[PATCH v4 06/15] fpga: dfl: fme: add DFL_FPGA_FME_PORT_RELEASE/ASSIGN ioctl support.

[Wu Hao]

In order to support virtualization usage via PCIe SRIOV, this patch
adds two ioctls under FPGA Management Engine (FME) to release and
assign back the port device. In order to safely turn Port from PF
into VF and enable PCIe SRIOV, it requires user to invoke this
PORT_RELEASE ioctl to release port firstly to remove userspace
interfaces, and then configure the PF/VF access register in FME.
After disable SRIOV, it requires user to invoke this PORT_ASSIGN
ioctl to attach the port back to PF.

 Ioctl interfaces:
 * DFL_FPGA_FME_PORT_RELEASE
   Release platform device of given port, it deletes port platform
   device to remove related userspace interfaces on PF, then
   configures PF/VF access mode to VF.

 * DFL_FPGA_FME_PORT_ASSIGN
   Assign platform device of given port back to PF, it configures
   PF/VF access mode to PF, then adds port platform device back to
   re-enable related userspace interfaces on PF.

Signed-off-by: Zhang Yi Z <yi.z.zhang@xxxxxxxxx>
Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
Signed-off-by: Wu Hao <hao.wu@xxxxxxxxx>
Acked-by: Alan Tull <atull@xxxxxxxxxx>
Acked-by: Moritz Fischer <mdf@xxxxxxxxxx>
---
v3: code rebase.
v4: no change.
---
 drivers/fpga/dfl-fme-main.c   |  54 +++++++++++++++++++++
 drivers/fpga/dfl.c            | 107 +++++++++++++++++++++++++++++++++++++-----
 drivers/fpga/dfl.h            |  10 ++++
 include/uapi/linux/fpga-dfl.h |  32 +++++++++++++
 4 files changed, 191 insertions(+), 12 deletions(-)

diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
index 076d74f..8b2a337 100644
--- a/drivers/fpga/dfl-fme-main.c
+++ b/drivers/fpga/dfl-fme-main.c
@@ -16,6 +16,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/uaccess.h>
 #include <linux/fpga-dfl.h>
 
 #include "dfl.h"
@@ -105,9 +106,62 @@ static void fme_hdr_uinit(struct platform_device *pdev,
 	sysfs_remove_files(&pdev->dev.kobj, fme_hdr_attrs);
 }
 
+static long fme_hdr_ioctl_release_port(struct dfl_feature_platform_data *pdata,
+				       void __user *arg)
+{
+	struct dfl_fpga_cdev *cdev = pdata->dfl_cdev;
+	struct dfl_fpga_fme_port_release release;
+	unsigned long minsz;
+
+	minsz = offsetofend(struct dfl_fpga_fme_port_release, port_id);
+
+	if (copy_from_user(&release, arg, minsz))
+		return -EFAULT;
+
+	if (release.argsz < minsz || release.flags)
+		return -EINVAL;
+
+	return dfl_fpga_cdev_config_port(cdev, release.port_id, true);
+}
+
+static long fme_hdr_ioctl_assign_port(struct dfl_feature_platform_data *pdata,
+				      void __user *arg)
+{
+	struct dfl_fpga_cdev *cdev = pdata->dfl_cdev;
+	struct dfl_fpga_fme_port_assign assign;
+	unsigned long minsz;
+
+	minsz = offsetofend(struct dfl_fpga_fme_port_assign, port_id);
+
+	if (copy_from_user(&assign, arg, minsz))
+		return -EFAULT;
+
+	if (assign.argsz < minsz || assign.flags)
+		return -EINVAL;
+
+	return dfl_fpga_cdev_config_port(cdev, assign.port_id, false);
+}
+
+static long fme_hdr_ioctl(struct platform_device *pdev,
+			  struct dfl_feature *feature,
+			  unsigned int cmd, unsigned long arg)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+
+	switch (cmd) {
+	case DFL_FPGA_FME_PORT_RELEASE:
+		return fme_hdr_ioctl_release_port(pdata, (void __user *)arg);
+	case DFL_FPGA_FME_PORT_ASSIGN:
+		return fme_hdr_ioctl_assign_port(pdata, (void __user *)arg);
+	}
+
+	return -ENODEV;
+}
+
 static const struct dfl_feature_ops fme_hdr_ops = {
 	.init = fme_hdr_init,
 	.uinit = fme_hdr_uinit,
+	.ioctl = fme_hdr_ioctl,
 };
 
 static struct dfl_feature_driver fme_feature_drvs[] = {
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index 4b66aaa..308c808 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -231,16 +231,20 @@ void dfl_fpga_port_ops_del(struct dfl_fpga_port_ops *ops)
  */
 int dfl_fpga_check_port_id(struct platform_device *pdev, void *pport_id)
 {
-	struct dfl_fpga_port_ops *port_ops = dfl_fpga_port_ops_get(pdev);
-	int port_id;
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct dfl_fpga_port_ops *port_ops;
+
+	if (pdata->id != FEATURE_DEV_ID_UNUSED)
+		return pdata->id == *(int *)pport_id;
 
+	port_ops = dfl_fpga_port_ops_get(pdev);
 	if (!port_ops || !port_ops->get_id)
 		return 0;
 
-	port_id = port_ops->get_id(pdev);
+	pdata->id = port_ops->get_id(pdev);
 	dfl_fpga_port_ops_put(port_ops);
 
-	return port_id == *(int *)pport_id;
+	return pdata->id == *(int *)pport_id;
 }
 EXPORT_SYMBOL_GPL(dfl_fpga_check_port_id);
 
@@ -474,6 +478,7 @@ static int build_info_commit_dev(struct build_feature_devs_info *binfo)
 	pdata->dev = fdev;
 	pdata->num = binfo->feature_num;
 	pdata->dfl_cdev = binfo->cdev;
+	pdata->id = FEATURE_DEV_ID_UNUSED;
 	mutex_init(&pdata->lock);
 	lockdep_set_class_and_name(&pdata->lock, &dfl_pdata_keys[type],
 				   dfl_pdata_key_strings[type]);
@@ -973,25 +978,27 @@ void dfl_fpga_feature_devs_remove(struct dfl_fpga_cdev *cdev)
 {
 	struct dfl_feature_platform_data *pdata, *ptmp;
 
-	remove_feature_devs(cdev);
-
 	mutex_lock(&cdev->lock);
-	if (cdev->fme_dev) {
-		/* the fme should be unregistered. */
-		WARN_ON(device_is_registered(cdev->fme_dev));
+	if (cdev->fme_dev)
 		put_device(cdev->fme_dev);
-	}
 
 	list_for_each_entry_safe(pdata, ptmp, &cdev->port_dev_list, node) {
 		struct platform_device *port_dev = pdata->dev;
 
-		/* the port should be unregistered. */
-		WARN_ON(device_is_registered(&port_dev->dev));
+		/* remove released ports */
+		if (!device_is_registered(&port_dev->dev)) {
+			dfl_id_free(feature_dev_id_type(port_dev),
+				    port_dev->id);
+			platform_device_put(port_dev);
+		}
+
 		list_del(&pdata->node);
 		put_device(&port_dev->dev);
 	}
 	mutex_unlock(&cdev->lock);
 
+	remove_feature_devs(cdev);
+
 	fpga_region_unregister(cdev->region);
 	devm_kfree(cdev->parent, cdev);
 }
@@ -1029,6 +1036,82 @@ struct platform_device *
 }
 EXPORT_SYMBOL_GPL(__dfl_fpga_cdev_find_port);
 
+static int attach_port_dev(struct dfl_fpga_cdev *cdev, u32 port_id)
+{
+	struct platform_device *port_pdev;
+	int ret = -ENODEV;
+
+	mutex_lock(&cdev->lock);
+	port_pdev = __dfl_fpga_cdev_find_port(cdev, &port_id,
+					      dfl_fpga_check_port_id);
+	if (!port_pdev)
+		goto unlock_exit;
+
+	if (device_is_registered(&port_pdev->dev)) {
+		ret = -EBUSY;
+		goto put_dev_exit;
+	}
+
+	ret = platform_device_add(port_pdev);
+	if (ret)
+		goto put_dev_exit;
+
+	dfl_feature_dev_use_end(dev_get_platdata(&port_pdev->dev));
+	cdev->released_port_num--;
+put_dev_exit:
+	put_device(&port_pdev->dev);
+unlock_exit:
+	mutex_unlock(&cdev->lock);
+	return ret;
+}
+
+static int detach_port_dev(struct dfl_fpga_cdev *cdev, u32 port_id)
+{
+	struct platform_device *port_pdev;
+	int ret = -ENODEV;
+
+	mutex_lock(&cdev->lock);
+	port_pdev = __dfl_fpga_cdev_find_port(cdev, &port_id,
+					      dfl_fpga_check_port_id);
+	if (!port_pdev)
+		goto unlock_exit;
+
+	if (!device_is_registered(&port_pdev->dev)) {
+		ret = -EBUSY;
+		goto put_dev_exit;
+	}
+
+	ret = dfl_feature_dev_use_begin(dev_get_platdata(&port_pdev->dev));
+	if (ret)
+		goto put_dev_exit;
+
+	platform_device_del(port_pdev);
+	cdev->released_port_num++;
+put_dev_exit:
+	put_device(&port_pdev->dev);
+unlock_exit:
+	mutex_unlock(&cdev->lock);
+	return ret;
+}
+
+/**
+ * dfl_fpga_cdev_config_port - configure a port feature dev
+ * @cdev: parent container device.
+ * @port_id: id of the port feature device.
+ * @release: release port or assign port back.
+ *
+ * This function allows user to release port platform device or assign it back.
+ * e.g. to safely turn one port from PF into VF for PCI device SRIOV support,
+ * release port platform device is one necessary step.
+ */
+int dfl_fpga_cdev_config_port(struct dfl_fpga_cdev *cdev,
+			      u32 port_id, bool release)
+{
+	return release ? detach_port_dev(cdev, port_id) :
+			 attach_port_dev(cdev, port_id);
+}
+EXPORT_SYMBOL_GPL(dfl_fpga_cdev_config_port);
+
 static int __init dfl_fpga_init(void)
 {
 	int ret;
diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
index 8851c6c..63f39ab 100644
--- a/drivers/fpga/dfl.h
+++ b/drivers/fpga/dfl.h
@@ -183,6 +183,8 @@ struct dfl_feature {
 
 #define DEV_STATUS_IN_USE	0
 
+#define FEATURE_DEV_ID_UNUSED	(-1)
+
 /**
  * struct dfl_feature_platform_data - platform data for feature devices
  *
@@ -191,6 +193,7 @@ struct dfl_feature {
  * @cdev: cdev of feature dev.
  * @dev: ptr to platform device linked with this platform data.
  * @dfl_cdev: ptr to container device.
+ * @id: id used for this feature device.
  * @disable_count: count for port disable.
  * @num: number for sub features.
  * @dev_status: dev status (e.g. DEV_STATUS_IN_USE).
@@ -203,6 +206,7 @@ struct dfl_feature_platform_data {
 	struct cdev cdev;
 	struct platform_device *dev;
 	struct dfl_fpga_cdev *dfl_cdev;
+	int id;
 	unsigned int disable_count;
 	unsigned long dev_status;
 	void *private;
@@ -378,6 +382,7 @@ int dfl_fpga_enum_info_add_dfl(struct dfl_fpga_enum_info *info,
  * @fme_dev: FME feature device under this container device.
  * @lock: mutex lock to protect the port device list.
  * @port_dev_list: list of all port feature devices under this container device.
+ * @released_port_num: released port number under this container device.
  */
 struct dfl_fpga_cdev {
 	struct device *parent;
@@ -385,6 +390,7 @@ struct dfl_fpga_cdev {
 	struct device *fme_dev;
 	struct mutex lock;
 	struct list_head port_dev_list;
+	int released_port_num;
 };
 
 struct dfl_fpga_cdev *
@@ -412,4 +418,8 @@ struct platform_device *
 
 	return pdev;
 }
+
+int dfl_fpga_cdev_config_port(struct dfl_fpga_cdev *cdev,
+			      u32 port_id, bool release);
+
 #endif /* __FPGA_DFL_H */
diff --git a/include/uapi/linux/fpga-dfl.h b/include/uapi/linux/fpga-dfl.h
index 2e324e5..e9a00e0 100644
--- a/include/uapi/linux/fpga-dfl.h
+++ b/include/uapi/linux/fpga-dfl.h
@@ -176,4 +176,36 @@ struct dfl_fpga_fme_port_pr {
 
 #define DFL_FPGA_FME_PORT_PR	_IO(DFL_FPGA_MAGIC, DFL_FME_BASE + 0)
 
+/**
+ * DFL_FPGA_FME_PORT_RELEASE - _IOW(DFL_FPGA_MAGIC, DFL_FME_BASE + 1,
+ *					struct dfl_fpga_fme_port_release)
+ *
+ * Driver releases the port per Port ID provided by caller.
+ * Return: 0 on success, -errno on failure.
+ */
+struct dfl_fpga_fme_port_release {
+	/* Input */
+	__u32 argsz;		/* Structure length */
+	__u32 flags;		/* Zero for now */
+	__u32 port_id;
+};
+
+#define DFL_FPGA_FME_PORT_RELEASE	_IO(DFL_FPGA_MAGIC, DFL_FME_BASE + 1)
+
+/**
+ * DFL_FPGA_FME_PORT_ASSIGN - _IOW(DFL_FPGA_MAGIC, DFL_FME_BASE + 2,
+ *					struct dfl_fpga_fme_port_assign)
+ *
+ * Driver assigns the port back per Port ID provided by caller.
+ * Return: 0 on success, -errno on failure.
+ */
+struct dfl_fpga_fme_port_assign {
+	/* Input */
+	__u32 argsz;		/* Structure length */
+	__u32 flags;		/* Zero for now */
+	__u32 port_id;
+};
+
+#define DFL_FPGA_FME_PORT_ASSIGN	_IO(DFL_FPGA_MAGIC, DFL_FME_BASE + 2)
+
 #endif /* _UAPI_LINUX_FPGA_DFL_H */
-- 
1.8.3.1