On 24.03.2016 13:42, Arnd Bergmann wrote:
On Thursday 24 March 2016 08:22:36 Stefan Roese wrote:
Arnd, thanks for your comments.
So we seem to agree, that one MBus window per SPI controller is the
way to go. Only how should this be described in the DT? I've come up
with these new DT properties in v2:
+- da-reg : The physical memory area that will be used for the direct
+ access mode, if enabled in one of the SPI devices.
+
+Per SPI device:
+- da-target-attribute : The target and attribute value for a specific
+ SPI-controller / SPI-device combination.
+ E.g. <0x01 0x5e>: SPI0-CS1 target and attribute
...
+Example with direct access mode:
+ spi@10600 {
+ compatible = "marvell,orion-spi";
+ status = "okay";
+ da-reg = <0xf2000000 0x100000>;
+
+ spi-fpga@1 {
+ compatible = "altera,stratix-v";
+ reg = <1>;
+ /* 0x01 0x5e: SPI0-CS1 target and attribute */
+ da-target-attribute = <0x01 0x5e>;
+ };
+ };
I've added the "da-*" (Direct Access) properties to enable the
SPI driver to dynamically allocate the MBus windows. Do you find
these new bindings reasonable? Or do you have better suggestions for
this per-SPI-device dynamic MBus allocation, perhaps by using
MBUS_ID somehow?
I was thinking it would be statically set up,
Really statically? Please see below.
but then we have a
problem with how it uses both internal-regs and and its own mbus
based reg, so we probably have to move the spi node outside of
the internal-regs node to achieve that, similar to how we handle
the devbus devices:
soc@ {
spi0 {
compatible = "marvell,armada-370-spi",
"marvell,orion-spi";
reg = <MBUS_ID(0xf0, 0x01) 0x10600 0x28>,
<MBUS_ID(0x01, 0x5e) 0 0x100000>;
#address-cells = <1>;
#size-cells = <0>;
pinctrl-0 = <&spi0_pins1>;
pinctrl-names = "default";
cell-index = <0>;
interrupts = <30>;
clocks = <&coreclk 0>;
status = "disabled";
};
};
Do I understand this correctly, that you suggest to list all MBus
windows here, that the SoC supports (e.g. 8 for the Armada XP).
And let the SPI driver then extract and dynamically enable (map)
the one that is currently used?
We also need a per-SPI-device DT property to enable this direct
access mode for this specific SPI device. As not all SPI devices
support this mode - at least not yet. How about this one:
flash0: flash@0 {
compatible = "m25p128";
reg = <0>;
direct-access-enable;
...
};
?
Thanks,
Stefan
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