ARM: bcm2835: expand Kconfig target descriptions
This adds an explanation of which Raspberry Pi models each target option
supports.
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-bcm283x/Kconfig b/arch/arm/mach-bcm283x/Kconfig
index dc67704..1f3031d 100644
--- a/arch/arm/mach-bcm283x/Kconfig
+++ b/arch/arm/mach-bcm283x/Kconfig
@@ -14,12 +14,38 @@
optional
config TARGET_RPI
- bool "Raspberry Pi"
+ bool "Raspberry Pi (all BCM2835 variants)"
+ help
+ Support for all ARM1176-/BCM2835-based Raspberry Pi variants, such as
+ the A, A+, B, B+, Compute Module, and Zero. This option cannot
+ support BCM2836/BCM2837-based Raspberry Pis such as the RPi 2 and
+ RPi 3 due to different peripheral address maps.
+
+ This option creates a build targetting the ARM1176 ISA.
select BCM2835
select CPU_ARM1176
config TARGET_RPI_2
bool "Raspberry Pi 2"
+ help
+ Support for all BCM2836-based Raspberry Pi variants, such as
+ the RPi 2 model B.
+
+ This option also supports BCM2837-based variants such as the RPi 3
+ Model B, when run in 32-bit mode, provided you have configured the
+ VideoCore firmware to select the PL011 UART for the console by:
+ a) config.txt should contain dtoverlay=pi3-miniuart-bt.
+ b) You should run the following to tell the VC FW to process DT when
+ booting, and copy u-boot.bin.img (rather than u-boot.bin) to the SD
+ card as the kernel image:
+
+ path/to/kernel/scripts/mkknlimg --dtok u-boot.bin u-boot.bin.img
+
+ This works as of firmware.git commit 046effa13ebc "firmware:
+ arm_loader: emmc clock depends on core clock See:
+ https://github.com/raspberrypi/firmware/issues/572".
+
+ This option creates a build targetting the ARMv7/AArch32 ISA.
select ARMV7_LPAE
select BCM2836
select CPU_V7