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spi: Allow SPI controller override device buswidth

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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>
This commit is contained in:
John Garry 2020-02-28 23:18:49 +08:00 committed by Mark Brown
parent 3d24b2a470
commit ea23578611
No known key found for this signature in database
GPG key ID: 24D68B725D5487D0
2 changed files with 6 additions and 1 deletions
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4
drivers/spi/spi.c
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@ -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;

3
include/linux/spi/spi.h
View file

@ -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)