PM debug: allow configurable wakeup from suspend on OMAP GPtimer

Using debugfs, export a configurable wakeup timer to be used to
wakeup system from suspend.

If a non-zero value is written to
/debug/pm_debug/wakeup_timer_seconds, A timer wakeup event will wake
the system and resume after the configured number of seconds.
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-omap2/pm-debug.c

@@ -596,6 +596,8 @@ static int __init pm_dbg_init(void)
 				   &enable_off_mode, &pm_dbg_option_fops);
 	(void) debugfs_create_file("sleep_while_idle", S_IRUGO | S_IWUGO, d,
 				   &sleep_while_idle, &pm_dbg_option_fops);
+	(void) debugfs_create_file("wakeup_timer_seconds", S_IRUGO | S_IWUGO, d,
+				   &wakeup_timer_seconds, &pm_dbg_option_fops);
 	pm_dbg_init_done = 1;
 
 	return 0;

arch/arm/mach-omap2/pm.h

@@ -22,6 +22,9 @@ extern void omap3_pm_off_mode_enable(int);
 extern int omap3_pm_get_suspend_state(struct powerdomain *pwrdm);
 extern int omap3_pm_set_suspend_state(struct powerdomain *pwrdm, int state);
 
+extern u32 wakeup_timer_seconds;
+extern struct omap_dm_timer *gptimer_wakeup;
+
 #ifdef CONFIG_PM_DEBUG
 extern void omap2_pm_dump(int mode, int resume, unsigned int us);
 extern int omap2_pm_debug;

arch/arm/mach-omap2/pm34xx.c

@@ -36,6 +36,7 @@
 #include <plat/prcm.h>
 #include <plat/gpmc.h>
 #include <plat/dma.h>
+#include <plat/dmtimer.h>
 
 #include <asm/tlbflush.h>
 
@@ -60,6 +61,7 @@
 
 u32 enable_off_mode;
 u32 sleep_while_idle;
+u32 wakeup_timer_seconds;
 
 struct power_state {
 	struct powerdomain *pwrdm;
@@ -535,6 +537,22 @@ out:
 #ifdef CONFIG_SUSPEND
 static suspend_state_t suspend_state;
 
+static void omap2_pm_wakeup_on_timer(u32 seconds)
+{
+	u32 tick_rate, cycles;
+
+	if (!seconds)
+		return;
+
+	tick_rate = clk_get_rate(omap_dm_timer_get_fclk(gptimer_wakeup));
+	cycles = tick_rate * seconds;
+	omap_dm_timer_stop(gptimer_wakeup);
+	omap_dm_timer_set_load_start(gptimer_wakeup, 0, 0xffffffff - cycles);
+
+	pr_info("PM: Resume timer in %d secs (%d ticks at %d ticks/sec.)\n",
+		seconds, cycles, tick_rate);
+}
+
 static int omap3_pm_prepare(void)
 {
 	disable_hlt();
@@ -546,6 +564,9 @@ static int omap3_pm_suspend(void)
 	struct power_state *pwrst;
 	int state, ret = 0;
 
+	if (wakeup_timer_seconds)
+		omap2_pm_wakeup_on_timer(wakeup_timer_seconds);
+
 	/* Read current next_pwrsts */
 	list_for_each_entry(pwrst, &pwrst_list, node)
 		pwrst->saved_state = pwrdm_read_next_pwrst(pwrst->pwrdm);

arch/arm/mach-omap2/timer-gp.c

@@ -47,6 +47,7 @@ static struct omap_dm_timer *gptimer;
 static struct clock_event_device clockevent_gpt;
 static u8 __initdata gptimer_id = 1;
 static u8 __initdata inited;
+struct omap_dm_timer *gptimer_wakeup;
 
 static irqreturn_t omap2_gp_timer_interrupt(int irq, void *dev_id)
 {
@@ -134,6 +135,7 @@ static void __init omap2_gp_clockevent_init(void)
 
 	gptimer = omap_dm_timer_request_specific(gptimer_id);
 	BUG_ON(gptimer == NULL);
+	gptimer_wakeup = gptimer;
 
 #if defined(CONFIG_OMAP_32K_TIMER)
 	src = OMAP_TIMER_SRC_32_KHZ;