ARC: RIP broken 64bit RTSC

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/Kconfig

@@ -311,11 +311,6 @@ config ARC_HAS_SWAPE
 	bool "Insn: SWAPE (endian-swap)"
 	default y
 
-config ARC_HAS_RTSC
-	bool "Insn: RTSC (64-bit r/o cycle counter)"
-	default y
-	depends on !SMP
-
 endmenu   # "ARC CPU Configuration"
 
 config LINUX_LINK_BASE

arch/arc/Makefile

@@ -33,7 +33,7 @@ cflags-$(atleast_gcc44)			+= -fsection-anchors
 
 cflags-$(CONFIG_ARC_HAS_LLSC)		+= -mlock
 cflags-$(CONFIG_ARC_HAS_SWAPE)		+= -mswape
-cflags-$(CONFIG_ARC_HAS_RTSC)		+= -mrtsc
+
 cflags-$(CONFIG_ARC_DW2_UNWIND)		+= -fasynchronous-unwind-tables
 
 # By default gcc 4.8 generates dwarf4 which kernel unwinder can't grok

arch/arc/configs/nsim_700_defconfig

@@ -23,7 +23,6 @@ CONFIG_MODULES=y
 # CONFIG_IOSCHED_DEADLINE is not set
 # CONFIG_IOSCHED_CFQ is not set
 CONFIG_ARC_PLAT_FPGA_LEGACY=y
-# CONFIG_ARC_HAS_RTSC is not set
 CONFIG_ARC_BUILTIN_DTB_NAME="angel4"
 CONFIG_PREEMPT=y
 # CONFIG_COMPACTION is not set

arch/arc/configs/nsimosci_defconfig

@@ -24,7 +24,6 @@ CONFIG_MODULES=y
 # CONFIG_IOSCHED_DEADLINE is not set
 # CONFIG_IOSCHED_CFQ is not set
 CONFIG_ARC_PLAT_FPGA_LEGACY=y
-# CONFIG_ARC_HAS_RTSC is not set
 CONFIG_ARC_BUILTIN_DTB_NAME="nsimosci"
 # CONFIG_COMPACTION is not set
 CONFIG_NET=y

arch/arc/configs/tb10x_defconfig

@@ -26,7 +26,6 @@ CONFIG_MODULE_UNLOAD=y
 # CONFIG_BLOCK is not set
 CONFIG_ARC_PLAT_TB10X=y
 CONFIG_ARC_CACHE_LINE_SHIFT=5
-# CONFIG_ARC_HAS_RTSC is not set
 CONFIG_ARC_STACK_NONEXEC=y
 CONFIG_HZ=250
 CONFIG_ARC_BUILTIN_DTB_NAME="abilis_tb100_dvk"

arch/arc/kernel/setup.c

@@ -180,10 +180,9 @@ static char *arc_cpu_mumbojumbo(int cpu_id, char *buf, int len)
 		       (unsigned int)(arc_get_core_freq() / 1000000),
 		       (unsigned int)(arc_get_core_freq() / 10000) % 100);
 
-	n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s\nISA Extn\t: ",
+	n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s\nISA Extn\t: ",
 		       IS_AVAIL1(cpu->timers.t0, "Timer0 "),
-		       IS_AVAIL1(cpu->timers.t1, "Timer1 "),
-		       IS_AVAIL2(cpu->timers.rtsc, "64-bit RTSC ", CONFIG_ARC_HAS_RTSC));
+		       IS_AVAIL1(cpu->timers.t1, "Timer1 "));
 
 	n += i = scnprintf(buf + n, len - n, "%s%s",
 			   IS_AVAIL2(atomic, "atomic ", CONFIG_ARC_HAS_LLSC));
@@ -254,9 +253,6 @@ static void arc_chk_core_config(void)
 	if (!cpu->timers.t1)
 		panic("Timer1 is not present!\n");
 
-	if (IS_ENABLED(CONFIG_ARC_HAS_RTSC) && !cpu->timers.rtsc)
-		panic("RTSC is not present\n");
-
 #ifdef CONFIG_ARC_HAS_DCCM
 	/*
 	 * DCCM can be arbit placed in hardware.

arch/arc/kernel/time.c

@@ -26,6 +26,7 @@
  * while TIMER1 for free running (clocksource)
  *
  * Newer ARC700 cores have 64bit clk fetching RTSC insn, preferred over TIMER1
+ * which however is currently broken
  */
 
 #include <linux/spinlock.h>
@@ -59,52 +60,6 @@
 
 /********** Clock Source Device *********/
 
-#ifdef CONFIG_ARC_HAS_RTSC
-
-int arc_counter_setup(void)
-{
-	/*
-	 * For SMP this needs to be 0. However Kconfig glue doesn't
-	 * enable this option for SMP configs
-	 */
-	return 1;
-}
-
-static cycle_t arc_counter_read(struct clocksource *cs)
-{
-	unsigned long flags;
-	union {
-#ifdef CONFIG_CPU_BIG_ENDIAN
-		struct { u32 high, low; };
-#else
-		struct { u32 low, high; };
-#endif
-		cycle_t  full;
-	} stamp;
-
-	flags = arch_local_irq_save();
-
-	__asm__ __volatile(
-	"	.extCoreRegister tsch, 58,  r, cannot_shortcut	\n"
-	"	rtsc %0, 0	\n"
-	"	mov  %1, 0	\n"
-	: "=r" (stamp.low), "=r" (stamp.high));
-
-	arch_local_irq_restore(flags);
-
-	return stamp.full;
-}
-
-static struct clocksource arc_counter = {
-	.name   = "ARC RTSC",
-	.rating = 300,
-	.read   = arc_counter_read,
-	.mask   = CLOCKSOURCE_MASK(32),
-	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
-};
-
-#else /* !CONFIG_ARC_HAS_RTSC */
-
 static bool is_usable_as_clocksource(void)
 {
 #ifdef CONFIG_SMP
@@ -139,8 +94,6 @@ static struct clocksource arc_counter = {
 	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-#endif
-
 /********** Clock Event Device *********/
 
 /*