Documentation/devicetree/bindings/arm/vexpress-sysreg.txt

   1 ARM Versatile Express system registers
   2 --------------------------------------
   3
   4 This is a system control registers block, providing multiple low level
   5 platform functions like board detection and identification, software
   6 interrupt generation, MMC and NOR Flash control etc.
   7
   8 Required node properties:
   9 - compatible value : = "arm,vexpress,sysreg";
  10 - reg : physical base address and the size of the registers window
  11
  12 Deprecated properties, replaced by GPIO subnodes (see below):
  13 - gpio-controller : specifies that the node is a GPIO controller
  14 - #gpio-cells : size of the GPIO specifier, should be 2:
  15   - first cell is the pseudo-GPIO line number:
  16     0 - MMC CARDIN
  17     1 - MMC WPROT
  18     2 - NOR FLASH WPn
  19   - second cell can take standard GPIO flags (currently ignored).
  20
  21 Control registers providing pseudo-GPIO lines must be represented
  22 by subnodes, each of them requiring the following properties:
  23 - compatible value : one of
  24                         "arm,vexpress-sysreg,sys_led"
  25                         "arm,vexpress-sysreg,sys_mci"
  26                         "arm,vexpress-sysreg,sys_flash"
  27 - gpio-controller : makes the node a GPIO controller
  28 - #gpio-cells : size of the GPIO specifier, must be 2:
  29   - first cell is the function number:
  30     - for sys_led : 0..7 = LED 0..7
  31     - for sys_mci : 0 = MMC CARDIN, 1 = MMC WPROT
  32     - for sys_flash : 0 = NOR FLASH WPn
  33   - second cell can take standard GPIO flags (currently ignored).
  34
  35 Example:
  36         v2m_sysreg: sysreg@10000000 {
  37                 compatible = "arm,vexpress-sysreg";
  38                 reg = <0x10000000 0x1000>;
  39
  40                 v2m_led_gpios: sys_led@08 {
  41                         compatible = "arm,vexpress-sysreg,sys_led";
  42                         gpio-controller;
  43                         #gpio-cells = <2>;
  44                 };
  45
  46                 v2m_mmc_gpios: sys_mci@48 {
  47                         compatible = "arm,vexpress-sysreg,sys_mci";
  48                         gpio-controller;
  49                         #gpio-cells = <2>;
  50                 };
  51
  52                 v2m_flash_gpios: sys_flash@4c {
  53                         compatible = "arm,vexpress-sysreg,sys_flash";
  54                         gpio-controller;
  55                         #gpio-cells = <2>;
  56                 };
  57         };
  58
  59 This block also can also act a bridge to the platform's configuration
  60 bus via "system control" interface, addressing devices with site number,
  61 position in the board stack, config controller, function and device
  62 numbers - see motherboard's TRM for more details. All configuration
  63 controller accessible via this interface must reference the sysreg
  64 node via "arm,vexpress,config-bridge" phandle and define appropriate
  65 topology properties - see main vexpress node documentation for more
  66 details. Each child of such node describes one function and must
  67 define the following properties:
  68 - compatible value : must be one of (corresponding to the TRM):
  69         "arm,vexpress-amp"
  70         "arm,vexpress-dvimode"
  71         "arm,vexpress-energy"
  72         "arm,vexpress-muxfpga"
  73         "arm,vexpress-osc"
  74         "arm,vexpress-power"
  75         "arm,vexpress-reboot"
  76         "arm,vexpress-reset"
  77         "arm,vexpress-scc"
  78         "arm,vexpress-shutdown"
  79         "arm,vexpress-temp"
  80         "arm,vexpress-volt"
  81 - arm,vexpress-sysreg,func : must contain a set of two cells long groups:
  82   - first cell of each group defines the function number
  83     (eg. 1 for clock generator, 2 for voltage regulators etc.)
  84   - second cell of each group defines device number (eg. osc 0,
  85     osc 1 etc.)
  86   - some functions (eg. energy meter, with its 64 bit long counter)
  87     are using more than one function/device number pair
  88
  89 Example:
  90         mcc {
  91                 compatible = "arm,vexpress,config-bus";
  92                 arm,vexpress,config-bridge = <&v2m_sysreg>;
  93
  94                 osc@0 {
  95                         compatible = "arm,vexpress-osc";
  96                         arm,vexpress-sysreg,func = <1 0>;
  97                 };
  98
  99                 energy@0 {
 100                         compatible = "arm,vexpress-energy";
 101                         arm,vexpress-sysreg,func = <13 0>, <13 1>;
 102                 };
 103         };