device property: Introduce firmware node type for platform data

Introduce data structures and code allowing "built-in" properties
to be associated with devices in such a way that they will be used
by the device_property_* API if no proper firmware node (neither DT
nor ACPI) is present for the given device.

Each property is to be represented by a property_entry structure.
An array of property_entry structures (terminated with a null
entry) can be pointed to by the properties field of struct
property_set that can be added as a firmware node to a struct
device using device_add_property_set().  That will cause the
device_property_* API to use that property_set as the source
of properties if the given device does not have a DT node or
an ACPI companion device object associated with it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 127 insertions, 5 deletions

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 62787bc89a1d..6a3f7d8af341 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -10,10 +10,96 @@
  * published by the Free Software Foundation.
  */
 
-#include <linux/property.h>
-#include <linux/export.h>
 #include <linux/acpi.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
 #include <linux/of.h>
+#include <linux/property.h>
+
+/**
+ * device_add_property_set - Add a collection of properties to a device object.
+ * @dev: Device to add properties to.
+ * @pset: Collection of properties to add.
+ *
+ * Associate a collection of device properties represented by @pset with @dev
+ * as its secondary firmware node.
+ */
+void device_add_property_set(struct device *dev, struct property_set *pset)
+{
+        if (pset)
+                pset->fwnode.type = FWNODE_PDATA;
+
+        set_secondary_fwnode(dev, &pset->fwnode);
+}
+EXPORT_SYMBOL_GPL(device_add_property_set);
+
+static inline bool is_pset(struct fwnode_handle *fwnode)
+{
+        return fwnode && fwnode->type == FWNODE_PDATA;
+}
+
+static inline struct property_set *to_pset(struct fwnode_handle *fwnode)
+{
+        return is_pset(fwnode) ?
+                container_of(fwnode, struct property_set, fwnode) : NULL;
+}
+
+static struct property_entry *pset_prop_get(struct property_set *pset,
+                                            const char *name)
+{
+        struct property_entry *prop;
+
+        if (!pset || !pset->properties)
+                return NULL;
+
+        for (prop = pset->properties; prop->name; prop++)
+                if (!strcmp(name, prop->name))
+                        return prop;
+
+        return NULL;
+}
+
+static int pset_prop_read_array(struct property_set *pset, const char *name,
+                                enum dev_prop_type type, void *val, size_t nval)
+{
+        struct property_entry *prop;
+        unsigned int item_size;
+
+        prop = pset_prop_get(pset, name);
+        if (!prop)
+                return -ENODATA;
+
+        if (prop->type != type)
+                return -EPROTO;
+
+        if (!val)
+                return prop->nval;
+
+        if (prop->nval < nval)
+                return -EOVERFLOW;
+
+        switch (type) {
+        case DEV_PROP_U8:
+                item_size = sizeof(u8);
+                break;
+        case DEV_PROP_U16:
+                item_size = sizeof(u16);
+                break;
+        case DEV_PROP_U32:
+                item_size = sizeof(u32);
+                break;
+        case DEV_PROP_U64:
+                item_size = sizeof(u64);
+                break;
+        case DEV_PROP_STRING:
+                item_size = sizeof(const char *);
+                break;
+        default:
+                return -EINVAL;
+        }
+        memcpy(val, prop->value.raw_data, nval * item_size);
+        return 0;
+}
 
 static inline struct fwnode_handle *dev_fwnode(struct device *dev)
 {
@@ -46,7 +132,7 @@ bool fwnode_property_present(struct fwnode_handle *fwnode, const char *propname)
         else if (is_acpi_node(fwnode))
                 return !acpi_dev_prop_get(acpi_node(fwnode), propname, NULL);
 
-        return false;
+        return !!pset_prop_get(to_pset(fwnode), propname);
 }
 EXPORT_SYMBOL_GPL(fwnode_property_present);
 
@@ -205,7 +291,8 @@ EXPORT_SYMBOL_GPL(device_property_read_string);
                 _ret_ = acpi_dev_prop_read(acpi_node(_fwnode_), _propname_, \
                                            _proptype_, _val_, _nval_); \
         else \
-                _ret_ = -ENXIO; \
+                _ret_ = pset_prop_read_array(to_pset(_fwnode_), _propname_, \
+                                             _proptype_, _val_, _nval_); \
         _ret_; \
 })
 
@@ -344,7 +431,8 @@ int fwnode_property_read_string_array(struct fwnode_handle *fwnode,
                 return acpi_dev_prop_read(acpi_node(fwnode), propname,
                                           DEV_PROP_STRING, val, nval);
 
-        return -ENXIO;
+        return pset_prop_read_array(to_pset(fwnode), propname,
+                                    DEV_PROP_STRING, val, nval);
 }
 EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);
 
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index fc30b84b532a..0408545bce42 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -16,6 +16,7 @@ enum fwnode_type {
         FWNODE_INVALID = 0,
         FWNODE_OF,
         FWNODE_ACPI,
+        FWNODE_PDATA,
 };
 
 struct fwnode_handle {
diff --git a/include/linux/property.h b/include/linux/property.h
index 31dfd3db35d6..de8bdf417a35 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -131,4 +131,37 @@ static inline int fwnode_property_read_u64(struct fwnode_handle *fwnode,
         return fwnode_property_read_u64_array(fwnode, propname, val, 1);
 }
 
+/**
+ * struct property_entry - "Built-in" device property representation.
+ * @name: Name of the property.
+ * @type: Type of the property.
+ * @nval: Number of items of type @type making up the value.
+ * @value: Value of the property (an array of @nval items of type @type).
+ */
+struct property_entry {
+        const char *name;
+        enum dev_prop_type type;
+        size_t nval;
+        union {
+                void *raw_data;
+                u8 *u8_data;
+                u16 *u16_data;
+                u32 *u32_data;
+                u64 *u64_data;
+                const char **str;
+        } value;
+};
+
+/**
+ * struct property_set - Collection of "built-in" device properties.
+ * @fwnode: Handle to be pointed to by the fwnode field of struct device.
+ * @properties: Array of properties terminated with a null entry.
+ */
+struct property_set {
+        struct fwnode_handle fwnode;
+        struct property_entry *properties;
+};
+
+void device_add_property_set(struct device *dev, struct property_set *pset);
+
 #endif /* _LINUX_PROPERTY_H_ */