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authorAlex Elder <elder@linaro.org>2014-07-01 02:09:45 +0400
committerMatt Porter <mporter@linaro.org>2014-07-28 17:41:05 +0400
commitbe37a8b5a371850c6367bc984ee61d9de3eacf6a (patch)
tree13a3d685dedbb3530252198858602d5c7cb58d8d /Documentation/devicetree/bindings/arm
parent9a3c4145af32125c5ee39c0272662b47307a8323 (diff)
downloadlinux-be37a8b5a371850c6367bc984ee61d9de3eacf6a.tar.xz
devicetree: bindings: document Broadcom CPU enable method
Broadcom mobile SoCs use a ROM-implemented holding pen for controlled boot of secondary cores. A special register is used to communicate to the ROM that a secondary core should start executing kernel code. This enable method is currently used for members of the bcm281xx and bcm21664 SoC families. The use of an enable method also allows the SMP operation vector to be assigned as a result of device tree content for these SoCs. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: Matt Porter <mporter@linaro.org>
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+Broadcom Kona Family CPU Enable Method
+--------------------------------------
+This binding defines the enable method used for starting secondary
+CPUs in the following Broadcom SoCs:
+ BCM11130, BCM11140, BCM11351, BCM28145, BCM28155, BCM21664
+
+The enable method is specified by defining the following required
+properties in the "cpus" device tree node:
+ - enable-method = "brcm,bcm11351-cpu-method";
+ - secondary-boot-reg = <...>;
+
+The secondary-boot-reg property is a u32 value that specifies the
+physical address of the register used to request the ROM holding pen
+code release a secondary CPU. The value written to the register is
+formed by encoding the target CPU id into the low bits of the
+physical start address it should jump to.
+
+Example:
+ cpus {
+ #address-cells = <1>;
+ #size-cells = <0>;
+ enable-method = "brcm,bcm11351-cpu-method";
+ secondary-boot-reg = <0x3500417c>;
+
+ cpu0: cpu@0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a9";
+ reg = <0>;
+ };
+
+ cpu1: cpu@1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a9";
+ reg = <1>;
+ };
+ };