1 files changed, 83 insertions, 21 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 4c49bb1330b5..e2ab46bfa666 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/kmod.h>
 #include <linux/sched.h>
 #include <linux/errno.h>
 #include <linux/err.h>
@@ -221,6 +222,49 @@ static struct devfreq_governor *find_devfreq_governor(const char *name)
 	return ERR_PTR(-ENODEV);
 }
 
+/**
+ * try_then_request_governor() - Try to find the governor and request the
+ *                               module if is not found.
+ * @name:	name of the governor
+ *
+ * Search the list of devfreq governors and request the module and try again
+ * if is not found. This can happen when both drivers (the governor driver
+ * and the driver that call devfreq_add_device) are built as modules.
+ * devfreq_list_lock should be held by the caller. Returns the matched
+ * governor's pointer or an error pointer.
+ */
+static struct devfreq_governor *try_then_request_governor(const char *name)
+{
+	struct devfreq_governor *governor;
+	int err = 0;
+
+	if (IS_ERR_OR_NULL(name)) {
+		pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+	WARN(!mutex_is_locked(&devfreq_list_lock),
+	     "devfreq_list_lock must be locked.");
+
+	governor = find_devfreq_governor(name);
+	if (IS_ERR(governor)) {
+		mutex_unlock(&devfreq_list_lock);
+
+		if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND,
+			     DEVFREQ_NAME_LEN))
+			err = request_module("governor_%s", "simpleondemand");
+		else
+			err = request_module("governor_%s", name);
+		/* Restore previous state before return */
+		mutex_lock(&devfreq_list_lock);
+		if (err)
+			return ERR_PTR(err);
+
+		governor = find_devfreq_governor(name);
+	}
+
+	return governor;
+}
+
 static int devfreq_notify_transition(struct devfreq *devfreq,
 		struct devfreq_freqs *freqs, unsigned int state)
 {
@@ -283,11 +327,11 @@ int update_devfreq(struct devfreq *devfreq)
 	max_freq = MIN(devfreq->scaling_max_freq, devfreq->max_freq);
 	min_freq = MAX(devfreq->scaling_min_freq, devfreq->min_freq);
 
-	if (min_freq && freq < min_freq) {
+	if (freq < min_freq) {
 		freq = min_freq;
 		flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
 	}
-	if (max_freq && freq > max_freq) {
+	if (freq > max_freq) {
 		freq = max_freq;
 		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
 	}
@@ -534,10 +578,6 @@ static void devfreq_dev_release(struct device *dev)
 	list_del(&devfreq->node);
 	mutex_unlock(&devfreq_list_lock);
 
-	if (devfreq->governor)
-		devfreq->governor->event_handler(devfreq,
-						 DEVFREQ_GOV_STOP, NULL);
-
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
 
@@ -646,9 +686,8 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	mutex_unlock(&devfreq->lock);
 
 	mutex_lock(&devfreq_list_lock);
-	list_add(&devfreq->node, &devfreq_list);
 
-	governor = find_devfreq_governor(devfreq->governor_name);
+	governor = try_then_request_governor(devfreq->governor_name);
 	if (IS_ERR(governor)) {
 		dev_err(dev, "%s: Unable to find governor for the device\n",
 			__func__);
@@ -664,15 +703,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
 			__func__);
 		goto err_init;
 	}
+
+	list_add(&devfreq->node, &devfreq_list);
+
 	mutex_unlock(&devfreq_list_lock);
 
 	return devfreq;
 
 err_init:
-	list_del(&devfreq->node);
 	mutex_unlock(&devfreq_list_lock);
 
-	device_unregister(&devfreq->dev);
+	devfreq_remove_device(devfreq);
 	devfreq = NULL;
 err_dev:
 	if (devfreq)
@@ -693,6 +734,9 @@ int devfreq_remove_device(struct devfreq *devfreq)
 	if (!devfreq)
 		return -EINVAL;
 
+	if (devfreq->governor)
+		devfreq->governor->event_handler(devfreq,
+						 DEVFREQ_GOV_STOP, NULL);
 	device_unregister(&devfreq->dev);
 
 	return 0;
@@ -991,7 +1035,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 
 	mutex_lock(&devfreq_list_lock);
-	governor = find_devfreq_governor(str_governor);
+	governor = try_then_request_governor(str_governor);
 	if (IS_ERR(governor)) {
 		ret = PTR_ERR(governor);
 		goto out;
@@ -1126,17 +1170,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
 	struct devfreq *df = to_devfreq(dev);
 	unsigned long value;
 	int ret;
-	unsigned long max;
 
 	ret = sscanf(buf, "%lu", &value);
 	if (ret != 1)
 		return -EINVAL;
 
 	mutex_lock(&df->lock);
-	max = df->max_freq;
-	if (value && max && value > max) {
-		ret = -EINVAL;
-		goto unlock;
+
+	if (value) {
+		if (value > df->max_freq) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+	} else {
+		unsigned long *freq_table = df->profile->freq_table;
+
+		/* Get minimum frequency according to sorting order */
+		if (freq_table[0] < freq_table[df->profile->max_state - 1])
+			value = freq_table[0];
+		else
+			value = freq_table[df->profile->max_state - 1];
 	}
 
 	df->min_freq = value;
@@ -1161,17 +1214,26 @@ static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
 	struct devfreq *df = to_devfreq(dev);
 	unsigned long value;
 	int ret;
-	unsigned long min;
 
 	ret = sscanf(buf, "%lu", &value);
 	if (ret != 1)
 		return -EINVAL;
 
 	mutex_lock(&df->lock);
-	min = df->min_freq;
-	if (value && min && value < min) {
-		ret = -EINVAL;
-		goto unlock;
+
+	if (value) {
+		if (value < df->min_freq) {
+			ret = -EINVAL;
+			goto unlock;
+		}
+	} else {
+		unsigned long *freq_table = df->profile->freq_table;
+
+		/* Get maximum frequency according to sorting order */
+		if (freq_table[0] < freq_table[df->profile->max_state - 1])
+			value = freq_table[df->profile->max_state - 1];
+		else
+			value = freq_table[0];
 	}
 
 	df->max_freq = value;