ARCv2: clocksource: Introduce 64bit local RTC counter

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

3 files changed, 62 insertions, 2 deletions

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 974ed9058018..f09e03a0d604 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -372,6 +372,11 @@ config ARC_HAS_LL64
           dest operands with 2 possible source operands.
         default y
 
+config ARC_HAS_RTC
+        bool "Local 64-bit r/o cycle counter"
+        default n
+        depends on !SMP
+
 config ARC_NUMBER_OF_INTERRUPTS
         int "Number of interrupts"
         range 8 240
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index ca71cef4bafd..a3d186211ed3 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -200,9 +200,11 @@ 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\nISA Extn\t: ",
+        n += scnprintf(buf + n, len - n, "Timers\t\t: %s%s%s%s\nISA Extn\t: ",
                        IS_AVAIL1(cpu->timers.t0, "Timer0 "),
-                       IS_AVAIL1(cpu->timers.t1, "Timer1 "));
+                       IS_AVAIL1(cpu->timers.t1, "Timer1 "),
+                       IS_AVAIL2(cpu->timers.rtc, "64-bit RTC ",
+                                 CONFIG_ARC_HAS_RTC));
 
         n += i = scnprintf(buf + n, len - n, "%s%s%s%s%s",
                            IS_AVAIL2(atomic, "atomic ", CONFIG_ARC_HAS_LLSC),
@@ -290,6 +292,9 @@ static void arc_chk_core_config(void)
         if (!cpu->timers.t1)
                 panic("Timer1 is not present!\n");
 
+        if (IS_ENABLED(CONFIG_ARC_HAS_RTC) && !cpu->timers.rtc)
+                panic("RTC is not present\n");
+
 #ifdef CONFIG_ARC_HAS_DCCM
         /*
          * DCCM can be arbit placed in hardware.
diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c
index 71493f75ae6b..da495478a40b 100644
--- a/arch/arc/kernel/time.c
+++ b/arch/arc/kernel/time.c
@@ -60,6 +60,54 @@
 
 /********** Clock Source Device *********/
 
+#ifdef CONFIG_ARC_HAS_RTC
+
+#define AUX_RTC_CTRL    0x103
+#define AUX_RTC_LOW     0x104
+#define AUX_RTC_HIGH    0x105
+
+int arc_counter_setup(void)
+{
+        write_aux_reg(AUX_RTC_CTRL, 1);
+
+        /* Not usable in SMP */
+        return !IS_ENABLED(CONFIG_SMP);
+}
+
+static cycle_t arc_counter_read(struct clocksource *cs)
+{
+        unsigned long status;
+        union {
+#ifdef CONFIG_CPU_BIG_ENDIAN
+                struct { u32 high, low; };
+#else
+                struct { u32 low, high; };
+#endif
+                cycle_t  full;
+        } stamp;
+
+
+        __asm__ __volatile(
+        "1:                                             \n"
+        "       lr              %0, [AUX_RTC_LOW]       \n"
+        "       lr              %1, [AUX_RTC_HIGH]      \n"
+        "       lr              %2, [AUX_RTC_CTRL]      \n"
+        "       bbit0.nt        %2, 31, 1b              \n"
+        : "=r" (stamp.low), "=r" (stamp.high), "=r" (status));
+
+        return stamp.full;
+}
+
+static struct clocksource arc_counter = {
+        .name   = "ARCv2 RTC",
+        .rating = 350,
+        .read   = arc_counter_read,
+        .mask   = CLOCKSOURCE_MASK(64),
+        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#else /* !CONFIG_ARC_HAS_RTC */
+
 /*
  * set 32bit TIMER1 to keep counting monotonically and wraparound
  */
@@ -86,6 +134,8 @@ static struct clocksource arc_counter = {
         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
+#endif
+
 /********** Clock Event Device *********/
 
 /*