How to make FreeBSD's kernel boot a RPi4B with modern RPi* firmware

I finally ran into EARLY_DRIVER_MODULE, BUS_PASS_RESOURCE,
BUS_PASS_ORDER_MIDDLE and the like and they allow being
sure that the brcm,bcm2835-dma related setup has been done
before any use of it is made, despite the order in the
Device Tree: use an earlier pass for brcm,bcm2835-dma
related attach. This avoids the kernel crashing during
boot.

The example context used below has: serial console with
USB3 SSD boot media (not requiring a usb_pgood_delay
setting), booting a stable/13. The RPI4B is a C0T one (no
3 GiByte limitation, for example: the PCIe wrapper logic
has been corrected).

stable/13's source code changes ( similarly for
releng/13.1 ):

diff --git a/sys/arm/broadcom/bcm2835/bcm2835_dma.c b/sys/arm/broadcom/bcm2835/bcm2835_dma.c
index cab8639bb607..d8b49acfe332 100644
--- a/sys/arm/broadcom/bcm2835/bcm2835_dma.c
+++ b/sys/arm/broadcom/bcm2835/bcm2835_dma.c
@@ -766,5 +766,6 @@ static driver_t bcm_dma_driver = {
 
 static devclass_t bcm_dma_devclass;
 
-DRIVER_MODULE(bcm_dma, simplebus, bcm_dma_driver, bcm_dma_devclass, 0, 0);
+EARLY_DRIVER_MODULE(bcm_dma, simplebus, bcm_dma_driver, bcm_dma_devclass,
+    0, 0, BUS_PASS_RESOURCE + BUS_PASS_ORDER_MIDDLE);
 MODULE_VERSION(bcm_dma, 1);


For reference, a 13S snapshot with my kernel build replacing
the snapshot's kernel, was booted with:

# strings /boot/msdos/start4.elf | grep VC_BUILD_ID_
VC_BUILD_ID_USER: dom
VC_BUILD_ID_TIME: 11:09:05
VC_BUILD_ID_VARIANT: start
VC_BUILD_ID_TIME: Oct 26 2022
VC_BUILD_ID_BRANCH: bcm2711_2
VC_BUILD_ID_HOSTNAME: buildbot
VC_BUILD_ID_PLATFORM: raspberrypi_linux
VC_BUILD_ID_VERSION: c72ad6b26ff40c91ef776b847436094ee63fabee (clean)

There are new things present that FreeBSD reports
but ignores, producing messages like:

clk_fixed4: <Fixed clock> disabled on ofwbus0
clk_fixed4: Cannot FDT parameters.
device_attach: clk_fixed4 attach returned 6

over and over during part of the boot. It seems to
retry as it goes and thus produce so many messages.

There was also:

fb0: <BCM2835 VT framebuffer driver> on simplebus0
fb0: changing fb bpp from 0 to 24
mbox0: mbox response error
fb0: bcm2835_mbox_fb_init failed, err=5
device_attach: fb0 attach returned 6

genet0 is working.

I've not checked if the microsd card slot can be used.

I used the normal FreeBSD U-Boot since I was not booting
the NVM3 media that requires extra time (usb_pgood_delay
would be assigned in my own U-Boot builds).

For reference, I used my typical sort of config.txt :

# more /boot/msdos/config.txt
[all]
arm_64bit=1
dtparam=audio=on,i2c_arm=on,spi=on
dtoverlay=mmc
dtoverlay=disable-bt
device_tree_address=0x4000
kernel=u-boot.bin

[pi4]
hdmi_safe=1
armstub=armstub8-gic.bin

#
[all]
#
# Local addition that avoids USB3 SSD boot failures that look like:
#   uhub_reattach_port: port ? reset failed, error=USB_ERR_TIMEOUT
#   uhub_reattach_port: device problem (USB_ERR_TIMEOUT), disabling port ?
initial_turbo=60
# U-Boot that has, for example, a built-in usb_pgood_delay assignment
# for a media specific issue added:
#kernel=u-boot.bin.2022.10.arm64
#
# Local additions:
enable_uart=1
uart_2ndstage=1
dtdebug=1
disable_commandline_tags=1
disable_overscan=1
#gpu_mem_1024=32
#
#program_usb_boot_mode=1
#program_usb_boot_timeout=1

# Old RPi3's/RPi2Bv1.2's may ignore [pi4] and the like.
# That would make the below inappropriate for such contexts.
[pi4]
# Locally avoid hdmi_safe's dislay scaling:
hdmi_safe=0
#
armstub=armstub8-gic.bin
#
# Local additions:
over_voltage=6
arm_freq=2000
sdram_freq_min=3200
force_turbo=1
#
#total_mem=1024
#total_mem=991
[all]

[pi3] 
armstub=armstub8.bin
dtoverlay=pwm
audio_pwm_mode=0
[all]


As for main [so: 14], the devclass_t use is gone, thus
the source code changes are:

diff --git a/sys/arm/broadcom/bcm2835/bcm2835_dma.c b/sys/arm/broadcom/bcm2835/bcm2835_dma.c
index 5f9ecb0b7981..83c4c493a66b 100644
--- a/sys/arm/broadcom/bcm2835/bcm2835_dma.c
+++ b/sys/arm/broadcom/bcm2835/bcm2835_dma.c
@@ -764,5 +764,6 @@ static driver_t bcm_dma_driver = {
        sizeof(struct bcm_dma_softc),
 };
 
-DRIVER_MODULE(bcm_dma, simplebus, bcm_dma_driver, 0, 0);
+EARLY_DRIVER_MODULE(bcm_dma, simplebus, bcm_dma_driver, 0, 0,
+    BUS_PASS_RESOURCE + BUS_PASS_ORDER_MIDDLE);
 MODULE_VERSION(bcm_dma, 1);


===
Mark Millard
marklmi at yahoo.com