104 lines
3.4 KiB
Plaintext
104 lines
3.4 KiB
Plaintext
ARM Versatile Express system registers
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--------------------------------------
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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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Deprecated properties, replaced by GPIO subnodes (see below):
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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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Control registers providing pseudo-GPIO lines must be represented
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by subnodes, each of them requiring the following properties:
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- compatible value : one of
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"arm,vexpress-sysreg,sys_led"
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"arm,vexpress-sysreg,sys_mci"
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"arm,vexpress-sysreg,sys_flash"
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- gpio-controller : makes the node a GPIO controller
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- #gpio-cells : size of the GPIO specifier, must be 2:
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- first cell is the function number:
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- for sys_led : 0..7 = LED 0..7
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- for sys_mci : 0 = MMC CARDIN, 1 = MMC WPROT
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- for sys_flash : 0 = 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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v2m_led_gpios: sys_led@08 {
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compatible = "arm,vexpress-sysreg,sys_led";
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gpio-controller;
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#gpio-cells = <2>;
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};
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v2m_mmc_gpios: sys_mci@48 {
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compatible = "arm,vexpress-sysreg,sys_mci";
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gpio-controller;
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#gpio-cells = <2>;
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};
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v2m_flash_gpios: sys_flash@4c {
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compatible = "arm,vexpress-sysreg,sys_flash";
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gpio-controller;
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#gpio-cells = <2>;
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};
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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. All configuration
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controller accessible via this interface must reference the sysreg
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node via "arm,vexpress,config-bridge" phandle and define appropriate
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topology properties - see main vexpress node documentation for more
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details. Each child of such node describes one function and must
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define the following properties:
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- compatible value : must be one of (corresponding to the TRM):
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"arm,vexpress-amp"
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"arm,vexpress-dvimode"
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"arm,vexpress-energy"
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"arm,vexpress-muxfpga"
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"arm,vexpress-osc"
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"arm,vexpress-power"
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"arm,vexpress-reboot"
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"arm,vexpress-reset"
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"arm,vexpress-scc"
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"arm,vexpress-shutdown"
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"arm,vexpress-temp"
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"arm,vexpress-volt"
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- arm,vexpress-sysreg,func : must contain a set of two cells long groups:
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- first cell of each group defines the function number
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(eg. 1 for clock generator, 2 for voltage regulators etc.)
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- second cell of each group defines device number (eg. osc 0,
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osc 1 etc.)
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- some functions (eg. energy meter, with its 64 bit long counter)
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are using more than one function/device number pair
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Example:
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mcc {
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compatible = "arm,vexpress,config-bus";
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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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energy@0 {
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compatible = "arm,vexpress-energy";
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arm,vexpress-sysreg,func = <13 0>, <13 1>;
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};
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};
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