ARM: OMAP4: CPUidle: Use coupled cpuidle states to implement SMP cpuidle.

OMAP4 CPUDILE driver is converted mainly based on notes from the
coupled cpuidle patch series.

The changes include :
- Register both CPUs and C-states to cpuidle driver.
- Set struct cpuidle_device.coupled_cpus
- Set struct cpuidle_device.safe_state to non coupled state.
- Set CPUIDLE_FLAG_COUPLED in struct cpuidle_state.flags for each
  state that affects multiple cpus.
- Separate ->enter hooks for coupled & simple idle.
- CPU0 wait loop for CPU1 power transition.
- CPU1 wakeup mechanism for the idle exit.
- Enabling ARCH_NEEDS_CPU_IDLE_COUPLED for OMAP4.

Thanks to Kevin Hilman and Colin Cross on the suggestions/fixes
on the intermediate version of this patch.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

2 files changed, 67 insertions, 46 deletions

diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index 4cf5142f22c..cc83f5e13d5 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -55,6 +55,7 @@ config ARCH_OMAP4
         select PM_OPP if PM
         select USB_ARCH_HAS_EHCI if USB_SUPPORT
         select ARM_CPU_SUSPEND if PM
+        select ARCH_NEEDS_CPU_IDLE_COUPLED
 
 comment "OMAP Core Type"
         depends on ARCH_OMAP2
diff --git a/arch/arm/mach-omap2/cpuidle44xx.c b/arch/arm/mach-omap2/cpuidle44xx.c
index be1617ca84b..25655eb6940 100644
--- a/arch/arm/mach-omap2/cpuidle44xx.c
+++ b/arch/arm/mach-omap2/cpuidle44xx.c
@@ -21,6 +21,7 @@
 #include "common.h"
 #include "pm.h"
 #include "prm.h"
+#include "clockdomain.h"
 
 #ifdef CONFIG_CPU_IDLE
 
@@ -49,10 +50,11 @@ static struct omap4_idle_statedata omap4_idle_data[] = {
         },
 };
 
-static struct powerdomain *mpu_pd, *cpu0_pd, *cpu1_pd;
+static struct powerdomain *mpu_pd, *cpu_pd[NR_CPUS];
+static struct clockdomain *cpu_clkdm[NR_CPUS];
 
 /**
- * omap4_enter_idle - Programs OMAP4 to enter the specified state
+ * omap4_enter_idle_coupled_[simple/coupled] - OMAP4 cpuidle entry functions
  * @dev: cpuidle device
  * @drv: cpuidle driver
  * @index: the index of state to be entered
@@ -61,60 +63,71 @@ static struct powerdomain *mpu_pd, *cpu0_pd, *cpu1_pd;
  * specified low power state selected by the governor.
  * Returns the amount of time spent in the low power state.
  */
-static int omap4_enter_idle(struct cpuidle_device *dev,
+static int omap4_enter_idle_simple(struct cpuidle_device *dev,
+                        struct cpuidle_driver *drv,
+                        int index)
+{
+        local_fiq_disable();
+        omap_do_wfi();
+        local_fiq_enable();
+
+        return index;
+}
+
+static int omap4_enter_idle_coupled(struct cpuidle_device *dev,
                         struct cpuidle_driver *drv,
                         int index)
 {
         struct omap4_idle_statedata *cx = &omap4_idle_data[index];
-        u32 cpu1_state;
         int cpu_id = smp_processor_id();
 
         local_fiq_disable();
 
         /*
-         * CPU0 has to stay ON (i.e in C1) until CPU1 is OFF state.
+         * CPU0 has to wait and stay ON until CPU1 is OFF state.
          * This is necessary to honour hardware recommondation
          * of triggeing all the possible low power modes once CPU1 is
          * out of coherency and in OFF mode.
-         * Update dev->last_state so that governor stats reflects right
-         * data.
          */
-        cpu1_state = pwrdm_read_pwrst(cpu1_pd);
-        if (cpu1_state != PWRDM_POWER_OFF) {
-                index = drv->safe_state_index;
-                cx = &omap4_idle_data[index];
+        if (dev->cpu == 0 && cpumask_test_cpu(1, cpu_online_mask)) {
+                while (pwrdm_read_pwrst(cpu_pd[1]) != PWRDM_POWER_OFF)
+                        cpu_relax();
         }
 
-        if (index > 0)
-                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu_id);
+        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu_id);
 
         /*
          * Call idle CPU PM enter notifier chain so that
          * VFP and per CPU interrupt context is saved.
          */
-        if (cx->cpu_state == PWRDM_POWER_OFF)
-                cpu_pm_enter();
-
-        pwrdm_set_logic_retst(mpu_pd, cx->mpu_logic_state);
-        omap_set_pwrdm_state(mpu_pd, cx->mpu_state);
-
-        /*
-         * Call idle CPU cluster PM enter notifier chain
-         * to save GIC and wakeupgen context.
-         */
-        if ((cx->mpu_state == PWRDM_POWER_RET) &&
-                (cx->mpu_logic_state == PWRDM_POWER_OFF))
-                        cpu_cluster_pm_enter();
+        cpu_pm_enter();
+
+        if (dev->cpu == 0) {
+                pwrdm_set_logic_retst(mpu_pd, cx->mpu_logic_state);
+                omap_set_pwrdm_state(mpu_pd, cx->mpu_state);
+
+                /*
+                 * Call idle CPU cluster PM enter notifier chain
+                 * to save GIC and wakeupgen context.
+                 */
+                if ((cx->mpu_state == PWRDM_POWER_RET) &&
+                        (cx->mpu_logic_state == PWRDM_POWER_OFF))
+                                cpu_cluster_pm_enter();
+        }
 
         omap4_enter_lowpower(dev->cpu, cx->cpu_state);
 
+        /* Wakeup CPU1 only if it is not offlined */
+        if (dev->cpu == 0 && cpumask_test_cpu(1, cpu_online_mask)) {
+                clkdm_wakeup(cpu_clkdm[1]);
+                clkdm_allow_idle(cpu_clkdm[1]);
+        }
+
         /*
          * Call idle CPU PM exit notifier chain to restore
-         * VFP and per CPU IRQ context. Only CPU0 state is
-         * considered since CPU1 is managed by CPU hotplug.
+         * VFP and per CPU IRQ context.
          */
-        if (pwrdm_read_prev_pwrst(cpu0_pd) == PWRDM_POWER_OFF)
-                cpu_pm_exit();
+        cpu_pm_exit();
 
         /*
          * Call idle CPU cluster PM exit notifier chain
@@ -123,8 +136,7 @@ static int omap4_enter_idle(struct cpuidle_device *dev,
         if (omap4_mpuss_read_prev_context_state())
                 cpu_cluster_pm_exit();
 
-        if (index > 0)
-                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu_id);
+        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu_id);
 
         local_fiq_enable();
 
@@ -143,7 +155,7 @@ struct cpuidle_driver omap4_idle_driver = {
                         .exit_latency = 2 + 2,
                         .target_residency = 5,
                         .flags = CPUIDLE_FLAG_TIME_VALID,
-                        .enter = omap4_enter_idle,
+                        .enter = omap4_enter_idle_simple,
                         .name = "C1",
                         .desc = "MPUSS ON"
                 },
@@ -151,8 +163,8 @@ struct cpuidle_driver omap4_idle_driver = {
                         /* C2 - CPU0 OFF + CPU1 OFF + MPU CSWR */
                         .exit_latency = 328 + 440,
                         .target_residency = 960,
-                        .flags = CPUIDLE_FLAG_TIME_VALID,
-                        .enter = omap4_enter_idle,
+                        .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED,
+                        .enter = omap4_enter_idle_coupled,
                         .name = "C2",
                         .desc = "MPUSS CSWR",
                 },
@@ -160,8 +172,8 @@ struct cpuidle_driver omap4_idle_driver = {
                         /* C3 - CPU0 OFF + CPU1 OFF + MPU OSWR */
                         .exit_latency = 460 + 518,
                         .target_residency = 1100,
-                        .flags = CPUIDLE_FLAG_TIME_VALID,
-                        .enter = omap4_enter_idle,
+                        .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_COUPLED,
+                        .enter = omap4_enter_idle_coupled,
                         .name = "C3",
                         .desc = "MPUSS OSWR",
                 },
@@ -182,19 +194,27 @@ int __init omap4_idle_init(void)
         unsigned int cpu_id = 0;
 
         mpu_pd = pwrdm_lookup("mpu_pwrdm");
-        cpu0_pd = pwrdm_lookup("cpu0_pwrdm");
-        cpu1_pd = pwrdm_lookup("cpu1_pwrdm");
-        if ((!mpu_pd) || (!cpu0_pd) || (!cpu1_pd))
+        cpu_pd[0] = pwrdm_lookup("cpu0_pwrdm");
+        cpu_pd[1] = pwrdm_lookup("cpu1_pwrdm");
+        if ((!mpu_pd) || (!cpu_pd[0]) || (!cpu_pd[1]))
+                return -ENODEV;
+
+        cpu_clkdm[0] = clkdm_lookup("mpu0_clkdm");
+        cpu_clkdm[1] = clkdm_lookup("mpu1_clkdm");
+        if (!cpu_clkdm[0] || !cpu_clkdm[1])
                 return -ENODEV;
 
-        dev = &per_cpu(omap4_idle_dev, cpu_id);
-        dev->cpu = cpu_id;
+        for_each_cpu(cpu_id, cpu_online_mask) {
+                dev = &per_cpu(omap4_idle_dev, cpu_id);
+                dev->cpu = cpu_id;
+                dev->coupled_cpus = *cpu_online_mask;
 
-        cpuidle_register_driver(&omap4_idle_driver);
+                cpuidle_register_driver(&omap4_idle_driver);
 
-        if (cpuidle_register_device(dev)) {
-                pr_err("%s: CPUidle register device failed\n", __func__);
-                return -EIO;
+                if (cpuidle_register_device(dev)) {
+                        pr_err("%s: CPUidle register failed\n", __func__);
+                        return -EIO;
+                }
         }
 
         return 0;