mfd: Fetch cell pointer from platform_device->mfd_cell

In order for MFD drivers to fetch their cell pointer but also their
platform data one, an mfd cell pointer is added to the platform_device
structure.
That allows all MFD sub devices drivers to be MFD agnostic, unless
they really need to access their MFD cell data. Most of them don't,
especially the ones for IPs used by both MFD and non MFD SoCs.

Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Greg KH <gregkh@suse.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/base/platform.c

@@ -149,6 +149,7 @@ static void platform_device_release(struct device *dev)
 
 	of_device_node_put(&pa->pdev.dev);
 	kfree(pa->pdev.dev.platform_data);
+	kfree(pa->pdev.mfd_cell);
 	kfree(pa->pdev.resource);
 	kfree(pa);
 }

drivers/mfd/mfd-core.c

@@ -55,6 +55,19 @@ int mfd_cell_disable(struct platform_device *pdev)
 }
 EXPORT_SYMBOL(mfd_cell_disable);
 
+static int mfd_platform_add_cell(struct platform_device *pdev,
+				 const struct mfd_cell *cell)
+{
+	if (!cell)
+		return 0;
+
+	pdev->mfd_cell = kmemdup(cell, sizeof(*cell), GFP_KERNEL);
+	if (!pdev->mfd_cell)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static int mfd_add_device(struct device *parent, int id,
 			  const struct mfd_cell *cell,
 			  struct resource *mem_base,
@@ -75,7 +88,7 @@ static int mfd_add_device(struct device *parent, int id,
 
 	pdev->dev.parent = parent;
 
-	ret = platform_device_add_data(pdev, cell, sizeof(*cell));
+	ret = mfd_platform_add_cell(pdev, cell);
 	if (ret)
 		goto fail_res;
 
@@ -123,7 +136,6 @@ static int mfd_add_device(struct device *parent, int id,
 
 	return 0;
 
-/*	platform_device_del(pdev); */
 fail_res:
 	kfree(res);
 fail_device:

include/linux/mfd/core.h

@@ -86,16 +86,25 @@ extern int mfd_clone_cell(const char *cell, const char **clones,
  */
 static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev)
 {
-	return pdev->dev.platform_data;
+	return pdev->mfd_cell;
 }
 
 /*
  * Given a platform device that's been created by mfd_add_devices(), fetch
  * the .mfd_data entry from the mfd_cell that created it.
+ * Otherwise just return the platform_data pointer.
+ * This maintains compatibility with platform drivers whose devices aren't
+ * created by the mfd layer, and expect platform_data to contain what would've
+ * otherwise been in mfd_data.
  */
 static inline void *mfd_get_data(struct platform_device *pdev)
 {
-	return mfd_get_cell(pdev)->mfd_data;
+	const struct mfd_cell *cell = mfd_get_cell(pdev);
+
+	if (cell)
+		return cell->mfd_data;
+	else
+		return pdev->dev.platform_data;
 }
 
 extern int mfd_add_devices(struct device *parent, int id,

include/linux/platform_device.h

@@ -14,6 +14,8 @@
 #include <linux/device.h>
 #include <linux/mod_devicetable.h>
 
+struct mfd_cell;
+
 struct platform_device {
 	const char	* name;
 	int		id;
@@ -23,6 +25,9 @@ struct platform_device {
 
 	const struct platform_device_id	*id_entry;
 
+	/* MFD cell pointer */
+	struct mfd_cell *mfd_cell;
+
 	/* arch specific additions */
 	struct pdev_archdata	archdata;
 };