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path: root/drivers/spi/spi-bcm2835aux.c
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Diffstat (limited to 'drivers/spi/spi-bcm2835aux.c')
-rw-r--r--drivers/spi/spi-bcm2835aux.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
index 5c89bbb05441..e075712c501e 100644
--- a/drivers/spi/spi-bcm2835aux.c
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -416,7 +416,18 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, master);
master->mode_bits = (SPI_CPOL | SPI_CS_HIGH | SPI_NO_CS);
master->bits_per_word_mask = SPI_BPW_MASK(8);
- master->num_chipselect = -1;
+ /* even though the driver never officially supported native CS
+ * allow a single native CS for legacy DT support purposes when
+ * no cs-gpio is configured.
+ * Known limitations for native cs are:
+ * * multiple chip-selects: cs0-cs2 are all simultaniously asserted
+ * whenever there is a transfer - this even includes SPI_NO_CS
+ * * SPI_CS_HIGH: is ignores - cs are always asserted low
+ * * cs_change: cs is deasserted after each spi_transfer
+ * * cs_delay_usec: cs is always deasserted one SCK cycle after
+ * a spi_transfer
+ */
+ master->num_chipselect = 1;
master->transfer_one = bcm2835aux_spi_transfer_one;
master->handle_err = bcm2835aux_spi_handle_err;
master->prepare_message = bcm2835aux_spi_prepare_message;