Various boot loaders for Exynos based boards use certain memory
addresses during booting for different purposes. Mostly this is one of
following :
1. as a CPU boot address,
2. for storing magic cookie related to low power mode (AFTR, sleep).
The document, based solely on kernel source code, tries to group the
information scattered over different files. This would help in the
future when adding support for new SoC or when extending features
related to low power modes.
Signed-off-by: Krzysztof Kozlowski <[email protected]>
---
Documentation/arm/Samsung/Bootloader-interface.txt | 53 ++++++++++++++++++++++
1 file changed, 53 insertions(+)
create mode 100644 Documentation/arm/Samsung/Bootloader-interface.txt
diff --git a/Documentation/arm/Samsung/Bootloader-interface.txt b/Documentation/arm/Samsung/Bootloader-interface.txt
new file mode 100644
index 000000000000..b96ead9a6919
--- /dev/null
+++ b/Documentation/arm/Samsung/Bootloader-interface.txt
@@ -0,0 +1,53 @@
+ Interface between kernel and boot loaders on Exynos boards
+ ==========================================================
+
+Author: Krzysztof Kozlowski
+Date : 6 June 2015
+
+The document tries to describe currently used interface between Linux kernel
+and boot loaders on Samsung Exynos based boards. This is not a definition
+of interface but rather a description of existing state, a reference
+for information purpose only.
+
+In the document "boot loader" means any of following: U-boot, proprietary
+SBOOT or any other firmware for ARMv7 and ARMv8 initializing the board before
+executing kernel.
+
+
+1. Non-Secure mode
+Address: sysram_ns_base_addr
+Offset Value Purpose
+=============================================================================
+0x08 exynos_cpu_resume_ns System suspend
+0x0c 0x00000bad (Magic cookie) System suspend
+0x1c exynos4_secondary_startup Secondary CPU boot
+0x1c + 4*cpu exynos4_secondary_startup (Exynos4412) Secondary CPU boot
+0x20 0xfcba0d10 (Magic cookie) AFTR
+0x24 exynos_cpu_resume_ns AFTR
+0x28 + 4*cpu 0x8 (Magic cookie, Exynos3250) AFTR
+
+
+2. Secure mode
+Address: sysram_base_addr
+Offset Value Purpose
+=============================================================================
+0x00 exynos4_secondary_startup Secondary CPU boot
+0x04 exynos4_secondary_startup (Exynos542x) Secondary CPU boot
+4*cpu exynos4_secondary_startup (Exynos4412) Secondary CPU boot
+0x20 exynos_cpu_resume (Exynos4210 r1.0) AFTR
+0x24 0xfcba0d10 (Magic cookie, Exynos4210 r1.0) AFTR
+
+Address: pmu_base_addr
+Offset Value Purpose
+=============================================================================
+0x0800 exynos_cpu_resume AFTR
+0x0814 exynos4_secondary_startup (Exynos4210 r1.1) Secondary CPU boot
+0x0818 0xfcba0d10 (Magic cookie, Exynos4210 r1.1) AFTR
+0x081C exynos_cpu_resume (Exynos4210 r1.1) AFTR
+
+
+3. Other (regardless of secure/non-secure mode)
+Address: pmu_base_addr
+Offset Value Purpose
+=============================================================================
+0x0908 Non-zero (only Exynos3250) Secondary CPU boot up indicator
--
2.1.4
>>>>> "Krzysztof" == Krzysztof Kozlowski <[email protected]> writes:
Krzysztof> Various boot loaders for Exynos based boards use certain
Krzysztof> memory addresses during booting for different
Krzysztof> purposes. Mostly this is one of following : 1. as a CPU
Krzysztof> boot address, 2. for storing magic cookie related to low
Krzysztof> power mode (AFTR, sleep).
Krzysztof> The document, based solely on kernel source code, tries to
Krzysztof> group the information scattered over different files. This
Krzysztof> would help in the future when adding support for new SoC or
Krzysztof> when extending features related to low power modes.
Is it worth grabbing the info from u=boot and documenting it here
(it's not documented other than in the hardkenel U=Boot source)?
I can send you the info, or you can see it in
https://github.com/hardkernel/u-boot/blob/odroidxu3-v2012.07/board/samsung/smdk5420/lowlevel_init.S
at symbol nscode_base near line 104
--
Dr Peter Chubb peter.chubb AT nicta.com.au
http://www.ssrg.nicta.com.au Software Systems Research Group/NICTA
2015-06-06 20:01 GMT+09:00 Peter Chubb <[email protected]>:
>>>>>> "Krzysztof" == Krzysztof Kozlowski <[email protected]> writes:
>
> Krzysztof> Various boot loaders for Exynos based boards use certain
> Krzysztof> memory addresses during booting for different
> Krzysztof> purposes. Mostly this is one of following : 1. as a CPU
> Krzysztof> boot address, 2. for storing magic cookie related to low
> Krzysztof> power mode (AFTR, sleep).
>
> Krzysztof> The document, based solely on kernel source code, tries to
> Krzysztof> group the information scattered over different files. This
> Krzysztof> would help in the future when adding support for new SoC or
> Krzysztof> when extending features related to low power modes.
>
> Is it worth grabbing the info from u=boot and documenting it here
> (it's not documented other than in the hardkenel U=Boot source)?
>
> I can send you the info, or you can see it in
> https://github.com/hardkernel/u-boot/blob/odroidxu3-v2012.07/board/samsung/smdk5420/lowlevel_init.S
> at symbol nscode_base near line 104
Hi,
+CC Łukasz Majewski (u-boot)
The patch actually covers u-boot. What is missing:
1, Reset - I think kernel does not set it.
2. LPA - There is no mainline support for it yet so I did not add it.
It should be added along with cpuidle LPA.
3. MCPM and Exynos542x stuff. There are some exceptions and weird
comments in the kernel (like "To increase the stability of KFC reset
we need to program the PMU SPARE3 register"). It would take me some
more time to understand it so I wanted to start with basic version and
get comments.
Best regards,
Krzysztof
On Sat, 6 Jun 2015 19:05:51 +0900
Krzysztof Kozlowski <[email protected]> wrote:
> The document, based solely on kernel source code, tries to group the
> information scattered over different files. This would help in the
> future when adding support for new SoC or when extending features
> related to low power modes.
I've applied this to the docs tree, thanks.
jon
Krzysztof Kozlowski <[email protected]> writes:
> Various boot loaders for Exynos based boards use certain memory
> addresses during booting for different purposes. Mostly this is one of
> following :
> 1. as a CPU boot address,
> 2. for storing magic cookie related to low power mode (AFTR, sleep).
>
> The document, based solely on kernel source code, tries to group the
> information scattered over different files. This would help in the
> future when adding support for new SoC or when extending features
> related to low power modes.
>
> Signed-off-by: Krzysztof Kozlowski <[email protected]>
Very nice, thank you for taking the time to pull all of this together
into one location.
Kevin