[kvm-unit-tests PATCH v2 08/14] powerpc/ppc64: add HV putchar

[Andrew Jones <drjones@redhat.com>]

Add the hvcall for putchar and use it in puts. That, along with a
couple more lines in start to prepare for C code, and a branch to
main(), gets us "hello world". Run with

qemu-system-ppc64 -M pseries            \
        -bios powerpc/boot_rom.bin      \
        -display none -serial stdio     \
        -kernel powerpc/selftest.elf

(We're still not relocating yet, that comes in a later patch. Thus,
 testing hello-world at this point requires a hacked QEMU and linking
 the unit test at QEMU's kernel load address.)

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 lib/powerpc/io.c        | 15 +++++++++++++--
 powerpc/Makefile.common |  1 +
 powerpc/cstart64.S      | 26 ++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/lib/powerpc/io.c b/lib/powerpc/io.c
index 0af45742fc900..5e1fa8dd96ab6 100644
--- a/lib/powerpc/io.c
+++ b/lib/powerpc/io.c
@@ -6,15 +6,26 @@
  * This work is licensed under the terms of the GNU LGPL, version 2.
  */
 #include <libcflat.h>
+#include <asm/spinlock.h>
+
+extern void halt(int code);
+extern void putchar(int c);
+
+static struct spinlock uart_lock;
 
 void io_init(void)
 {
 }
 
-void puts(const char *s __unused)
+void puts(const char *s)
 {
+	spin_lock(&uart_lock);
+	while (*s)
+		putchar(*s++);
+	spin_unlock(&uart_lock);
 }
 
-void exit(int code __unused)
+void exit(int code)
 {
+	halt(code);
 }
diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common
index cc1a521f1a269..89ad7a1907ac9 100644
--- a/powerpc/Makefile.common
+++ b/powerpc/Makefile.common
@@ -21,6 +21,7 @@ CFLAGS += -ffreestanding
 CFLAGS += -Wextra
 CFLAGS += -O2
 CFLAGS += -I lib -I lib/libfdt
+CFLAGS += -Wa,-mregnames
 
 asm-offsets = lib/$(ARCH)/asm-offsets.h
 include scripts/asm-offsets.mak
diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S
index 4692f2d9d057e..466ec800313b3 100644
--- a/powerpc/cstart64.S
+++ b/powerpc/cstart64.S
@@ -6,14 +6,40 @@
  * This work is licensed under the terms of the GNU LGPL, version 2.
  */
 
+#define H_PUT_TERM_CHAR		0x58
+
+#define LOAD_REG_IMMEDIATE(reg,expr)		\
+	lis	reg,(expr)@highest;		\
+	ori	reg,reg,(expr)@higher;		\
+	rldicr	reg,reg,32,31;			\
+	oris	reg,reg,(expr)@h;		\
+	ori	reg,reg,(expr)@l;
+
+#define LOAD_REG_ADDR(reg,name)			\
+	ld	reg,name@got(r2)
+
 .section .init
 
 .globl start
 start:
+	LOAD_REG_IMMEDIATE(r1, stackptr)
+	LOAD_REG_IMMEDIATE(r2, tocptr)
+	bl	main
+	bl	exit
 	b	halt
 
 .text
+.align 3
 
 .globl halt
 halt:
 1:	b	1b
+
+.globl putchar
+putchar:
+	sldi	r6, r3, 56
+	li	r3, H_PUT_TERM_CHAR
+	li	r4, 0	/* vty-reg 0 means to use the default vty */
+	li	r5, 1	/* sending just 1 byte */
+	sc	1
+	blr
-- 
2.4.3