s390/sclp_early: Add function to detect sclp console capabilities

Add SCLP console detect functions to encapsulate detection of SCLP console
capabilities, for example, VT220 support.  Reuse the sclp_send/receive masks
that were stored by the most recent sclp_set_event_mask() call to prevent
unnecessary SCLP calls.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/sclp.h

@@ -52,8 +52,8 @@ int sclp_chp_configure(struct chp_id chpid);
 int sclp_chp_deconfigure(struct chp_id chpid);
 int sclp_chp_read_info(struct sclp_chp_info *info);
 void sclp_get_ipl_info(struct sclp_ipl_info *info);
-bool sclp_has_linemode(void);
-bool sclp_has_vt220(void);
+bool __init sclp_has_linemode(void);
+bool __init sclp_has_vt220(void);
 int sclp_pci_configure(u32 fid);
 int sclp_pci_deconfigure(u32 fid);
 int memcpy_hsa(void *dest, unsigned long src, size_t count, int mode);

drivers/s390/char/sclp_early.c

@@ -36,6 +36,8 @@ struct read_info_sccb {
 } __packed __aligned(PAGE_SIZE);
 
 static char sccb_early[PAGE_SIZE] __aligned(PAGE_SIZE) __initdata;
+static unsigned int sclp_con_has_vt220 __initdata;
+static unsigned int sclp_con_has_linemode __initdata;
 static unsigned long sclp_hsa_size;
 static struct sclp_ipl_info sclp_ipl_info;
 
@@ -109,26 +111,12 @@ static void __init sclp_facilities_detect(struct read_info_sccb *sccb)
 
 bool __init sclp_has_linemode(void)
 {
-	struct init_sccb *sccb = (void *) &sccb_early;
-
-	if (sccb->header.response_code != 0x20)
-		return 0;
-	if (!(sccb->sclp_send_mask & (EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK)))
-		return 0;
-	if (!(sccb->sclp_receive_mask & (EVTYP_MSG_MASK | EVTYP_PMSGCMD_MASK)))
-		return 0;
-	return 1;
+	return !!sclp_con_has_linemode;
 }
 
 bool __init sclp_has_vt220(void)
 {
-	struct init_sccb *sccb = (void *) &sccb_early;
-
-	if (sccb->header.response_code != 0x20)
-		return 0;
-	if (sccb->sclp_send_mask & EVTYP_VT220MSG_MASK)
-		return 1;
-	return 0;
+	return !!sclp_con_has_vt220;
 }
 
 unsigned long long sclp_get_rnmax(void)
@@ -240,11 +228,37 @@ static void __init sclp_hsa_size_detect(void *sccb)
 	sclp_hsa_size = size;
 }
 
+static unsigned int __init sclp_con_check_linemode(struct init_sccb *sccb)
+{
+	if (!(sccb->sclp_send_mask & (EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK)))
+		return 0;
+	if (!(sccb->sclp_receive_mask & (EVTYP_MSG_MASK | EVTYP_PMSGCMD_MASK)))
+		return 0;
+	return 1;
+}
+
+static void __init sclp_console_detect(struct init_sccb *sccb)
+{
+	if (sccb->header.response_code != 0x20)
+		return;
+
+	if (sccb->sclp_send_mask & EVTYP_VT220MSG_MASK)
+		sclp_con_has_vt220 = 1;
+
+	if (sclp_con_check_linemode(sccb))
+		sclp_con_has_linemode = 1;
+}
+
 void __init sclp_early_detect(void)
 {
 	void *sccb = &sccb_early;
 
 	sclp_facilities_detect(sccb);
 	sclp_hsa_size_detect(sccb);
+
+	/* Turn off SCLP event notifications.  Also save remote masks in the
+	 * sccb.  These are sufficient to detect sclp console capabilities.
+	 */
 	sclp_set_event_mask(sccb, 0, 0);
+	sclp_console_detect(sccb);
 }