[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>

1 files changed, 54 insertions, 0 deletions

diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index ec127826f221..77f4aff630fe 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -19,6 +19,7 @@
 #include <asm/cpcmd.h>
 #include <asm/cio.h>
 #include <asm/ebcdic.h>
+#include <asm/reset.h>
 
 #define IPL_PARM_BLOCK_VERSION 0
 #define LOADPARM_LEN 8
@@ -1024,3 +1025,56 @@ static int __init s390_ipl_init(void)
 }
 
 __initcall(s390_ipl_init);
+
+static LIST_HEAD(rcall);
+static DEFINE_MUTEX(rcall_mutex);
+
+void register_reset_call(struct reset_call *reset)
+{
+        mutex_lock(&rcall_mutex);
+        list_add(&reset->list, &rcall);
+        mutex_unlock(&rcall_mutex);
+}
+EXPORT_SYMBOL_GPL(register_reset_call);
+
+void unregister_reset_call(struct reset_call *reset)
+{
+        mutex_lock(&rcall_mutex);
+        list_del(&reset->list);
+        mutex_unlock(&rcall_mutex);
+}
+EXPORT_SYMBOL_GPL(unregister_reset_call);
+
+static void do_reset_calls(void)
+{
+        struct reset_call *reset;
+
+        list_for_each_entry(reset, &rcall, list)
+                reset->fn();
+}
+
+extern void reset_mcck_handler(void);
+
+void s390_reset_system(void)
+{
+        struct _lowcore *lc;
+
+        /* Disable all interrupts/machine checks */
+        __load_psw_mask(PSW_KERNEL_BITS & ~PSW_MASK_MCHECK);
+
+        /* Stack for interrupt/machine check handler */
+        lc = (struct _lowcore *)(unsigned long) store_prefix();
+        lc->panic_stack = S390_lowcore.panic_stack;
+
+        /* Disable prefixing */
+        set_prefix(0);
+
+        /* Disable lowcore protection */
+        __ctl_clear_bit(0,28);
+
+        /* Set new machine check handler */
+        S390_lowcore.mcck_new_psw.mask = PSW_KERNEL_BITS & ~PSW_MASK_MCHECK;
+        S390_lowcore.mcck_new_psw.addr =
+                PSW_ADDR_AMODE | (unsigned long) &reset_mcck_handler;
+        do_reset_calls();
+}