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diff --git a/Documentation/devicetree/bindings/arm/l2c2x0.txt b/Documentation/devicetree/bindings/arm/l2c2x0.txt new file mode 100644 index 0000000000..fbe6cb21f4 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/l2c2x0.txt @@ -0,0 +1,114 @@ +* ARM L2 Cache Controller + +ARM cores often have a separate L2C210/L2C220/L2C310 (also known as PL210/PL220/ +PL310 and variants) based level 2 cache controller. All these various implementations +of the L2 cache controller have compatible programming models (Note 1). +Some of the properties that are just prefixed "cache-*" are taken from section +3.7.3 of the Devicetree Specification which can be found at: +https://www.devicetree.org/specifications/ + +The ARM L2 cache representation in the device tree should be done as follows: + +Required properties: + +- compatible : should be one of: + "arm,pl310-cache" + "arm,l220-cache" + "arm,l210-cache" + "bcm,bcm11351-a2-pl310-cache": DEPRECATED by "brcm,bcm11351-a2-pl310-cache" + "brcm,bcm11351-a2-pl310-cache": For Broadcom bcm11351 chipset where an + offset needs to be added to the address before passing down to the L2 + cache controller + "marvell,aurora-system-cache": Marvell Controller designed to be + compatible with the ARM one, with system cache mode (meaning + maintenance operations on L1 are broadcasted to the L2 and L2 + performs the same operation). + "marvell,aurora-outer-cache": Marvell Controller designed to be + compatible with the ARM one with outer cache mode. + "marvell,tauros3-cache": Marvell Tauros3 cache controller, compatible + with arm,pl310-cache controller. +- cache-unified : Specifies the cache is a unified cache. +- cache-level : Should be set to 2 for a level 2 cache. +- reg : Physical base address and size of cache controller's memory mapped + registers. + +Optional properties: + +- arm,data-latency : Cycles of latency for Data RAM accesses. Specifies 3 cells of + read, write and setup latencies. Minimum valid values are 1. Controllers + without setup latency control should use a value of 0. +- arm,tag-latency : Cycles of latency for Tag RAM accesses. Specifies 3 cells of + read, write and setup latencies. Controllers without setup latency control + should use 0. Controllers without separate read and write Tag RAM latency + values should only use the first cell. +- arm,dirty-latency : Cycles of latency for Dirty RAMs. This is a single cell. +- arm,filter-ranges : <start length> Starting address and length of window to + filter. Addresses in the filter window are directed to the M1 port. Other + addresses will go to the M0 port. +- arm,io-coherent : indicates that the system is operating in an hardware + I/O coherent mode. Valid only when the arm,pl310-cache compatible + string is used. +- interrupts : 1 combined interrupt. +- cache-size : specifies the size in bytes of the cache +- cache-sets : specifies the number of associativity sets of the cache +- cache-block-size : specifies the size in bytes of a cache block +- cache-line-size : specifies the size in bytes of a line in the cache, + if this is not specified, the line size is assumed to be equal to the + cache block size +- cache-id-part: cache id part number to be used if it is not present + on hardware +- wt-override: If present then L2 is forced to Write through mode +- arm,double-linefill : Override double linefill enable setting. Enable if + non-zero, disable if zero. +- arm,double-linefill-incr : Override double linefill on INCR read. Enable + if non-zero, disable if zero. +- arm,double-linefill-wrap : Override double linefill on WRAP read. Enable + if non-zero, disable if zero. +- arm,prefetch-drop : Override prefetch drop enable setting. Enable if non-zero, + disable if zero. +- arm,prefetch-offset : Override prefetch offset value. Valid values are + 0-7, 15, 23, and 31. +- arm,shared-override : The default behavior of the L220 or PL310 cache + controllers with respect to the shareable attribute is to transform "normal + memory non-cacheable transactions" into "cacheable no allocate" (for reads) + or "write through no write allocate" (for writes). + On systems where this may cause DMA buffer corruption, this property must be + specified to indicate that such transforms are precluded. +- arm,parity-enable : enable parity checking on the L2 cache (L220 or PL310). +- arm,parity-disable : disable parity checking on the L2 cache (L220 or PL310). +- arm,outer-sync-disable : disable the outer sync operation on the L2 cache. + Some core tiles, especially ARM PB11MPCore have a faulty L220 cache that + will randomly hang unless outer sync operations are disabled. +- prefetch-data : Data prefetch. Value: <0> (forcibly disable), <1> + (forcibly enable), property absent (retain settings set by firmware) +- prefetch-instr : Instruction prefetch. Value: <0> (forcibly disable), + <1> (forcibly enable), property absent (retain settings set by + firmware) +- arm,dynamic-clock-gating : L2 dynamic clock gating. Value: <0> (forcibly + disable), <1> (forcibly enable), property absent (OS specific behavior, + preferably retain firmware settings) +- arm,standby-mode: L2 standby mode enable. Value <0> (forcibly disable), + <1> (forcibly enable), property absent (OS specific behavior, + preferably retain firmware settings) +- arm,early-bresp-disable : Disable the CA9 optimization Early BRESP (PL310) +- arm,full-line-zero-disable : Disable the CA9 optimization Full line of zero + write (PL310) + +Example: + +L2: cache-controller { + compatible = "arm,pl310-cache"; + reg = <0xfff12000 0x1000>; + arm,data-latency = <1 1 1>; + arm,tag-latency = <2 2 2>; + arm,filter-ranges = <0x80000000 0x8000000>; + cache-unified; + cache-level = <2>; + interrupts = <45>; +}; + +Note 1: The description in this document doesn't apply to integrated L2 + cache controllers as found in e.g. Cortex-A15/A7/A57/A53. These + integrated L2 controllers are assumed to be all preconfigured by + early secure boot code. Thus no need to deal with their configuration + in the kernel at all. |