powerpc/powernv: Check OPAL elog calls exist before using

Check that the OPAL_ELOG_READ token exists before initalising the elog
infrastructure.

This avoids littering the OPAL console with:
  "OPAL: Called with bad token 74"

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/powernv/opal-elog.c b/arch/powerpc/platforms/powernv/opal-elog.c
index bbdb3ffaab98..518fe95dbf24 100644
--- a/arch/powerpc/platforms/powernv/opal-elog.c
+++ b/arch/powerpc/platforms/powernv/opal-elog.c
@@ -295,6 +295,10 @@ int __init opal_elog_init(void)
 {
         int rc = 0;
 
+        /* ELOG not supported by firmware */
+        if (!opal_check_token(OPAL_ELOG_READ))
+                return -1;
+
         elog_kset = kset_create_and_add("elog", NULL, opal_kobj);
         if (!elog_kset) {
                 pr_warn("%s: failed to create elog kset\n", __func__);