Unverified Commit 2733092b authored by David Lechner's avatar David Lechner Committed by Mark Brown
Browse files

spi: bcm2835: implement ctlr->max_transfer_size 



The core SPI code will handle splitting transfers if needed as long
as ctlr->max_transfer_size is implemented. It does this in
__spi_pump_transfer_message() immediately before calling
ctlr->prepare_message. So effectively, this change does not
alter the behavior of the driver.

Also, several peripheral drivers make use of spi_max_transfer_size(),
so this should improve compatibility with those drivers.

Signed-off-by: default avatarDavid Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20240126220024.3926403-2-dlechner@baylibre.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent c8bec335

drivers/spi/spi-bcm2835.c

+14 −13
Original line number Diff line number Diff line
@@ -1117,19 +1117,6 @@ static int bcm2835_spi_prepare_message(struct spi_controller *ctlr, 
	struct spi_device *spi = msg->spi;

	struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);

	struct bcm2835_spidev *target = spi_get_ctldata(spi);

	int ret;



	if (ctlr->can_dma) {

		/*

		 * DMA transfers are limited to 16 bit (0 to 65535 bytes) by

		 * the SPI HW due to DLEN. Split up transfers (32-bit FIFO

		 * aligned) if the limit is exceeded.

		 */

		ret = spi_split_transfers_maxsize(ctlr, msg, 65532,

						  GFP_KERNEL | GFP_DMA);

		if (ret)

			return ret;

	}



	/*

	 * Set up clock polarity before spi_transfer_one_message() asserts
@@ -1219,6 +1206,19 @@ static int bcm2835_spi_setup_dma(struct spi_controller *ctlr, 
	return 0;

}



static size_t bcm2835_spi_max_transfer_size(struct spi_device *spi)

{

	/*

	 * DMA transfers are limited to 16 bit (0 to 65535 bytes) by

	 * the SPI HW due to DLEN. Split up transfers (32-bit FIFO

	 * aligned) if the limit is exceeded.

	 */

	if (spi->controller->can_dma)

		return 65532;



	return SIZE_MAX;

}



static int bcm2835_spi_setup(struct spi_device *spi)

{

	struct spi_controller *ctlr = spi->controller;
@@ -1348,6 +1348,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) 
	ctlr->mode_bits = BCM2835_SPI_MODE_BITS;

	ctlr->bits_per_word_mask = SPI_BPW_MASK(8);

	ctlr->num_chipselect = 3;

	ctlr->max_transfer_size = bcm2835_spi_max_transfer_size;

	ctlr->setup = bcm2835_spi_setup;

	ctlr->cleanup = bcm2835_spi_cleanup;

	ctlr->transfer_one = bcm2835_spi_transfer_one;