dts: bcm2712-rpi: Add aliases for the CSI/DSI I2Cs

[pelwell]

Older Pis arrange that the camera I2C ports appear as /dev/i2c-10. Add aliases so that on the Pi 5 family, i2c_csi_dsi0 becomes i2c-10 and i2c_csi_dsi1 becomes i2c-11. Only the I2C buses that appear on the 40-pin header, i.e. I2C0 to I2C3, get a low bus number.

Also add hints for our udev rules about which symlinks to create for backwards-compatibility with the previous bus numbers. Note that lower numbers have priority, so i2c-0 on CM5 masks i2c-11, forcing i2c-11 to be a symlink to i2c-0, not vice versa.

[pelwell]

A suitably updated /lib/udev/rules.d/60-i2c-tools.rules would be:

SUBSYSTEM=="i2c-dev",KERNEL=="i2c-[0-9]*", GROUP="i2c", MODE="0660", PROGRAM="/bin/sh -c '\
        DTNODE=/sys/class/i2c-dev/%k/device/of_node; \
        if [ -e $$DTNODE/symlink ]; then \
            cat $$DTNODE/symlink; \
        else \
            exit 1; \
        fi \
'", SYMLINK+="%c"

[pelwell]

This is Pi 5 with this PR and the above udev rule:

$ ls -l /dev/i2c*
crw-rw---- 1 root i2c 89, 13 Oct 16 15:57 /dev/i2c-13
crw-rw---- 1 root i2c 89, 14 Oct 16 15:57 /dev/i2c-14
$ i2cdetect -l
i2c-13  i2c             107d508200.i2c                          I2C adapter
i2c-14  i2c             107d508280.i2c                          I2C adapter

$ sudo dtparam i2c_csi_dsi0
$ ls -l /dev/i2c*
crw-rw---- 1 root i2c  89, 10 Oct 16 15:58 /dev/i2c-10
crw-rw---- 1 root i2c  89, 13 Oct 16 15:57 /dev/i2c-13
crw-rw---- 1 root i2c  89, 14 Oct 16 15:57 /dev/i2c-14
lrwxrwxrwx 1 root root      6 Oct 16 15:58 /dev/i2c-6 -> i2c-10
$ i2cdetect -l
i2c-10  i2c             Synopsys DesignWare I2C adapter         I2C adapter
i2c-13  i2c             107d508200.i2c                          I2C adapter
i2c-14  i2c             107d508280.i2c                          I2C adapter

$ sudo dtparam i2c_csi_dsi1
$ ls -l /dev/i2c*
crw-rw---- 1 root i2c  89, 10 Oct 16 15:58 /dev/i2c-10
crw-rw---- 1 root i2c  89, 11 Oct 16 15:58 /dev/i2c-11
crw-rw---- 1 root i2c  89, 13 Oct 16 15:57 /dev/i2c-13
crw-rw---- 1 root i2c  89, 14 Oct 16 15:57 /dev/i2c-14
lrwxrwxrwx 1 root root      6 Oct 16 15:58 /dev/i2c-4 -> i2c-11
lrwxrwxrwx 1 root root      6 Oct 16 15:58 /dev/i2c-6 -> i2c-10
$ i2cdetect -l
i2c-10  i2c             Synopsys DesignWare I2C adapter         I2C adapter
i2c-11  i2c             Synopsys DesignWare I2C adapter         I2C adapter
i2c-13  i2c             107d508200.i2c                          I2C adapter
i2c-14  i2c             107d508280.i2c                          I2C adapter