s390/tty3270: add support for diag 8c

The current code uses diag210 to infer the 3270 geometry from the
model number when running on z/VM. This doesn't work well as almost
all 3270 software clients report as 3279-2 with a custom resolution.
tty3270 assumes it has a 80x24 terminal connected because of the -2
suffix. Use diag 8c to fetch the realy geometry from z/VM.

Note that this doesn't allow dynamic resizing, i.e. reconnecting to
a z/VM session with a different geometry.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

3 files changed, 53 insertions, 0 deletions

diff --git a/arch/s390/include/asm/diag.h b/arch/s390/include/asm/diag.h
index 56e99c286d12..9488b7ffb21c 100644
--- a/arch/s390/include/asm/diag.h
+++ b/arch/s390/include/asm/diag.h
@@ -12,6 +12,7 @@
 #include <linux/if_ether.h>
 #include <linux/percpu.h>
 #include <asm/asm-extable.h>
+#include <asm/cio.h>
 
 enum diag_stat_enum {
 	DIAG_STAT_X008,
@@ -20,6 +21,7 @@ enum diag_stat_enum {
 	DIAG_STAT_X014,
 	DIAG_STAT_X044,
 	DIAG_STAT_X064,
+	DIAG_STAT_X08C,
 	DIAG_STAT_X09C,
 	DIAG_STAT_X0DC,
 	DIAG_STAT_X204,
@@ -83,6 +85,16 @@ struct diag210 {
 
 extern int diag210(struct diag210 *addr);
 
+struct diag8c {
+	u8 flags;
+	u8 num_partitions;
+	u16 width;
+	u16 height;
+	u8 data[0];
+} __packed __aligned(4);
+
+extern int diag8c(struct diag8c *out, struct ccw_dev_id *devno);
+
 /* bit is set in flags, when physical cpu info is included in diag 204 data */
 #define DIAG204_LPAR_PHYS_FLG 0x80
 #define DIAG204_LPAR_NAME_LEN 8		/* lpar name len in diag 204 data */
@@ -318,6 +330,7 @@ struct diag_ops {
 	int (*diag210)(struct diag210 *addr);
 	int (*diag26c)(void *req, void *resp, enum diag26c_sc subcode);
 	int (*diag14)(unsigned long rx, unsigned long ry1, unsigned long subcode);
+	int (*diag8c)(struct diag8c *addr, struct ccw_dev_id *devno, size_t len);
 	void (*diag0c)(struct hypfs_diag0c_entry *entry);
 	void (*diag308_reset)(void);
 };
@@ -330,5 +343,6 @@ int _diag26c_amode31(void *req, void *resp, enum diag26c_sc subcode);
 int _diag14_amode31(unsigned long rx, unsigned long ry1, unsigned long subcode);
 void _diag0c_amode31(struct hypfs_diag0c_entry *entry);
 void _diag308_reset_amode31(void);
+int _diag8c_amode31(struct diag8c *addr, struct ccw_dev_id *devno, size_t len);
 
 #endif /* _ASM_S390_DIAG_H */
diff --git a/arch/s390/kernel/diag.c b/arch/s390/kernel/diag.c
index a778714e4d8b..a6a0222a35cf 100644
--- a/arch/s390/kernel/diag.c
+++ b/arch/s390/kernel/diag.c
@@ -35,6 +35,7 @@ static const struct diag_desc diag_map[NR_DIAG_STAT] = {
 	[DIAG_STAT_X014] = { .code = 0x014, .name = "Spool File Services" },
 	[DIAG_STAT_X044] = { .code = 0x044, .name = "Voluntary Timeslice End" },
 	[DIAG_STAT_X064] = { .code = 0x064, .name = "NSS Manipulation" },
+	[DIAG_STAT_X08C] = { .code = 0x08c, .name = "Access 3270 Display Device Information" },
 	[DIAG_STAT_X09C] = { .code = 0x09c, .name = "Relinquish Timeslice" },
 	[DIAG_STAT_X0DC] = { .code = 0x0dc, .name = "Appldata Control" },
 	[DIAG_STAT_X204] = { .code = 0x204, .name = "Logical-CPU Utilization" },
@@ -57,12 +58,16 @@ struct diag_ops __amode31_ref diag_amode31_ops = {
 	.diag26c = _diag26c_amode31,
 	.diag14 = _diag14_amode31,
 	.diag0c = _diag0c_amode31,
+	.diag8c = _diag8c_amode31,
 	.diag308_reset = _diag308_reset_amode31
 };
 
 static struct diag210 _diag210_tmp_amode31 __section(".amode31.data");
 struct diag210 __amode31_ref *__diag210_tmp_amode31 = &_diag210_tmp_amode31;
 
+static struct diag8c _diag8c_tmp_amode31 __section(".amode31.data");
+struct diag8c __amode31_ref *__diag8c_tmp_amode31 = &_diag8c_tmp_amode31;
+
 static int show_diag_stat(struct seq_file *m, void *v)
 {
 	struct diag_stat *stat;
@@ -194,6 +199,27 @@ int diag210(struct diag210 *addr)
 }
 EXPORT_SYMBOL(diag210);
 
+/*
+ * Diagnose 210: Get information about a virtual device
+ */
+int diag8c(struct diag8c *addr, struct ccw_dev_id *devno)
+{
+	static DEFINE_SPINLOCK(diag8c_lock);
+	unsigned long flags;
+	int ccode;
+
+	spin_lock_irqsave(&diag8c_lock, flags);
+
+	diag_stat_inc(DIAG_STAT_X08C);
+	ccode = diag_amode31_ops.diag8c(__diag8c_tmp_amode31, devno, sizeof(*addr));
+
+	*addr = *__diag8c_tmp_amode31;
+	spin_unlock_irqrestore(&diag8c_lock, flags);
+
+	return ccode;
+}
+EXPORT_SYMBOL(diag8c);
+
 int diag224(void *ptr)
 {
 	int rc = -EOPNOTSUPP;
diff --git a/arch/s390/kernel/text_amode31.S b/arch/s390/kernel/text_amode31.S
index 2c8b14cc5556..e0f01ce251f5 100644
--- a/arch/s390/kernel/text_amode31.S
+++ b/arch/s390/kernel/text_amode31.S
@@ -63,6 +63,19 @@ ENTRY(_diag210_amode31)
 ENDPROC(_diag210_amode31)
 
 /*
+ * int diag8c(struct diag8c *addr, struct ccw_dev_id *devno, size_t len)
+*/
+ENTRY(_diag8c_amode31)
+	llgf	%r3,0(%r3)
+	sam31
+	diag	%r2,%r4,0x8c
+.Ldiag8c_ex:
+	sam64
+	lgfr	%r2,%r3
+	BR_EX_AMODE31_r14
+	EX_TABLE_AMODE31(.Ldiag8c_ex, .Ldiag8c_ex)
+ENDPROC(_diag8c_amode31)
+/*
  * int _diag26c_amode31(void *req, void *resp, enum diag26c_sc subcode)
  */
 ENTRY(_diag26c_amode31)