[PATCH v3] fpga: dfl: afu: use PFN_DOWN() helper macro

[Peter Colberg <peter.colberg@intel.com>]

Replace right shifts by PAGE_SHIFT with PFN_DOWN() helper macro to convert
from physical addresses to page frame numbers.

These changes are cosmetic only; no functional changes.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Peter Colberg <peter.colberg@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
v3:
- Revert afu_mmap(), which calculates file offsets, not physical pages
v2:
- Comment in commit message that changes are cosmetic only
---
 drivers/fpga/dfl-afu-dma-region.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/fpga/dfl-afu-dma-region.c b/drivers/fpga/dfl-afu-dma-region.c
index 02b60fde0430..e8d54cfbb301 100644
--- a/drivers/fpga/dfl-afu-dma-region.c
+++ b/drivers/fpga/dfl-afu-dma-region.c
@@ -10,6 +10,7 @@
  */
 
 #include <linux/dma-mapping.h>
+#include <linux/pfn.h>
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
 #include <linux/mm.h>
@@ -34,7 +35,7 @@ void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
 static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
 			     struct dfl_afu_dma_region *region)
 {
-	int npages = region->length >> PAGE_SHIFT;
+	int npages = PFN_DOWN(region->length);
 	struct device *dev = &pdata->dev->dev;
 	int ret, pinned;
 
@@ -82,7 +83,7 @@ static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
 static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
 				struct dfl_afu_dma_region *region)
 {
-	long npages = region->length >> PAGE_SHIFT;
+	long npages = PFN_DOWN(region->length);
 	struct device *dev = &pdata->dev->dev;
 
 	unpin_user_pages(region->pages, npages);
@@ -101,7 +102,7 @@ static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
  */
 static bool afu_dma_check_continuous_pages(struct dfl_afu_dma_region *region)
 {
-	int npages = region->length >> PAGE_SHIFT;
+	int npages = PFN_DOWN(region->length);
 	int i;
 
 	for (i = 0; i < npages - 1; i++)
-- 
2.28.0