Re: [PATCH V5 XRT Alveo 06/20] fpga: xrt: char dev node helper functions
From: Tom Rix
Date: Mon May 03 2021 - 09:27:24 EST
On 4/27/21 1:54 PM, Lizhi Hou wrote:
Helper functions for char device node creation / removal for xrt
drivers. This is part of xrt 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 | 210 ++++++++++++++++++++++++++++++++++++
1 file changed, 210 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..4edd2c1d459b
--- /dev/null
+++ b/drivers/fpga/xrt/lib/cdev.c
@@ -0,0 +1,210 @@
+// 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 "xrt"
ok
+#define INODE2PDATA(inode) \
+ container_of((inode)->i_cdev, struct xrt_subdev_platdata, xsp_cdev)
+#define INODE2PDEV(inode) \
+ to_xrt_dev(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 xrt_device *xdev)
+{
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(xdev);
+
+ /* 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 void xleaf_devnode_disallowed(struct xrt_device *xdev)
+{
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(xdev);
+
+ mutex_lock(&pdata->xsp_devnode_lock);
+
+ /* Prevent new opens. */
+ pdata->xsp_devnode_online = false;
+ /* Wait for existing user to close. */
+ while (pdata->xsp_devnode_ref) {
+ mutex_unlock(&pdata->xsp_devnode_lock);
+ wait_for_completion(&pdata->xsp_devnode_comp);
+ mutex_lock(&pdata->xsp_devnode_lock);
+ }
+
+ mutex_unlock(&pdata->xsp_devnode_lock);
+}
+
+static struct xrt_device *
+__xleaf_devnode_open(struct inode *inode, bool excl)
+{
+ struct xrt_subdev_platdata *pdata = INODE2PDATA(inode);
+ struct xrt_device *xdev = INODE2PDEV(inode);
+ bool opened = false;
+
+ mutex_lock(&pdata->xsp_devnode_lock);
+
+ if (pdata->xsp_devnode_online) {
+ if (excl && pdata->xsp_devnode_ref) {
+ xrt_err(xdev, "%s has already been opened exclusively",
+ CDEV_NAME(pdata->xsp_sysdev));
+ } else if (!excl && pdata->xsp_devnode_excl) {
+ xrt_err(xdev, "%s has been opened exclusively",
+ CDEV_NAME(pdata->xsp_sysdev));
+ } else {
+ pdata->xsp_devnode_ref++;
+ pdata->xsp_devnode_excl = excl;
+ opened = true;
+ xrt_info(xdev, "opened %s, ref=%d",
+ CDEV_NAME(pdata->xsp_sysdev),
+ pdata->xsp_devnode_ref);
+ }
+ } else {
+ xrt_err(xdev, "%s is offline", CDEV_NAME(pdata->xsp_sysdev));
+ }
+
+ mutex_unlock(&pdata->xsp_devnode_lock);
+
+ xdev = opened ? xdev : NULL;
+ return xdev;
+}
+
+struct xrt_device *
+xleaf_devnode_open_excl(struct inode *inode)
+{
+ return __xleaf_devnode_open(inode, true);
ok
+}
+
+struct xrt_device *
+xleaf_devnode_open(struct inode *inode)
+{
+ return __xleaf_devnode_open(inode, false);
+}
+EXPORT_SYMBOL_GPL(xleaf_devnode_open);
ok
+
+void xleaf_devnode_close(struct inode *inode)
+{
+ struct xrt_subdev_platdata *pdata = INODE2PDATA(inode);
+ struct xrt_device *xdev = 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(xdev, "closed %s", CDEV_NAME(pdata->xsp_sysdev));
ok
+ else
+ xrt_info(xdev, "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_dev_file_mode
+devnode_mode(struct xrt_device *xdev)
+{
+ return DEV_FILE_OPS(xdev)->xsf_mode;
+}
+
+int xleaf_devnode_create(struct xrt_device *xdev, const char *file_name,
+ const char *inst_name)
+{
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(xdev);
+ struct xrt_dev_file_ops *fops = DEV_FILE_OPS(xdev);
+ 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(xdev)->xsp_cdev;
+ cdev_init(cdevp, &fops->xsf_ops);
+ cdevp->owner = fops->xsf_ops.owner;
+ cdevp->dev = MKDEV(MAJOR(fops->xsf_dev_t), xdev->instance);
+
+ /*
+ * Set xdev as parent of cdev so that when xdev (and its platform
+ * data) will not be freed when cdev is not freed.
+ */
+ cdev_set_parent(cdevp, &DEV(xdev)->kobj);
+
+ ret = cdev_add(cdevp, cdevp->dev, 1);
+ if (ret) {
+ xrt_err(xdev, "failed to add cdev: %d", ret);
+ goto failed;
+ }
+ if (!file_name)
+ file_name = xdev->name;
+ if (!inst_name) {
+ if (devnode_mode(xdev) == XRT_DEV_FILE_MULTI_INST) {
+ snprintf(fname, sizeof(fname), "%s/%s/%s.%u",
+ XRT_CDEV_DIR, DEV_PDATA(xdev)->xsp_root_name,
+ file_name, xdev->instance);
+ } else {
+ snprintf(fname, sizeof(fname), "%s/%s/%s",
+ XRT_CDEV_DIR, DEV_PDATA(xdev)->xsp_root_name,
+ file_name);
+ }
+ } else {
+ snprintf(fname, sizeof(fname), "%s/%s/%s.%s", XRT_CDEV_DIR,
+ DEV_PDATA(xdev)->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(xdev, "failed to create device node: %d", ret);
+ goto failed_cdev_add;
+ }
+ pdata->xsp_sysdev = sysdev;
+
+ xleaf_devnode_allowed(xdev);
+
+ xrt_info(xdev, "created (%d, %d): /dev/%s",
+ MAJOR(cdevp->dev), xdev->instance, fname);
+ return 0;
+
+failed_cdev_add:
+ cdev_del(cdevp);
+failed:
+ cdevp->owner = NULL;
+ return ret;
+}
+
+void xleaf_devnode_destroy(struct xrt_device *xdev)
+{
+ struct xrt_subdev_platdata *pdata = DEV_PDATA(xdev);
+ struct cdev *cdevp = &pdata->xsp_cdev;
+ dev_t dev = cdevp->dev;
+
+ xleaf_devnode_disallowed(xdev);
ok
Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
+
+ xrt_info(xdev, "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);
+}