path: root/Documentation/mips
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authorLinus Torvalds <>2019-09-22 09:30:30 -0700
committerLinus Torvalds <>2019-09-22 09:30:30 -0700
commit5c6bd5de3c2e5bc8a17451e281ed2613375a7fd5 (patch)
treeec6af5a1dfddef30f92da4a2742bf3da04b520f9 /Documentation/mips
parentf7c3bf8fa7e5a8e45f4a8e82be6466157854b59b (diff)
parent05d013a0366d50f4f0dbebf8c1b22b42020bf49a (diff)
Merge tag 'mips_5.4' of git://
Pull MIPS updates from Paul Burton: "Main MIPS changes: - boot_mem_map is removed, providing a nice cleanup made possible by the recent removal of bootmem. - Some fixes to atomics, in general providing compiler barriers for smp_mb__{before,after}_atomic plus fixes specific to Loongson CPUs or MIPS32 systems using cmpxchg64(). - Conversion to the new generic VDSO infrastructure courtesy of Vincenzo Frascino. - Removal of undefined behavior in set_io_port_base(), fixing the behavior of some MIPS kernel configurations when built with recent clang versions. - Initial MIPS32 huge page support, functional on at least Ingenic SoCs. - pte_special() is now supported for some configurations, allowing among other things generic fast GUP to be used. - Miscellaneous fixes & cleanups. And platform specific changes: - Major improvements to Ingenic SoC support from Paul Cercueil, mostly enabled by the inclusion of the new TCU (timer-counter unit) drivers he's spent a very patient year or so working on. Plus some fixes for X1000 SoCs from Zhou Yanjie. - Netgear R6200 v1 systems are now supported by the bcm47xx platform. - DT updates for BMIPS, Lantiq & Microsemi Ocelot systems" * tag 'mips_5.4' of git:// (89 commits) MIPS: Detect bad _PFN_SHIFT values MIPS: Disable pte_special() for MIPS32 with RiXi MIPS: ralink: deactivate PCI support for SOC_MT7621 mips: compat: vdso: Use legacy syscalls as fallback MIPS: Drop Loongson _CACHE_* definitions MIPS: tlbex: Remove cpu_has_local_ebase MIPS: tlbex: Simplify r3k check MIPS: Select R3k-style TLB in Kconfig MIPS: PCI: refactor ioc3 special handling mips: remove ioremap_cachable mips/atomic: Fix smp_mb__{before,after}_atomic() mips/atomic: Fix loongson_llsc_mb() wreckage mips/atomic: Fix cmpxchg64 barriers MIPS: Octeon: remove duplicated include from dma-octeon.c firmware: bcm47xx_nvram: Allow COMPILE_TEST firmware: bcm47xx_nvram: Correct size_t printf format MIPS: Treat Loongson Extensions as ASEs MIPS: Remove dev_err() usage after platform_get_irq() MIPS: dts: mscc: describe the PTP ready interrupt MIPS: dts: mscc: describe the PTP register range ...
Diffstat (limited to 'Documentation/mips')
2 files changed, 77 insertions, 3 deletions
diff --git a/Documentation/mips/index.rst b/Documentation/mips/index.rst
index fd9023c8a89f..a93c2f65884c 100644
--- a/Documentation/mips/index.rst
+++ b/Documentation/mips/index.rst
@@ -1,11 +1,14 @@
.. SPDX-License-Identifier: GPL-2.0
-MIPS architecture
+MIPS-specific Documentation
.. toctree::
:maxdepth: 2
+ :numbered:
+ ingenic-tcu
diff --git a/Documentation/mips/ingenic-tcu.rst b/Documentation/mips/ingenic-tcu.rst
new file mode 100644
index 000000000000..c4ef4c45aade
--- /dev/null
+++ b/Documentation/mips/ingenic-tcu.rst
@@ -0,0 +1,71 @@
+.. SPDX-License-Identifier: GPL-2.0
+Ingenic JZ47xx SoCs Timer/Counter Unit hardware
+The Timer/Counter Unit (TCU) in Ingenic JZ47xx SoCs is a multi-function
+hardware block. It features up to to eight channels, that can be used as
+counters, timers, or PWM.
+- JZ4725B, JZ4750, JZ4755 only have six TCU channels. The other SoCs all
+ have eight channels.
+- JZ4725B introduced a separate channel, called Operating System Timer
+ (OST). It is a 32-bit programmable timer. On JZ4760B and above, it is
+ 64-bit.
+- Each one of the TCU channels has its own clock, which can be reparented to three
+ different clocks (pclk, ext, rtc), gated, and reclocked, through their TCSR register.
+ - The watchdog and OST hardware blocks also feature a TCSR register with the same
+ format in their register space.
+ - The TCU registers used to gate/ungate can also gate/ungate the watchdog and
+ OST clocks.
+- Each TCU channel works in one of two modes:
+ - mode TCU1: channels cannot work in sleep mode, but are easier to
+ operate.
+ - mode TCU2: channels can work in sleep mode, but the operation is a bit
+ more complicated than with TCU1 channels.
+- The mode of each TCU channel depends on the SoC used:
+ - On the oldest SoCs (up to JZ4740), all of the eight channels operate in
+ TCU1 mode.
+ - On JZ4725B, channel 5 operates as TCU2, the others operate as TCU1.
+ - On newest SoCs (JZ4750 and above), channels 1-2 operate as TCU2, the
+ others operate as TCU1.
+- Each channel can generate an interrupt. Some channels share an interrupt
+ line, some don't, and this changes between SoC versions:
+ - on older SoCs (JZ4740 and below), channel 0 and channel 1 have their
+ own interrupt line; channels 2-7 share the last interrupt line.
+ - On JZ4725B, channel 0 has its own interrupt; channels 1-5 share one
+ interrupt line; the OST uses the last interrupt line.
+ - on newer SoCs (JZ4750 and above), channel 5 has its own interrupt;
+ channels 0-4 and (if eight channels) 6-7 all share one interrupt line;
+ the OST uses the last interrupt line.
+The functionalities of the TCU hardware are spread across multiple drivers:
+=========== =====
+clocks drivers/clk/ingenic/tcu.c
+interrupts drivers/irqchip/irq-ingenic-tcu.c
+timers drivers/clocksource/ingenic-timer.c
+OST drivers/clocksource/ingenic-ost.c
+PWM drivers/pwm/pwm-jz4740.c
+watchdog drivers/watchdog/jz4740_wdt.c
+=========== =====
+Because various functionalities of the TCU that belong to different drivers
+and frameworks can be controlled from the same registers, all of these
+drivers access their registers through the same regmap.
+For more information regarding the devicetree bindings of the TCU drivers,
+have a look at Documentation/devicetree/bindings/mfd/ingenic,tcu.txt.