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| author |   Rasmus Villemoes <rasmus.villemoes@prevas.dk> | 2019-03-06 10:32:05 +0000 |
|---|---|---|
| committer |   Mark Brown <broonie@kernel.org> | 2019-03-18 14:47:24 +0000 |
| commit | 69b921acae8a5b7feef03921d9b42c3634f3b9d1 (patch) | |
| tree | e58070328b6fbd2601d2f300fa3315b2f75b9691 /Documentation/devicetree | |
| parent | spi: orion: Support spi_xfer->word_delay_usecs (diff) | |
| download | linux-dev-69b921acae8a5b7feef03921d9b42c3634f3b9d1.tar.xz linux-dev-69b921acae8a5b7feef03921d9b42c3634f3b9d1.zip | |
spi: spi-fsl-spi: support use of the SPISEL_BOOT signal on MPC8309
The MPC8309 has a dedicated signal, SPISEL_BOOT, usually used as chip
select for the flash device from which the bootloader is loaded. It is
not an ordinary gpio, but is simply controlled via the SPI_CS register
in the system configuration.
To allow accessing such a spi slave, we need to teach
fsl_spi_cs_control() how to control the SPISEL_BOOT signal. To
distinguish the gpio-controlled slaves, continue to have those use
chip_select values of 0..ngpios-1, and use chip_select == ngpios for
the boot flash.
I'm not too happy with all the ifdeffery, but it seems to be necessary
for guarding the sysdev/fsl_soc.h and use of
get_immrbase() (spi-fsl-lib.c already contains similar ifdeffery).
Googling suggests that the MPC8306 is similar, with the SPI_CS
register at the same offset.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'Documentation/devicetree')
| -rw-r--r-- | Documentation/devicetree/bindings/spi/fsl-spi.txt | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/spi/fsl-spi.txt b/Documentation/devicetree/bindings/spi/fsl-spi.txt index 8854004a1d3a..411375eac54d 100644 --- a/Documentation/devicetree/bindings/spi/fsl-spi.txt +++ b/Documentation/devicetree/bindings/spi/fsl-spi.txt @@ -18,6 +18,10 @@ Optional properties: - gpios : specifies the gpio pins to be used for chipselects. The gpios will be referred to as reg = <index> in the SPI child nodes. If unspecified, a single SPI device without a chip select can be used. +- fsl,spisel_boot : for the MPC8306 and MPC8309, specifies that the + SPISEL_BOOT signal is used as chip select for a slave device. Use + reg = <number of gpios> in the corresponding child node, i.e. 0 if + the gpios property is not present. Example: spi@4c0 { |