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SubjectRe: [PATCH V3 XRT Alveo 04/18] fpga: xrt: xrt-lib platform driver manager
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On 2/17/21 10:40 PM, Lizhi Hou wrote:
> xrt-lib kernel module infrastructure code to register and manage all
> leaf driver modules.
>
> Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
> Signed-off-by: Max Zhen <max.zhen@xilinx.com>
> Signed-off-by: Lizhi Hou <lizhih@xilinx.com>
> ---
> drivers/fpga/xrt/lib/main.c | 274 ++++++++++++++++++++++++++++++++++++
> drivers/fpga/xrt/lib/main.h | 17 +++
> 2 files changed, 291 insertions(+)
> create mode 100644 drivers/fpga/xrt/lib/main.c
> create mode 100644 drivers/fpga/xrt/lib/main.h

Not sure if 'main' is a good base name for something going into a lib.

>
> diff --git a/drivers/fpga/xrt/lib/main.c b/drivers/fpga/xrt/lib/main.c
> new file mode 100644
> index 000000000000..36fb62710843
> --- /dev/null
> +++ b/drivers/fpga/xrt/lib/main.c
> @@ -0,0 +1,274 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Xilinx Alveo FPGA Support
> + *
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + * Cheng Zhen <maxz@xilinx.com>
> + */
> +
> +#include <linux/module.h>
> +#include "xleaf.h"
> +#include "xroot.h"
> +#include "main.h"
> +
> +#define XRT_IPLIB_MODULE_NAME "xrt-lib"
> +#define XRT_IPLIB_MODULE_VERSION "4.0.0"
> +#define XRT_MAX_DEVICE_NODES 128
> +#define XRT_DRVNAME(drv) ((drv)->driver.name)
> +
> +/*
> + * Subdev driver is known by ID to others. We map the ID to it's
by it's ID
> + * struct platform_driver, which contains it's binding name and driver/file ops.
> + * We also map it to the endpoint name in DTB as well, if it's different
> + * than the driver's binding name.
> + */
> +struct xrt_drv_map {
> + struct list_head list;
> + enum xrt_subdev_id id;
> + struct platform_driver *drv;
> + struct xrt_subdev_endpoints *eps;
> + struct ida ida; /* manage driver instance and char dev minor */
> +};
> +
> +static DEFINE_MUTEX(xrt_lib_lock); /* global lock protecting xrt_drv_maps list */
> +static LIST_HEAD(xrt_drv_maps);
> +struct class *xrt_class;
> +
> +static inline struct xrt_subdev_drvdata *
> +xrt_drv_map2drvdata(struct xrt_drv_map *map)
> +{
> + return (struct xrt_subdev_drvdata *)map->drv->id_table[0].driver_data;
> +}
> +
> +static struct xrt_drv_map *
> +xrt_drv_find_map_by_id_nolock(enum xrt_subdev_id id)

name could be by convention

__xrt_drv_find_map_id

> +{
> + const struct list_head *ptr;
> +
> + list_for_each(ptr, &xrt_drv_maps) {
> + struct xrt_drv_map *tmap = list_entry(ptr, struct xrt_drv_map, list);
> +
> + if (tmap->id == id)
> + return tmap;
> + }
> + return NULL;
> +}
> +
> +static struct xrt_drv_map *
> +xrt_drv_find_map_by_id(enum xrt_subdev_id id)
> +{
> + struct xrt_drv_map *map;
> +
> + mutex_lock(&xrt_lib_lock);
> + map = xrt_drv_find_map_by_id_nolock(id);
> + mutex_unlock(&xrt_lib_lock);
> + /*
> + * map should remain valid even after lock is dropped since a registered
even after the lock
> + * driver should only be unregistered when driver module is being unloaded,
> + * which means that the driver should not be used by then.
> + */
> + return map;
> +}
> +
> +static int xrt_drv_register_driver(struct xrt_drv_map *map)
> +{
> + struct xrt_subdev_drvdata *drvdata;
> + int rc = 0;
> + const char *drvname = XRT_DRVNAME(map->drv);
> +
> + rc = platform_driver_register(map->drv);
> + if (rc) {
> + pr_err("register %s platform driver failed\n", drvname);
> + return rc;
> + }
> +
> + drvdata = xrt_drv_map2drvdata(map);
> + if (drvdata) {
> + /* Initialize dev_t for char dev node. */
> + if (xleaf_devnode_enabled(drvdata)) {
> + rc = alloc_chrdev_region(&drvdata->xsd_file_ops.xsf_dev_t, 0,
> + XRT_MAX_DEVICE_NODES, drvname);
> + if (rc) {
> + platform_driver_unregister(map->drv);
> + pr_err("failed to alloc dev minor for %s: %d\n", drvname, rc);
> + return rc;
> + }
> + } else {
> + drvdata->xsd_file_ops.xsf_dev_t = (dev_t)-1;
> + }
> + }
> +
> + ida_init(&map->ida);
> +
> + pr_info("%s registered successfully\n", drvname);
> +
> + return 0;
> +}
> +
> +static void xrt_drv_unregister_driver(struct xrt_drv_map *map)
> +{
> + const char *drvname = XRT_DRVNAME(map->drv);
> + struct xrt_subdev_drvdata *drvdata;
> +
> + ida_destroy(&map->ida);
> +
> + drvdata = xrt_drv_map2drvdata(map);
> + if (drvdata && drvdata->xsd_file_ops.xsf_dev_t != (dev_t)-1) {
> + unregister_chrdev_region(drvdata->xsd_file_ops.xsf_dev_t,
> + XRT_MAX_DEVICE_NODES);
> + }
> +
> + platform_driver_unregister(map->drv);
> +
> + pr_info("%s unregistered successfully\n", drvname);
> +}
> +
> +int xleaf_register_driver(enum xrt_subdev_id id,
> + struct platform_driver *drv,
> + struct xrt_subdev_endpoints *eps)
> +{
> + struct xrt_drv_map *map;
> +
> + mutex_lock(&xrt_lib_lock);

Trying to minimize length of lock being held.

Could holding this lock be split or the alloc moved above ?

> +
> + map = xrt_drv_find_map_by_id_nolock(id);
> + if (map) {
> + mutex_unlock(&xrt_lib_lock);
> + pr_err("Id %d already has a registered driver, 0x%p\n",
> + id, map->drv);
> + return -EEXIST;
> + }
> +
> + map = vzalloc(sizeof(*map));

general issue

map is small, so kzalloc

> + if (!map) {
> + mutex_unlock(&xrt_lib_lock);
> + return -ENOMEM;
> + }
> + map->id = id;
> + map->drv = drv;
> + map->eps = eps;
> +
> + xrt_drv_register_driver(map);

xrt_drv_register_driver failure is unhandled.

This is the only time xrt_drv_register_driver is called, consider expanding the function here and removing the call.

> +
> + list_add(&map->list, &xrt_drv_maps);
> +
> + mutex_unlock(&xrt_lib_lock);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(xleaf_register_driver);
> +
> +void xleaf_unregister_driver(enum xrt_subdev_id id)
> +{
> + struct xrt_drv_map *map;
> +
> + mutex_lock(&xrt_lib_lock);
> +
> + map = xrt_drv_find_map_by_id_nolock(id);
> + if (!map) {
> + mutex_unlock(&xrt_lib_lock);
> + pr_err("Id %d has no registered driver\n", id);
> + return;
> + }
> +
> + list_del(&map->list);
> +
> + mutex_unlock(&xrt_lib_lock);
> +
> + xrt_drv_unregister_driver(map);
> + vfree(map);
> +}
> +EXPORT_SYMBOL_GPL(xleaf_unregister_driver);
> +
> +const char *xrt_drv_name(enum xrt_subdev_id id)
> +{
> + struct xrt_drv_map *map = xrt_drv_find_map_by_id(id);
> +
> + if (map)
> + return XRT_DRVNAME(map->drv);
> + return NULL;
> +}
> +
> +int xrt_drv_get_instance(enum xrt_subdev_id id)
> +{
> + struct xrt_drv_map *map = xrt_drv_find_map_by_id(id);
> +
> + return ida_alloc_range(&map->ida, 0, XRT_MAX_DEVICE_NODES, GFP_KERNEL);
> +}
> +
> +void xrt_drv_put_instance(enum xrt_subdev_id id, int instance)
> +{
> + struct xrt_drv_map *map = xrt_drv_find_map_by_id(id);
> +
> + ida_free(&map->ida, instance);
> +}
> +
> +struct xrt_subdev_endpoints *xrt_drv_get_endpoints(enum xrt_subdev_id id)
> +{
> + struct xrt_drv_map *map = xrt_drv_find_map_by_id(id);
> + struct xrt_subdev_endpoints *eps;
> +
> + eps = map ? map->eps : NULL;
> + return eps;
> +}
> +
> +/* Leaf driver's module init/fini callbacks. */

These constructor/destructor calls needs to be more dynamic.

calls are made even if there are no subdevices to go with the id's.

Also this list can not grow.  How would a new id be added by a module ?

> +static void (*leaf_init_fini_cbs[])(bool) = {
> + group_leaf_init_fini,
> + vsec_leaf_init_fini,
> + devctl_leaf_init_fini,
> + axigate_leaf_init_fini,
> + icap_leaf_init_fini,
> + calib_leaf_init_fini,
> + clkfreq_leaf_init_fini,
> + clock_leaf_init_fini,
> + ucs_leaf_init_fini,
> +};
> +
> +static __init int xrt_lib_init(void)
> +{
> + int i;
> +
> + xrt_class = class_create(THIS_MODULE, XRT_IPLIB_MODULE_NAME);
> + if (IS_ERR(xrt_class))
> + return PTR_ERR(xrt_class);
> +
> + for (i = 0; i < ARRAY_SIZE(leaf_init_fini_cbs); i++)
> + leaf_init_fini_cbs[i](true);
> + return 0;
> +}
> +
> +static __exit void xrt_lib_fini(void)
> +{
> + struct xrt_drv_map *map;
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(leaf_init_fini_cbs); i++)
> + leaf_init_fini_cbs[i](false);
> +
> + mutex_lock(&xrt_lib_lock);
> +
> + while (!list_empty(&xrt_drv_maps)) {
> + map = list_first_entry_or_null(&xrt_drv_maps, struct xrt_drv_map, list);
> + pr_err("Unloading module with %s still registered\n", XRT_DRVNAME(map->drv));
> + list_del(&map->list);
> + mutex_unlock(&xrt_lib_lock);
> + xrt_drv_unregister_driver(map);
> + vfree(map);
> + mutex_lock(&xrt_lib_lock);
> + }
> +
> + mutex_unlock(&xrt_lib_lock);
> +
> + class_destroy(xrt_class);
> +}
> +
> +module_init(xrt_lib_init);
> +module_exit(xrt_lib_fini);
> +
> +MODULE_VERSION(XRT_IPLIB_MODULE_VERSION);
> +MODULE_AUTHOR("XRT Team <runtime@xilinx.com>");
> +MODULE_DESCRIPTION("Xilinx Alveo IP Lib driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/fpga/xrt/lib/main.h b/drivers/fpga/xrt/lib/main.h
> new file mode 100644
> index 000000000000..f3bfc87ee614
> --- /dev/null
> +++ b/drivers/fpga/xrt/lib/main.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + * Cheng Zhen <maxz@xilinx.com>
> + */
> +
> +#ifndef _XRT_MAIN_H_
> +#define _XRT_MAIN_H_
> +
> +const char *xrt_drv_name(enum xrt_subdev_id id);

To be self contained, the header defining enum xrt_subdev_id should be included.

This is subdev_id.h which comes in with patch 6

A dependency on a future patch breaks bisectablity.

It may make sense to collect these small headers into a single large header for the ip infra lib and bring them all in this patch.

Tom

> +int xrt_drv_get_instance(enum xrt_subdev_id id);
> +void xrt_drv_put_instance(enum xrt_subdev_id id, int instance);
> +struct xrt_subdev_endpoints *xrt_drv_get_endpoints(enum xrt_subdev_id id);
> +
> +#endif /* _XRT_MAIN_H_ */

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