PM / OPP: Parse 'opp-supported-hw' binding

OPP bindings allow a platform to enable OPPs based on the version of the
hardware they are used for.

Add support to the OPP-core to parse these bindings, by introducing
dev_pm_opp_{set|put}_supported_hw() 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, 153 insertions, 0 deletions

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 6aa172be6e8e..55cf1a99b532 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -559,6 +559,9 @@ static void _remove_device_opp(struct device_opp *dev_opp)
         if (!list_empty(&dev_opp->opp_list))
                 return;
 
+        if (dev_opp->supported_hw)
+                return;
+
         list_dev = list_first_entry(&dev_opp->dev_list, struct device_list_opp,
                                     node);
 
@@ -834,6 +837,145 @@ static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev)
 }
 
 /**
+ * dev_pm_opp_set_supported_hw() - Set supported platforms
+ * @dev: Device for which supported-hw has to be set.
+ * @versions: Array of hierarchy of versions to match.
+ * @count: Number of elements in the array.
+ *
+ * This is required only for the V2 bindings, and it enables a platform to
+ * specify the hierarchy of versions it supports. OPP layer will then enable
+ * OPPs, which are available for those versions, based on its 'opp-supported-hw'
+ * property.
+ *
+ * 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_supported_hw(struct device *dev, const u32 *versions,
+                                unsigned int count)
+{
+        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 version hierarchy associated with dev_opp? */
+        if (dev_opp->supported_hw) {
+                dev_err(dev, "%s: Already have supported hardware list\n",
+                        __func__);
+                ret = -EBUSY;
+                goto err;
+        }
+
+        dev_opp->supported_hw = kmemdup(versions, count * sizeof(*versions),
+                                        GFP_KERNEL);
+        if (!dev_opp->supported_hw) {
+                ret = -ENOMEM;
+                goto err;
+        }
+
+        dev_opp->supported_hw_count = count;
+        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_supported_hw);
+
+/**
+ * dev_pm_opp_put_supported_hw() - Releases resources blocked for supported hw
+ * @dev: Device for which supported-hw has to be set.
+ *
+ * This is required only for the V2 bindings, and is called for a matching
+ * dev_pm_opp_set_supported_hw(). 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_supported_hw(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->supported_hw) {
+                dev_err(dev, "%s: Doesn't have supported hardware list\n",
+                        __func__);
+                goto unlock;
+        }
+
+        kfree(dev_opp->supported_hw);
+        dev_opp->supported_hw = NULL;
+        dev_opp->supported_hw_count = 0;
+
+        /* 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_supported_hw);
+
+static bool _opp_is_supported(struct device *dev, struct device_opp *dev_opp,
+                              struct device_node *np)
+{
+        unsigned int count = dev_opp->supported_hw_count;
+        u32 version;
+        int ret;
+
+        if (!dev_opp->supported_hw)
+                return true;
+
+        while (count--) {
+                ret = of_property_read_u32_index(np, "opp-supported-hw", count,
+                                                 &version);
+                if (ret) {
+                        dev_warn(dev, "%s: failed to read opp-supported-hw property at index %d: %d\n",
+                                 __func__, count, ret);
+                        return false;
+                }
+
+                /* Both of these are bitwise masks of the versions */
+                if (!(version & dev_opp->supported_hw[count]))
+                        return false;
+        }
+
+        return true;
+}
+
+/**
  * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
  * @dev:        device for which we do this operation
  * @np:         device node
@@ -879,6 +1021,12 @@ static int _opp_add_static_v2(struct device *dev, struct device_node *np)
                 goto free_opp;
         }
 
+        /* Check if the OPP supports hardware's hierarchy of versions or not */
+        if (!_opp_is_supported(dev, dev_opp, np)) {
+                dev_dbg(dev, "OPP not supported by hardware: %llu\n", rate);
+                goto free_opp;
+        }
+
         /*
          * Rate is defined as an unsigned long in clk API, and so casting
          * explicitly to its type. Must be fixed once rate is 64 bit
diff --git a/drivers/base/power/opp/opp.h b/drivers/base/power/opp/opp.h
index b8880c7f8be1..70f4564a6ab9 100644
--- a/drivers/base/power/opp/opp.h
+++ b/drivers/base/power/opp/opp.h
@@ -129,6 +129,8 @@ struct device_list_opp {
  * @clock_latency_ns_max: Max clock latency in nanoseconds.
  * @shared_opp: OPP is shared between multiple devices.
  * @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.
  * @dentry:     debugfs dentry pointer of the real device directory (not links).
  * @dentry_name: Name of the real dentry.
  *
@@ -153,6 +155,9 @@ struct device_opp {
         bool shared_opp;
         struct dev_pm_opp *suspend_opp;
 
+        unsigned int *supported_hw;
+        unsigned int supported_hw_count;
+
 #ifdef CONFIG_DEBUG_FS
         struct dentry *dentry;
         char dentry_name[NAME_MAX];