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ARM Versatile Express system registers
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This is a system control registers block, providing multiple low level
platform functions like board detection and identification, software
interrupt generation, MMC and NOR Flash control etc.
Required node properties:
- compatible value : = "arm,vexpress,sysreg";
- reg : physical base address and the size of the registers window
- gpio-controller : specifies that the node is a GPIO controller
- #gpio-cells : size of the GPIO specifier, should be 2:
- first cell is the pseudo-GPIO line number:
0 - MMC CARDIN
1 - MMC WPROT
2 - NOR FLASH WPn
- second cell can take standard GPIO flags (currently ignored).
Example:
v2m_sysreg: sysreg@10000000 {
compatible = "arm,vexpress-sysreg";
reg = <0x10000000 0x1000>;
gpio-controller;
#gpio-cells = <2>;
};
This block also can also act a bridge to the platform's configuration
bus via "system control" interface, addressing devices with site number,
position in the board stack, config controller, function and device
numbers - see motherboard's TRM for more details.
The node describing a config device must refer to the sysreg node via
"arm,vexpress,config-bridge" phandle (can be also defined in the node's
parent) and relies on the board topology properties - see main vexpress
node documentation for more details. It must also define the following
property:
- arm,vexpress-sysreg,func : must contain two cells:
- first cell defines function number (eg. 1 for clock generator,
2 for voltage regulators etc.)
- device number (eg. osc 0, osc 1 etc.)
Example:
mcc {
arm,vexpress,config-bridge = <&v2m_sysreg>;
osc@0 {
compatible = "arm,vexpress-osc";
arm,vexpress-sysreg,func = <1 0>;
};
};
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