[S390] Add ipl/reipl loadparm attribute.

If multiple kernel images are installed on one DASD, the loadparm can be used
to select the boot configuration. This patch introduces the following two new
sysfs attributes:

/sys/firmware/ipl/loadparm: shows loadparm of current system (ro)
/sys/firmware/reipl/ccw/loadparm: loadparm used for next reboot (rw)

Signed-off-by: Michael Holzheu <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/kernel/ipl.c

···
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/reboot.h>
+#include <linux/ctype.h>
 #include <asm/smp.h>
 #include <asm/setup.h>
 #include <asm/cpcmd.h>
 #include <asm/cio.h>
+#include <asm/ebcdic.h>
 
 #define IPL_PARM_BLOCK_VERSION 0
+#define LOADPARM_LEN 8
+
+extern char s390_readinfo_sccb[];
+#define SCCB_VALID (*((__u16*)&s390_readinfo_sccb[6]) == 0x0010)
+#define SCCB_LOADPARM (&s390_readinfo_sccb[24])
+#define SCCB_FLAG (s390_readinfo_sccb[91])
 
 enum ipl_type {
 	IPL_TYPE_NONE	 = 1,
···
 
 /* CCW ipl device attributes */
 
+static ssize_t ipl_ccw_loadparm_show(struct subsystem *subsys, char *page)
+{
+	char loadparm[LOADPARM_LEN + 1] = {};
+
+	if (!SCCB_VALID)
+		return sprintf(page, "#unknown#\n");
+	memcpy(loadparm, SCCB_LOADPARM, LOADPARM_LEN);
+	EBCASC(loadparm, LOADPARM_LEN);
+	strstrip(loadparm);
+	return sprintf(page, "%s\n", loadparm);
+}
+
+static struct subsys_attribute sys_ipl_ccw_loadparm_attr =
+	__ATTR(loadparm, 0444, ipl_ccw_loadparm_show, NULL);
+
 static struct attribute *ipl_ccw_attrs[] = {
 	&sys_ipl_type_attr.attr,
 	&sys_ipl_device_attr.attr,
+	&sys_ipl_ccw_loadparm_attr.attr,
 	NULL,
 };
 
···
 DEFINE_IPL_ATTR_RW(reipl_ccw, device, "0.0.%04llx\n", "0.0.%llx\n",
 	reipl_block_ccw->ipl_info.ccw.devno);
 
+static void reipl_get_ascii_loadparm(char *loadparm)
+{
+	memcpy(loadparm, &reipl_block_ccw->ipl_info.ccw.load_param,
+	       LOADPARM_LEN);
+	EBCASC(loadparm, LOADPARM_LEN);
+	loadparm[LOADPARM_LEN] = 0;
+	strstrip(loadparm);
+}
+
+static ssize_t reipl_ccw_loadparm_show(struct subsystem *subsys, char *page)
+{
+	char buf[LOADPARM_LEN + 1];
+
+	reipl_get_ascii_loadparm(buf);
+	return sprintf(page, "%s\n", buf);
+}
+
+static ssize_t reipl_ccw_loadparm_store(struct subsystem *subsys,
+					const char *buf, size_t len)
+{
+	int i, lp_len;
+
+	/* ignore trailing newline */
+	lp_len = len;
+	if ((len > 0) && (buf[len - 1] == '\n'))
+		lp_len--;
+	/* loadparm can have max 8 characters and must not start with a blank */
+	if ((lp_len > LOADPARM_LEN) || ((lp_len > 0) && (buf[0] == ' ')))
+		return -EINVAL;
+	/* loadparm can only contain "a-z,A-Z,0-9,SP,." */
+	for (i = 0; i < lp_len; i++) {
+		if (isalpha(buf[i]) || isdigit(buf[i]) || (buf[i] == ' ') ||
+		    (buf[i] == '.'))
+			continue;
+		return -EINVAL;
+	}
+	/* initialize loadparm with blanks */
+	memset(&reipl_block_ccw->ipl_info.ccw.load_param, ' ', LOADPARM_LEN);
+	/* copy and convert to ebcdic */
+	memcpy(&reipl_block_ccw->ipl_info.ccw.load_param, buf, lp_len);
+	ASCEBC(reipl_block_ccw->ipl_info.ccw.load_param, LOADPARM_LEN);
+	return len;
+}
+
+static struct subsys_attribute sys_reipl_ccw_loadparm_attr =
+	__ATTR(loadparm, 0644, reipl_ccw_loadparm_show,
+	       reipl_ccw_loadparm_store);
+
 static struct attribute *reipl_ccw_attrs[] = {
 	&sys_reipl_ccw_device_attr.attr,
+	&sys_reipl_ccw_loadparm_attr.attr,
 	NULL,
 };
 
···
 {
 	struct ccw_dev_id devid;
 	static char buf[100];
+	char loadparm[LOADPARM_LEN + 1];
 
 	switch (reipl_type) {
 	case IPL_TYPE_CCW:
+		reipl_get_ascii_loadparm(loadparm);
 		printk(KERN_EMERG "reboot on ccw device: 0.0.%04x\n",
 			reipl_block_ccw->ipl_info.ccw.devno);
+		printk(KERN_EMERG "loadparm = '%s'\n", loadparm);
 		break;
 	case IPL_TYPE_FCP:
 		printk(KERN_EMERG "reboot on fcp device:\n");
···
 		reipl_ccw_dev(&devid);
 		break;
 	case IPL_METHOD_CCW_VM:
-		sprintf(buf, "IPL %X", reipl_block_ccw->ipl_info.ccw.devno);
+		if (strlen(loadparm) == 0)
+			sprintf(buf, "IPL %X",
+				reipl_block_ccw->ipl_info.ccw.devno);
+		else
+			sprintf(buf, "IPL %X LOADPARM '%s'",
+				reipl_block_ccw->ipl_info.ccw.devno, loadparm);
 		cpcmd(buf, NULL, 0, NULL);
 		break;
 	case IPL_METHOD_CCW_DIAG:
···
 	reipl_block_ccw->hdr.version = IPL_PARM_BLOCK_VERSION;
 	reipl_block_ccw->hdr.blk0_len = sizeof(reipl_block_ccw->ipl_info.ccw);
 	reipl_block_ccw->hdr.pbt = DIAG308_IPL_TYPE_CCW;
+	/* check if read scp info worked and set loadparm */
+	if (SCCB_VALID)
+		memcpy(reipl_block_ccw->ipl_info.ccw.load_param,
+		       SCCB_LOADPARM, LOADPARM_LEN);
+	else
+		/* read scp info failed: set empty loadparm (EBCDIC blanks) */
+		memset(reipl_block_ccw->ipl_info.ccw.load_param, 0x40,
+		       LOADPARM_LEN);
+	/* FIXME: check for diag308_set_works when enabling diag ccw reipl */
+	if (!MACHINE_IS_VM)
+		sys_reipl_ccw_loadparm_attr.attr.mode = S_IRUGO;
 	if (ipl_get_type() == IPL_TYPE_CCW)
 		reipl_block_ccw->ipl_info.ccw.devno = ipl_devno;
 	reipl_capabilities |= IPL_TYPE_CCW;
···
 	return 0;
 }
 
-extern char s390_readinfo_sccb[];
-
 static int __init dump_fcp_init(void)
 {
 	int rc;
 
-	if(!(s390_readinfo_sccb[91] & 0x2))
+	if(!(SCCB_FLAG & 0x2) || !SCCB_VALID)
 		return 0; /* LDIPL DUMP is not installed */
 	if (!diag308_set_works)
 		return 0;