[PATCH 1/4] powerpc/rtas: Handle special return format for RTAS_FN_IBM_OPEN_ERRINJCT

[Narayana Murty N]

RTAS_FN_IBM_OPEN_ERRINJCT returns results in special format:
  rets[0] = session token (output)
  rets[1] = status code
  rets[2..] = additional outputs (if any)

Unlike standard RTAS calls where:
  rets[0] = status code
  rets[1..] = outputs

This patch adds special handling for OPEN_ERRINJCT to:
1. Check correct status position (rets[1]) for __fetch_rtas_last_error()
2. Copy all rets[0..nret-1] to outputs[] (including token at rets[0])
3. Return status from rets[1] instead of rets[0]

Reference: OpenPOWER PAPR documentation
           https://files.openpower.foundation/s/XFgfMaqLMD5Bcm8
Signed-off-by: Narayana Murty N <nnmli...@linux.ibm.com>
---
 arch/powerpc/kernel/rtas.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 8d81c1e7a8db..04c8438aadda 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1183,7 +1183,7 @@ int rtas_call(int token, int nargs, int nret, int 
*outputs, ...)
        unsigned long flags;
        struct rtas_args *args;
        char *buff_copy = NULL;
-       int ret;
+       int ret = 0;
 
        if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
                return -1;
@@ -1213,15 +1213,33 @@ int rtas_call(int token, int nargs, int nret, int 
*outputs, ...)
        va_rtas_call_unlocked(args, token, nargs, nret, list);
        va_end(list);
 
+       /* Special handling for RTAS_FN_IBM_OPEN_ERRINJCT for error fetching */
        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
-       if (be32_to_cpu(args->rets[0]) == -1)
+
+       if (token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT) && nret > 1)
+               ret = be32_to_cpu(args->rets[1]);
+       else if (nret > 0)
+               ret = be32_to_cpu(args->rets[0]);
+
+       if (ret == -1)
                buff_copy = __fetch_rtas_last_error(NULL);
 
-       if (nret > 1 && outputs != NULL)
-               for (i = 0; i < nret-1; ++i)
-                       outputs[i] = be32_to_cpu(args->rets[i + 1]);
-       ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;
+       /* Handle outputs and return status */
+       if (nret > 1 && outputs != NULL) {
+               if (token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT)) {
+                       /* Special case: rets[0]=token, rets[1]=status, 
rets[2..]=outputs */
+                       for (i = 0; i < nret; ++i)
+                               outputs[i] = be32_to_cpu(args->rets[i]);
+               } else {
+                       /* Normal case: rets[0]=status, rets[1..]=outputs */
+                       for (i = 0; i < nret - 1; ++i)
+                               outputs[i] = be32_to_cpu(args->rets[i + 1]);
+               }
+       } else {
+               /* No outputs: just ret is status */
+               ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0;
+       }
 
        lockdep_unpin_lock(&rtas_lock, cookie);
        raw_spin_unlock_irqrestore(&rtas_lock, flags);
-- 
2.51.1