[PATCH v2 3/3] fpga: region: Add runtime PM support

[Nava kishore Manne <nava.manne@xilinx.com>]

Add support to handle FPGA/PL power domain. With this patch,
the PL power domain will be turned on before loading the bitstream
into the targeted region and turned off while removing/unloading the
bitstream from the targeted region using overlays. This can be achieved
by adding the runtime PM support to the fpga regions.

Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
---
Changes for v2:
              - Updated commit message.
              - Updated runtime PM handling logic to fix the PM ref count
                imbalance issues.

 drivers/fpga/of-fpga-region.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/fpga/of-fpga-region.c b/drivers/fpga/of-fpga-region.c
index ae82532fc127..f14bb5916d97 100644
--- a/drivers/fpga/of-fpga-region.c
+++ b/drivers/fpga/of-fpga-region.c
@@ -15,6 +15,7 @@
 #include <linux/of_platform.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/pm_runtime.h>
 
 static const struct of_device_id fpga_region_of_match[] = {
 	{ .compatible = "fpga-region", },
@@ -301,10 +302,17 @@ static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
 		return -EINVAL;
 	}
 
+	ret = pm_runtime_resume_and_get(dev->parent);
+	if (ret < 0) {
+		fpga_image_info_free(info);
+		return ret;
+	}
+
 	region->info = info;
 	ret = fpga_region_program_fpga(region);
 	if (ret) {
 		/* error; reject overlay */
+		pm_runtime_put_sync(dev->parent);
 		fpga_image_info_free(info);
 		region->info = NULL;
 	}
@@ -324,10 +332,13 @@ static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
 static void of_fpga_region_notify_post_remove(struct fpga_region *region,
 					      struct of_overlay_notify_data *nd)
 {
+	struct device *dev = &region->dev;
+
 	fpga_bridges_disable(&region->bridge_list);
 	fpga_bridges_put(&region->bridge_list);
 	fpga_image_info_free(region->info);
 	region->info = NULL;
+	pm_runtime_put_sync(dev->parent);
 }
 
 /**
@@ -411,6 +422,8 @@ static int of_fpga_region_probe(struct platform_device *pdev)
 		goto eprobe_mgr_put;
 	}
 
+	pm_runtime_enable(&pdev->dev);
+
 	of_platform_populate(np, fpga_region_of_match, NULL, &region->dev);
 	platform_set_drvdata(pdev, region);
 
@@ -430,6 +443,7 @@ static int of_fpga_region_remove(struct platform_device *pdev)
 
 	fpga_region_unregister(region);
 	fpga_mgr_put(mgr);
+	pm_runtime_disable(region->dev.parent);
 
 	return 0;
 }
-- 
2.25.1