@@ -8,11 +8,10 @@ in slave mode.
The SPI master node requires the following properties:
- #address-cells - number of cells required to define a chip select
- address on the SPI bus.
+ address on the SPI bus.
- #size-cells - should be zero.
- compatible - name of SPI bus controller following generic names
- recommended practice.
-- cs-gpios - (optional) gpios chip select.
+ recommended practice.
No other properties are required in the SPI bus node. It is assumed
that a driver for an SPI bus device will understand that it is an SPI bus.
However, the binding does not attempt to define the specific method for
@@ -22,11 +21,12 @@ assumption that board specific platform code will be used to manage
chip selects. Individual drivers can define additional properties to
support describing the chip select layout.
-Optional property:
-- num-cs : total number of chipselects
+Optional properties:
+- cs-gpios - gpios chip select.
+- num-cs - total number of chipselects.
-If cs-gpios is used the number of chip select will automatically increased
-with max(cs-gpios > hw cs)
+If cs-gpios is used the number of chip selects will be increased automatically
+with max(cs-gpios > hw cs).
So if for example the controller has 2 CS lines, and the cs-gpios
property looks like this:
@@ -45,29 +45,30 @@ SPI slave nodes must be children of the SPI master node and can
contain the following properties.
- reg - (required) chip select address of device.
- compatible - (required) name of SPI device following generic names
- recommended practice
-- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz
+ recommended practice.
+- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz.
- spi-cpol - (optional) Empty property indicating device requires
- inverse clock polarity (CPOL) mode
+ inverse clock polarity (CPOL) mode.
- spi-cpha - (optional) Empty property indicating device requires
- shifted clock phase (CPHA) mode
+ shifted clock phase (CPHA) mode.
- spi-cs-high - (optional) Empty property indicating device requires
- chip select active high
+ chip select active high.
- spi-3wire - (optional) Empty property indicating device requires
- 3-wire mode.
+ 3-wire mode.
- spi-lsb-first - (optional) Empty property indicating device requires
LSB first mode.
-- spi-tx-bus-width - (optional) The bus width(number of data wires) that
+- spi-tx-bus-width - (optional) The bus width (number of data wires) that is
used for MOSI. Defaults to 1 if not present.
-- spi-rx-bus-width - (optional) The bus width(number of data wires) that
+- spi-rx-bus-width - (optional) The bus width (number of data wires) that is
used for MISO. Defaults to 1 if not present.
- spi-rx-delay-us - (optional) Microsecond delay after a read transfer.
- spi-tx-delay-us - (optional) Microsecond delay after a write transfer.
Some SPI controllers and devices support Dual and Quad SPI transfer mode.
-It allows data in the SPI system to be transferred in 2 wires(DUAL) or 4 wires(QUAD).
+It allows data in the SPI system to be transferred using 2 wires (DUAL) or 4
+wires (QUAD).
Now the value that spi-tx-bus-width and spi-rx-bus-width can receive is
-only 1(SINGLE), 2(DUAL) and 4(QUAD).
+only 1 (SINGLE), 2 (DUAL) and 4 (QUAD).
Dual/Quad mode is not allowed when 3-wire mode is used.
If a gpio chipselect is used for the SPI slave the gpio number will be passed
- Add missing verbs and periods, - Add spaces before opening parentheses, - Align list layout, - Correct grammar, - Move "cs-gpios" from the required to the optional properties section, - Remove spaces before tabs. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- Documentation/devicetree/bindings/spi/spi-bus.txt | 35 ++++++++++++----------- 1 file changed, 18 insertions(+), 17 deletions(-)