PM / devfreq: add relation of recommended frequency.

The semantics of "target frequency" given to devfreq driver from
devfreq framework has always been interpretted as "at least" or GLB
(greatest lower bound). However, the framework might want the
device driver to limit its max frequency (LUB: least upper bound),
especially if it is given by thermal framework (it's too hot).

Thus, the target fuction should have another parameter to express
whether the framework wants GLB or LUB. And, the additional parameter,
"u32 flags", does it.

With the update, devfreq_recommended_opp() is also updated.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mike Turquette <mturquette@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 48 insertions, 8 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index a129a7b6bfd1..70c31d43fff3 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -83,6 +83,7 @@ int update_devfreq(struct devfreq *devfreq)
 {
         unsigned long freq;
         int err = 0;
+        u32 flags = 0;
 
         if (!mutex_is_locked(&devfreq->lock)) {
                 WARN(true, "devfreq->lock must be locked by the caller.\n");
@@ -94,7 +95,24 @@ int update_devfreq(struct devfreq *devfreq)
         if (err)
                 return err;
 
-        err = devfreq->profile->target(devfreq->dev.parent, &freq);
+        /*
+         * Adjust the freuqency with user freq and QoS.
+         *
+         * List from the highest proiority
+         * max_freq (probably called by thermal when it's too hot)
+         * min_freq
+         */
+
+        if (devfreq->min_freq && freq < devfreq->min_freq) {
+                freq = devfreq->min_freq;
+                flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
+        }
+        if (devfreq->max_freq && freq > devfreq->max_freq) {
+                freq = devfreq->max_freq;
+                flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
+        }
+
+        err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
         if (err)
                 return err;
 
@@ -625,14 +643,30 @@ module_exit(devfreq_exit);
  *                           freq value given to target callback.
  * @dev         The devfreq user device. (parent of devfreq)
  * @freq        The frequency given to target function
+ * @flags       Flags handed from devfreq framework.
  *
  */
-struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
+struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
+                                    u32 flags)
 {
-        struct opp *opp = opp_find_freq_ceil(dev, freq);
+        struct opp *opp;
 
-        if (opp == ERR_PTR(-ENODEV))
+        if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
+                /* The freq is an upper bound. opp should be lower */
                 opp = opp_find_freq_floor(dev, freq);
+
+                /* If not available, use the closest opp */
+                if (opp == ERR_PTR(-ENODEV))
+                        opp = opp_find_freq_ceil(dev, freq);
+        } else {
+                /* The freq is an lower bound. opp should be higher */
+                opp = opp_find_freq_ceil(dev, freq);
+
+                /* If not available, use the closest opp */
+                if (opp == ERR_PTR(-ENODEV))
+                        opp = opp_find_freq_floor(dev, freq);
+        }
+
         return opp;
 }
 
diff --git a/drivers/devfreq/exynos4_bus.c b/drivers/devfreq/exynos4_bus.c
index 590d6865e388..1a361e99965a 100644
--- a/drivers/devfreq/exynos4_bus.c
+++ b/drivers/devfreq/exynos4_bus.c
@@ -619,13 +619,19 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp,
         return err;
 }
 
-static int exynos4_bus_target(struct device *dev, unsigned long *_freq)
+static int exynos4_bus_target(struct device *dev, unsigned long *_freq,
+                              u32 flags)
 {
         int err = 0;
-        struct busfreq_data *data = dev_get_drvdata(dev);
-        struct opp *opp = devfreq_recommended_opp(dev, _freq);
-        unsigned long old_freq = opp_get_freq(data->curr_opp);
+        struct platform_device *pdev = container_of(dev, struct platform_device,
+                                                    dev);
+        struct busfreq_data *data = platform_get_drvdata(pdev);
+        struct opp *opp = devfreq_recommended_opp(dev, _freq, flags);
         unsigned long freq = opp_get_freq(opp);
+        unsigned long old_freq = opp_get_freq(data->curr_opp);
+
+        if (IS_ERR(opp))
+                return PTR_ERR(opp);
 
         if (old_freq == freq)
                 return 0;