From 22362a0e23182d230527a5add690b4027860d7d3 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Wed, 8 Jul 2015 10:20:04 +0200
Subject: s390/sclp: convert early sclp console code to C

The 31-bit assembler code for the early sclp console is error
prone as git commit fde24b54d976cc123506695c17db01438a11b673
"s390/sclp: clear upper register halves in _sclp_print_early"
has shown.

Convert the assembler code to C.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/kernel/sclp.c | 160 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 arch/s390/kernel/sclp.c

(limited to 'arch/s390/kernel/sclp.c')

diff --git a/arch/s390/kernel/sclp.c b/arch/s390/kernel/sclp.c
new file mode 100644
index 000000000000..fa0bdff1d413
--- /dev/null
+++ b/arch/s390/kernel/sclp.c
@@ -0,0 +1,160 @@
+/*
+ *    Copyright IBM Corp. 2015
+ *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+#include <linux/kernel.h>
+#include <asm/ebcdic.h>
+#include <asm/irq.h>
+#include <asm/lowcore.h>
+#include <asm/processor.h>
+#include <asm/sclp.h>
+
+static char _sclp_work_area[4096] __aligned(PAGE_SIZE);
+
+static void _sclp_wait_int(void)
+{
+	unsigned long cr0, cr0_new, psw_mask, addr;
+	psw_t psw_ext_save, psw_wait;
+
+	__ctl_store(cr0, 0, 0);
+	cr0_new = cr0 | 0x200;
+	__ctl_load(cr0_new, 0, 0);
+
+	psw_ext_save = S390_lowcore.external_new_psw;
+	psw_mask = __extract_psw() & (PSW_MASK_EA | PSW_MASK_BA);
+	S390_lowcore.external_new_psw.mask = psw_mask;
+	psw_wait.mask = psw_mask | PSW_MASK_EXT | PSW_MASK_WAIT;
+	S390_lowcore.ext_int_code = 0;
+
+	do {
+		asm volatile(
+			"	larl	%[addr],0f\n"
+			"	stg	%[addr],%[psw_wait_addr]\n"
+			"	stg	%[addr],%[psw_ext_addr]\n"
+			"	lpswe	%[psw_wait]\n"
+			"0:\n"
+			: [addr] "=&d" (addr),
+			  [psw_wait_addr] "=Q" (psw_wait.addr),
+			  [psw_ext_addr] "=Q" (S390_lowcore.external_new_psw.addr)
+			: [psw_wait] "Q" (psw_wait)
+			: "cc", "memory");
+	} while (S390_lowcore.ext_int_code != EXT_IRQ_SERVICE_SIG);
+
+	__ctl_load(cr0, 0, 0);
+	S390_lowcore.external_new_psw = psw_ext_save;
+}
+
+static int _sclp_servc(unsigned int cmd, char *sccb)
+{
+	unsigned int cc;
+
+	do {
+		asm volatile(
+			"	.insn	rre,0xb2200000,%1,%2\n"
+			"	ipm	%0\n"
+			: "=d" (cc) : "d" (cmd), "a" (sccb)
+			: "cc", "memory");
+		cc >>= 28;
+		if (cc == 3)
+			return -EINVAL;
+		_sclp_wait_int();
+	} while (cc != 0);
+	return (*(unsigned short *)(sccb + 6) == 0x20) ? 0 : -EIO;
+}
+
+static int _sclp_setup(int disable)
+{
+	static unsigned char init_sccb[] = {
+		0x00, 0x1c,
+		0x00, 0x00, 0x00, 0x00,	0x00, 0x00, 0x00, 0x00,
+		0x00, 0x04,
+		0x80, 0x00, 0x00, 0x00,	0x40, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00,	0x00, 0x00, 0x00, 0x00
+	};
+	unsigned int *masks;
+	int rc;
+
+	memcpy(_sclp_work_area, init_sccb, 28);
+	masks = (unsigned int *)(_sclp_work_area + 12);
+	if (disable)
+		memset(masks, 0, 16);
+	/* SCLP write mask */
+	rc = _sclp_servc(0x00780005, _sclp_work_area);
+	if (rc)
+		return rc;
+	if ((masks[0] & masks[3]) != masks[0] ||
+	    (masks[1] & masks[2]) != masks[1])
+		return -EIO;
+	return 0;
+}
+
+static int _sclp_print(const char *str)
+{
+	static unsigned char write_head[] = {
+		/* sccb header */
+		0x00, 0x52,					/* 0 */
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		/* 2 */
+		/* evbuf */
+		0x00, 0x4a,					/* 8 */
+		0x02, 0x00, 0x00, 0x00,				/* 10 */
+		/* mdb */
+		0x00, 0x44,					/* 14 */
+		0x00, 0x01,					/* 16 */
+		0xd4, 0xc4, 0xc2, 0x40,				/* 18 */
+		0x00, 0x00, 0x00, 0x01,				/* 22 */
+		/* go */
+		0x00, 0x38,					/* 26 */
+		0x00, 0x01,					/* 28 */
+		0x00, 0x00, 0x00, 0x00,				/* 30 */
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	/* 34 */
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	/* 42 */
+		0x00, 0x00, 0x00, 0x00,				/* 50 */
+		0x00, 0x00,					/* 54 */
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	/* 56 */
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	/* 64 */
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	/* 72 */
+		0x00, 0x00,					/* 80 */
+	};
+	static unsigned char write_mto[] = {
+		/* mto	*/
+		0x00, 0x0a,					/* 0 */
+		0x00, 0x04,					/* 2 */
+		0x10, 0x00,					/* 4 */
+		0x00, 0x00, 0x00, 0x00				/* 6 */
+	};
+	unsigned char *ptr, ch;
+	unsigned int count;
+
+	memcpy(_sclp_work_area, write_head, sizeof(write_head));
+	ptr = _sclp_work_area + sizeof(write_head);
+	do {
+		memcpy(ptr, write_mto, sizeof(write_mto));
+		for (count = sizeof(write_mto); (ch = *str++) != 0; count++) {
+			if (ch == 0x0a)
+				break;
+			ptr[count] = _ascebc[ch];
+		}
+		/* Update length fields in mto, mdb, evbuf and sccb */
+		*(unsigned short *) ptr = count;
+		*(unsigned short *)(_sclp_work_area + 14) += count;
+		*(unsigned short *)(_sclp_work_area + 8) += count;
+		*(unsigned short *)(_sclp_work_area + 0) += count;
+		ptr += count;
+	} while (ch != 0);
+
+	/* SCLP write data */
+	return _sclp_servc(0x00760005, _sclp_work_area);
+}
+
+int _sclp_print_early(const char *str)
+{
+	int rc;
+
+	rc = _sclp_setup(0);
+	if (rc)
+		return rc;
+	rc = _sclp_print(str);
+	if (rc)
+		return rc;
+	return _sclp_setup(1);
+}
-- 
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