From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rasmus Villemoes Date: Wed, 21 Apr 2021 10:02:48 +0200 Subject: [PATCH 1/2] env: allow environment to be amended from control dtb In-Reply-To: References: <20210413224345.2692591-1-rasmus.villemoes@prevas.dk> <20210413224345.2692591-2-rasmus.villemoes@prevas.dk> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 21/04/2021 09.14, Simon Glass wrote: > Hi Rasmus, > > On Wed, 14 Apr 2021 at 10:43, Rasmus Villemoes > wrote: >> >> It can be useful to use the same U-Boot binary for multiple purposes, >> say the normal one, one for developers that allow breaking into the >> U-Boot shell, and one for use during bootstrapping which runs a >> special-purpose bootcmd. Or one can have several board variants that >> can share almost all boot logic, but just needs a few tweaks in the >> variables used by the boot script. >> >> To that end, allow the control dtb to contain a /config/enviroment >> node (or whatever one puts in fdt_env_path variable), whose >> property/value pairs are used to update the run-time environment after >> it has been loaded from its persistent location. >> >> The indirection via fdt_env_path is for maximum flexibility - for >> example, should the user wish (or board logic dictate) that the values >> in the DTB should no longer be applied, one simply needs to delete the >> fdt_env_path variable; that can even be done automatically by >> including a >> >> fdt_env_path = ""; >> >> property in the DTB node. >> >> Signed-off-by: Rasmus Villemoes >> --- >> common/board_r.c | 2 ++ >> env/Kconfig | 18 ++++++++++++++++++ >> env/common.c | 23 +++++++++++++++++++++++ >> include/env.h | 15 +++++++++++++++ >> include/env_default.h | 3 +++ >> 5 files changed, 61 insertions(+) >> > > Reviewed-by: Simon Glass > > Some suggestions below > >> diff --git a/common/board_r.c b/common/board_r.c >> index c835ff8e26..3f82404772 100644 >> --- a/common/board_r.c >> +++ b/common/board_r.c >> @@ -459,6 +459,8 @@ static int initr_env(void) >> else >> env_set_default(NULL, 0); >> >> + env_import_fdt(); >> + >> if (IS_ENABLED(CONFIG_OF_CONTROL)) >> env_set_hex("fdtcontroladdr", >> (unsigned long)map_to_sysmem(gd->fdt_blob)); >> diff --git a/env/Kconfig b/env/Kconfig >> index b473d7cfe1..aa800e37ce 100644 >> --- a/env/Kconfig >> +++ b/env/Kconfig >> @@ -647,6 +647,24 @@ config DELAY_ENVIRONMENT >> later by U-Boot code. With CONFIG_OF_CONTROL this is instead >> controlled by the value of /config/load-environment. >> >> +config ENV_IMPORT_FDT >> + bool "Amend environment by FDT properties" >> + depends on OF_CONTROL >> + help >> + If selected, after the environment has been loaded from its >> + persistent location, the "env_fdt_path" variable is looked >> + up and used as a path to a node in the control DTB. The >> + property/value pairs in that node is then used to update the >> + run-time environment. This can be useful to use the same >> + U-Boot binary with different board variants. >> + >> +config ENV_FDT_PATH >> + string "Default value for env_fdt_path variable" >> + depends on ENV_IMPORT_FDT >> + default "/config/environment" >> + help >> + The initial value of the env_fdt_path variable. >> + >> config ENV_APPEND >> bool "Always append the environment with new data" >> default n >> diff --git a/env/common.c b/env/common.c >> index 2ee423beb5..af45e561ce 100644 >> --- a/env/common.c >> +++ b/env/common.c >> @@ -345,3 +345,26 @@ int env_complete(char *var, int maxv, char *cmdv[], int bufsz, char *buf, >> return found; >> } >> #endif >> + >> +#ifdef CONFIG_ENV_IMPORT_FDT >> +void env_import_fdt(void) >> +{ >> + const void *blob = gd->fdt_blob; >> + const char *path; >> + int offset, prop; >> + >> + path = env_get("env_fdt_path"); >> + if (!path || !path[0]) >> + return; > > How about returning an error code indicating what happened? I considered that, but I'm not sure what the (single) caller would do with that. Not having env_fdt_path set is a supported use case as I explain. So here it's not really an error. However, if env_fdt_path is set, but there's no such node in the DT blob, it might be worth printing a warning (i.e. in the "offset < 0" case below). >> + offset = fdt_path_offset(blob, path); > > Could we use the livetree API here (ofnode)? Dunno, what's that? Have U-Boot started deserializing the FDT blob like the linux kernel does and build an in-memory representation that's easier to traverse? Thanks, Rasmus