[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>

3 files changed, 31 insertions, 4 deletions

diff --git a/include/asm-s390/cio.h b/include/asm-s390/cio.h
index 81287d86329d..cabd5bb74b5a 100644
--- a/include/asm-s390/cio.h
+++ b/include/asm-s390/cio.h
@@ -285,10 +285,6 @@ extern int diag210(struct diag210 *addr);
 
 extern void wait_cons_dev(void);
 
-extern void clear_all_subchannels(void);
-
-extern void cio_reset_channel_paths(void);
-
 extern void css_schedule_reprobe(void);
 
 extern void reipl_ccw_dev(struct ccw_dev_id *id);
diff --git a/include/asm-s390/lowcore.h b/include/asm-s390/lowcore.h
index 06583ed0bde7..74f7389bd3ee 100644
--- a/include/asm-s390/lowcore.h
+++ b/include/asm-s390/lowcore.h
@@ -362,6 +362,14 @@ static inline void set_prefix(__u32 address)
         asm volatile("spx %0" : : "m" (address) : "memory");
 }
 
+static inline __u32 store_prefix(void)
+{
+        __u32 address;
+
+        asm volatile("stpx %0" : "=m" (address));
+        return address;
+}
+
 #define __PANIC_MAGIC           0xDEADC0DE
 
 #endif
diff --git a/include/asm-s390/reset.h b/include/asm-s390/reset.h
new file mode 100644
index 000000000000..9b439cf67800
--- /dev/null
+++ b/include/asm-s390/reset.h
@@ -0,0 +1,23 @@
+/*
+ *  include/asm-s390/reset.h
+ *
+ *    Copyright IBM Corp. 2006
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#ifndef _ASM_S390_RESET_H
+#define _ASM_S390_RESET_H
+
+#include <linux/list.h>
+
+struct reset_call {
+        struct list_head list;
+        void (*fn)(void);
+};
+
+extern void register_reset_call(struct reset_call *reset);
+extern void unregister_reset_call(struct reset_call *reset);
+extern void s390_reset_system(void);
+extern void (*s390_reset_mcck_handler)(void);
+
+#endif /* _ASM_S390_RESET_H */