s390/sclp: make early sclp code readable

This patch

 - unifies the old sclp early code and the sclp early printk code, so
   they can use common functions

 - makes sure all sclp early functions and variables have the same
   "sclp_early" prefix

 - converts the sclp early printk code into readable code by using
   existing data structures instead of hard coded magic arrays

 - splits the early sclp code into two files: sclp_early.c and
   sclp_early_core.c. The core file contains everything that is
   required by the kernel decompressor and may not call functions not
   contained within the core file. Otherwise the result would be a
   link error.

 - changes interrupt handling to be completely synchronous. The old
   early sclp code had a small window which allowed to receive several
   interrupts instead of exactly the single expected interrupt. This
   did hide a subtle potential bug, which is fixed with this large
   rework.

 - contains a couple of small cleanups.

Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 33 insertions, 1 deletions

diff --git a/drivers/s390/char/sclp.h b/drivers/s390/char/sclp.h
index 0c1fa376df9e..78d5f542d979 100644
--- a/drivers/s390/char/sclp.h
+++ b/drivers/s390/char/sclp.h
@@ -204,7 +204,6 @@ void sclp_unregister(struct sclp_register *reg);
 int sclp_remove_processed(struct sccb_header *sccb);
 int sclp_deactivate(void);
 int sclp_reactivate(void);
-int sclp_service_call(sclp_cmdw_t command, void *sccb);
 int sclp_sync_request(sclp_cmdw_t command, void *sccb);
 int sclp_sync_request_timeout(sclp_cmdw_t command, void *sccb, int timeout);
 
@@ -222,8 +221,41 @@ extern int sclp_console_pages;
 extern int sclp_console_drop;
 extern unsigned long sclp_console_full;
 
+extern char sclp_early_sccb[PAGE_SIZE];
+
+void sclp_early_wait_irq(void);
+int sclp_early_cmd_sync(sclp_cmdw_t cmd, void *sccb);
+int sclp_early_cmd(sclp_cmdw_t cmd, void *sccb);
+unsigned int sclp_early_con_check_linemode(struct init_sccb *sccb);
+int sclp_early_set_event_mask(struct init_sccb *sccb,
+			      unsigned long receive_mask,
+			      unsigned long send_mask);
+
 /* useful inlines */
 
+/* Perform service call. Return 0 on success, non-zero otherwise. */
+static inline int sclp_service_call(sclp_cmdw_t command, void *sccb)
+{
+	int cc = 4; /* Initialize for program check handling */
+
+	asm volatile(
+		"0:	.insn	rre,0xb2200000,%1,%2\n"	 /* servc %1,%2 */
+		"1:	ipm	%0\n"
+		"	srl	%0,28\n"
+		"2:\n"
+		EX_TABLE(0b, 2b)
+		EX_TABLE(1b, 2b)
+		: "+&d" (cc) : "d" (command), "a" ((unsigned long)sccb)
+		: "cc", "memory");
+	if (cc == 4)
+		return -EINVAL;
+	if (cc == 3)
+		return -EIO;
+	if (cc == 2)
+		return -EBUSY;
+	return 0;
+}
+
 /* VM uses EBCDIC 037, LPAR+native(SE+HMC) use EBCDIC 500 */
 /* translate single character from ASCII to EBCDIC */
 static inline unsigned char