build tooling

alt-trees/README.md

@@ -5,25 +5,23 @@ Copy the desired `.dts` file to the [build-trees](../build-trees) folder and fol
 
 There are instructions at the end of that document on how you can use a custom `.dtb` and make it permanent across reboots and kernel upgrades.
 
-The issue with using these trees is that **if** the upstream device tree or includes is modified you need to manually rebuild these trees. 
+The issue with using these trees is that **if** the upstream device tree or includes is modified you need to manually rebuild these trees.
 
 EG any changes to the upstream `sun20i-d1-mangopi-mq-pro.dts` source needs to be detected and applied too. You need to examine file histories to do this.
 - Fortunately this should not be an issue in practice; the kernel *should* remain very stable going forward. Ubuntu 24.04.1 is a LTS release..
 
 The authors personal advice is to use this only if needed; or as a learning excercise.
 
-## Common
-[A common (generic) device tree I, suitable for many occasions](./common)
-* Has 2x UART (plus the console uart), 2x I2C. 1xSPI
-* 12 unassigned GPIO pins
+## SPI and I2C
+[SPI plus I2C interfaces](./spi_i2c)
+* 1x SPI
+* 4x I2C
+* 3x UART (plus the console uart)
+* 6 unassigned GPIO pins
 
 ## Serial
-[Four UART interfaces *and* Four I2C interfaces](./serial)
-* Has 4x UART (plus the console uart), 4x I2C
-* UART3 has RTC/CTS pins available too
-* 10 unassigned GPIO pins
-
-## SPI
-[SPI plus Serial interfaces](./spi)
-* Has 3x UART (plus the console uart), 3x I2C. 1xSPI
-* 8 unassigned GPIO pins
+[Four UART interfaces](./serial)
+* 4x UART (plus the console uart)
+  * UART3 has RTC/CTS pins available too
+* 2x I2C
+* 12 unassigned GPIO pins