--- /dev/null
- - arm,shared-override : The default behavior of the pl310 cache controller 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).
+* 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 ePAPR v1.1 specification which can be found at:
+https://www.power.org/wp-content/uploads/2012/06/Power_ePAPR_APPROVED_v1.1.pdf
+
+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)
+
+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.
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff