summaryrefslogtreecommitdiffstats
path: root/Documentation/arm
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-08 11:34:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-08 11:34:32 -0700
commit10c8e0562057b5d64ea170feab148e1550420030 (patch)
treecfd387208c85e893c93d24e324d147eb6e9abfc9 /Documentation/arm
parentd4e1f5a14e17d4f0e8034c0967511884bcb12fba (diff)
parent3e528cb7bae00ba0d73def6645d0f2fa906ee3e8 (diff)
downloadlinux-10c8e0562057b5d64ea170feab148e1550420030.tar.bz2
Merge tag 'drivers-for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
Pull ARM SoC driver changes from Olof Johansson: "A handful of driver-related changes. We've had a bunch of them going in through other branches as well, so it's only a part of what we really have this release. Larger pieces are: - Removal of a now unused PWM driver for atmel [ This includes AVR32 changes that have been appropriately acked ] - Performance counter support for the arm CCN interconnect - OMAP mailbox driver cleanups and consolidation - PCI and SATA PHY drivers for SPEAr 13xx platforms - Redefinition (with backwards compatibility!) of PCI DT bindings for Tegra to better model regulators/power" Note: this merge also fixes up the semantic conflict with the new calling convention for devm_phy_create(), see commit f0ed817638b5 ("phy: core: Let node ptr of PHY point to PHY and not of PHY provider") that came in through Greg's USB tree. Semantic merge patch by Stephen Rothwell <sfr@canb.auug.org.au> through the next tree. * tag 'drivers-for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (38 commits) bus: arm-ccn: Fix error handling at event allocation mailbox/omap: add a parent structure for every IP instance mailbox/omap: remove the private mailbox structure mailbox/omap: consolidate OMAP mailbox driver mailbox/omap: simplify the fifo assignment by using macros mailbox/omap: remove omap_mbox_type_t from mailbox ops mailbox/omap: remove OMAP1 mailbox driver mailbox/omap: use devm_* interfaces bus: ARM CCN: add PERF_EVENTS dependency bus: ARM CCN PMU driver PCI: spear: Remove spear13xx_pcie_remove() PCI: spear: Fix Section mismatch compilation warning for probe() ARM: tegra: Remove legacy PCIe power supply properties PCI: tegra: Remove deprecated power supply properties PCI: tegra: Implement accurate power supply scheme ARM: SPEAr13xx: Update defconfigs ARM: SPEAr13xx: Add pcie and miphy DT nodes ARM: SPEAr13xx: Add bindings and dt node for misc block ARM: SPEAr13xx: Fix static mapping table phy: Add drivers for PCIe and SATA phy on SPEAr13xx ...
Diffstat (limited to 'Documentation/arm')
-rw-r--r--Documentation/arm/CCN.txt52
1 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/arm/CCN.txt b/Documentation/arm/CCN.txt
new file mode 100644
index 000000000000..0632b3aad83e
--- /dev/null
+++ b/Documentation/arm/CCN.txt
@@ -0,0 +1,52 @@
+ARM Cache Coherent Network
+==========================
+
+CCN-504 is a ring-bus interconnect consisting of 11 crosspoints
+(XPs), with each crosspoint supporting up to two device ports,
+so nodes (devices) 0 and 1 are connected to crosspoint 0,
+nodes 2 and 3 to crosspoint 1 etc.
+
+PMU (perf) driver
+-----------------
+
+The CCN driver registers a perf PMU driver, which provides
+description of available events and configuration options
+in sysfs, see /sys/bus/event_source/devices/ccn*.
+
+The "format" directory describes format of the config, config1
+and config2 fields of the perf_event_attr structure. The "events"
+directory provides configuration templates for all documented
+events, that can be used with perf tool. For example "xp_valid_flit"
+is an equivalent of "type=0x8,event=0x4". Other parameters must be
+explicitly specified. For events originating from device, "node"
+defines its index. All crosspoint events require "xp" (index),
+"port" (device port number) and "vc" (virtual channel ID) and
+"dir" (direction). Watchpoints (special "event" value 0xfe) also
+require comparator values ("cmp_l" and "cmp_h") and "mask", being
+index of the comparator mask.
+
+Masks are defined separately from the event description
+(due to limited number of the config values) in the "cmp_mask"
+directory, with first 8 configurable by user and additional
+4 hardcoded for the most frequent use cases.
+
+Cycle counter is described by a "type" value 0xff and does
+not require any other settings.
+
+Example of perf tool use:
+
+/ # perf list | grep ccn
+ ccn/cycles/ [Kernel PMU event]
+<...>
+ ccn/xp_valid_flit/ [Kernel PMU event]
+<...>
+
+/ # perf stat -C 0 -e ccn/cycles/,ccn/xp_valid_flit,xp=1,port=0,vc=1,dir=1/ \
+ sleep 1
+
+The driver does not support sampling, therefore "perf record" will
+not work. Also notice that only single cpu is being selected
+("-C 0") - this is because perf framework does not support
+"non-CPU related" counters (yet?) so system-wide session ("-a")
+would try (and in most cases fail) to set up the same event
+per each CPU.