Re: set rockchip-specific uboot bootmode flags on reboot

From: Andy Yan
Date: Mon Sep 28 2015 - 05:56:59 EST

Hi Heiko:

On 2015å09æ23æ 07:16, Heiko StÃbner wrote:
Hi Andy,


Am Donnerstag, 17. September 2015, 19:07:06 schrieb Andy Yan:
On 2015å09æ10æ 02:05, Simon Glass wrote:
Hi,

On 8 September 2015 at 16:46, Heiko StÃbner <heiko@xxxxxxxxx> wrote:
Hi Andy,

Am Dienstag, 8. September 2015, 20:43:07 schrieb Andy Yan:
rockchip platform have a protocol to pass the the kernel
reboot mode to bootloader by some special registers when
system reboot.By this way the bootloader can take different
action according to the different kernel reboot mode, for
example, command "reboot loader" will reboot the board to
rockusb mode, this is a very convenient way to get the board
to download mode.

Signed-off-by: Andy Yan <andy.yan@xxxxxxxxxxxxxx>
[...]

@@ -0,0 +1,22 @@
+#ifndef __MACH_ROCKCHIP_LOADER_H
+#define __MACH_ROCKCHIP_LOADER_H
+
+/*high 24 bits is tag, low 8 bits is type*/
+#define SYS_LOADER_REBOOT_FLAG 0x5242C300
+
+enum {
+ BOOT_NORMAL = 0, /* normal boot */
+ BOOT_LOADER, /* enter loader rockusb mode */
+ BOOT_MASKROM, /* enter maskrom rockusb mode (not support now)
*/
+ BOOT_RECOVER, /* enter recover */
+ BOOT_NORECOVER, /* do not enter recover */
+ BOOT_SECONDOS, /* boot second OS (not support now)*/
+ BOOT_WIPEDATA, /* enter recover and wipe data. */
+ BOOT_WIPEALL, /* enter recover and wipe all data. */
+ BOOT_CHECKIMG, /* check firmware img with backup part*/
+ BOOT_FASTBOOT, /* enter fast boot mode */
+ BOOT_SECUREBOOT_DISABLE,
+ BOOT_CHARGING, /* enter charge mode */
+ BOOT_MAX /* MAX VALID BOOT TYPE.*/
+};
+#endif
These flags rely on code in the bootloader to actually handle the target
action. Nowadays this is uboot, but still a rockchip-specific fork. And
we're actively moving away from that, with the recent rk3288 addition to
mainline uboot.

So unless you convince uboot people that the _underlying special
functionality_ behind these flags should be part of uboot, I don't think
this is going to fly.


In a way this is similar to gpu kernel code talking to proprietary
userspace libs - these are also not eligible for the kernel. (meaning
stuff like the mali kernel driver not being allowed).
I don't want to comment on what Linux does or does not want. But I can
see this sort of feature being useful for devs at least. So long as it
is defined in a way that is not Rockchip-specific (and the above enum
looks pretty reasonable on that front, I think it makes sense.

Of course it's a bit odd to target a downstream U-Boot with a Linux
feature. But hopefully Rockchip's U-Boot support and development will
move to mainline with time.
Is there any chance for this patch to be landed?
As Simon says, it is useful for development. And
he is upstreaming Rockchip U-boot.
Sorry that I'm still dragging my feet with this, but I'm still struggling with
what to do.

I did talk to the arm-soc maintainers and doing this in general seems to be
fine. Olof was very in favour, others pointed out that just passing through
the command into the register might be the best solution - without having to
translate stuff in the kernel.
Some commands are very long(recovery,bootloader, fastboot etc),
they can't be stored into a register directly. And this also bring compatible
problems to the old boot loader.

So I guess the translation table (string to number) is the thing to talk
about. I guess my worries are three-fold:

- will this actually be stable or do we get a future where this translation
gets to be soc-specific, like "if rk3288 table_a; if rk3368 table_b ..." ?
All Rockchip base socs use this mechanism, but this commands may
stored in different registers in different soc.

- can we trim that down to actually supported modes?
I have take a look at exynos and msm android base platforms, they
use the same mechanism[1][2], so I think many platforms need this
function.
[1] https://github.com/droidroidz/Manta_kernel/blob/master/arch/arm/mach-exynos/board-manta-power.c
[2] https://github.com/msm7x30/android_kernel_qcom_msm7x30/blob/android-3.10/arch/arm/mach-msm/restart_7k.c


- I forgot that we already have other mass-production bootloaders, so what
does coreboot on veyron devices do with these register-values?

coreboot use different download mechanism, it doesn't touch this
register.
As it is probably also valid for rk3368 and following, I guess it should live
somehow in drivers/soc/rockchip too.
Yes, rk3368 also need this function, so maybe we should put it in
drivers/soc/rockchip.

Thanks.


Heiko

[...]

+static int rockchip_reboot_notify(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ u32 flag;
+
+ rockchip_get_reboot_flag(cmd, &flag);
+ regmap_write(regmap, flag_reg, flag);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block rockchip_reboot_handler = {
+ .notifier_call = rockchip_reboot_notify,
+ .priority = 150,
+};
the restart handlers are meant to really only restart the system, not to
execute some actions before the restart happens.

See https://lkml.org/lkml/2015/6/3/707 for a similar case.


Heiko
Regards,
Simon
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