spi: Allow SPI controller override device buswidth (ea235786) · Commits · 戴 / test

Currently ACPI firmware description for a SPI device does not have any method to describe the data buswidth on the board. So even through the controller and device may support higher modes than standard SPI, it cannot be assumed that the board does - as such, that device is limited to standard SPI in such a circumstance. As a workaround, allow the controller driver supply buswidth override bits, which are used inform the core code that the controller driver knows the buswidth supported on that board for that device. A host controller driver might know this info from DMI tables, for example. Signed-off-by:

John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/1582903131-160033-2-git-send-email-john.garry@huawei.com Signed-off-by:

Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -510,6 +510,7 @@ struct spi_device spi_alloc_device(struct spi_controller ctlr)
		spi->dev.bus = &spi_bus_type;
		spi->dev.release = spidev_release;
		spi->cs_gpio = -ENOENT;
		spi->mode = ctlr->buswidth_override_bits;

		spin_lock_init(&spi->statistics.lock);

		@@ -2181,9 +2182,10 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
		return AE_NO_MEMORY;
		}


		ACPI_COMPANION_SET(&spi->dev, adev);
		spi->max_speed_hz = lookup.max_speed_hz;
		spi->mode = lookup.mode;
		spi->mode \|= lookup.mode;
		spi->irq = lookup.irq;
		spi->bits_per_word = lookup.bits_per_word;
		spi->chip_select = lookup.chip_select;

include/linux/spi/spi.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -481,6 +481,9 @@ struct spi_controller {
		/* spi_device.mode flags understood by this controller driver */
		u32 mode_bits;

		/* spi_device.mode flags override flags for this controller */
		u32 buswidth_override_bits;

		/* bitmask of supported bits_per_word for transfers */
		u32 bits_per_word_mask;
		#define SPI_BPW_MASK(bits) BIT((bits) - 1)

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