powerpc/powernv: Allow manually invoking special reboots

OPAL provides several different kinds of reboot for the kernel to use,
namely forcing a full reboot, platform error reboot and MPIPL. Right now
triggering the alternative resets requires some ad-hoc method such as
triggering a kernel crash and hoping the stars align. It's sometimes handy
to be able to trigger one of these resets directly, so add a way to do
that.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191101085522.3055-2-oohall@gmail.com

arch/powerpc/platforms/powernv/setup.c

@@ -233,6 +233,10 @@ static void  __noreturn pnv_restart(char *cmd)
 			rc = opal_cec_reboot();
 		else if (strcmp(cmd, "full") == 0)
 			rc = opal_cec_reboot2(OPAL_REBOOT_FULL_IPL, NULL);
+		else if (strcmp(cmd, "mpipl") == 0)
+			rc = opal_cec_reboot2(OPAL_REBOOT_MPIPL, NULL);
+		else if (strcmp(cmd, "error") == 0)
+			rc = opal_cec_reboot2(OPAL_REBOOT_PLATFORM_ERROR, NULL);
 		else
 			rc = OPAL_UNSUPPORTED;