PM / OPP: Parse 'opp-<prop>-<name>' bindings

OPP bindings (for few properties) allow a platform to choose a
value/range among a set of available options. The options are present as
opp-<prop>-<name>, where the platform needs to supply the <name> string.

The OPP properties which allow such an option are: opp-microvolt and
opp-microamp.

Add support to the OPP-core to parse these bindings, by introducing
dev_pm_opp_{set|put}_prop_name() APIs.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 152 insertions, 15 deletions

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 55cf1a99b532..5c01fec1ed14 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -562,6 +562,9 @@ static void _remove_device_opp(struct device_opp *dev_opp)
         if (dev_opp->supported_hw)
                 return;
 
+        if (dev_opp->prop_name)
+                return;
+
         list_dev = list_first_entry(&dev_opp->dev_list, struct device_list_opp,
                                     node);
 
@@ -794,35 +797,48 @@ unlock:
 }
 
 /* TODO: Support multiple regulators */
-static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev)
+static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
+                              struct device_opp *dev_opp)
 {
         u32 microvolt[3] = {0};
         u32 val;
         int count, ret;
+        struct property *prop = NULL;
+        char name[NAME_MAX];
+
+        /* Search for "opp-microvolt-<name>" */
+        if (dev_opp->prop_name) {
+                sprintf(name, "opp-microvolt-%s", dev_opp->prop_name);
+                prop = of_find_property(opp->np, name, NULL);
+        }
+
+        if (!prop) {
+                /* Search for "opp-microvolt" */
+                name[13] = '\0';
+                prop = of_find_property(opp->np, name, NULL);
 
-        /* Missing property isn't a problem, but an invalid entry is */
-        if (!of_find_property(opp->np, "opp-microvolt", NULL))
-                return 0;
+                /* Missing property isn't a problem, but an invalid entry is */
+                if (!prop)
+                        return 0;
+        }
 
-        count = of_property_count_u32_elems(opp->np, "opp-microvolt");
+        count = of_property_count_u32_elems(opp->np, name);
         if (count < 0) {
-                dev_err(dev, "%s: Invalid opp-microvolt property (%d)\n",
-                        __func__, count);
+                dev_err(dev, "%s: Invalid %s property (%d)\n",
+                        __func__, name, count);
                 return count;
         }
 
         /* There can be one or three elements here */
         if (count != 1 && count != 3) {
-                dev_err(dev, "%s: Invalid number of elements in opp-microvolt property (%d)\n",
-                        __func__, count);
+                dev_err(dev, "%s: Invalid number of elements in %s property (%d)\n",
+                        __func__, name, count);
                 return -EINVAL;
         }
 
-        ret = of_property_read_u32_array(opp->np, "opp-microvolt", microvolt,
-                                         count);
+        ret = of_property_read_u32_array(opp->np, name, microvolt, count);
         if (ret) {
-                dev_err(dev, "%s: error parsing opp-microvolt: %d\n", __func__,
-                        ret);
+                dev_err(dev, "%s: error parsing %s: %d\n", __func__, name, ret);
                 return -EINVAL;
         }
 
@@ -830,7 +846,20 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev)
         opp->u_volt_min = microvolt[1];
         opp->u_volt_max = microvolt[2];
 
-        if (!of_property_read_u32(opp->np, "opp-microamp", &val))
+        /* Search for "opp-microamp-<name>" */
+        prop = NULL;
+        if (dev_opp->prop_name) {
+                sprintf(name, "opp-microamp-%s", dev_opp->prop_name);
+                prop = of_find_property(opp->np, name, NULL);
+        }
+
+        if (!prop) {
+                /* Search for "opp-microamp" */
+                name[12] = '\0';
+                prop = of_find_property(opp->np, name, NULL);
+        }
+
+        if (prop && !of_property_read_u32(opp->np, name, &val))
                 opp->u_amp = val;
 
         return 0;
@@ -948,6 +977,112 @@ unlock:
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_put_supported_hw);
 
+/**
+ * dev_pm_opp_set_prop_name() - Set prop-extn name
+ * @dev: Device for which the regulator has to be set.
+ * @name: name to postfix to properties.
+ *
+ * This is required only for the V2 bindings, and it enables a platform to
+ * specify the extn to be used for certain property names. The properties to
+ * which the extension will apply are opp-microvolt and opp-microamp. OPP core
+ * should postfix the property name with -<name> while looking for them.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * Hence this function internally uses RCU updater strategy with mutex locks
+ * to keep the integrity of the internal data structures. Callers should ensure
+ * that this function is *NOT* called under RCU protection or in contexts where
+ * mutex cannot be locked.
+ */
+int dev_pm_opp_set_prop_name(struct device *dev, const char *name)
+{
+        struct device_opp *dev_opp;
+        int ret = 0;
+
+        /* Hold our list modification lock here */
+        mutex_lock(&dev_opp_list_lock);
+
+        dev_opp = _add_device_opp(dev);
+        if (!dev_opp) {
+                ret = -ENOMEM;
+                goto unlock;
+        }
+
+        /* Make sure there are no concurrent readers while updating dev_opp */
+        WARN_ON(!list_empty(&dev_opp->opp_list));
+
+        /* Do we already have a prop-name associated with dev_opp? */
+        if (dev_opp->prop_name) {
+                dev_err(dev, "%s: Already have prop-name %s\n", __func__,
+                        dev_opp->prop_name);
+                ret = -EBUSY;
+                goto err;
+        }
+
+        dev_opp->prop_name = kstrdup(name, GFP_KERNEL);
+        if (!dev_opp->prop_name) {
+                ret = -ENOMEM;
+                goto err;
+        }
+
+        mutex_unlock(&dev_opp_list_lock);
+        return 0;
+
+err:
+        _remove_device_opp(dev_opp);
+unlock:
+        mutex_unlock(&dev_opp_list_lock);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_set_prop_name);
+
+/**
+ * dev_pm_opp_put_prop_name() - Releases resources blocked for prop-name
+ * @dev: Device for which the regulator has to be set.
+ *
+ * This is required only for the V2 bindings, and is called for a matching
+ * dev_pm_opp_set_prop_name(). Until this is called, the device_opp structure
+ * will not be freed.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * Hence this function internally uses RCU updater strategy with mutex locks
+ * to keep the integrity of the internal data structures. Callers should ensure
+ * that this function is *NOT* called under RCU protection or in contexts where
+ * mutex cannot be locked.
+ */
+void dev_pm_opp_put_prop_name(struct device *dev)
+{
+        struct device_opp *dev_opp;
+
+        /* Hold our list modification lock here */
+        mutex_lock(&dev_opp_list_lock);
+
+        /* Check for existing list for 'dev' first */
+        dev_opp = _find_device_opp(dev);
+        if (IS_ERR(dev_opp)) {
+                dev_err(dev, "Failed to find dev_opp: %ld\n", PTR_ERR(dev_opp));
+                goto unlock;
+        }
+
+        /* Make sure there are no concurrent readers while updating dev_opp */
+        WARN_ON(!list_empty(&dev_opp->opp_list));
+
+        if (!dev_opp->prop_name) {
+                dev_err(dev, "%s: Doesn't have a prop-name\n", __func__);
+                goto unlock;
+        }
+
+        kfree(dev_opp->prop_name);
+        dev_opp->prop_name = NULL;
+
+        /* Try freeing device_opp if this was the last blocking resource */
+        _remove_device_opp(dev_opp);
+
+unlock:
+        mutex_unlock(&dev_opp_list_lock);
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_put_prop_name);
+
 static bool _opp_is_supported(struct device *dev, struct device_opp *dev_opp,
                               struct device_node *np)
 {
@@ -1042,7 +1177,7 @@ static int _opp_add_static_v2(struct device *dev, struct device_node *np)
         if (!of_property_read_u32(np, "clock-latency-ns", &val))
                 new_opp->clock_latency_ns = val;
 
-        ret = opp_parse_supplies(new_opp, dev);
+        ret = opp_parse_supplies(new_opp, dev, dev_opp);
         if (ret)
                 goto free_opp;
 
diff --git a/drivers/base/power/opp/opp.h b/drivers/base/power/opp/opp.h
index 70f4564a6ab9..690638ef36ee 100644
--- a/drivers/base/power/opp/opp.h
+++ b/drivers/base/power/opp/opp.h
@@ -131,6 +131,7 @@ struct device_list_opp {
  * @suspend_opp: Pointer to OPP to be used during device suspend.
  * @supported_hw: Array of version number to support.
  * @supported_hw_count: Number of elements in supported_hw array.
+ * @prop_name: A name to postfix to many DT properties, while parsing them.
  * @dentry:     debugfs dentry pointer of the real device directory (not links).
  * @dentry_name: Name of the real dentry.
  *
@@ -157,6 +158,7 @@ struct device_opp {
 
         unsigned int *supported_hw;
         unsigned int supported_hw_count;
+        const char *prop_name;
 
 #ifdef CONFIG_DEBUG_FS
         struct dentry *dentry;