PM / devfreq: tegra30: Support variable polling interval

The ACTMON governor is interrupt-driven and currently hardware's polling
interval is fixed to 16ms in the driver. Devfreq supports variable polling
interval by the generic governors, let's re-use the generic interface for
changing of the polling interval. Now the polling interval can be changed
dynamically via /sys/class/devfreq/devfreq0/polling_interval.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index 3bd9208..e44f1a4 100644 (file)
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -171,6 +171,8 @@ struct tegra_devfreq {
        struct tegra_devfreq_device devices[ARRAY_SIZE(actmon_device_configs)];
 
        unsigned int            irq;
+
+       bool                    started;
 };
 
 struct tegra_actmon_emc_ratio {
@@ -209,18 +211,26 @@ static void device_writel(struct tegra_devfreq_device *dev, u32 val,
        writel_relaxed(val, dev->regs + offset);
 }
 
-static unsigned long do_percent(unsigned long val, unsigned int pct)
+static unsigned long do_percent(unsigned long long val, unsigned int pct)
 {
-       return val * pct / 100;
+       val = val * pct;
+       do_div(val, 100);
+
+       /*
+        * High freq + high boosting percent + large polling interval are
+        * resulting in integer overflow when watermarks are calculated.
+        */
+       return min_t(u64, val, U32_MAX);
 }
 
 static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
                                           struct tegra_devfreq_device *dev)
 {
-       u32 avg = dev->avg_count;
        u32 avg_band_freq = tegra->max_freq * ACTMON_DEFAULT_AVG_BAND / KHZ;
-       u32 band = avg_band_freq * ACTMON_SAMPLING_PERIOD;
+       u32 band = avg_band_freq * tegra->devfreq->profile->polling_ms;
+       u32 avg;
 
+       avg = min(dev->avg_count, U32_MAX - band);
        device_writel(dev, avg + band, ACTMON_DEV_AVG_UPPER_WMARK);
 
        avg = max(dev->avg_count, band);
@@ -230,7 +240,7 @@ static void tegra_devfreq_update_avg_wmark(struct tegra_devfreq *tegra,
 static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
                                       struct tegra_devfreq_device *dev)
 {
-       u32 val = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
+       u32 val = tegra->cur_freq * tegra->devfreq->profile->polling_ms;
 
        device_writel(dev, do_percent(val, dev->config->boost_up_threshold),
                      ACTMON_DEV_UPPER_WMARK);
@@ -309,7 +319,7 @@ static unsigned long actmon_device_target_freq(struct tegra_devfreq *tegra,
        unsigned int avg_sustain_coef;
        unsigned long target_freq;
 
-       target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD;
+       target_freq = dev->avg_count / tegra->devfreq->profile->polling_ms;
        avg_sustain_coef = 100 * 100 / dev->config->boost_up_threshold;
        target_freq = do_percent(target_freq, avg_sustain_coef);
 
@@ -469,7 +479,7 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
 
        dev->target_freq = tegra->cur_freq;
 
-       dev->avg_count = tegra->cur_freq * ACTMON_SAMPLING_PERIOD;
+       dev->avg_count = tegra->cur_freq * tegra->devfreq->profile->polling_ms;
        device_writel(dev, dev->avg_count, ACTMON_DEV_INIT_AVG);
 
        tegra_devfreq_update_avg_wmark(tegra, dev);
@@ -505,12 +515,15 @@ static void tegra_actmon_stop_devices(struct tegra_devfreq *tegra)
        }
 }
 
-static int tegra_actmon_start(struct tegra_devfreq *tegra)
+static int tegra_actmon_resume(struct tegra_devfreq *tegra)
 {
        unsigned int i;
        int err;
 
-       actmon_writel(tegra, ACTMON_SAMPLING_PERIOD - 1,
+       if (!tegra->devfreq->profile->polling_ms || !tegra->started)
+               return 0;
+
+       actmon_writel(tegra, tegra->devfreq->profile->polling_ms - 1,
                      ACTMON_GLB_PERIOD_CTRL);
 
        /*
@@ -558,8 +571,26 @@ err_stop:
        return err;
 }
 
-static void tegra_actmon_stop(struct tegra_devfreq *tegra)
+static int tegra_actmon_start(struct tegra_devfreq *tegra)
 {
+       int ret = 0;
+
+       if (!tegra->started) {
+               tegra->started = true;
+
+               ret = tegra_actmon_resume(tegra);
+               if (ret)
+                       tegra->started = false;
+       }
+
+       return ret;
+}
+
+static void tegra_actmon_pause(struct tegra_devfreq *tegra)
+{
+       if (!tegra->devfreq->profile->polling_ms || !tegra->started)
+               return;
+
        disable_irq(tegra->irq);
 
        cpufreq_unregister_notifier(&tegra->cpu_rate_change_nb,
@@ -572,6 +603,12 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
        clk_notifier_unregister(tegra->emc_clock, &tegra->clk_rate_change_nb);
 }
 
+static void tegra_actmon_stop(struct tegra_devfreq *tegra)
+{
+       tegra_actmon_pause(tegra);
+       tegra->started = false;
+}
+
 static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
                                u32 flags)
 {
@@ -629,7 +666,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
        stat->busy_time *= 100 / BUS_SATURATION_RATIO;
 
        /* Number of cycles in a sampling period */
-       stat->total_time = ACTMON_SAMPLING_PERIOD * cur_freq;
+       stat->total_time = tegra->devfreq->profile->polling_ms * cur_freq;
 
        stat->busy_time = min(stat->busy_time, stat->total_time);
 
@@ -637,7 +674,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
 }
 
 static struct devfreq_dev_profile tegra_devfreq_profile = {
-       .polling_ms     = 0,
+       .polling_ms     = ACTMON_SAMPLING_PERIOD,
        .target         = tegra_devfreq_target,
        .get_dev_status = tegra_devfreq_get_dev_status,
 };
@@ -677,6 +714,7 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
                                        unsigned int event, void *data)
 {
        struct tegra_devfreq *tegra = dev_get_drvdata(devfreq->dev.parent);
+       unsigned int *new_delay = data;
        int ret = 0;
 
        /*
@@ -696,6 +734,21 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,
                devfreq_monitor_stop(devfreq);
                break;
 
+       case DEVFREQ_GOV_INTERVAL:
+               /*
+                * ACTMON hardware supports up to 256 milliseconds for the
+                * sampling period.
+                */
+               if (*new_delay > 256) {
+                       ret = -EINVAL;
+                       break;
+               }
+
+               tegra_actmon_pause(tegra);
+               devfreq_interval_update(devfreq, new_delay);
+               ret = tegra_actmon_resume(tegra);
+               break;
+
        case DEVFREQ_GOV_SUSPEND:
                tegra_actmon_stop(tegra);
                devfreq_monitor_suspend(devfreq);
@@ -715,6 +768,7 @@ static struct devfreq_governor tegra_devfreq_governor = {
        .get_target_freq = tegra_governor_get_target,
        .event_handler = tegra_governor_event_handler,
        .immutable = true,
+       .interrupt_driven = true,
 };
 
 static int tegra_devfreq_probe(struct platform_device *pdev)