From 0791bc02b8fbf9d55626b57f45255ba1b6ea83d5 Mon Sep 17 00:00:00 2001 From: Laurent Vivier Date: Fri, 12 Mar 2021 22:41:44 +0100 Subject: m68k: add a system controller Add a system controller for the m68k-virt machine. This controller allows the kernel to power off or reset the machine. Signed-off-by: Laurent Vivier Reviewed-by: Richard Henderson Reviewed-by: Philippe Mathieu-Daudé Tested-by: Philippe Mathieu-Daudé Message-Id: <20210312214145.2936082-5-laurent@vivier.eu> --- docs/specs/virt-ctlr.txt | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 docs/specs/virt-ctlr.txt (limited to 'docs/specs') diff --git a/docs/specs/virt-ctlr.txt b/docs/specs/virt-ctlr.txt new file mode 100644 index 0000000000..24d38084f7 --- /dev/null +++ b/docs/specs/virt-ctlr.txt @@ -0,0 +1,26 @@ +Virtual System Controller +========================= + +This device is a simple interface defined for the pure virtual machine with no +hardware reference implementation to allow the guest kernel to send command +to the host hypervisor. + +The specification can evolve, the current state is defined as below. + +This is a MMIO mapped device using 256 bytes. + +Two 32bit registers are defined: + +1- the features register (read-only, address 0x00) + + This register allows the device to report features supported by the + controller. + The only feature supported for the moment is power control (0x01). + +2- the command register (write-only, address 0x04) + + This register allows the kernel to send the commands to the hypervisor. + The implemented commands are part of the power control feature and + are reset (1), halt (2) and panic (3). + A basic command, no-op (0), is always present and can be used to test the + register access. This command has no effect. -- cgit v1.2.3-55-g7522