + * @adc: The ADC device structure + * @chan: The channel specification + * Return: 0 on success, a negative error code on failure + * + * Perform a conversion and acquisition of a single sample using the + * pre-optimized adc->msg. + * + * Upon successful return adc->sample.raw will contain the conversion result + * (or adc->chain_mode_buf if the device is using chain mode). + */ +static int ad7944_convert_and_acquire(struct ad7944_adc *adc, + const struct iio_chan_spec *chan) +{ + int ret; + + /* + * In 4-wire mode, the CNV line is held high for the entire conversion + * and acquisition process. In other modes adc->cnv is NULL and is + * ignored (CS is wired to CNV in those cases). + */ + gpiod_set_value_cansleep(adc->cnv, 1); + ret = spi_sync(adc->spi, &adc->msg); + gpiod_set_value_cansleep(adc->cnv, 0); + + return ret; +} + +static int ad7944_single_conversion(struct ad7944_adc *adc, + const struct iio_chan_spec *chan, + int *val) +{ + int ret; + + ret = ad7944_convert_and_acquire(adc, chan); + if (ret) + return ret; + + if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) { + if (chan->scan_type.storagebits > 16) + *val = ((u32 *)adc->chain_mode_buf)[chan->scan_index]; + else + *val = ((u16 *)adc->chain_mode_buf)[chan->scan_index]; + } else { + if (chan->scan_type.storagebits > 16) + *val = adc->sample.raw.u32; + else + *val = adc->sample.raw.u16; + } + + if (chan->scan_type.sign == 's') + *val = sign_extend32(*val, chan->scan_type.realbits - 1); + + return IIO_VAL_INT; +} + +static int ad7944_read_raw(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + int *val, int *val2, long info) +{ + struct ad7944_adc *adc = iio_priv(indio_dev); + int ret; + + switch (info) { + case IIO_CHAN_INFO_RAW: + ret = iio_device_claim_direct_mode(indio_dev); + if (ret) + return ret; + + ret = ad7944_single_conversion(adc, chan, val); + iio_device_release_direct_mode(indio_dev); + return ret; + + case IIO_CHAN_INFO_SCALE: + switch (chan->type) { + case IIO_VOLTAGE: + *val = adc->ref_mv; + + if (chan->scan_type.sign == 's') + *val2 = chan->scan_type.realbits - 1; + else + *val2 = chan->scan_type.realbits; + + return IIO_VAL_FRACTIONAL_LOG2; + default: + return -EINVAL; + } + + default: + return -EINVAL; + } +} + +static const struct iio_info ad7944_iio_info = { + .read_raw = &ad7944_read_raw, +}; + +static irqreturn_t ad7944_trigger_handler(int irq, void *p) +{ + struct iio_poll_func *pf = p; + struct iio_dev *indio_dev = pf->indio_dev; + struct ad7944_adc *adc = iio_priv(indio_dev); + int ret; + + ret = ad7944_convert_and_acquire(adc, &indio_dev->channels[0]); + if (ret) + goto out; + + if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) + iio_push_to_buffers_with_timestamp(indio_dev, adc->chain_mode_buf, + pf->timestamp); + else + iio_push_to_buffers_with_timestamp(indio_dev, &adc->sample.raw, + pf->timestamp); + +out: + iio_trigger_notify_done(indio_dev->trig); + + return IRQ_HANDLED; +} + +/** + * ad7944_chain_mode_alloc - allocate and initialize channel specs and buffers + * for daisy-chained devices + * @dev: The device for devm_ functions + * @chan_template: The channel template for the devices (array of 2 channels + * voltage and timestamp) + * @n_chain_dev: The number of devices in the chain + * @chain_chan: Pointer to receive the allocated channel specs + * @chain_mode_buf: Pointer to receive the allocated rx buffer + * @chain_scan_masks: Pointer to receive the allocated scan masks + * Return: 0 on success, a negative error code on failure + */ +static int ad7944_chain_mode_alloc(struct device *dev, + const struct iio_chan_spec *chan_template, + u32 n_chain_dev, + struct iio_chan_spec **chain_chan, + void **chain_mode_buf, + unsigned long **chain_scan_masks) +{ + struct iio_chan_spec *chan; + size_t chain_mode_buf_size; + unsigned long *scan_masks; + void *buf; + int i; + + /* 1 channel for each device in chain plus 1 for soft timestamp */ + + chan = devm_kcalloc(dev, n_chain_dev + 1, sizeof(*chan), GFP_KERNEL); + if (!chan) + return -ENOMEM; + + for (i = 0; i < n_chain_dev; i++) { + chan[i] = chan_template[0]; + + if (chan_template[0].differential) { + chan[i].channel = 2 * i; + chan[i].channel2 = 2 * i + 1; + } else { + chan[i].channel = i; + } + + chan[i].scan_index = i; + } + + /* soft timestamp */ + chan[i] = chan_template[1]; + chan[i].scan_index = i; + + *chain_chan = chan; + + /* 1 word for each voltage channel + aligned u64 for timestamp */ + + chain_mode_buf_size = ALIGN(n_chain_dev * + BITS_TO_BYTES(chan[0].scan_type.storagebits), sizeof(u64)) + + sizeof(u64); + buf = devm_kzalloc(dev, chain_mode_buf_size, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + *chain_mode_buf = buf; + + /* + * Have to limit n_chain_dev due to current implementation of + * available_scan_masks. + */ + if (n_chain_dev > BITS_PER_LONG) + return dev_err_probe(dev, -EINVAL, + "chain is limited to 32 devices\n"); + + scan_masks = devm_kcalloc(dev, 2, sizeof(*scan_masks), GFP_KERNEL); + if (!scan_masks) + return -ENOMEM; + + /* + * Scan mask is needed since we always have to read all devices in the + * chain in one SPI transfer. + */ + scan_masks[0] = GENMASK(n_chain_dev - 1, 0); + + *chain_scan_masks = scan_masks; + + return 0; +} + +static const char * const ad7944_power_supplies[] = { + "avdd", "dvdd", "bvdd", "vio" +}; + +static void ad7944_ref_disable(void *ref) +{ + regulator_disable(ref); +} + +static int ad7944_probe(struct spi_device *spi) +{ + const struct ad7944_chip_info *chip_info; + struct device *dev = &spi->dev; + struct iio_dev *indio_dev; + struct ad7944_adc *adc; + bool have_refin = false; + struct regulator *ref; + struct iio_chan_spec *chain_chan; + unsigned long *chain_scan_masks; + u32 n_chain_dev; + int ret; + + indio_dev = devm_iio_device_alloc(dev, sizeof(*adc)); + if (!indio_dev) + return -ENOMEM; + + adc = iio_priv(indio_dev); + adc->spi = spi; + + chip_info = spi_get_device_match_data(spi); + if (!chip_info) + return dev_err_probe(dev, -EINVAL, "no chip info\n"); + + adc->timing_spec = chip_info->timing_spec; + + ret = device_property_match_property_string(dev, "adi,spi-mode", + ad7944_spi_modes, + ARRAY_SIZE(ad7944_spi_modes)); + /* absence of adi,spi-mode property means default mode */ + if (ret == -EINVAL) + adc->spi_mode = AD7944_SPI_MODE_DEFAULT; + else if (ret < 0) + return dev_err_probe(dev, ret, + "getting adi,spi-mode property failed\n"); + else + adc->spi_mode = ret; + + /* + * Some chips use unusual word sizes, so check now instead of waiting + * for the first xfer. + */ + if (!spi_is_bpw_supported(spi, chip_info->channels[0].scan_type.realbits)) + return dev_err_probe(dev, -EINVAL, + "SPI host does not support %d bits per word\n", + chip_info->channels[0].scan_type.realbits); + + ret = devm_regulator_bulk_get_enable(dev, + ARRAY_SIZE(ad7944_power_supplies), + ad7944_power_supplies); + if (ret) + return dev_err_probe(dev, ret, + "failed to get and enable supplies\n"); + + /* + * Sort out what is being used for the reference voltage. Options are: + * - internal reference: neither REF or REFIN is connected + * - internal reference with external buffer: REF not connected, REFIN + * is connected + * - external reference: REF is connected, REFIN is not connected + */ + + ref = devm_regulator_get_optional(dev, "ref"); + if (IS_ERR(ref)) { + if (PTR_ERR(ref) != -ENODEV) + return dev_err_probe(dev, PTR_ERR(ref), + "failed to get REF supply\n"); + + ref = NULL; + } + + ret = devm_regulator_get_enable_optional(dev, "refin"); + if (ret == 0) + have_refin = true; + else if (ret != -ENODEV) + return dev_err_probe(dev, ret, + "failed to get and enable REFIN supply\n"); + + if (have_refin && ref) + return dev_err_probe(dev, -EINVAL, + "cannot have both refin and ref supplies\n"); + + if (ref) { + ret = regulator_enable(ref); + if (ret) + return dev_err_probe(dev, ret, + "failed to enable REF supply\n"); + + ret = devm_add_action_or_reset(dev, ad7944_ref_disable, ref); + if (ret) + return ret; + + ret = regulator_get_voltage(ref); + if (ret < 0) + return dev_err_probe(dev, ret, + "failed to get REF voltage\n"); + + /* external reference */ + adc->ref_mv = ret / 1000; + } else { + /* internal reference */ + adc->ref_mv = AD7944_INTERNAL_REF_MV; + } + + adc->cnv = devm_gpiod_get_optional(dev, "cnv", GPIOD_OUT_LOW); + if (IS_ERR(adc->cnv)) + return dev_err_probe(dev, PTR_ERR(adc->cnv), + "failed to get CNV GPIO\n"); + + if (!adc->cnv && adc->spi_mode == AD7944_SPI_MODE_DEFAULT) + return dev_err_probe(&spi->dev, -EINVAL, "CNV GPIO is required\n"); + if (adc->cnv && adc->spi_mode != AD7944_SPI_MODE_DEFAULT) + return dev_err_probe(&spi->dev, -EINVAL, + "CNV GPIO in single and chain mode is not currently supported\n"); + + adc->turbo = devm_gpiod_get_optional(dev, "turbo", GPIOD_OUT_LOW); + if (IS_ERR(adc->turbo)) + return dev_err_probe(dev, PTR_ERR(adc->turbo), + "failed to get TURBO GPIO\n"); + + adc->always_turbo = device_property_present(dev, "adi,always-turbo"); + + if (adc->turbo && adc->always_turbo) + return dev_err_probe(dev, -EINVAL, + "cannot have both turbo-gpios and adi,always-turbo\n"); + + if (adc->spi_mode == AD7944_SPI_MODE_CHAIN && adc->always_turbo) + return dev_err_probe(dev, -EINVAL, + "cannot have both chain mode and always turbo\n"); + + switch (adc->spi_mode) { + case AD7944_SPI_MODE_DEFAULT: + ret = ad7944_4wire_mode_init_msg(dev, adc, &chip_info->channels[0]); + if (ret) + return ret; + + break; + case AD7944_SPI_MODE_SINGLE: + ret = ad7944_3wire_cs_mode_init_msg(dev, adc, &chip_info->channels[0]); + if (ret) + return ret; + + break; + case AD7944_SPI_MODE_CHAIN: + ret = device_property_read_u32(dev, "#daisy-chained-devices", + &n_chain_dev); + if (ret) + return dev_err_probe(dev, ret, + "failed to get #daisy-chained-devices\n"); + + ret = ad7944_chain_mode_alloc(dev, chip_info->channels, + n_chain_dev, &chain_chan, + &adc->chain_mode_buf, + &chain_scan_masks); + if (ret) + return ret; + + ret = ad7944_chain_mode_init_msg(dev, adc, &chain_chan[0], + n_chain_dev); + if (ret) + return ret; + + break; + } + + indio_dev->name = chip_info->name; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &ad7944_iio_info; + + if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) { + indio_dev->available_scan_masks = chain_scan_masks; + indio_dev->channels = chain_chan; + indio_dev->num_channels = n_chain_dev + 1; + } else { + indio_dev->channels = chip_info->channels; + indio_dev->num_channels = ARRAY_SIZE(chip_info->channels); + } + + ret = devm_iio_triggered_buffer_setup(dev, indio_dev, + iio_pollfunc_store_time, + ad7944_trigger_handler, NULL); + if (ret) + return ret; + + return devm_iio_device_register(dev, indio_dev); +} + +static const struct of_device_id ad7944_of_match[] = { + { .compatible = "adi,ad7944", .data = &ad7944_chip_info }, + { .compatible = "adi,ad7985", .data = &ad7985_chip_info }, + { .compatible = "adi,ad7986", .data = &ad7986_chip_info }, + { } +}; +MODULE_DEVICE_TABLE(of, ad7944_of_match); + +static const struct spi_device_id ad7944_spi_id[] = { + { "ad7944", (kernel_ulong_t)&ad7944_chip_info }, + { "ad7985", (kernel_ulong_t)&ad7985_chip_info }, + { "ad7986", (kernel_ulong_t)&ad7986_chip_info }, + { } + +}; +MODULE_DEVICE_TABLE(spi, ad7944_spi_id); + +static struct spi_driver ad7944_driver = { + .driver = { + .name = "ad7944", + .of_match_table = ad7944_of_match, + }, + .probe = ad7944_probe, + .id_table = ad7944_spi_id, +}; +module_spi_driver(ad7944_driver); + +MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>"); +MODULE_DESCRIPTION("Analog Devices AD7944 PulSAR ADC family driver"); +MODULE_LICENSE("GPL"); |