iio: adc: ad_sigma_delta: add SPI offload support

Add SPI offload support to the ad_sigma_delta module.

When the SPI controller has SPI offload capabilities, the module will
now use that for buffered reads instead of the RDY interrupt trigger.

Drivers that use the ad_sigma_delta module will have to opt into this
by setting supports_spi_offload since each driver will likely need
additional changes before SPI offload can be used. This will allow us
to gradually enable SPI offload support for each driver.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250701-iio-adc-ad7173-add-spi-offload-support-v3-11-42abb83e3dac@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 124c42e19f2e25723b67ea38f7d016f00ff91342..9d2dba0a0ee6d7fe60c8ea188ed614100419081d 100644 (file)
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/property.h>
 #include <linux/slab.h>
+#include <linux/spi/offload/consumer.h>
 #include <linux/spi/spi.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
@@ -27,6 +28,7 @@
 #include <linux/unaligned.h>
 
 #include <linux/iio/adc/ad_sigma_delta.h>
+#include <linux/iio/buffer-dmaengine.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/trigger_consumer.h>
@@ -467,8 +469,7 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
        const struct iio_scan_type *scan_type = &indio_dev->channels[0].scan_type;
        struct spi_transfer *xfer = sigma_delta->sample_xfer;
-       unsigned int i, slot, samples_buf_size;
-       unsigned int channel, scan_size;
+       unsigned int i, slot, channel;
        u8 *samples_buf;
        int ret;
 
@@ -496,25 +497,35 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
        sigma_delta->active_slots = slot;
        sigma_delta->current_slot = 0;
 
-       if (sigma_delta->active_slots > 1) {
-               ret = ad_sigma_delta_append_status(sigma_delta, true);
-               if (ret)
-                       return ret;
-       }
+       if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
+               xfer[1].offload_flags = SPI_OFFLOAD_XFER_RX_STREAM;
+               xfer[1].bits_per_word = scan_type->realbits;
+               xfer[1].len = spi_bpw_to_bytes(scan_type->realbits);
+       } else {
+               unsigned int samples_buf_size, scan_size;
 
-       samples_buf_size = ALIGN(slot * BITS_TO_BYTES(scan_type->storagebits),
-                                sizeof(s64));
-       samples_buf_size += sizeof(s64);
-       samples_buf = devm_krealloc(&sigma_delta->spi->dev, sigma_delta->samples_buf,
-                                   samples_buf_size, GFP_KERNEL);
-       if (!samples_buf)
-               return -ENOMEM;
+               if (sigma_delta->active_slots > 1) {
+                       ret = ad_sigma_delta_append_status(sigma_delta, true);
+                       if (ret)
+                               return ret;
+               }
 
-       sigma_delta->samples_buf = samples_buf;
-       scan_size = BITS_TO_BYTES(scan_type->realbits + scan_type->shift);
-       /* For 24-bit data, there is an extra byte of padding. */
-       xfer[1].rx_buf = &sigma_delta->rx_buf[scan_size == 3 ? 1 : 0];
-       xfer[1].len = scan_size + (sigma_delta->status_appended ? 1 : 0);
+               samples_buf_size =
+                       ALIGN(slot * BITS_TO_BYTES(scan_type->storagebits),
+                             sizeof(s64));
+               samples_buf_size += sizeof(s64);
+               samples_buf = devm_krealloc(&sigma_delta->spi->dev,
+                                           sigma_delta->samples_buf,
+                                           samples_buf_size, GFP_KERNEL);
+               if (!samples_buf)
+                       return -ENOMEM;
+
+               sigma_delta->samples_buf = samples_buf;
+               scan_size = BITS_TO_BYTES(scan_type->realbits + scan_type->shift);
+               /* For 24-bit data, there is an extra byte of padding. */
+               xfer[1].rx_buf = &sigma_delta->rx_buf[scan_size == 3 ? 1 : 0];
+               xfer[1].len = scan_size + (sigma_delta->status_appended ? 1 : 0);
+       }
        xfer[1].cs_change = 1;
 
        if (sigma_delta->info->has_registers) {
@@ -530,6 +541,8 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
                                                &xfer[1], 1);
        }
 
+       sigma_delta->sample_msg.offload = sigma_delta->offload;
+
        ret = spi_optimize_message(sigma_delta->spi, &sigma_delta->sample_msg);
        if (ret)
                return ret;
@@ -546,7 +559,19 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
        if (ret)
                goto err_unlock;
 
-       ad_sd_enable_irq(sigma_delta);
+       if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
+               struct spi_offload_trigger_config config = {
+                       .type = SPI_OFFLOAD_TRIGGER_DATA_READY,
+               };
+
+               ret = spi_offload_trigger_enable(sigma_delta->offload,
+                                                sigma_delta->offload_trigger,
+                                                &config);
+               if (ret)
+                       goto err_unlock;
+       } else {
+               ad_sd_enable_irq(sigma_delta);
+       }
 
        return 0;
 
@@ -561,10 +586,15 @@ static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
 {
        struct ad_sigma_delta *sigma_delta = iio_device_get_drvdata(indio_dev);
 
-       reinit_completion(&sigma_delta->completion);
-       wait_for_completion_timeout(&sigma_delta->completion, HZ);
+       if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
+               spi_offload_trigger_disable(sigma_delta->offload,
+                                           sigma_delta->offload_trigger);
+       } else {
+               reinit_completion(&sigma_delta->completion);
+               wait_for_completion_timeout(&sigma_delta->completion, HZ);
 
-       ad_sd_disable_irq(sigma_delta);
+               ad_sd_disable_irq(sigma_delta);
+       }
 
        sigma_delta->keep_cs_asserted = false;
        ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
@@ -679,7 +709,8 @@ static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
        if ((!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) &&
            ad_sd_disable_irq(sigma_delta)) {
                complete(&sigma_delta->completion);
-               iio_trigger_poll(sigma_delta->trig);
+               if (sigma_delta->trig)
+                       iio_trigger_poll(sigma_delta->trig);
 
                return IRQ_HANDLED;
        }
@@ -712,17 +743,6 @@ static int devm_ad_sd_probe_trigger(struct device *dev, struct iio_dev *indio_de
        unsigned long irq_flags = irq_get_trigger_type(sigma_delta->irq_line);
        int ret;
 
-       if (dev != &sigma_delta->spi->dev) {
-               dev_err(dev, "Trigger parent should be '%s', got '%s'\n",
-                       dev_name(dev), dev_name(&sigma_delta->spi->dev));
-               return -EFAULT;
-       }
-
-       sigma_delta->trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name,
-                                                  iio_device_id(indio_dev));
-       if (sigma_delta->trig == NULL)
-               return -ENOMEM;
-
        init_completion(&sigma_delta->completion);
 
        sigma_delta->irq_dis = true;
@@ -742,14 +762,33 @@ static int devm_ad_sd_probe_trigger(struct device *dev, struct iio_dev *indio_de
        if (ret)
                return ret;
 
-       iio_trigger_set_drvdata(sigma_delta->trig, sigma_delta);
+       if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
+               sigma_delta->offload_trigger =
+                       devm_spi_offload_trigger_get(dev, sigma_delta->offload,
+                                                    SPI_OFFLOAD_TRIGGER_DATA_READY);
+               if (IS_ERR(sigma_delta->offload_trigger))
+                       return dev_err_probe(dev, PTR_ERR(sigma_delta->offload_trigger),
+                                            "Failed to get SPI offload trigger\n");
+       } else {
+               if (dev != &sigma_delta->spi->dev)
+                       return dev_err_probe(dev, -EFAULT,
+                               "Trigger parent should be '%s', got '%s'\n",
+                               dev_name(dev), dev_name(&sigma_delta->spi->dev));
 
-       ret = devm_iio_trigger_register(dev, sigma_delta->trig);
-       if (ret)
-               return ret;
+               sigma_delta->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
+                       indio_dev->name, iio_device_id(indio_dev));
+               if (!sigma_delta->trig)
+                       return -ENOMEM;
 
-       /* select default trigger */
-       indio_dev->trig = iio_trigger_get(sigma_delta->trig);
+               iio_trigger_set_drvdata(sigma_delta->trig, sigma_delta);
+
+               ret = devm_iio_trigger_register(dev, sigma_delta->trig);
+               if (ret)
+                       return ret;
+
+               /* select default trigger */
+               indio_dev->trig = iio_trigger_get(sigma_delta->trig);
+       }
 
        return 0;
 }
@@ -769,12 +808,29 @@ int devm_ad_sd_setup_buffer_and_trigger(struct device *dev, struct iio_dev *indi
        if (!sigma_delta->slots)
                return -ENOMEM;
 
-       ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
-                                             &iio_pollfunc_store_time,
-                                             &ad_sd_trigger_handler,
-                                             &ad_sd_buffer_setup_ops);
-       if (ret)
-               return ret;
+       if (ad_sigma_delta_has_spi_offload(sigma_delta)) {
+               struct dma_chan *rx_dma;
+
+               rx_dma = devm_spi_offload_rx_stream_request_dma_chan(dev,
+                       sigma_delta->offload);
+               if (IS_ERR(rx_dma))
+                       return dev_err_probe(dev, PTR_ERR(rx_dma),
+                                            "Failed to get RX DMA channel\n");
+
+               ret = devm_iio_dmaengine_buffer_setup_with_handle(dev, indio_dev,
+                       rx_dma, IIO_BUFFER_DIRECTION_IN);
+               if (ret)
+                       return dev_err_probe(dev, ret, "Cannot setup DMA buffer\n");
+
+               indio_dev->setup_ops = &ad_sd_buffer_setup_ops;
+       } else {
+               ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+                                                     &iio_pollfunc_store_time,
+                                                     &ad_sd_trigger_handler,
+                                                     &ad_sd_buffer_setup_ops);
+               if (ret)
+                       return ret;
+       }
 
        return devm_ad_sd_probe_trigger(dev, indio_dev);
 }
@@ -837,6 +893,20 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
                        return sigma_delta->irq_line;
        }
 
+       if (info->supports_spi_offload) {
+               struct spi_offload_config offload_config = {
+                       .capability_flags = SPI_OFFLOAD_CAP_TRIGGER |
+                                           SPI_OFFLOAD_CAP_RX_STREAM_DMA,
+               };
+               int ret;
+
+               sigma_delta->offload = devm_spi_offload_get(&spi->dev, spi,
+                                                           &offload_config);
+               ret = PTR_ERR_OR_ZERO(sigma_delta->offload);
+               if (ret && ret != -ENODEV)
+                       return dev_err_probe(&spi->dev, ret, "Failed to get SPI offload\n");
+       }
+
        iio_device_set_drvdata(indio_dev, sigma_delta);
 
        return 0;
@@ -846,3 +916,4 @@ EXPORT_SYMBOL_NS_GPL(ad_sd_init, "IIO_AD_SIGMA_DELTA");
 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 MODULE_DESCRIPTION("Analog Devices Sigma-Delta ADCs");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");

diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
index 2037bb68b44115681ff48f66b580b63f50c2ea9e..6e70a412e218d54bbf9bb6861b1a4cc89be868e8 100644 (file)
--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -31,6 +31,8 @@ struct ad_sigma_delta;
 struct device;
 struct gpio_desc;
 struct iio_dev;
+struct spi_offload;
+struct spi_offload_trigger;
 
 /**
  * struct ad_sigma_delta_info - Sigma Delta driver specific callbacks and options
@@ -47,6 +49,10 @@ struct iio_dev;
  * @has_registers: true if the device has writable and readable registers, false
  *             if there is just one read-only sample data shift register.
  * @has_named_irqs: Set to true if there is more than one IRQ line.
+ * @supports_spi_offload: Set to true if the driver supports SPI offload. Often
+ *             special considerations are needed for scan_type and other channel
+ *             info, so individual drivers have to set this to let the core
+ *             code know that it can use SPI offload if it is available.
  * @addr_shift: Shift of the register address in the communications register.
  * @read_mask: Mask for the communications register having the read bit set.
  * @status_ch_mask: Mask for the channel number stored in status register.
@@ -65,6 +71,7 @@ struct ad_sigma_delta_info {
        int (*postprocess_sample)(struct ad_sigma_delta *, unsigned int raw_sample);
        bool has_registers;
        bool has_named_irqs;
+       bool supports_spi_offload;
        unsigned int addr_shift;
        unsigned int read_mask;
        unsigned int status_ch_mask;
@@ -108,6 +115,8 @@ struct ad_sigma_delta {
        struct spi_message      sample_msg;
        struct spi_transfer     sample_xfer[2];
        u8                      *samples_buf;
+       struct spi_offload      *offload;
+       struct spi_offload_trigger *offload_trigger;
 
        /*
         * DMA (thus cache coherency maintenance) requires the
@@ -121,6 +130,11 @@ struct ad_sigma_delta {
        u8                              sample_addr;
 };
 
+static inline bool ad_sigma_delta_has_spi_offload(struct ad_sigma_delta *sd)
+{
+       return sd->offload != NULL;
+}
+
 static inline int ad_sigma_delta_set_channel(struct ad_sigma_delta *sd,
        unsigned int channel)
 {