2
0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-24 21:24:00 +08:00
linux-next/Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
Andy Gross 4a8573abe9 spi: qup: Remove chip select function
This patch removes the chip select function.  Chip select should instead be
supported using GPIOs, defining the DT entry "cs-gpios", and letting the SPI
core assert/deassert the chip select as it sees fit.

The chip select control inside the controller is buggy.  It is supposed to
automatically assert the chip select based on the activity in the controller,
but it is buggy and doesn't work at all.  So instead we elect to use GPIOs.

Signed-off-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-06-22 11:48:09 +01:00

92 lines
2.6 KiB
Plaintext

Qualcomm Universal Peripheral (QUP) Serial Peripheral Interface (SPI)
The QUP core is an AHB slave that provides a common data path (an output FIFO
and an input FIFO) for serial peripheral interface (SPI) mini-core.
SPI in master mode supports up to 50MHz, up to four chip selects, programmable
data path from 4 bits to 32 bits and numerous protocol variants.
Required properties:
- compatible: Should contain "qcom,spi-qup-v2.1.1" or "qcom,spi-qup-v2.2.1"
- reg: Should contain base register location and length
- interrupts: Interrupt number used by this controller
- clocks: Should contain the core clock and the AHB clock.
- clock-names: Should be "core" for the core clock and "iface" for the
AHB clock.
- #address-cells: Number of cells required to define a chip select
address on the SPI bus. Should be set to 1.
- #size-cells: Should be zero.
Optional properties:
- spi-max-frequency: Specifies maximum SPI clock frequency,
Units - Hz. Definition as per
Documentation/devicetree/bindings/spi/spi-bus.txt
- num-cs: total number of chipselects
- cs-gpios: should specify GPIOs 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.
SPI slave nodes must be children of the SPI master node and can contain
properties described in Documentation/devicetree/bindings/spi/spi-bus.txt
Example:
spi_8: spi@f9964000 { /* BLSP2 QUP2 */
compatible = "qcom,spi-qup-v2";
#address-cells = <1>;
#size-cells = <0>;
reg = <0xf9964000 0x1000>;
interrupts = <0 102 0>;
spi-max-frequency = <19200000>;
clocks = <&gcc GCC_BLSP2_QUP2_SPI_APPS_CLK>, <&gcc GCC_BLSP2_AHB_CLK>;
clock-names = "core", "iface";
pinctrl-names = "default";
pinctrl-0 = <&spi8_default>;
device@0 {
compatible = "arm,pl022-dummy";
#address-cells = <1>;
#size-cells = <1>;
reg = <0>; /* Chip select 0 */
spi-max-frequency = <19200000>;
spi-cpol;
};
device@1 {
compatible = "arm,pl022-dummy";
#address-cells = <1>;
#size-cells = <1>;
reg = <1>; /* Chip select 1 */
spi-max-frequency = <9600000>;
spi-cpha;
};
device@2 {
compatible = "arm,pl022-dummy";
#address-cells = <1>;
#size-cells = <1>;
reg = <2>; /* Chip select 2 */
spi-max-frequency = <19200000>;
spi-cpol;
spi-cpha;
};
device@3 {
compatible = "arm,pl022-dummy";
#address-cells = <1>;
#size-cells = <1>;
reg = <3>; /* Chip select 3 */
spi-max-frequency = <19200000>;
spi-cpol;
spi-cpha;
spi-cs-high;
};
};