ARM: OMAP2+: Fix l4ls clk domain handling in STANDBY

Don't put the l4ls clk domain to sleep in case of standby.
Since CM3 PM FW[1](ti-v4.1.y) doesn't wake-up/enable the l4ls clk domain
upon wake-up, CM3 PM FW fails to wake-up the MPU.

[1] https://git.ti.com/cgit/processor-firmware/ti-amx3-cm3-pm-firmware/

Signed-off-by: Sukrut Bellary <sbellary@baylibre.com>
Tested-by: Judith Mendez <jm@ti.com>
Link: https://lore.kernel.org/r/20250318230042.3138542-2-sbellary@baylibre.com
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Author: Sukrut Bellary

arch/arm/mach-omap2/clockdomain.h

@@ -48,6 +48,7 @@
 #define CLKDM_NO_AUTODEPS			(1 << 4)
 #define CLKDM_ACTIVE_WITH_MPU			(1 << 5)
 #define CLKDM_MISSING_IDLE_REPORTING		(1 << 6)
+#define CLKDM_STANDBY_FORCE_WAKEUP		BIT(7)
 
 #define CLKDM_CAN_HWSUP		(CLKDM_CAN_ENABLE_AUTO | CLKDM_CAN_DISABLE_AUTO)
 #define CLKDM_CAN_SWSUP		(CLKDM_CAN_FORCE_SLEEP | CLKDM_CAN_FORCE_WAKEUP)

arch/arm/mach-omap2/clockdomains33xx_data.c

@@ -19,7 +19,7 @@ static struct clockdomain l4ls_am33xx_clkdm = {
 	.pwrdm		= { .name = "per_pwrdm" },
 	.cm_inst	= AM33XX_CM_PER_MOD,
 	.clkdm_offs	= AM33XX_CM_PER_L4LS_CLKSTCTRL_OFFSET,
-	.flags		= CLKDM_CAN_SWSUP,
+	.flags		= CLKDM_CAN_SWSUP | CLKDM_STANDBY_FORCE_WAKEUP,
 };
 
 static struct clockdomain l3s_am33xx_clkdm = {

arch/arm/mach-omap2/cm33xx.c

@@ -20,6 +20,9 @@
 #include "cm-regbits-34xx.h"
 #include "cm-regbits-33xx.h"
 #include "prm33xx.h"
+#if IS_ENABLED(CONFIG_SUSPEND)
+#include <linux/suspend.h>
+#endif
 
 /*
  * CLKCTRL_IDLEST_*: possible values for the CM_*_CLKCTRL.IDLEST bitfield:
@@ -328,8 +331,17 @@ static int am33xx_clkdm_clk_disable(struct clockdomain *clkdm)
 {
 	bool hwsup = false;
 
+#if IS_ENABLED(CONFIG_SUSPEND)
+	/*
+	 * In case of standby, Don't put the l4ls clk domain to sleep.
+	 * Since CM3 PM FW doesn't wake-up/enable the l4ls clk domain
+	 * upon wake-up, CM3 PM FW fails to wake-up th MPU.
+	 */
+	if (pm_suspend_target_state == PM_SUSPEND_STANDBY &&
+	    (clkdm->flags & CLKDM_STANDBY_FORCE_WAKEUP))
+		return 0;
+#endif
 	hwsup = am33xx_cm_is_clkdm_in_hwsup(clkdm->cm_inst, clkdm->clkdm_offs);
-
 	if (!hwsup && (clkdm->flags & CLKDM_CAN_FORCE_SLEEP))
 		am33xx_clkdm_sleep(clkdm);