Hi,
On Thu, Feb 21, 2019 at 10:28:47AM +0100, Tomaz Solc wrote:
> On Raspberry Pi, VideoCore firmware creates a device tree that contains
> information about peripherals that were initialized by VideoCore based
> on settings in config.txt. Normally this device tree is passed to the
> Linux kernel via a pointer in the r2 register. A bootloader needs to
> pass this device tree to the kernel, or some peripherals will not work
> correctly.
>
> Since the VideoCore device tree is not compatible with barebox, we can't
> just pass it to barebox_arm_entry() as the internal barebox device tree.
>
> This commit makes the prebootloader code copy the device tree from
> VideoCore into a scrap RAM area just above the area reserved for the
> bootloader. Board initialization code in the bootloader proper then
> copies it into a file /vc.dtb. The bootloader environment is then free
> to pass this file to the kernel at boot (e.g. via bootm -o).
> ---
> Documentation/boards/bcm2835.rst | 4 ++
> arch/arm/boards/raspberry-pi/lowlevel.c | 68 ++++++++++++++++++++++---------
> arch/arm/boards/raspberry-pi/lowlevel.h | 9 ++++
> arch/arm/boards/raspberry-pi/rpi-common.c | 34 ++++++++++++++++
> 4 files changed, 96 insertions(+), 19 deletions(-)
> create mode 100644 arch/arm/boards/raspberry-pi/lowlevel.h
>
[...]
> diff --git a/arch/arm/boards/raspberry-pi/rpi-common.c b/arch/arm/boards/raspberry-pi/rpi-common.c
> index b5d16a15c..f17384857 100644
> --- a/arch/arm/boards/raspberry-pi/rpi-common.c
> +++ b/arch/arm/boards/raspberry-pi/rpi-common.c
> @@ -370,12 +375,41 @@ static int rpi_env_init(void)
> return 0;
> }
>
> +static void rpi_vc_fdt(void)
> +{
> + void *saved_vc_fdt;
> + struct fdt_header *oftree;
> + unsigned long magic, size;
> +
> + /* VideoCore FDT was copied in PBL just above Barebox memory */
> + saved_vc_fdt = (void *)(arm_mem_endmem_get());
> +
> + oftree = saved_vc_fdt;
> + magic = be32_to_cpu(oftree->magic);
> + if (magic != FDT_MAGIC) {
> + printf("videocore fdt saved in pbl has invalid magic\n");
It's more idiomatic to use pr_err() here
> +
> + if (magic == VIDEOCORE_FDT_ERROR) {
> + printf("there was an error copying fdt in pbl: %d\n",
> + be32_to_cpu(oftree->totalsize));
and here
> + }
> + return;
> + }
> +
> + size = be32_to_cpu(oftree->totalsize);
> + if (write_file("/vc.dtb", saved_vc_fdt, size)) {
> + printf("failed to save videocore fdt to a file\n");
and here.
- Roland
> + return;
> + }
> +}
> +
> static int rpi_devices_init(void)
> {
> rpi_model_init();
> bcm2835_register_fb();
> armlinux_set_architecture(MACH_TYPE_BCM2708);
> rpi_env_init();
> + rpi_vc_fdt();
> return 0;
> }
> late_initcall(rpi_devices_init);
> --
> 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 |
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