88e0abcd7a
This is a platform driver for Versatile Express' "system register" block. It's a random collection of registers providing the following functionality: - low level platform functions like board ID access; in order to use those, the driver must be initialized early, either statically or based on the DT - config bus bridge via "system control" interface; as the response from the controller does not generate interrupt (yet), the status register is periodically polled using a timer - pseudo GPIO lines providing MMC card status and Flash WP# signal control - LED interface for a set of 8 LEDs on the motherboard, with "heartbeat", "mmc0" and "cpu0" to "cpu5" as default triggers Signed-off-by: Pawel Moll <pawel.moll@arm.com>
51 lines
1.7 KiB
Plaintext
51 lines
1.7 KiB
Plaintext
ARM Versatile Express system registers
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This is a system control registers block, providing multiple low level
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platform functions like board detection and identification, software
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interrupt generation, MMC and NOR Flash control etc.
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Required node properties:
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- compatible value : = "arm,vexpress,sysreg";
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- reg : physical base address and the size of the registers window
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- gpio-controller : specifies that the node is a GPIO controller
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- #gpio-cells : size of the GPIO specifier, should be 2:
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- first cell is the pseudo-GPIO line number:
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0 - MMC CARDIN
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1 - MMC WPROT
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2 - NOR FLASH WPn
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- second cell can take standard GPIO flags (currently ignored).
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Example:
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v2m_sysreg: sysreg@10000000 {
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compatible = "arm,vexpress-sysreg";
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reg = <0x10000000 0x1000>;
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gpio-controller;
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#gpio-cells = <2>;
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};
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This block also can also act a bridge to the platform's configuration
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bus via "system control" interface, addressing devices with site number,
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position in the board stack, config controller, function and device
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numbers - see motherboard's TRM for more details.
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The node describing a config device must refer to the sysreg node via
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"arm,vexpress,config-bridge" phandle (can be also defined in the node's
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parent) and relies on the board topology properties - see main vexpress
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node documentation for more details. It must must also define the
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following property:
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- arm,vexpress-sysreg,func : must contain two cells:
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- first cell defines function number (eg. 1 for clock generator,
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2 for voltage regulators etc.)
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- device number (eg. osc 0, osc 1 etc.)
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Example:
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mcc {
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arm,vexpress,config-bridge = <&v2m_sysreg>;
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osc@0 {
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compatible = "arm,vexpress-osc";
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arm,vexpress-sysreg,func = <1 0>;
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};
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};
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