sparc64: add hot-patched and inlined get_tick()

Add the new get_tick() function that is hot-patched during boot based on
processor we are booting on.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 60 insertions, 0 deletions

diff --git a/arch/sparc/include/asm/timer_64.h b/arch/sparc/include/asm/timer_64.h
index 61d07251792c..51bc3bc54bfe 100644
--- a/arch/sparc/include/asm/timer_64.h
+++ b/arch/sparc/include/asm/timer_64.h
@@ -34,4 +34,64 @@ unsigned long sparc64_get_clock_tick(unsigned int cpu);
 void setup_sparc64_timer(void);
 void __init time_init(void);
 
+#define TICK_PRIV_BIT		BIT(63)
+#define TICKCMP_IRQ_BIT		BIT(63)
+
+#define HBIRD_STICKCMP_ADDR	0x1fe0000f060UL
+#define HBIRD_STICK_ADDR	0x1fe0000f070UL
+
+#define GET_TICK_NINSTR		13
+struct get_tick_patch {
+	unsigned int	addr;
+	unsigned int	tick[GET_TICK_NINSTR];
+	unsigned int	stick[GET_TICK_NINSTR];
+};
+
+extern struct get_tick_patch __get_tick_patch;
+extern struct get_tick_patch __get_tick_patch_end;
+
+static inline unsigned long get_tick(void)
+{
+	unsigned long tick, tmp1, tmp2;
+
+	__asm__ __volatile__(
+	/* read hbtick 13 instructions */
+	"661:\n"
+	"	mov	0x1fe, %1\n"
+	"	sllx	%1, 0x20, %1\n"
+	"	sethi	%%hi(0xf000), %2\n"
+	"	or	%2, 0x70, %2\n"
+	"	or	%1, %2, %1\n"	/* %1 = HBIRD_STICK_ADDR */
+	"	add	%1, 8, %2\n"
+	"	ldxa	[%2]%3, %0\n"
+	"	ldxa	[%1]%3, %1\n"
+	"	ldxa	[%2]%3, %2\n"
+	"	sub	%2, %0, %0\n"	/* don't modify %xcc */
+	"	brnz,pn	%0, 661b\n"	/* restart to save one register */
+	"	 sllx	%2, 32, %2\n"
+	"	or	%2, %1, %0\n"
+	/* Common/not patched code */
+	"	sllx	%0, 1, %0\n"
+	"	srlx	%0, 1, %0\n"	/* Clear TICK_PRIV_BIT */
+	/* Beginning of patch section */
+	"	.section .get_tick_patch, \"ax\"\n"
+	"	.word	661b\n"
+	/* read tick 2 instructions and 11 skipped */
+	"	ba	1f\n"
+	"	 rd	%%tick, %0\n"
+	"	.skip	4 * (%4 - 2)\n"
+	"1:\n"
+	/* read stick 2 instructions and 11 skipped */
+	"	ba	1f\n"
+	"	 rd	%%asr24, %0\n"
+	"	.skip	4 * (%4 - 2)\n"
+	"1:\n"
+	/* End of patch section */
+	"	.previous\n"
+	: "=&r" (tick), "=&r" (tmp1), "=&r" (tmp2)
+	: "i" (ASI_PHYS_BYPASS_EC_E), "i" (GET_TICK_NINSTR));
+
+	return tick;
+}
+
 #endif /* _SPARC64_TIMER_H */