cpuidle, OMAP4: Push RCU-idle into omap4_enter_lowpower()

OMAP4 uses full SoC suspend modes as idle states, as such it needs the
whole power-domain and clock-domain code from the idle path.

All that code is not suitable to run with RCU disabled, as such push
RCU-idle deeper still.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r/Yqcv6crSNKuSWoTu@atomide.com
Link: https://lore.kernel.org/r/20230112195541.660272394@infradead.org

arch/arm/mach-omap2/common.h

@@ -284,11 +284,13 @@ extern u32 omap4_get_cpu1_ns_pa_addr(void);
 
 #if defined(CONFIG_SMP) && defined(CONFIG_PM)
 extern int omap4_mpuss_init(void);
-extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state);
+extern int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state,
+				bool rcuidle);
 extern int omap4_hotplug_cpu(unsigned int cpu, unsigned int power_state);
 #else
 static inline int omap4_enter_lowpower(unsigned int cpu,
-					unsigned int power_state)
+					unsigned int power_state,
+					bool rcuidle)
 {
 	cpu_do_idle();
 	return 0;

arch/arm/mach-omap2/cpuidle44xx.c

@@ -105,9 +105,7 @@ static int omap_enter_idle_smp(struct cpuidle_device *dev,
 	}
 	raw_spin_unlock_irqrestore(&mpu_lock, flag);
 
-	ct_cpuidle_enter();
-	omap4_enter_lowpower(dev->cpu, cx->cpu_state);
-	ct_cpuidle_exit();
+	omap4_enter_lowpower(dev->cpu, cx->cpu_state, true);
 
 	raw_spin_lock_irqsave(&mpu_lock, flag);
 	if (cx->mpu_state_vote == num_online_cpus())
@@ -186,10 +184,8 @@ static int omap_enter_idle_coupled(struct cpuidle_device *dev,
 		}
 	}
 
-	ct_cpuidle_enter();
-	omap4_enter_lowpower(dev->cpu, cx->cpu_state);
+	omap4_enter_lowpower(dev->cpu, cx->cpu_state, true);
 	cpu_done[dev->cpu] = true;
-	ct_cpuidle_exit();
 
 	/* Wakeup CPU1 only if it is not offlined */
 	if (dev->cpu == 0 && cpumask_test_cpu(1, cpu_online_mask)) {

arch/arm/mach-omap2/omap-mpuss-lowpower.c

@@ -33,6 +33,7 @@
  * and first to wake-up when MPUSS low power states are excercised
  */
 
+#include <linux/cpuidle.h>
 #include <linux/kernel.h>
 #include <linux/io.h>
 #include <linux/errno.h>
@@ -214,6 +215,7 @@ static void __init save_l2x0_context(void)
  * of OMAP4 MPUSS subsystem
  * @cpu : CPU ID
  * @power_state: Low power state.
+ * @rcuidle: RCU needs to be idled
  *
  * MPUSS states for the context save:
  * save_state =
@@ -222,7 +224,8 @@ static void __init save_l2x0_context(void)
  *	2 - CPUx L1 and logic lost + GIC lost: MPUSS OSWR
  *	3 - CPUx L1 and logic lost + GIC + L2 lost: DEVICE OFF
  */
-int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
+int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state,
+			 bool rcuidle)
 {
 	struct omap4_cpu_pm_info *pm_info = &per_cpu(omap4_pm_info, cpu);
 	unsigned int save_state = 0, cpu_logic_state = PWRDM_POWER_RET;
@@ -268,6 +271,10 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
 	cpu_clear_prev_logic_pwrst(cpu);
 	pwrdm_set_next_pwrst(pm_info->pwrdm, power_state);
 	pwrdm_set_logic_retst(pm_info->pwrdm, cpu_logic_state);
+
+	if (rcuidle)
+		ct_cpuidle_enter();
+
 	set_cpu_wakeup_addr(cpu, __pa_symbol(omap_pm_ops.resume));
 	omap_pm_ops.scu_prepare(cpu, power_state);
 	l2x0_pwrst_prepare(cpu, save_state);
@@ -283,6 +290,9 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
 	if (IS_PM44XX_ERRATUM(PM_OMAP4_ROM_SMP_BOOT_ERRATUM_GICD) && cpu)
 		gic_dist_enable();
 
+	if (rcuidle)
+		ct_cpuidle_exit();
+
 	/*
 	 * Restore the CPUx power state to ON otherwise CPUx
 	 * power domain can transitions to programmed low power

arch/arm/mach-omap2/pm44xx.c

@@ -76,7 +76,7 @@ static int omap4_pm_suspend(void)
 	 * domain CSWR is not supported by hardware.
 	 * More details can be found in OMAP4430 TRM section 4.3.4.2.
 	 */
-	omap4_enter_lowpower(cpu_id, cpu_suspend_state);
+	omap4_enter_lowpower(cpu_id, cpu_suspend_state, false);
 
 	/* Restore next powerdomain state */
 	list_for_each_entry(pwrst, &pwrst_list, node) {