[PATCH v16 3/5] fpga: image-load: signal eventfd when complete

[Russ Weight <russell.h.weight@xxxxxxxxx>]

Amend the FPGA_IMAGE_LOAD_WRITE IOCTL implementation to include an
eventfd file descriptor as a parameter. The eventfd will be triggered
when the image upload completes.

Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
---
v16:
 - Some cleanup of documentation for the FPGA_IMAGE_LOAD_WRITE IOCTL.
v15:
 - This patch is new to the patch-set, and adds an eventfd to the
   FPGA_IMAGE_LOAD_WRITE IOCTL. The eventfd is signalled upon completion
   of an update.
---
 Documentation/fpga/fpga-image-load.rst | 12 +++++++-----
 drivers/fpga/fpga-image-load.c         | 22 ++++++++++++++++++++--
 include/linux/fpga/fpga-image-load.h   |  2 ++
 include/uapi/linux/fpga-image-load.h   |  3 ++-
 4 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/Documentation/fpga/fpga-image-load.rst b/Documentation/fpga/fpga-image-load.rst
index ba371c7c0ca0..22a455421bb4 100644
--- a/Documentation/fpga/fpga-image-load.rst
+++ b/Documentation/fpga/fpga-image-load.rst
@@ -27,8 +27,10 @@ ioctl
 
 FPGA_IMAGE_LOAD_WRITE:
 
-Start an image upload with the provided image buffer. This IOCTL returns
-immediately after starting a kernel worker thread to process the image
-upload which could take as long a 40 minutes depending on the actual device
-being updated. This is an exclusive operation; an attempt to start
-concurrent image uploads for the same device will fail with EBUSY.
+Start an image upload with the provided image buffer. This IOCTL returns
+immediately after starting a kernel worker thread to process the image
+upload which could take as long a 40 minutes depending on the actual device
+being updated. This is an exclusive operation; an attempt to start
+concurrent image loads for the same device will fail with EBUSY. An eventfd
+file descriptor parameter is provided to this IOCTL. It will be signalled
+at the completion of the image upload.
diff --git a/drivers/fpga/fpga-image-load.c b/drivers/fpga/fpga-image-load.c
index 65f553b59011..09164a0258a5 100644
--- a/drivers/fpga/fpga-image-load.c
+++ b/drivers/fpga/fpga-image-load.c
@@ -34,6 +34,7 @@ static void fpga_image_prog_complete(struct fpga_image_load *imgld)
 {
 	mutex_lock(&imgld->lock);
 	imgld->progress = FPGA_IMAGE_PROG_IDLE;
+	eventfd_signal(imgld->finished, 1);
 	mutex_unlock(&imgld->lock);
 }
 
@@ -112,6 +113,8 @@ static void fpga_image_do_load(struct work_struct *work)
 	vfree(imgld->data);
 	imgld->data = NULL;
 	fpga_image_prog_complete(imgld);
+	eventfd_ctx_put(imgld->finished);
+	imgld->finished = NULL;
 }
 
 static int fpga_image_load_ioctl_write(struct fpga_image_load *imgld,
@@ -119,6 +122,7 @@ static int fpga_image_load_ioctl_write(struct fpga_image_load *imgld,
 {
 	struct fpga_image_write wb;
 	unsigned long minsz;
+	int ret;
 	u8 *buf;
 
 	if (imgld->driver_unload || imgld->progress != FPGA_IMAGE_PROG_IDLE)
@@ -135,13 +139,23 @@ static int fpga_image_load_ioctl_write(struct fpga_image_load *imgld,
 	if (wb.size & 0x3)
 		return -EINVAL;
 
+	if (wb.evtfd < 0)
+		return -EINVAL;
+
 	buf = vzalloc(wb.size);
 	if (!buf)
 		return -ENOMEM;
 
 	if (copy_from_user(buf, u64_to_user_ptr(wb.buf), wb.size)) {
-		vfree(buf);
-		return -EFAULT;
+		ret = -EFAULT;
+		goto exit_free;
+	}
+
+	imgld->finished = eventfd_ctx_fdget(wb.evtfd);
+	if (IS_ERR(imgld->finished)) {
+		ret = PTR_ERR(imgld->finished);
+		imgld->finished = NULL;
+		goto exit_free;
 	}
 
 	imgld->data = buf;
@@ -151,6 +165,10 @@ static int fpga_image_load_ioctl_write(struct fpga_image_load *imgld,
 	queue_work(system_unbound_wq, &imgld->work);
 
 	return 0;
+
+exit_free:
+	vfree(buf);
+	return ret;
 }
 
 static long fpga_image_load_ioctl(struct file *filp, unsigned int cmd,
diff --git a/include/linux/fpga/fpga-image-load.h b/include/linux/fpga/fpga-image-load.h
index 41ab63cf7b20..7d39daa4d921 100644
--- a/include/linux/fpga/fpga-image-load.h
+++ b/include/linux/fpga/fpga-image-load.h
@@ -9,6 +9,7 @@
 
 #include <linux/cdev.h>
 #include <linux/device.h>
+#include <linux/eventfd.h>
 #include <linux/mutex.h>
 #include <linux/types.h>
 #include <uapi/linux/fpga-image-load.h>
@@ -52,6 +53,7 @@ struct fpga_image_load {
 	u32 progress;
 	u32 err_code;			/* image load error code */
 	bool driver_unload;
+	struct eventfd_ctx *finished;
 	void *priv;
 };
 
diff --git a/include/uapi/linux/fpga-image-load.h b/include/uapi/linux/fpga-image-load.h
index 0382078c5a6c..152a8e1c031f 100644
--- a/include/uapi/linux/fpga-image-load.h
+++ b/include/uapi/linux/fpga-image-load.h
@@ -38,7 +38,7 @@
  *				struct fpga_image_write)
  *
  * Upload a data buffer to the target device. The user must provide the
- * data buffer and size.
+ * data buffer, size, and an eventfd file descriptor.
  *
  * Return: 0 on success, -errno on failure.
  */
@@ -46,6 +46,7 @@ struct fpga_image_write {
 	/* Input */
 	__u32 flags;		/* Zero for now */
 	__u32 size;		/* Data size (in bytes) to be written */
+	__s32 evtfd;		/* File descriptor for completion signal */
 	__u64 buf;		/* User space address of source data */
 };
 
-- 
2.25.1