On Thu, Feb 21, 2019 at 10:28:48AM +0100, Tomaz Solc wrote: > When booting a Raspberry Pi, it is useful to extract bootargs from the > device tree that was created by the VideoCore firmware. These bootargs > contain for example settings for the framebuffer that the kernel needs > to properly set the video output. > > This commit adds an of_bootargs command that extracts a bootargs > property from a device tree and saves it to a global variable. > > For example, a bootloader environment can use this command to extract > the bootargs to linux.bootargs.vc, which then gets included into the > final bootargs for the kernel using CONFIG_FLEXIBLE_BOOTARGS. > --- > Documentation/boards/bcm2835.rst | 4 ++ > commands/Kconfig | 13 ++++++ > commands/Makefile | 1 + > commands/of_bootargs.c | 99 ++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 117 insertions(+) > create mode 100644 commands/of_bootargs.c > > diff --git a/Documentation/boards/bcm2835.rst b/Documentation/boards/bcm2835.rst > index 95e910896..b8a6c18ea 100644 > --- a/Documentation/boards/bcm2835.rst > +++ b/Documentation/boards/bcm2835.rst > @@ -34,5 +34,9 @@ VideoCore firmware creates a device tree based on the entries in ``config.txt``. > > bootm -o /vc.dtb /boot/kernel7.img > > +VideoCore device tree also contains the kernel command-line that is constructed from ``cmdline.txt`` and other parameters internally determined by the VideoCore firmware. Normally in Barebox this command-line gets overwritten by the Linux bootargs (see :ref:`booting_linux`). You can extract the VideoCore command-line from the device tree using the following command:: > + > + of_bootargs /vc.dtb linux.bootargs.vc > + > .. _Raspberry Pi firmware: https://codeload.github.com/raspberrypi/firmware/zip/80e1fbeb78f9df06701d28c0ed3a3060a3f557ef > .. _documentation for config.txt: https://www.raspberrypi.org/documentation/configuration/config-txt/ > diff --git a/commands/Kconfig b/commands/Kconfig > index c14332c9d..0ae6d526f 100644 > --- a/commands/Kconfig > +++ b/commands/Kconfig > @@ -2015,6 +2015,19 @@ config CMD_OF_DUMP > Options: > -f <dtb> work on <dtb> instead of internal devicetree > > +config CMD_OF_BOOTARGS > + tristate > + select OFTREE > + prompt "of_bootargs" > + help > + Extract bootargs from a device tree into a global variable > + > + Usage: of_bootargs [DTB] [VAR] > + > + DTB is path to a device tree file (e.g. /vc.dtb). > + VAR is a name of the global variable to set (e.g. linux.bootargs.vc) > + > + > config CMD_OF_NODE > tristate > select OFTREE > diff --git a/commands/Makefile b/commands/Makefile > index 358671bb5..f554f6041 100644 > --- a/commands/Makefile > +++ b/commands/Makefile > @@ -76,6 +76,7 @@ obj-$(CONFIG_CMD_OFTREE) += oftree.o > obj-$(CONFIG_CMD_OF_PROPERTY) += of_property.o > obj-$(CONFIG_CMD_OF_NODE) += of_node.o > obj-$(CONFIG_CMD_OF_DUMP) += of_dump.o > +obj-$(CONFIG_CMD_OF_BOOTARGS) += of_bootargs.o > obj-$(CONFIG_CMD_OF_DISPLAY_TIMINGS) += of_display_timings.o > obj-$(CONFIG_CMD_OF_FIXUP_STATUS) += of_fixup_status.o > obj-$(CONFIG_CMD_MAGICVAR) += magicvar.o > diff --git a/commands/of_bootargs.c b/commands/of_bootargs.c > new file mode 100644 > index 000000000..93e7b74b1 > --- /dev/null > +++ b/commands/of_bootargs.c > @@ -0,0 +1,99 @@ > +/* > + * of_dump.c - dump devicetrees to the console > + * > + * Copyright (c) 2014 Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>, Pengutronix Is this true? :-) And please add a SPDX-License-Identifier to the new files. See [9] for an explanation (and replace "Linux" by "barebox" in your head when reading it :)) [9]: https://www.kernel.org/doc/html/latest/process/license-rules.html > + * > + * See file CREDITS for list of people who contributed to this > + * project. Leave out this paragraph, that file does not exist. - Roland > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 > + * as published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + */ > + > +#include <common.h> > +#include <libfile.h> > +#include <of.h> > +#include <command.h> > +#include <malloc.h> > +#include <complete.h> > +#include <linux/ctype.h> > +#include <errno.h> > +#include <linux/err.h> > +#include <globalvar.h> > + > +static int do_of_bootargs(int argc, char *argv[]) > +{ > + int ret = 0; > + struct device_node *root = NULL, *node; > + char *dtbfile, *varname; > + void *fdt; > + > + size_t size; > + const char *cmdline; > + > + if (argc != 3) { > + return COMMAND_ERROR_USAGE; > + } > + > + dtbfile = argv[1]; > + varname = argv[2]; > + > + fdt = read_file(dtbfile, &size); > + if (!fdt) { > + printf("unable to read %s: %s\n", dtbfile, strerror(errno)); > + return -errno; > + } > + > + root = of_unflatten_dtb(fdt); > + > + free(fdt); > + > + if (IS_ERR(root)) { > + ret = PTR_ERR(root); > + root = NULL; > + goto out; > + } > + > + node = of_find_node_by_path_from(root, "/chosen"); > + if (!node) { > + printf("no /chosen node\n"); > + ret = -ENOENT; > + goto out; > + } > + > + cmdline = of_get_property(node, "bootargs", NULL); > + if (!cmdline) { > + printf("no bootargs property in the /chosen node\n"); > + ret = -ENOENT; > + goto out; > + } > + > + globalvar_add_simple(varname, cmdline); > + > +out: > + if (root) > + of_delete_node(root); > + > + return ret; > +} > + > +BAREBOX_CMD_HELP_START(of_bootargs) > +BAREBOX_CMD_HELP_TEXT("DTB is path to a device tree file (e.g. /vc.dtb).") > +BAREBOX_CMD_HELP_TEXT("VAR is a name of the global variable to set (e.g. linux.bootargs.vc)") > +BAREBOX_CMD_HELP_END > + > +BAREBOX_CMD_START(of_bootargs) > + .cmd = do_of_bootargs, > + BAREBOX_CMD_DESC("extract bootargs from a device tree into a global variable") > + BAREBOX_CMD_OPTS("[DTB] [VAR]") > + BAREBOX_CMD_GROUP(CMD_GRP_MISC) > + BAREBOX_CMD_COMPLETE(devicetree_file_complete) > + BAREBOX_CMD_HELP(cmd_of_bootargs_help) > +BAREBOX_CMD_END > -- > 2.11.0 > > > _______________________________________________ > barebox mailing list > barebox@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/barebox > -- Roland Hieber | r.hieber@xxxxxxxxxxxxxx | Pengutronix e.K. | https://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim | Phone: +49-5121-206917-5086 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
