[PATCH v3 2/2] iio: adc: tsc2046: add sanity check to avoid to big allocations

[Oleksij Rempel <o.rempel@pengutronix.de>]

To avoid problematic devicetree configurations. Set allocation limit
with error message and suggestion on what can be done to solve this
issue.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/iio/adc/ti-tsc2046.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
index 95771ceba206..55b35570ad8b 100644
--- a/drivers/iio/adc/ti-tsc2046.c
+++ b/drivers/iio/adc/ti-tsc2046.c
@@ -679,6 +679,12 @@ static int tsc2046_adc_setup_spi_msg(struct tsc2046_adc_priv *priv)
 	for (ch_idx = 0; ch_idx < ARRAY_SIZE(priv->l); ch_idx++)
 		size += tsc2046_adc_group_set_layout(priv, ch_idx, ch_idx);
 
+	if (size > PAGE_SIZE) {
+		dev_err(&priv->spi->dev,
+			"Calculated scan buffer is too big. Try to reduce spi-max-frequency, settling-time-us or oversampling-ratio\n");
+		return -ENOSPC;
+	}
+
 	priv->tx = devm_kzalloc(&priv->spi->dev, size, GFP_KERNEL);
 	if (!priv->tx)
 		return -ENOMEM;
-- 
2.30.2