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authorRasmus Villemoes <rasmus.villemoes@prevas.dk>2019-03-06 10:32:05 +0000
committerMark Brown <broonie@kernel.org>2019-03-18 14:47:24 +0000
commit69b921acae8a5b7feef03921d9b42c3634f3b9d1 (patch)
treee58070328b6fbd2601d2f300fa3315b2f75b9691 /Documentation/devicetree
parent84d8df745b622ada89ef427541ad03e928269f09 (diff)
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.txt4
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 {