We need this to boot with a custom DTB on BCM2711C0-based Pi 4s
Signed-off-by: Ilya Katsnelson me@0upti.me --- board/raspberrypi/rpi/rpi.c | 63 +++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+)
diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c index 372b26b6f2..f074540091 100644 --- a/board/raspberrypi/rpi/rpi.c +++ b/board/raspberrypi/rpi/rpi.c @@ -495,6 +495,67 @@ void *board_fdt_blob_setup(void) return (void *)fw_dtb_pointer; }
+void copy_emmc_config(void *our_fdt) +{ + /* + * As of 2021-09-28, the Pi 4 has two different revisions, one using a + * B0 stepping of the BCM2711 SoC, and one using a C0 stepping. + * + * The two SoC versions have different, incompatible DMA mappings for + * the on-board eMMC controller, which would normally make them require + * two different DTs. + * + * Unfortunately for us, the different revisions don't actually _use_ + * different DTs - instead, the proprietary stage0 bootloader reads the DT, + * patches it in-memory, then passes the corrected DT to the OS. + * + * In our case, the OS is actually U-Boot, and U-Boot can choose to + * completely disregard the firmware-supplied DT and load a custom one + * instead, which is used by, e.g., NixOS. + * + * When that happens, the DT patches applied by the firmware are also + * thrown out, which leads to BCM2711C0 boards being unable to boot + * due to them trying to use the hardcoded DMA mappings in the DT + * (which are for the B0 revision). + * + * Work around that by manually copying the DMA region setup from the + * firmware-provided DT into whatever DT we're actually being asked + * to load. + A*/ + void *fw_fdt = (void *)fw_dtb_pointer; + int fw_emmc_node; + int our_emmc_node; + int length; + const void *fw_value; + int result; + + fw_emmc_node = fdt_path_offset(fw_fdt, "emmc2bus"); + if (fw_emmc_node < 0) { + printf("RPi: Failed to find EMMC config in FW DT: %d\n", fw_emmc_node); + return; + } + + our_emmc_node = fdt_path_offset(our_fdt, "emmc2bus"); + if (our_emmc_node < 0) { + printf("RPi: Failed to find EMMC config in our DT: %d\n", our_emmc_node); + return; + } + + *fw_value = fdt_getprop(fw_fdt, fw_emmc_node, "dma-ranges", &length); + if (!fw_value) { + printf("RPi: Failed to get EMMC DMA ranges property from FW DT: %d\n", length); + return; + } + + result = fdt_setprop(our_fdt, our_emmc_node, "dma-ranges", fw_value, length); + if (result != 0) { + printf("RPi: Failed to set EMMC DMA ranges property in our DT: %d\n", result); + return; + } + + printf("RPi: successfully copied FW DT EMMC configuration to our DT!\n"); +} + int ft_board_setup(void *blob, struct bd_info *bd) { int node; @@ -509,5 +570,7 @@ int ft_board_setup(void *blob, struct bd_info *bd) EFI_RESERVED_MEMORY_TYPE); #endif
+ copy_emmc_config(blob); + return 0; }