[S390] add mini sclp driver

This adds a mini sclp device driver for very early use. The primary
and probably only use will be to emit a message to the console if the
cpu doesn't provide the minimum required capabilities to run the kernel.
After printing the message a disabled wait will be loaded and the
machine stops operating.
Printing the message is also part of this patch.

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

3 files changed, 342 insertions, 5 deletions

diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 228e3105ded7..0657de7944fe 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -22,7 +22,7 @@ CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
 obj-y	:=  bitmap.o traps.o time.o process.o base.o early.o setup.o \
 	    processor.o sys_s390.o ptrace.o signal.o cpcmd.o ebcdic.o \
 	    s390_ext.o debug.o irq.o ipl.o dis.o diag.o mem_detect.o \
-	    vdso.o vtime.o sysinfo.o nmi.o
+	    vdso.o vtime.o sysinfo.o nmi.o sclp.o
 
 obj-y	+= $(if $(CONFIG_64BIT),entry64.o,entry.o)
 obj-y	+= $(if $(CONFIG_64BIT),reipl64.o,reipl.o)
diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index bf8cf1caeffc..6d227413cbe7 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -1,7 +1,5 @@
 /*
- *  arch/s390/kernel/head.S
- *
- * Copyright (C) IBM Corp. 1999,2006
+ * Copyright IBM Corp. 1999,2009
  *
  *    Author(s): Hartmut Penner <hp@de.ibm.com>
  *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
@@ -494,7 +492,19 @@ startup:basr	%r13,0			# get base
 	n	%r0,2f+12-.LPG0(%r13)
 	cl	%r0,2f+12-.LPG0(%r13)
 	je	3f
-1:	lpsw	2f-.LPG0(13)		# machine type not good enough, crash
+1:	l	%r15,.Lstack-.LPG0(%r13)
+	ahi	%r15,1<<(PAGE_SHIFT+THREAD_ORDER) # init_task_union+THREAD_SIZE
+	ahi	%r15,-96
+	la	%r2,.Lals_string-.LPG0(%r13)
+	l	%r3,.Lsclp_print-.LPG0(%r13)
+	basr	%r14,%r3
+	lpsw	2f-.LPG0(%r13)		# machine type not good enough, crash
+.Lals_string:
+	.asciz	"The Linux kernel requires more recent processor hardware"
+.Lsclp_print:
+	.long	_sclp_print_early
+.Lstack:
+	.long	init_thread_union
 	.align 16
 2:	.long	0x000a0000,0x8badcccc
 #if defined(CONFIG_64BIT)
diff --git a/arch/s390/kernel/sclp.S b/arch/s390/kernel/sclp.S
new file mode 100644
index 000000000000..20639dfe0c42
--- /dev/null
+++ b/arch/s390/kernel/sclp.S
@@ -0,0 +1,327 @@
+/*
+ * Mini SCLP driver.
+ *
+ * Copyright IBM Corp. 2004,2009
+ *
+ *   Author(s):	Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>,
+ *		Heiko Carstens <heiko.carstens@de.ibm.com>,
+ *
+ */
+
+LC_EXT_NEW_PSW		= 0x58			# addr of ext int handler
+LC_EXT_INT_PARAM	= 0x80			# addr of ext int parameter
+LC_EXT_INT_CODE		= 0x86			# addr of ext int code
+
+#
+# Subroutine which waits synchronously until either an external interruption
+# or a timeout occurs.
+#
+# Parameters:
+#   R2	= 0 for no timeout, non-zero for timeout in (approximated) seconds
+#
+# Returns:
+#   R2	= 0 on interrupt, 2 on timeout
+#   R3	= external interruption parameter if R2=0
+#
+
+.section ".init.text","ax"
+
+_sclp_wait_int:
+	stm	%r6,%r15,24(%r15)		# save registers
+	basr	%r13,0				# get base register
+.LbaseS1:
+	ahi	%r15,-96			# create stack frame
+	la	%r8,LC_EXT_NEW_PSW		# register int handler
+	mvc	.LoldpswS1-.LbaseS1(8,%r13),0(%r8)
+	mvc	0(8,%r8),.LextpswS1-.LbaseS1(%r13)
+	lhi	%r6,0x0200			# cr mask for ext int (cr0.54)
+	ltr	%r2,%r2
+	jz	.LsetctS1
+	ahi	%r6,0x0800			# cr mask for clock int (cr0.52)
+	stck	.LtimeS1-.LbaseS1(%r13)		# initiate timeout
+	al	%r2,.LtimeS1-.LbaseS1(%r13)
+	st	%r2,.LtimeS1-.LbaseS1(%r13)
+	sckc	.LtimeS1-.LbaseS1(%r13)
+
+.LsetctS1:
+	stctl	%c0,%c0,.LctlS1-.LbaseS1(%r13)	# enable required interrupts
+	l	%r0,.LctlS1-.LbaseS1(%r13)
+	lhi	%r1,~(0x200 | 0x800)		# clear old values
+	nr	%r1,%r0
+	or	%r1,%r6				# set new value
+	st	%r1,.LctlS1-.LbaseS1(%r13)
+	lctl	%c0,%c0,.LctlS1-.LbaseS1(%r13)
+	st	%r0,.LctlS1-.LbaseS1(%r13)
+	lhi	%r2,2				# return code for timeout
+.LloopS1:
+	lpsw	.LwaitpswS1-.LbaseS1(%r13)	# wait until interrupt
+.LwaitS1:
+	lh	%r7,LC_EXT_INT_CODE
+	chi	%r7,0x1004			# timeout?
+	je	.LtimeoutS1
+	chi	%r7,0x2401			# service int?
+	jne	.LloopS1
+	sr	%r2,%r2
+	l	%r3,LC_EXT_INT_PARAM
+.LtimeoutS1:
+	lctl	%c0,%c0,.LctlS1-.LbaseS1(%r13)	# restore interrupt setting
+	# restore old handler
+	mvc	0(8,%r8),.LoldpswS1-.LbaseS1(%r13)
+	lm	%r6,%r15,120(%r15)		# restore registers
+	br	%r14				# return to caller
+
+	.align	8
+.LoldpswS1:
+	.long	0, 0				# old ext int PSW
+.LextpswS1:
+	.long	0x00080000, 0x80000000+.LwaitS1	# PSW to handle ext int
+.LwaitpswS1:
+	.long	0x010a0000, 0x00000000+.LloopS1	# PSW to wait for ext int
+.LtimeS1:
+	.quad	0				# current time
+.LctlS1:
+	.long	0				# CT0 contents
+
+#
+# Subroutine to synchronously issue a service call.
+#
+# Parameters:
+#   R2	= command word
+#   R3	= sccb address
+#
+# Returns:
+#   R2	= 0 on success, 1 on failure
+#   R3	= sccb response code if R2 = 0
+#
+
+_sclp_servc:
+	stm	%r6,%r15,24(%r15)		# save registers
+	ahi	%r15,-96			# create stack frame
+	lr	%r6,%r2				# save command word
+	lr	%r7,%r3				# save sccb address
+.LretryS2:
+	lhi	%r2,1				# error return code
+	.insn	rre,0xb2200000,%r6,%r7		# servc
+	brc	1,.LendS2			# exit if not operational
+	brc	8,.LnotbusyS2			# go on if not busy
+	sr	%r2,%r2				# wait until no longer busy
+	bras	%r14,_sclp_wait_int
+	j	.LretryS2			# retry
+.LnotbusyS2:
+	sr	%r2,%r2				# wait until result
+	bras	%r14,_sclp_wait_int
+	sr	%r2,%r2
+	lh	%r3,6(%r7)
+.LendS2:
+	lm	%r6,%r15,120(%r15)		# restore registers
+	br	%r14
+
+#
+# Subroutine to set up the SCLP interface.
+#
+# Parameters:
+#   R2	= 0 to activate, non-zero to deactivate
+#
+# Returns:
+#   R2	= 0 on success, non-zero on failure
+#
+
+_sclp_setup:
+	stm	%r6,%r15,24(%r15)		# save registers
+	ahi	%r15,-96			# create stack frame
+	basr	%r13,0				# get base register
+.LbaseS3:
+	l	%r6,.LsccbS0-.LbaseS3(%r13)	# prepare init mask sccb
+	mvc	0(.LinitendS3-.LinitsccbS3,%r6),.LinitsccbS3-.LbaseS3(%r13)
+	ltr	%r2,%r2				# initialization?
+	jz	.LdoinitS3			# go ahead
+	# clear masks
+	xc	.LinitmaskS3-.LinitsccbS3(8,%r6),.LinitmaskS3-.LinitsccbS3(%r6)
+.LdoinitS3:
+	l	%r2,.LwritemaskS3-.LbaseS3(%r13)# get command word
+	lr	%r3,%r6				# get sccb address
+	bras	%r14,_sclp_servc		# issue service call
+	ltr	%r2,%r2				# servc successful?
+	jnz	.LerrorS3
+	chi	%r3,0x20			# write mask successful?
+	jne	.LerrorS3
+	# check masks
+	la	%r2,.LinitmaskS3-.LinitsccbS3(%r6)
+	l	%r1,0(%r2)			# receive mask ok?
+	n	%r1,12(%r2)
+	cl	%r1,0(%r2)
+	jne	.LerrorS3
+	l	%r1,4(%r2)			# send mask ok?
+	n	%r1,8(%r2)
+	cl	%r1,4(%r2)
+	sr	%r2,%r2
+	je	.LendS3
+.LerrorS3:
+	lhi	%r2,1				# error return code
+.LendS3:
+	lm	%r6,%r15,120(%r15)		# restore registers
+	br	%r14
+.LwritemaskS3:
+	.long	0x00780005			# SCLP command for write mask
+.LinitsccbS3:
+	.word	.LinitendS3-.LinitsccbS3
+	.byte	0,0,0,0
+	.word	0
+	.word	0
+	.word	4
+.LinitmaskS3:
+	.long	0x80000000
+	.long	0x40000000
+	.long	0
+	.long	0
+.LinitendS3:
+
+#
+# Subroutine which prints a given text to the SCLP console.
+#
+# Parameters:
+#   R2	= address of nil-terminated ASCII text
+#
+# Returns:
+#   R2	= 0 on success, 1 on failure
+#
+
+_sclp_print:
+	stm	%r6,%r15,24(%r15)		# save registers
+	ahi	%r15,-96			# create stack frame
+	basr	%r13,0				# get base register
+.LbaseS4:
+	l	%r8,.LsccbS0-.LbaseS4(%r13)	# prepare write data sccb
+	mvc	0(.LmtoS4-.LwritesccbS4,%r8),.LwritesccbS4-.LbaseS4(%r13)
+	la	%r7,.LmtoS4-.LwritesccbS4(%r8)	# current mto addr
+	sr	%r0,%r0
+	l	%r10,.Lascebc-.LbaseS4(%r13)	# address of translation table
+.LinitmtoS4:
+	# initialize mto
+	mvc	0(.LmtoendS4-.LmtoS4,%r7),.LmtoS4-.LbaseS4(%r13)
+	lhi	%r6,.LmtoendS4-.LmtoS4		# current mto length
+.LloopS4:
+	ic	%r0,0(%r2)			# get character
+	ahi	%r2,1
+	ltr	%r0,%r0				# end of string?
+	jz	.LfinalizemtoS4
+	chi	%r0,0x15			# end of line (NL)?
+	jz	.LfinalizemtoS4
+	stc	%r0,0(%r6,%r7)			# copy to mto
+	la	%r11,0(%r6,%r7)
+	tr	0(1,%r11),0(%r10)		# translate to EBCDIC
+	ahi	%r6,1
+	j	.LloopS4
+.LfinalizemtoS4:
+	sth	%r6,0(%r7)			# update mto length
+	lh	%r9,.LmdbS4-.LwritesccbS4(%r8)	# update mdb length
+	ar	%r9,%r6
+	sth	%r9,.LmdbS4-.LwritesccbS4(%r8)
+	lh	%r9,.LevbufS4-.LwritesccbS4(%r8)# update evbuf length
+	ar	%r9,%r6
+	sth	%r9,.LevbufS4-.LwritesccbS4(%r8)
+	lh	%r9,0(%r8)			# update sccb length
+	ar	%r9,%r6
+	sth	%r9,0(%r8)
+	ar	%r7,%r6				# update current mto adress
+	ltr	%r0,%r0				# more characters?
+	jnz	.LinitmtoS4
+	l	%r2,.LwritedataS4-.LbaseS4(%r13)# write data
+	lr	%r3,%r8
+	bras	%r14,_sclp_servc
+	ltr	%r2,%r2				# servc successful?
+	jnz	.LendS4
+	chi	%r3,0x20			# write data successful?
+	je	.LendS4
+	lhi	%r2,1				# error return code
+.LendS4:
+	lm	%r6,%r15,120(%r15)		# restore registers
+	br	%r14
+
+#
+# Function which prints a given text to the SCLP console.
+#
+# Parameters:
+#   R2	= address of nil-terminated ASCII text
+#
+# Returns:
+#   R2	= 0 on success, 1 on failure
+#
+
+	.globl _sclp_print_early
+_sclp_print_early:
+	stm	%r6,%r15,24(%r15)		# save registers
+	ahi	%r15,-96			# create stack frame
+	lr	%r10,%r2			# save string pointer
+	lhi	%r2,0
+	bras	%r14,_sclp_setup		# enable console
+	ltr	%r2,%r2
+	jnz	.LendS5
+	lr	%r2,%r10
+	bras	%r14,_sclp_print		# print string
+	ltr	%r2,%r2
+	jnz	.LendS5
+	lhi	%r2,1
+	bras	%r14,_sclp_setup		# disable console
+.LendS5:
+	lm	%r6,%r15,120(%r15)		# restore registers
+	br	%r14
+
+.LwritedataS4:
+	.long	0x00760005			# SCLP command for write data
+.LwritesccbS4:
+	# sccb
+	.word	.LmtoS4-.LwritesccbS4
+	.byte	0
+	.byte	0,0,0
+	.word	0
+
+	# evbuf
+.LevbufS4:
+	.word	.LmtoS4-.LevbufS4
+	.byte	0x02
+	.byte	0
+	.word	0
+
+.LmdbS4:
+	# mdb
+	.word	.LmtoS4-.LmdbS4
+	.word	1
+	.long	0xd4c4c240
+	.long	1
+
+	# go
+.LgoS4:
+	.word	.LmtoS4-.LgoS4
+	.word	1
+	.long	0
+	.byte	0,0,0,0,0,0,0,0
+	.byte	0,0,0
+	.byte	0
+	.byte	0,0,0,0,0,0,0
+	.byte	0
+	.word	0
+	.byte	0,0,0,0,0,0,0,0,0,0
+	.byte	0,0,0,0,0,0,0,0
+	.byte	0,0,0,0,0,0,0,0
+
+.LmtoS4:
+	.word	.LmtoendS4-.LmtoS4
+	.word	4
+	.word	0x1000
+	.byte	0
+	.byte	0,0,0
+.LmtoendS4:
+
+	# Global constants
+.LsccbS0:
+	.long	_sclp_work_area
+.Lascebc:
+	.long	_ascebc
+.previous
+
+.section ".init.data","a"
+	.balign 4096
+_sclp_work_area:
+	.fill	4096
+.previous