Le 2018-03-18 00:52, Randy Dunlap a écrit :
On 03/17/2018 04:28 PM, Paul Cercueil wrote:
Add a documentation file about the Timer/Counter Unit (TCU)
present in the Ingenic JZ47xx SoCs.
Signed-off-by: Paul Cercueil <p...@crapouillou.net>
---
Documentation/mips/00-INDEX | 3 +++
Documentation/mips/ingenic-tcu.txt | 50
++++++++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
create mode 100644 Documentation/mips/ingenic-tcu.txt
v4: New patch in this series
diff --git a/Documentation/mips/ingenic-tcu.txt
b/Documentation/mips/ingenic-tcu.txt
new file mode 100644
index 000000000000..2508e5793da8
--- /dev/null
+++ b/Documentation/mips/ingenic-tcu.txt
@@ -0,0 +1,50 @@
+Ingenic JZ47xx SoCs Timer/Counter Unit hardware
+-----------------------------------------------
+
+The Timer/Counter Unit (TCU) in Ingenic JZ47xx SoCs is a
multi-function
+hardware block. It features eight channels, that can be used as
counters,
drop comma ............. ^
Ok.
+timers, or PWM.
+
+- JZ4770 introduced a separate channel, called Operating System Timer
(OST).
+ It is a 64-bit programmable timer.
+
+- Each one of the eight 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.
+
+- On SoCs >= JZ4770, there are two different modes:
+ * Channels 0, 3-7 operate in TCU1 mode: they cannot work in sleep
mode,
+ but are easier to operate.
+ * Channels 1-2 operate in TCU2 mode: they can work in sleep mode,
but
+ the operation is a bit more complicated than with TCU1 channels.
+
+- Each channel can generate an interrupt. Some channels share an
interrupt
+ line, some don't, and this changes between SoC versions:
+ * on JZ4740, timer 0 and timer 1 have their own interrupt line;
others share
+ one interrupt line.
+ * on JZ4770 and JZ4780, timer 5 has its own interrupt; timers 0-4
and 6-7 all
+ use one interrupt line; the OST uses the last interrupt.
"The OST uses the last interrupt." is not clear to someone who doesn't
know
about this hardware. (I can read it several ways.)
Does it mean that the 4770 and 4780 have 3 interrupt lines used like
so?
- timer 5 uses one interrupt line
- timers 0-4 and 6-7 use a second interrupt line
- the OST uses a third interrupt line
Correct. I'll make it more obvious.
Thanks,
-Paul
