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34bba87577
Use two suitable GPIOs to implement a simple arbitration scheme. Each side owns one of the GPIOs, which are normally pulled high. When one side wants to use I2C as a master, it pulls its GPIO low, waits for a short period to make sure that the other side is not also pulling its GPIO low, and then goes ahead with the transaction. When the transaction is over, the GPIO is released, thus freeing the I2C bus up for use by the other end. For simplicity the terminolgy used here is EC for us, and AP for the other end. BUG=chrome-os-partner:10888 TEST=manual: build for all boards boot on snow (cannot test i2c as it is broken) Change-Id: I97d9fbd5aba8248c8c1240baaec17db22860665c Signed-off-by: Simon Glass <sjg@chromium.org> Reviewed-on: https://gerrit.chromium.org/gerrit/26142
- EC Lib
This wraps Blizzard driverlib and implements the EC chip interface defined
by Google. See below diagram for architecture.
+--------------------+
| Host BIOS/OS |
+--------------------+
---- host interface ----
+--------------------+
| Google EC features |
+--------------------+
---- chip interface ---- The interface is defined in
src/platform/ec/chip_interface/*.
+--------------------+ But the real implementation is in EC Lib.
| EC Lib |
+--------------------+
| Blizzard low level |
| driver, the |
| driverlib. |
+--------------------+
Build Options
=============
- CONFIG_WATCHDOG_HELP
Try to detect a watchdog that is about to fire, and print a trace.
This is needed on STM32, where the independent watchdog has no early
warning feature and the windowed watchdog has a very short period.
- CONFIG_PANIC_NEW_STACK
When reporting a panic, change to a completely new stack. This might
help get a useful trace out a situation where the stack or stack
pointer has been corrupted.
- CONFIG_PANIC_HELP
Report extra information about a panic, such as the fault address,
here shown as bfar. This shows the reason for the fault and may help
to determine the cause.
=== EXCEPTION: 03 ====== xPSR: 01000000 ===========
r0 :0000000b r1 :00000047 r2 :60000000 r3 :200013dd
r4 :00000000 r5 :080053f4 r6 :200013d0 r7 :00000002
r8 :00000000 r9 :200013de r10:00000000 r11:00000000
r12:00000000 sp :200009a0 lr :08002b85 pc :08003a8a
Precise data bus error, Forced hard fault, Vector catch, bfar = 60000000
mmfs = 00008200, shcsr = 00000000, hfsr = 40000000, dfsr = 00000008
- CONFIG_ASSERT_HELP
Report assertion failures in a vebose manner to aid debugging. When
enabled an ASSERT() which fails will produce message in the form:
ASSERTION FAILURE '<expr>' in function() at file:line