doc: board: apple: Update Apple M1 documentation

U-Boot now supports NVMe storage and on the laptop models, the
SPI keyboard.  Since we now disable the debug console by default
provide instructions on how the enable the debug console including
a table listing the appropriate UART base address for each of the
supported SoCs.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>

doc/board/apple/m1.rst

@@ -7,18 +7,21 @@ Allows Apple Silicon Macs to boot U-Boot via the m1n1 bootloader
 developed by the Asahi Linux project.  At this point the machines with
 the following SoCs work:
 
- - Apple M1 SoC
+ - Apple M1 SoC (t8103)
+ - Apple M1 Pro SoC (t6000)
+ - Apple M1 Max SoC (t6001)
 
 On these SoCs the following hardware is supported:
 
  - S5L serial port
+ - SPI keyboard (on laptops)
  - Framebuffer
+ - NVMe storage
  - USB 3.1 Type-C ports
 
-Device trees are currently provided for the M1 Mac mini (2020, J274)
-and M1 MacBook Pro 13" (2020, J293).  The M1 MacBook Air (2020) is
-expected to work with the J293 device tree.  The M1 iMac (2021) may
-work with the J274 device tree.
+Device trees are currently provided for the M1 Mac mini (2020, J274),
+M1 MacBook Pro 13" (2020, J293), M1 MacBook Air (2020, J313) and M1
+iMac (2021, J456/J457).
 
 Building U-Boot
 ---------------
@@ -57,3 +60,23 @@ Instructions on how to install U-Boot on your Mac can be found at:
     https://github.com/AsahiLinux/docs/wiki/Developer-Quickstart
 
 Just replace ``m1n1.macho`` with ``u-boot.macho`` in the instructions.
+
+Debug UART
+----------
+
+Since the base address of the UART is SoC-dependent, the debug UART is
+not enabled by default.  To enable the debug UART the base address
+needs to be adjusted and the CONFIG_DEBUG_UART option needs to be
+enabled.  The table below gives the correct base address for the
+supported SoCs.
+
+.. list-table::
+   :widths: 32 16
+   :header-rows: 1
+
+   * - SoC
+     - Base Address
+   * - M1 (t8103)
+     - 0x235200000
+   * - M1 Pro/Max (t6000/t6001)
+     - 0x39b200000