[S390] zcrypt: Introduce check for 4096 bit support.

Implemented an asm in the ap bus and made it accessible for the card
specific parts of the zcrypt driver. Thus when a cex3a is recognized
a check can be performed to dermine whether the card supports 4096 bit
RSA keys.

Signed-off-by: Felix Beck <felix.beck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 4f37c45ee114..67302b944ab3 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -222,6 +222,69 @@ ap_queue_interruption_control(ap_qid_t qid, void *ind)
 }
 #endif
 
+static inline struct ap_queue_status __ap_4096_commands_available(ap_qid_t qid,
+                                                                  int *support)
+{
+        register unsigned long reg0 asm ("0") = 0UL | qid | (1UL << 23);
+        register struct ap_queue_status reg1 asm ("1");
+        register unsigned long reg2 asm ("2") = 0UL;
+
+        asm volatile(
+                ".long 0xb2af0000\n"
+                "0: la    %1,0\n"
+                "1:\n"
+                EX_TABLE(0b, 1b)
+                : "+d" (reg0), "=d" (reg1), "=d" (reg2)
+                :
+                : "cc");
+
+        if (reg2 & 0x6000000000000000ULL)
+                *support = 1;
+        else
+                *support = 0;
+
+        return reg1;
+}
+
+/**
+ * ap_4096_commands_availablen(): Check for availability of 4096 bit RSA
+ * support.
+ * @qid: The AP queue number
+ *
+ * Returns 1 if 4096 bit RSA keys are support fo the AP, returns 0 if not.
+ */
+int ap_4096_commands_available(ap_qid_t qid)
+{
+        struct ap_queue_status status;
+        int i, support = 0;
+        status = __ap_4096_commands_available(qid, &support);
+
+        for (i = 0; i < AP_MAX_RESET; i++) {
+                switch (status.response_code) {
+                case AP_RESPONSE_NORMAL:
+                        return support;
+                case AP_RESPONSE_RESET_IN_PROGRESS:
+                case AP_RESPONSE_BUSY:
+                        break;
+                case AP_RESPONSE_Q_NOT_AVAIL:
+                case AP_RESPONSE_DECONFIGURED:
+                case AP_RESPONSE_CHECKSTOPPED:
+                case AP_RESPONSE_INVALID_ADDRESS:
+                        return 0;
+                case AP_RESPONSE_OTHERWISE_CHANGED:
+                        break;
+                default:
+                        break;
+                }
+                if (i < AP_MAX_RESET - 1) {
+                        udelay(5);
+                        status = __ap_4096_commands_available(qid, &support);
+                }
+        }
+        return support;
+}
+EXPORT_SYMBOL(ap_4096_commands_available);
+
 /**
  * ap_queue_enable_interruption(): Enable interruption on an AP.
  * @qid: The AP queue number