[S390] Reset infrastructure for re-IPL.

In case of re-IPL and diag308 doesn't work we have to reset all devices
manually and wait synchronously that each reset finished.
This patch adds the necessary infrastucture and the first exploiter of it.

Subsystems that need to add a function that needs to be called at re-IPL
may register/unregister this function via

struct reset_call {
	struct reset_call *next;
	void (*fn)(void);
};

void register_reset_call(struct reset_call *reset);
void unregister_reset_call(struct reset_call *reset);

When the registered function get called the context is:

- all cpus beside the current one are stopped
- all machine checks and interrupts are disabled
- prefixing is disabled
- a default machine check handler is available for use

The registered functions may not take any locks are sleep.

For the common I/O layer part of this patch:

Introduce a reset_call css_reset that does the following:
- clear all subchannels
- perform a rchp on all channel paths and wait for the resulting
  machine checks
This replaces the calls to clear_all_subchannels() and
cio_reset_channel_paths() for kexec and ccw reipl. reipl_ccw_dev() now
uses reipl_find_schid() to determine the subchannel id for a given
device id.
Also remove cio_reset_channel_paths() and friends since they are not
needed anymore.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 100 insertions, 63 deletions

diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index 2d78f0f4a40fc..9d92540bd99e8 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -1465,41 +1465,6 @@ chsc_get_chp_desc(struct subchannel *sch, int chp_no)
 	return desc;
 }
 
-static int reset_channel_path(struct channel_path *chp)
-{
-	int cc;
-
-	cc = rchp(chp->id);
-	switch (cc) {
-	case 0:
-		return 0;
-	case 2:
-		return -EBUSY;
-	default:
-		return -ENODEV;
-	}
-}
-
-static void reset_channel_paths_css(struct channel_subsystem *css)
-{
-	int i;
-
-	for (i = 0; i <= __MAX_CHPID; i++) {
-		if (css->chps[i])
-			reset_channel_path(css->chps[i]);
-	}
-}
-
-void cio_reset_channel_paths(void)
-{
-	int i;
-
-	for (i = 0; i <= __MAX_CSSID; i++) {
-		if (css[i] && css[i]->valid)
-			reset_channel_paths_css(css[i]);
-	}
-}
-
 static int __init
 chsc_alloc_sei_area(void)
 {
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 8936e460a807c..20aee27838472 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -21,6 +21,7 @@
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
 #include <asm/setup.h>
+#include <asm/reset.h>
 #include "airq.h"
 #include "cio.h"
 #include "css.h"
@@ -28,6 +29,7 @@
 #include "ioasm.h"
 #include "blacklist.h"
 #include "cio_debug.h"
+#include "../s390mach.h"
 
 debug_info_t *cio_debug_msg_id;
 debug_info_t *cio_debug_trace_id;
@@ -841,26 +843,12 @@ __clear_subchannel_easy(struct subchannel_id schid)
 	return -EBUSY;
 }
 
-struct sch_match_id {
-	struct subchannel_id schid;
-	struct ccw_dev_id devid;
-	int rc;
-};
-
-static int __shutdown_subchannel_easy_and_match(struct subchannel_id schid,
-	void *data)
+static int __shutdown_subchannel_easy(struct subchannel_id schid, void *data)
 {
 	struct schib schib;
-	struct sch_match_id *match_id = data;
 
 	if (stsch_err(schid, &schib))
 		return -ENXIO;
-	if (match_id && schib.pmcw.dnv &&
-		(schib.pmcw.dev == match_id->devid.devno) &&
-		(schid.ssid == match_id->devid.ssid)) {
-		match_id->schid = schid;
-		match_id->rc = 0;
-	}
 	if (!schib.pmcw.ena)
 		return 0;
 	switch(__disable_subchannel_easy(schid, &schib)) {
@@ -876,27 +864,111 @@ static int __shutdown_subchannel_easy_and_match(struct subchannel_id schid,
 	return 0;
 }
 
-static int clear_all_subchannels_and_match(struct ccw_dev_id *devid,
-	struct subchannel_id *schid)
+static atomic_t chpid_reset_count;
+
+static void s390_reset_chpids_mcck_handler(void)
+{
+	struct crw crw;
+	struct mci *mci;
+
+	/* Check for pending channel report word. */
+	mci = (struct mci *)&S390_lowcore.mcck_interruption_code;
+	if (!mci->cp)
+		return;
+	/* Process channel report words. */
+	while (stcrw(&crw) == 0) {
+		/* Check for responses to RCHP. */
+		if (crw.slct && crw.rsc == CRW_RSC_CPATH)
+			atomic_dec(&chpid_reset_count);
+	}
+}
+
+#define RCHP_TIMEOUT (30 * USEC_PER_SEC)
+static void css_reset(void)
+{
+	int i, ret;
+	unsigned long long timeout;
+
+	/* Reset subchannels. */
+	for_each_subchannel(__shutdown_subchannel_easy,  NULL);
+	/* Reset channel paths. */
+	s390_reset_mcck_handler = s390_reset_chpids_mcck_handler;
+	/* Enable channel report machine checks. */
+	__ctl_set_bit(14, 28);
+	/* Temporarily reenable machine checks. */
+	local_mcck_enable();
+	for (i = 0; i <= __MAX_CHPID; i++) {
+		ret = rchp(i);
+		if ((ret == 0) || (ret == 2))
+			/*
+			 * rchp either succeeded, or another rchp is already
+			 * in progress. In either case, we'll get a crw.
+			 */
+			atomic_inc(&chpid_reset_count);
+	}
+	/* Wait for machine check for all channel paths. */
+	timeout = get_clock() + (RCHP_TIMEOUT << 12);
+	while (atomic_read(&chpid_reset_count) != 0) {
+		if (get_clock() > timeout)
+			break;
+		cpu_relax();
+	}
+	/* Disable machine checks again. */
+	local_mcck_disable();
+	/* Disable channel report machine checks. */
+	__ctl_clear_bit(14, 28);
+	s390_reset_mcck_handler = NULL;
+}
+
+static struct reset_call css_reset_call = {
+	.fn = css_reset,
+};
+
+static int __init init_css_reset_call(void)
+{
+	atomic_set(&chpid_reset_count, 0);
+	register_reset_call(&css_reset_call);
+	return 0;
+}
+
+arch_initcall(init_css_reset_call);
+
+struct sch_match_id {
+	struct subchannel_id schid;
+	struct ccw_dev_id devid;
+	int rc;
+};
+
+static int __reipl_subchannel_match(struct subchannel_id schid, void *data)
+{
+	struct schib schib;
+	struct sch_match_id *match_id = data;
+
+	if (stsch_err(schid, &schib))
+		return -ENXIO;
+	if (schib.pmcw.dnv &&
+	    (schib.pmcw.dev == match_id->devid.devno) &&
+	    (schid.ssid == match_id->devid.ssid)) {
+		match_id->schid = schid;
+		match_id->rc = 0;
+		return 1;
+	}
+	return 0;
+}
+
+static int reipl_find_schid(struct ccw_dev_id *devid,
+			    struct subchannel_id *schid)
 {
 	struct sch_match_id match_id;
 
 	match_id.devid = *devid;
 	match_id.rc = -ENODEV;
-	local_irq_disable();
-	for_each_subchannel(__shutdown_subchannel_easy_and_match, &match_id);
+	for_each_subchannel(__reipl_subchannel_match, &match_id);
 	if (match_id.rc == 0)
 		*schid = match_id.schid;
 	return match_id.rc;
 }
 
-
-void clear_all_subchannels(void)
-{
-	local_irq_disable();
-	for_each_subchannel(__shutdown_subchannel_easy_and_match, NULL);
-}
-
 extern void do_reipl_asm(__u32 schid);
 
 /* Make sure all subchannels are quiet before we re-ipl an lpar. */
@@ -904,9 +976,9 @@ void reipl_ccw_dev(struct ccw_dev_id *devid)
 {
 	struct subchannel_id schid;
 
-	if (clear_all_subchannels_and_match(devid, &schid))
+	s390_reset_system();
+	if (reipl_find_schid(devid, &schid) != 0)
 		panic("IPL Device not found\n");
-	cio_reset_channel_paths();
 	do_reipl_asm(*((__u32*)&schid));
 }