[S390] Convert memory detection into C code.

Hopefully this will make it more maintainable and less error prone.
Code makes use of search_exception_tables(). Since it calls this
function before the kernel exeception table is sorted, there is an
early call to sort_main_extable().

This way it's easy to use the already present infrastructure of fixup
sections. Also this would allows to easily convert the rest of
head[31|64].S into C code.

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

1 files changed, 57 insertions, 0 deletions

diff --git a/drivers/s390/char/sclp_info.c b/drivers/s390/char/sclp_info.c
new file mode 100644
index 00000000000..7bcbe643b08
--- /dev/null
+++ b/drivers/s390/char/sclp_info.c
@@ -0,0 +1,57 @@
+/*
+ *  drivers/s390/char/sclp_info.c
+ *
+ *    Copyright IBM Corp. 2007
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <asm/sclp.h>
+#include "sclp.h"
+
+struct sclp_readinfo_sccb s390_readinfo_sccb;
+
+void __init sclp_readinfo_early(void)
+{
+	sclp_cmdw_t command;
+	struct sccb_header *sccb;
+	int ret;
+
+	__ctl_set_bit(0, 9); /* enable service signal subclass mask */
+
+	sccb = &s390_readinfo_sccb.header;
+	command = SCLP_CMDW_READ_SCP_INFO_FORCED;
+	while (1) {
+		u16 response;
+
+		memset(&s390_readinfo_sccb, 0, sizeof(s390_readinfo_sccb));
+		sccb->length = sizeof(s390_readinfo_sccb);
+		sccb->control_mask[2] = 0x80;
+
+		ret = sclp_service_call(command, &s390_readinfo_sccb);
+
+		if (ret == -EIO)
+			goto out;
+		if (ret == -EBUSY)
+			continue;
+
+		__load_psw_mask(PSW_BASE_BITS | PSW_MASK_EXT |
+				PSW_MASK_WAIT | PSW_DEFAULT_KEY);
+		local_irq_disable();
+		barrier();
+
+		response = sccb->response_code;
+
+		if (response == 0x10)
+			break;
+
+		if (response != 0x1f0 || command == SCLP_CMDW_READ_SCP_INFO)
+			break;
+
+		command = SCLP_CMDW_READ_SCP_INFO;
+	}
+out:
+	__ctl_clear_bit(0, 9); /* disable service signal subclass mask */
+}