[RFC PATCH 5/5] firmware: upload: Enable cancel of firmware upload

[Russ Weight]

Extend the Firmware Upload framework to include a cancel IOCTL that can be
used to request that a firmware upload be cancelled. The IOCTL may return
ENODEV if there is no update in progress.

Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
---
 .../driver-api/firmware/firmware-upload.rst   |  8 +++++++
 drivers/firmware/firmware-upload.c            | 24 +++++++++++++++++--
 include/linux/firmware/firmware-upload.h      |  4 ++++
 include/uapi/linux/firmware-upload.h          |  2 ++
 4 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/Documentation/driver-api/firmware/firmware-upload.rst b/Documentation/driver-api/firmware/firmware-upload.rst
index bf079d648b5c..1a0a487fd4d6 100644
--- a/Documentation/driver-api/firmware/firmware-upload.rst
+++ b/Documentation/driver-api/firmware/firmware-upload.rst
@@ -44,3 +44,11 @@ FW_UPLOAD_STATUS:
 Collect status for an on-going firmware upload. The status returned includes
 how much data remains to be transferred, the progress of the upload, and
 error information in the case of a failure.
+
+FW_UPLOAD_CANCEL:
+
+Request that an on-going firmware upload be cancelled. This IOCTL will
+return ENODEV if there is no upload in progress. Depending on the
+implementation of the lower-level driver, the cancellation may take affect
+immediately or it could block until a critical operation such as a FLASH
+is safely completed.
diff --git a/drivers/firmware/firmware-upload.c b/drivers/firmware/firmware-upload.c
index 507cd0f3740e..7677121ba49e 100644
--- a/drivers/firmware/firmware-upload.c
+++ b/drivers/firmware/firmware-upload.c
@@ -181,11 +181,20 @@ static int fw_upload_ioctl_status(struct fw_upload *fwl, unsigned long arg)
 	return 0;
 }
 
+static int fw_upload_ioctl_cancel(struct fw_upload *fwl, unsigned long arg)
+{
+	if (fwl->progress == FW_UPLOAD_PROG_IDLE)
+		return -ENODEV;
+
+	fwl->ops->cancel(fwl);
+	return 0;
+}
+
 static long fw_upload_ioctl(struct file *filp, unsigned int cmd,
 			    unsigned long arg)
 {
 	struct fw_upload *fwl = filp->private_data;
-	int ret = -ENOTTY;
+	int ret = 0;
 
 	mutex_lock(&fwl->lock);
 
@@ -196,6 +205,12 @@ static long fw_upload_ioctl(struct file *filp, unsigned int cmd,
 	case FW_UPLOAD_STATUS:
 		ret = fw_upload_ioctl_status(fwl, arg);
 		break;
+	case FW_UPLOAD_CANCEL:
+		ret = fw_upload_ioctl_cancel(fwl, arg);
+		break;
+	default:
+		ret = -ENOTTY;
+		break;
 	}
 
 	mutex_unlock(&fwl->lock);
@@ -226,6 +241,8 @@ static int fw_upload_release(struct inode *inode, struct file *filp)
 		goto close_exit;
 	}
 
+	fwl->ops->cancel(fwl);
+
 	mutex_unlock(&fwl->lock);
 	flush_work(&fwl->work);
 
@@ -260,7 +277,8 @@ fw_upload_register(struct device *parent, const struct fw_upload_ops *ops,
 	struct fw_upload *fwl;
 	int ret;
 
-	if (!ops || !ops->prepare || !ops->write || !ops->poll_complete) {
+	if (!ops || !ops->cancel || !ops->prepare ||
+	    !ops->write || !ops->poll_complete) {
 		dev_err(parent, "Attempt to register without all required ops\n");
 		return ERR_PTR(-ENOMEM);
 	}
@@ -339,6 +357,8 @@ void fw_upload_unregister(struct fw_upload *fwl)
 		goto unregister;
 	}
 
+	fwl->ops->cancel(fwl);
+
 	mutex_unlock(&fwl->lock);
 	flush_work(&fwl->work);
 
diff --git a/include/linux/firmware/firmware-upload.h b/include/linux/firmware/firmware-upload.h
index 63c6c65e7489..6f3971b8e117 100644
--- a/include/linux/firmware/firmware-upload.h
+++ b/include/linux/firmware/firmware-upload.h
@@ -26,6 +26,9 @@ struct fw_upload;
  *			    written.
  * @poll_complete:	    Required: Check for the completion of the
  *			    HW authentication/programming process.
+ * @cancel:		    Required: Request cancellation of update. This op
+ *			    is called from the context of a different kernel
+ *			    thread, so race conditions need to be considered.
  * @cleanup:		    Optional: Complements the prepare()
  *			    function and is called at the completion
  *			    of the update, whether success or failure,
@@ -36,6 +39,7 @@ struct fw_upload_ops {
 	s32 (*write)(struct fw_upload *fwl, const u8 *data,
 		     u32 offset, u32 size);
 	u32 (*poll_complete)(struct fw_upload *fwl);
+	void (*cancel)(struct fw_upload *fwl);
 	void (*cleanup)(struct fw_upload *fwl);
 };
 
diff --git a/include/uapi/linux/firmware-upload.h b/include/uapi/linux/firmware-upload.h
index b8d96ee3f646..3bf985d27256 100644
--- a/include/uapi/linux/firmware-upload.h
+++ b/include/uapi/linux/firmware-upload.h
@@ -68,4 +68,6 @@ struct fw_upload_status {
 
 #define FW_UPLOAD_STATUS	_IOR(FW_UPLOAD_MAGIC, 1, struct fw_upload_status)
 
+#define FW_UPLOAD_CANCEL	_IO(FW_UPLOAD_MAGIC, 2)
+
 #endif /* _UAPI_LINUX_FW_UPLOAD_H */
-- 
2.25.1