Subject: set rockchip-specific uboot bootmode flags on reboot (was: [PATCH] ARM: rockchip: add reboot notifier)

From: [email-masked] (Heiko Stübner)
Date: Wed, 09 Sep 2015 00:46:07 +0200

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 <[email-masked]>

[...]

> @@ -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). 

[...]

> +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