[PATCH] powerpc/powernv: Make possible for user to force a full ipl cec reboot

[Vaibhav Jain]

Ever since fast reboot is enabled by default in opal,
opal_cec_reboot() will use fast-reset instead of full IPL to perform
system reboot. This leaves the user with no direct way to force a full
IPL reboot except changing an nvram setting that persistently disables
fast-reset for all subsequent reboots.

This patch provides a more direct way for the user to force a one-shot
full IPL reboot by passing the command line argument 'full' to the
reboot command. So the user will be able to tweak the reboot behavior
via:

  $ sudo reboot full    # Force a full ipl reboot skipping fast-reset

  or
  $ sudo reboot         # default reboot path (usually fast-reset)

The reboot command passes the un-parsed command argument to the kernel
via the 'Reboot' syscall which is then passed on to the arch function
pnv_restart(). The patch updates pnv_restart() to handle this cmd-arg
and issues opal_cec_reboot2 with OPAL_REBOOT_FULL_IPL to force a full
IPL reset.

Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com>
---
 arch/powerpc/include/asm/opal-api.h    | 1 +
 arch/powerpc/platforms/powernv/setup.c | 8 +++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/opal-api.h 
b/arch/powerpc/include/asm/opal-api.h
index 8365353330b4..870fb7b239ea 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -1050,6 +1050,7 @@ enum OpalSysCooling {
 enum {
        OPAL_REBOOT_NORMAL              = 0,
        OPAL_REBOOT_PLATFORM_ERROR      = 1,
+       OPAL_REBOOT_FULL_IPL            = 2,
 };
 
 /* Argument to OPAL_PCI_TCE_KILL */
diff --git a/arch/powerpc/platforms/powernv/setup.c 
b/arch/powerpc/platforms/powernv/setup.c
index adddde023622..33d2faeacff8 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -224,7 +224,13 @@ static void  __noreturn pnv_restart(char *cmd)
        pnv_prepare_going_down();
 
        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
-               rc = opal_cec_reboot();
+
+               /* See if we need to do a full IPL reboot */
+               if (cmd && strcmp(cmd, "full") == 0)
+                       rc = opal_cec_reboot2(OPAL_REBOOT_FULL_IPL, NULL);
+               else
+                       rc = opal_cec_reboot();
+
                if (rc == OPAL_BUSY_EVENT)
                        opal_poll_events(NULL);
                else
-- 
2.17.1