powerpc/powernv: Update firmware archaeology around OPAL_HANDLE_HMI

The first machines to ship with OPAL firmware all got firmware updates
that have the new call, but just in case someone is foolish enough to
believe the first 4 months of firmware is the best, we keep this code
around.

Comment is updated to not refer to late 2014 as recent or the future.

Signed-off-by: Stewart Smith <stewart@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index f2b063b..89b6ddc 100644 (file)
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -206,16 +206,18 @@ static int __init opal_register_exception_handlers(void)
        glue = 0x7000;
 
        /*
-        * Check if we are running on newer firmware that exports
-        * OPAL_HANDLE_HMI token. If yes, then don't ask OPAL to patch
-        * the HMI interrupt and we catch it directly in Linux.
+        * Only ancient OPAL firmware requires this.
+        * Specifically, firmware from FW810.00 (released June 2014)
+        * through FW810.20 (Released October 2014).
         *
-        * For older firmware (i.e currently released POWER8 System Firmware
-        * as of today <= SV810_087), we fallback to old behavior and let OPAL
-        * patch the HMI vector and handle it inside OPAL firmware.
+        * Check if we are running on newer (post Oct 2014) firmware that
+        * exports the OPAL_HANDLE_HMI token. If yes, then don't ask OPAL to
+        * patch the HMI interrupt and we catch it directly in Linux.
         *
-        * For newer firmware (in development/yet to be released) we will
-        * start catching/handling HMI directly in Linux.
+        * For older firmware (i.e < FW810.20), we fallback to old behavior and
+        * let OPAL patch the HMI vector and handle it inside OPAL firmware.
+        *
+        * For newer firmware we catch/handle the HMI directly in Linux.
         */
        if (!opal_check_token(OPAL_HANDLE_HMI)) {
                pr_info("Old firmware detected, OPAL handles HMIs.\n");
@@ -225,6 +227,11 @@ static int __init opal_register_exception_handlers(void)
                glue += 128;
        }
 
+       /*
+        * Only applicable to ancient firmware, all modern
+        * (post March 2015/skiboot 5.0) firmware will just return
+        * OPAL_UNSUPPORTED.
+        */
        opal_register_exception_handler(OPAL_SOFTPATCH_HANDLER, 0, glue);
 #endif