parisc: use legacy_timer_tick

parisc has selected CONFIG_GENERIC_CLOCKEVENTS since commit 43b1f6abd5
("parisc: Switch to generic sched_clock implementation"), but does not
appear to actually be using it, and instead calls the low-level
timekeeping functions directly.

Remove the GENERIC_CLOCKEVENTS select again, and instead convert to
the newly added legacy_timer_tick() helper.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Documentation/features/time/clockevents/arch-support.txt

@@ -21,7 +21,7 @@
     |       nds32: |  ok  |
     |       nios2: |  ok  |
     |    openrisc: |  ok  |
-    |      parisc: |  ok  |
+    |      parisc: | TODO |
     |     powerpc: |  ok  |
     |       riscv: |  ok  |
     |        s390: |  ok  |

arch/parisc/Kconfig

@@ -52,7 +52,7 @@ config PARISC
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select GENERIC_SCHED_CLOCK
 	select HAVE_UNSTABLE_SCHED_CLOCK if SMP
-	select GENERIC_CLOCKEVENTS
+	select LEGACY_TIMER_TICK
 	select CPU_NO_EFFICIENT_FFS
 	select NEED_DMA_MAP_STATE
 	select NEED_SG_DMA_LENGTH

arch/parisc/kernel/time.c

@@ -70,8 +70,6 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
 	/* gcc can optimize for "read-only" case with a local clocktick */
 	unsigned long cpt = clocktick;
 
-	profile_tick(CPU_PROFILING);
-
 	/* Initialize next_tick to the old expected tick time. */
 	next_tick = cpuinfo->it_value;
 
@@ -86,10 +84,9 @@ irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
 	cpuinfo->it_value = next_tick;
 
 	/* Go do system house keeping. */
-	if (cpu == 0)
-		xtime_update(ticks_elapsed);
-
-	update_process_times(user_mode(get_irq_regs()));
+	if (cpu != 0)
+		ticks_elapsed = 0;
+	legacy_timer_tick(ticks_elapsed);
 
 	/* Skip clockticks on purpose if we know we would miss those.
 	 * The new CR16 must be "later" than current CR16 otherwise