Doc: Add instructions to test SYSTEM SUSPEND
This patch adds instructions to the user-guide.md to test SYSTEM SUSPEND
on Juno.
Change-Id: Icd01d10e1c1fb14b0db880d0ff134e505f097d2b
diff --git a/docs/user-guide.md b/docs/user-guide.md
index 8f271cf..7987d10 100644
--- a/docs/user-guide.md
+++ b/docs/user-guide.md
@@ -1084,6 +1084,52 @@
* Install and run the Juno binaries on the board
* Obtain any other Juno software information
+### Testing SYSTEM SUSPEND on Juno
+
+The SYSTEM SUSPEND is a PSCI API which can be used to implement system suspend
+to RAM. For more details refer to section 5.16 of [PSCI]. The [Linaro releases]
+contains the required SCP and motherboard firmware support for this feature on
+Juno. The mainline linux kernel does not yet have support for this feature on
+Juno but it is queued to be merged in v4.4. Till that becomes available, the
+feature can be tested by using a custom kernel built from the following repo:
+
+ git clone git://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/linux.git
+ cd linux
+ git checkout firmware/psci-1.0
+
+Configure the linux kernel:
+
+ export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-
+ make ARCH=arm64 defconfig
+
+The feature is tested conveniently by using the RTC. Enable the RTC driver in
+menuconfig
+
+ make ARCH=arm64 menuconfig
+
+The PL031 RTC driver can be enabled at the following location in menuconfig
+
+ ARM AMBA PL031 RTC
+ | Location:
+ | -> Device Drivers
+ | -> Real Time Clock
+
+Build the kernel
+
+ make ARCH=arm64 Image -j8
+
+Replace the kernel image in `SOFTWARE/` directory of Juno with the `Image` from
+arch/arm64/boot/ of the linux directory as explained in the
+[Juno Software Guide].
+
+Reset the board and wait for it to boot. At the shell prompt issue the
+following command:
+
+ echo +10 > /sys/class/rtc/rtc1/wakealarm
+ echo -n mem > /sys/power/state
+
+The Juno board should suspend to RAM and then wakeup after 10 seconds due to
+wakeup interrupt from RTC.
- - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -1098,4 +1144,5 @@
[DS-5]: http://www.arm.com/products/tools/software-tools/ds-5/index.php
[mbedTLS Repository]: https://github.com/ARMmbed/mbedtls.git
[Porting Guide]: ./porting-guide.md
+[PSCI]: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf "Power State Coordination Interface PDD (ARM DEN 0022C)"
[Trusted Board Boot]: trusted-board-boot.md
