OMAP: CLK: CLKSRC: Add suspend resume hooks

Add the save and restore for clksrc as part of suspend and resume
so that it saves the counter value and restores. This is needed in
modes like rtc+ddr in self-refresh not doing this stalls the time.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/timer.c

@@ -71,6 +71,9 @@ static struct clock_event_device clockevent_gpt;
 /* Clockevent hwmod for am335x and am437x suspend */
 static struct omap_hwmod *clockevent_gpt_hwmod;
 
+/* Clockesource hwmod for am437x suspend */
+static struct omap_hwmod *clocksource_gpt_hwmod;
+
 #ifdef CONFIG_SOC_HAS_REALTIME_COUNTER
 static unsigned long arch_timer_freq;
 
@@ -442,6 +445,26 @@ static int __init __maybe_unused omap2_sync32k_clocksource_init(void)
 	return ret;
 }
 
+static unsigned int omap2_gptimer_clksrc_load;
+
+static void omap2_gptimer_clksrc_suspend(struct clocksource *unused)
+{
+	omap2_gptimer_clksrc_load =
+		__omap_dm_timer_read_counter(&clksrc, OMAP_TIMER_NONPOSTED);
+
+	omap_hwmod_idle(clocksource_gpt_hwmod);
+}
+
+static void omap2_gptimer_clksrc_resume(struct clocksource *unused)
+{
+	omap_hwmod_enable(clocksource_gpt_hwmod);
+
+	__omap_dm_timer_load_start(&clksrc,
+				   OMAP_TIMER_CTRL_ST | OMAP_TIMER_CTRL_AR,
+				   omap2_gptimer_clksrc_load,
+				   OMAP_TIMER_NONPOSTED);
+}
+
 static void __init omap2_gptimer_clocksource_init(int gptimer_id,
 						  const char *fck_source,
 						  const char *property)
@@ -454,6 +477,15 @@ static void __init omap2_gptimer_clocksource_init(int gptimer_id,
 	res = omap_dm_timer_init_one(&clksrc, fck_source, property,
 				     &clocksource_gpt.name,
 				     OMAP_TIMER_NONPOSTED);
+
+	if (soc_is_am43xx()) {
+		clocksource_gpt.suspend = omap2_gptimer_clksrc_suspend;
+		clocksource_gpt.resume = omap2_gptimer_clksrc_resume;
+
+		clocksource_gpt_hwmod =
+			omap_hwmod_lookup(clocksource_gpt.name);
+	}
+
 	BUG_ON(res);
 
 	__omap_dm_timer_load_start(&clksrc,