[02/10] iio: adc: at91-sama5d2_adc: use struct with aligned_s64 timestamp

Commit Message

David Lechner April 18, 2025, 7:58 p.m. UTC

Use a struct with aligned s64 timestamp_instead of a padded array for
the buffer used for iio_push_to_buffers_with_ts(). This makes it easier
to see the correctness of the size and alignment of the buffer.

Signed-off-by: David Lechner <[e-mail]>
---
 drivers/iio/adc/at91-sama5d2_adc.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

Patch

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 414610afcb2c4128a63cf76767803c32cb01ac5e..07ced924f7a6ae36fe538021a45adbf7d76c2e69 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -21,6 +21,7 @@ 
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/sched.h>
+#include <linux/types.h>
 #include <linux/units.h>
 #include <linux/wait.h>
 #include <linux/iio/iio.h>
@@ -586,15 +587,6 @@  struct at91_adc_temp {
 	u16				saved_oversampling;
 };
 
-/*
- * Buffer size requirements:
- * No channels * bytes_per_channel(2) + timestamp bytes (8)
- * Divided by 2 because we need half words.
- * We assume 32 channels for now, has to be increased if needed.
- * Nobody minds a buffer being too big.
- */
-#define AT91_BUFFER_MAX_HWORDS ((32 * 2 + 8) / 2)
-
 struct at91_adc_state {
 	void __iomem			*base;
 	int				irq;
@@ -617,7 +609,10 @@  struct at91_adc_state {
 	struct iio_dev			*indio_dev;
 	struct device			*dev;
 	/* Ensure naturally aligned timestamp */
-	u16				buffer[AT91_BUFFER_MAX_HWORDS] __aligned(8);
+	struct {
+		u16 data[32];
+		aligned_s64 timestamp;
+	} buffer;
 	/*
 	 * lock to prevent concurrent 'single conversion' requests through
 	 * sysfs.
@@ -1481,14 +1476,14 @@  static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
 		if (chan->type == IIO_VOLTAGE) {
 			val = at91_adc_read_chan(st, chan->address);
 			at91_adc_adjust_val_osr(st, &val);
-			st->buffer[i] = val;
+			st->buffer.data[i] = val;
 		} else {
-			st->buffer[i] = 0;
+			st->buffer.data[i] = 0;
 			WARN(true, "This trigger cannot handle this type of channel");
 		}
 		i++;
 	}
-	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,
+	iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
 					   pf->timestamp);
 }
 
@@ -1643,7 +1638,7 @@  static void at91_adc_touch_data_handler(struct iio_dev *indio_dev)
 			at91_adc_read_pressure(st, chan->channel, &val);
 		else
 			continue;
-		st->buffer[i] = val;
+		st->buffer.data[i] = val;
 		i++;
 	}
 	/*
@@ -1691,7 +1686,7 @@  static void at91_adc_workq_handler(struct work_struct *workq)
 					struct at91_adc_state, touch_st);
 	struct iio_dev *indio_dev = st->indio_dev;
 
-	iio_push_to_buffers(indio_dev, st->buffer);
+	iio_push_to_buffers(indio_dev, st->buffer.data);
 }
 
 static irqreturn_t at91_adc_interrupt(int irq, void *private)