platform: introduce OF style 'modalias' support for platform bus

Fix a problem that, the platform bus supports the OF style modalias
in .uevent() call, but not in its device 'modalias' sysfs attribute.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

3 files changed, 13 insertions, 0 deletions

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 2f4aea2428b2..bc78848dd59a 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -679,6 +679,10 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
         struct platform_device  *pdev = to_platform_device(dev);
         int len;
 
+        len = of_device_get_modalias(dev, buf, PAGE_SIZE -1);
+        if (len != -ENODEV)
+                return len;
+
         len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
         if (len != -ENODEV)
                 return len;
diff --git a/drivers/of/device.c b/drivers/of/device.c
index f685e55e0717..dafb9736ab9b 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -85,6 +85,9 @@ ssize_t of_device_get_modalias(struct device *dev, char *str, ssize_t len)
         int cplen, i;
         ssize_t tsize, csize, repend;
 
+        if ((!dev) || (!dev->of_node))
+                return -ENODEV;
+
         /* Name & Type */
         csize = snprintf(str, len, "of:N%sT%s", dev->of_node->name,
                          dev->of_node->type);
diff --git a/include/linux/of_device.h b/include/linux/of_device.h
index 82ce324fdce7..8d7dd6768cb7 100644
--- a/include/linux/of_device.h
+++ b/include/linux/of_device.h
@@ -64,6 +64,12 @@ static inline int of_driver_match_device(struct device *dev,
 static inline void of_device_uevent(struct device *dev,
                         struct kobj_uevent_env *env) { }
 
+static inline int of_device_get_modalias(struct device *dev,
+                                   char *str, ssize_t len)
+{
+        return -ENODEV;
+}
+
 static inline int of_device_uevent_modalias(struct device *dev,
                                    struct kobj_uevent_env *env)
 {