linux/arch/s390/kernel/sclp.c

/*
 *    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);
}