Helper functions for char device node creation / removal for platform
drivers. This is part of platform driver infrastructure.
Signed-off-by: Sonal Santan <sonal.santan@xxxxxxxxxx>
Signed-off-by: Max Zhen <max.zhen@xxxxxxxxxx>
Signed-off-by: Lizhi Hou <lizhi.hou@xxxxxxxxxx>
---
drivers/fpga/xrt/lib/cdev.c | 232 ++++++++++++++++++++++++++++++++++++
1 file changed, 232 insertions(+)
create mode 100644 drivers/fpga/xrt/lib/cdev.c
diff --git a/drivers/fpga/xrt/lib/cdev.c b/drivers/fpga/xrt/lib/cdev.c
new file mode 100644
index 000000000000..38efd24b6e10
--- /dev/null
+++ b/drivers/fpga/xrt/lib/cdev.c
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xilinx Alveo FPGA device node helper functions.
+ *
+ * Copyright (C) 2020-2021 Xilinx, Inc.
+ *
+ * Authors:
+ * Cheng Zhen <maxz@xxxxxxxxxx>
+ */
+
+#include "xleaf.h"
+
+extern struct class *xrt_class;
+
+#define XRT_CDEV_DIR "xfpga"
+#define INODE2PDATA(inode) \
+ container_of((inode)->i_cdev, struct xrt_subdev_platdata, xsp_cdev)
+#define INODE2PDEV(inode) \
+ to_platform_device(kobj_to_dev((inode)->i_cdev->kobj.parent))
+#define CDEV_NAME(sysdev) (strchr((sysdev)->kobj.name, '!') + 1)
+
+/* Allow it to be accessed from cdev. */
+static void xleaf_devnode_allowed(struct platform_device *pdev)
+{
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
+
+ /* Allow new opens. */
+ mutex_lock(&pdata->xsp_devnode_lock);
+ pdata->xsp_devnode_online = true;
+ mutex_unlock(&pdata->xsp_devnode_lock);
+}
+
+/* Turn off access from cdev and wait for all existing user to go away. */
+static int xleaf_devnode_disallowed(struct platform_device *pdev)
+{
+ int ret = 0;
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
+
+ mutex_lock(&pdata->xsp_devnode_lock);
+
+ /* Prevent new opens. */
+ pdata->xsp_devnode_online = false;
+ /* Wait for existing user to close. */
+ while (!ret && pdata->xsp_devnode_ref) {
+ int rc;
+
+ mutex_unlock(&pdata->xsp_devnode_lock);
+ rc = wait_for_completion_killable(&pdata->xsp_devnode_comp);
+ mutex_lock(&pdata->xsp_devnode_lock);
+
+ if (rc == -ERESTARTSYS) {
+ /* Restore online state. */
+ pdata->xsp_devnode_online = true;
+ xrt_err(pdev, "%s is in use, ref=%d",
+ CDEV_NAME(pdata->xsp_sysdev),
+ pdata->xsp_devnode_ref);
+ ret = -EBUSY;
+ }
+ }
+
+ mutex_unlock(&pdata->xsp_devnode_lock);
+
+ return ret;
+}
+
+static struct platform_device *
+__xleaf_devnode_open(struct inode *inode, bool excl)
+{
+ struct xrt_subdev_platdata *pdata = INODE2PDATA(inode);
+ struct platform_device *pdev = INODE2PDEV(inode);
+ bool opened = false;
+
+ mutex_lock(&pdata->xsp_devnode_lock);
+
+ if (pdata->xsp_devnode_online) {
+ if (excl && pdata->xsp_devnode_ref) {
+ xrt_err(pdev, "%s has already been opened exclusively",
+ CDEV_NAME(pdata->xsp_sysdev));
+ } else if (!excl && pdata->xsp_devnode_excl) {
+ xrt_err(pdev, "%s has been opened exclusively",
+ CDEV_NAME(pdata->xsp_sysdev));
+ } else {
+ pdata->xsp_devnode_ref++;
+ pdata->xsp_devnode_excl = excl;
+ opened = true;
+ xrt_info(pdev, "opened %s, ref=%d",
+ CDEV_NAME(pdata->xsp_sysdev),
+ pdata->xsp_devnode_ref);
+ }
+ } else {
+ xrt_err(pdev, "%s is offline", CDEV_NAME(pdata->xsp_sysdev));
+ }
+
+ mutex_unlock(&pdata->xsp_devnode_lock);
+
+ pdev = opened ? pdev : NULL;
+ return pdev;
+}
+
+struct platform_device *
+xleaf_devnode_open_excl(struct inode *inode)
+{
+ return __xleaf_devnode_open(inode, true);
+}
+
+struct platform_device *
+xleaf_devnode_open(struct inode *inode)
+{
+ return __xleaf_devnode_open(inode, false);
+}
+EXPORT_SYMBOL_GPL(xleaf_devnode_open);
+
+void xleaf_devnode_close(struct inode *inode)
+{
+ struct xrt_subdev_platdata *pdata = INODE2PDATA(inode);
+ struct platform_device *pdev = INODE2PDEV(inode);
+ bool notify = false;
+
+ mutex_lock(&pdata->xsp_devnode_lock);
+
+ WARN_ON(pdata->xsp_devnode_ref == 0);
+ pdata->xsp_devnode_ref--;
+ if (pdata->xsp_devnode_ref == 0) {
+ pdata->xsp_devnode_excl = false;
+ notify = true;
+ }
+ if (notify) {
+ xrt_info(pdev, "closed %s, ref=%d",
+ CDEV_NAME(pdata->xsp_sysdev), pdata->xsp_devnode_ref);
+ } else {
+ xrt_info(pdev, "closed %s, notifying waiter",
+ CDEV_NAME(pdata->xsp_sysdev));
+ }
+
+ mutex_unlock(&pdata->xsp_devnode_lock);
+
+ if (notify)
+ complete(&pdata->xsp_devnode_comp);
+}
+EXPORT_SYMBOL_GPL(xleaf_devnode_close);
+
+static inline enum xrt_subdev_file_mode
+devnode_mode(struct xrt_subdev_drvdata *drvdata)
+{
+ return drvdata->xsd_file_ops.xsf_mode;
+}
+
+int xleaf_devnode_create(struct platform_device *pdev, const char *file_name,
+ const char *inst_name)
+{
+ struct xrt_subdev_drvdata *drvdata = DEV_DRVDATA(pdev);
+ struct xrt_subdev_file_ops *fops = &drvdata->xsd_file_ops;
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
+ struct cdev *cdevp;
+ struct device *sysdev;
+ int ret = 0;
+ char fname[256];
+
+ mutex_init(&pdata->xsp_devnode_lock);
+ init_completion(&pdata->xsp_devnode_comp);
+
+ cdevp = &DEV_PDATA(pdev)->xsp_cdev;
+ cdev_init(cdevp, &fops->xsf_ops);
+ cdevp->owner = fops->xsf_ops.owner;
+ cdevp->dev = MKDEV(MAJOR(fops->xsf_dev_t), pdev->id);
+
+ /*
+ * Set pdev as parent of cdev so that when pdev (and its platform
+ * data) will not be freed when cdev is not freed.
+ */
+ cdev_set_parent(cdevp, &DEV(pdev)->kobj);
+
+ ret = cdev_add(cdevp, cdevp->dev, 1);
+ if (ret) {
+ xrt_err(pdev, "failed to add cdev: %d", ret);
+ goto failed;
+ }
+ if (!file_name)
+ file_name = pdev->name;
+ if (!inst_name) {
+ if (devnode_mode(drvdata) == XRT_SUBDEV_FILE_MULTI_INST) {
+ snprintf(fname, sizeof(fname), "%s/%s/%s.%u",
+ XRT_CDEV_DIR, DEV_PDATA(pdev)->xsp_root_name,
+ file_name, pdev->id);
+ } else {
+ snprintf(fname, sizeof(fname), "%s/%s/%s",
+ XRT_CDEV_DIR, DEV_PDATA(pdev)->xsp_root_name,
+ file_name);
+ }
+ } else {
+ snprintf(fname, sizeof(fname), "%s/%s/%s.%s", XRT_CDEV_DIR,
+ DEV_PDATA(pdev)->xsp_root_name, file_name, inst_name);
+ }
+ sysdev = device_create(xrt_class, NULL, cdevp->dev, NULL, "%s", fname);
+ if (IS_ERR(sysdev)) {
+ ret = PTR_ERR(sysdev);
+ xrt_err(pdev, "failed to create device node: %d", ret);
+ goto failed_cdev_add;
+ }
+ pdata->xsp_sysdev = sysdev;
+
+ xleaf_devnode_allowed(pdev);
+
+ xrt_info(pdev, "created (%d, %d): /dev/%s",
+ MAJOR(cdevp->dev), pdev->id, fname);
+ return 0;
+
+failed_cdev_add:
+ cdev_del(cdevp);
+failed:
+ cdevp->owner = NULL;
+ return ret;
+}
+
+int xleaf_devnode_destroy(struct platform_device *pdev)
+{
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
+ struct cdev *cdevp = &pdata->xsp_cdev;
+ dev_t dev = cdevp->dev;
+ int rc;
+
+ rc = xleaf_devnode_disallowed(pdev);
+ if (rc)
+ return rc;
+
+ xrt_info(pdev, "removed (%d, %d): /dev/%s/%s", MAJOR(dev), MINOR(dev),
+ XRT_CDEV_DIR, CDEV_NAME(pdata->xsp_sysdev));
+ device_destroy(xrt_class, cdevp->dev);
+ pdata->xsp_sysdev = NULL;
+ cdev_del(cdevp);
+ return 0;
+}
--
2.27.0
