* Copyright 2024 BayLibre, SAS
*/
+#include <linux/align.h>
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/delay.h>
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. */
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
* 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.
+ * 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)
if (ret)
return ret;
- if (chan->scan_type.storagebits > 16)
- *val = adc->sample.raw.u32;
- else
- *val = adc->sample.raw.u16;
+ 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);
if (ret)
goto out;
- iio_push_to_buffers_with_timestamp(indio_dev, &adc->sample.raw,
- pf->timestamp);
+ 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"
};
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));
break;
case AD7944_SPI_MODE_CHAIN:
- return dev_err_probe(dev, -EINVAL, "chain mode is not implemented\n");
+ 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;
- indio_dev->channels = chip_info->channels;
- indio_dev->num_channels = ARRAY_SIZE(chip_info->channels);
+
+ 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,
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