Date:   Mon, 3 May 2021 06:10:05 -0700
From:   Tom Rix <trix@...hat.com>
To:     Lizhi Hou <lizhi.hou@...inx.com>, linux-kernel@...r.kernel.org
Cc:     linux-fpga@...r.kernel.org, maxz@...inx.com,
        sonal.santan@...inx.com, yliu@...inx.com, michal.simek@...inx.com,
        stefanos@...inx.com, devicetree@...r.kernel.org, mdf@...nel.org,
        robh@...nel.org, Max Zhen <max.zhen@...inx.com>
Subject: Re: [PATCH V5 XRT Alveo 05/20] fpga: xrt: group driver


On 4/27/21 1:54 PM, Lizhi Hou wrote:
> group driver that manages life cycle of a bunch of leaf driver instances
> and bridges them with root.
>
> Signed-off-by: Sonal Santan <sonal.santan@...inx.com>
> Signed-off-by: Max Zhen <max.zhen@...inx.com>
> Signed-off-by: Lizhi Hou <lizhi.hou@...inx.com>
> ---
>   drivers/fpga/xrt/include/group.h |  25 +++
>   drivers/fpga/xrt/lib/group.c     | 278 +++++++++++++++++++++++++++++++
>   2 files changed, 303 insertions(+)
>   create mode 100644 drivers/fpga/xrt/include/group.h
>   create mode 100644 drivers/fpga/xrt/lib/group.c
>
> diff --git a/drivers/fpga/xrt/include/group.h b/drivers/fpga/xrt/include/group.h
> new file mode 100644
> index 000000000000..09e9d03f53fe
> --- /dev/null
> +++ b/drivers/fpga/xrt/include/group.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + *	Cheng Zhen <maxz@...inx.com>
> + */
> +
> +#ifndef _XRT_GROUP_H_
> +#define _XRT_GROUP_H_
> +
> +#include "xleaf.h"
> +
> +/*
> + * Group driver leaf calls.
> + */
> +enum xrt_group_leaf_cmd {
> +	XRT_GROUP_GET_LEAF = XRT_XLEAF_CUSTOM_BASE, /* See comments in xleaf.h */
> +	XRT_GROUP_PUT_LEAF,
> +	XRT_GROUP_INIT_CHILDREN,
> +	XRT_GROUP_FINI_CHILDREN,
> +	XRT_GROUP_TRIGGER_EVENT,
> +};
> +
> +#endif	/* _XRT_GROUP_H_ */
> diff --git a/drivers/fpga/xrt/lib/group.c b/drivers/fpga/xrt/lib/group.c
> new file mode 100644
> index 000000000000..b45f05449e0b
> --- /dev/null
> +++ b/drivers/fpga/xrt/lib/group.c
> @@ -0,0 +1,278 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Xilinx Alveo FPGA Group Driver
> + *
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + *	Cheng Zhen <maxz@...inx.com>
> + */
> +
> +#include <linux/mod_devicetable.h>
> +#include "xleaf.h"
> +#include "subdev_pool.h"
> +#include "group.h"
> +#include "metadata.h"
> +#include "lib-drv.h"
> +
> +#define XRT_GRP "xrt_group"
> +
> +struct xrt_group {
> +	struct xrt_device *xdev;
> +	struct xrt_subdev_pool leaves;
> +	bool leaves_created;
> +	struct mutex lock; /* lock for group */
> +};
> +
> +static int xrt_grp_root_cb(struct device *dev, void *parg,
> +			   enum xrt_root_cmd cmd, void *arg)
> +{
> +	int rc;
> +	struct xrt_device *xdev =
> +		container_of(dev, struct xrt_device, dev);
> +	struct xrt_group *xg = (struct xrt_group *)parg;
> +
> +	switch (cmd) {
> +	case XRT_ROOT_GET_LEAF_HOLDERS: {
> +		struct xrt_root_get_holders *holders =
> +			(struct xrt_root_get_holders *)arg;
> +		rc = xrt_subdev_pool_get_holders(&xg->leaves,
> +						 holders->xpigh_xdev,
> +						 holders->xpigh_holder_buf,
> +						 holders->xpigh_holder_buf_len);
> +		break;
> +	}
> +	default:
> +		/* Forward parent call to root. */
> +		rc = xrt_subdev_root_request(xdev, cmd, arg);
> +		break;
> +	}
> +
> +	return rc;
> +}
> +
> +/*
> + * Cut subdev's dtb from group's dtb based on passed-in endpoint descriptor.
> + * Return the subdev's dtb through dtbp, if found.
> + */
> +static int xrt_grp_cut_subdev_dtb(struct xrt_group *xg, struct xrt_dev_endpoints *eps,
> +				  char *grp_dtb, char **dtbp)
> +{
> +	int ret, i, ep_count = 0;
> +	char *dtb = NULL;
> +
> +	ret = xrt_md_create(DEV(xg->xdev), &dtb);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; eps->xse_names[i].ep_name || eps->xse_names[i].compat; i++) {
> +		const char *ep_name = eps->xse_names[i].ep_name;
> +		const char *compat = eps->xse_names[i].compat;
> +
> +		if (!ep_name)
> +			xrt_md_get_compatible_endpoint(DEV(xg->xdev), grp_dtb, compat, &ep_name);
> +		if (!ep_name)
> +			continue;
> +
> +		ret = xrt_md_copy_endpoint(DEV(xg->xdev), dtb, grp_dtb, ep_name, compat, NULL);
> +		if (ret)
> +			continue;
> +		xrt_md_del_endpoint(DEV(xg->xdev), grp_dtb, ep_name, compat);
> +		ep_count++;
> +	}
> +	/* Found enough endpoints, return the subdev's dtb. */
> +	if (ep_count >= eps->xse_min_ep) {
> +		*dtbp = dtb;
> +		return 0;
> +	}
> +
> +	/* Cleanup - Restore all endpoints that has been deleted, if any. */
> +	if (ep_count > 0) {
> +		xrt_md_copy_endpoint(DEV(xg->xdev), grp_dtb, dtb,
> +				     XRT_MD_NODE_ENDPOINTS, NULL, NULL);
> +	}
> +	vfree(dtb);
> +	*dtbp = NULL;
> +	return 0;
> +}
> +
> +static int xrt_grp_create_leaves(struct xrt_group *xg)
> +{
> +	struct xrt_subdev_platdata *pdata = DEV_PDATA(xg->xdev);
> +	struct xrt_dev_endpoints *eps = NULL;
> +	int ret = 0, failed = 0;
> +	enum xrt_subdev_id did;
> +	char *grp_dtb = NULL;
> +	unsigned long mlen;
> +
> +	if (!pdata)
> +		return -EINVAL;
> +
> +	mlen = xrt_md_size(DEV(xg->xdev), pdata->xsp_dtb);
> +	if (mlen == XRT_MD_INVALID_LENGTH) {
> +		xrt_err(xg->xdev, "invalid dtb, len %ld", mlen);
> +		return -EINVAL;
> +	}
> +
> +	mutex_lock(&xg->lock);
> +
> +	if (xg->leaves_created) {
> +		/*
> +		 * This is expected since caller does not keep track of the state of the group
> +		 * and may, in some cases, still try to create leaves after it has already been
> +		 * created. This special error code will let the caller know what is going on.
> +		 */

ok

Reviewed-by: Tom Rix <trix@...hat.com>

> +		mutex_unlock(&xg->lock);
> +		return -EEXIST;
> +	}
> +
> +	grp_dtb = vmalloc(mlen);
> +	if (!grp_dtb) {
> +		mutex_unlock(&xg->lock);
> +		return -ENOMEM;
> +	}
> +
> +	/* Create all leaves based on dtb. */
> +	xrt_info(xg->xdev, "bringing up leaves...");
> +	memcpy(grp_dtb, pdata->xsp_dtb, mlen);
> +	for (did = 0; did < XRT_SUBDEV_NUM; did++) {
> +		eps = xrt_drv_get_endpoints(did);
> +		while (eps && eps->xse_names) {
> +			char *dtb = NULL;
> +
> +			ret = xrt_grp_cut_subdev_dtb(xg, eps, grp_dtb, &dtb);
> +			if (ret) {
> +				failed++;
> +				xrt_err(xg->xdev, "failed to cut subdev dtb for drv %s: %d",
> +					xrt_drv_name(did), ret);
> +			}
> +			if (!dtb) {
> +				/*
> +				 * No more dtb to cut or bad things happened for this instance,
> +				 * switch to the next one.
> +				 */
> +				eps++;
> +				continue;
> +			}
> +
> +			/* Found a dtb for this instance, let's add it. */
> +			ret = xrt_subdev_pool_add(&xg->leaves, did, xrt_grp_root_cb, xg, dtb);
> +			if (ret < 0) {
> +				/*
> +				 * It is not a fatal error here. Some functionality is not usable
> +				 * due to this missing device, but the error can be handled
> +				 * when the functionality is used.
ok
> +				 */
> +				failed++;
> +				xrt_err(xg->xdev, "failed to add %s: %d", xrt_drv_name(did), ret);
> +			}
> +			vfree(dtb);
> +			/* Continue searching for the same instance from grp_dtb. */
> +		}
> +	}
> +
> +	xg->leaves_created = true;
> +	vfree(grp_dtb);
> +	mutex_unlock(&xg->lock);
> +	return failed == 0 ? 0 : -ECHILD;
> +}
> +
> +static void xrt_grp_remove_leaves(struct xrt_group *xg)
> +{
> +	mutex_lock(&xg->lock);
> +
> +	if (!xg->leaves_created) {
> +		mutex_unlock(&xg->lock);
> +		return;
> +	}
> +
> +	xrt_info(xg->xdev, "tearing down leaves...");
> +	xrt_subdev_pool_fini(&xg->leaves);
> +	xg->leaves_created = false;
> +
> +	mutex_unlock(&xg->lock);
> +}
> +
> +static int xrt_grp_probe(struct xrt_device *xdev)
> +{
> +	struct xrt_group *xg;
> +
> +	xrt_info(xdev, "probing...");
> +
> +	xg = devm_kzalloc(&xdev->dev, sizeof(*xg), GFP_KERNEL);
> +	if (!xg)
> +		return -ENOMEM;
> +
> +	xg->xdev = xdev;
> +	mutex_init(&xg->lock);
> +	xrt_subdev_pool_init(DEV(xdev), &xg->leaves);
> +	xrt_set_drvdata(xdev, xg);
> +
> +	return 0;
> +}
> +
> +static void xrt_grp_remove(struct xrt_device *xdev)
> +{
> +	struct xrt_group *xg = xrt_get_drvdata(xdev);
> +
> +	xrt_info(xdev, "leaving...");
> +	xrt_grp_remove_leaves(xg);
> +}
> +
> +static int xrt_grp_leaf_call(struct xrt_device *xdev, u32 cmd, void *arg)
> +{
> +	int rc = 0;
> +	struct xrt_group *xg = xrt_get_drvdata(xdev);
> +
> +	switch (cmd) {
> +	case XRT_XLEAF_EVENT:
> +		/* Simply forward to every child. */
> +		xrt_subdev_pool_handle_event(&xg->leaves,
> +					     (struct xrt_event *)arg);
> +		break;
> +	case XRT_GROUP_GET_LEAF: {
> +		struct xrt_root_get_leaf *get_leaf =
> +			(struct xrt_root_get_leaf *)arg;
> +
> +		rc = xrt_subdev_pool_get(&xg->leaves, get_leaf->xpigl_match_cb,
> +					 get_leaf->xpigl_match_arg,
> +					 DEV(get_leaf->xpigl_caller_xdev),
> +					 &get_leaf->xpigl_tgt_xdev);
> +		break;
> +	}
> +	case XRT_GROUP_PUT_LEAF: {
> +		struct xrt_root_put_leaf *put_leaf =
> +			(struct xrt_root_put_leaf *)arg;
> +
> +		rc = xrt_subdev_pool_put(&xg->leaves, put_leaf->xpipl_tgt_xdev,
> +					 DEV(put_leaf->xpipl_caller_xdev));
> +		break;
> +	}
> +	case XRT_GROUP_INIT_CHILDREN:
> +		rc = xrt_grp_create_leaves(xg);
> +		break;
> +	case XRT_GROUP_FINI_CHILDREN:
> +		xrt_grp_remove_leaves(xg);
> +		break;
> +	case XRT_GROUP_TRIGGER_EVENT:
> +		xrt_subdev_pool_trigger_event(&xg->leaves, (enum xrt_events)(uintptr_t)arg);
> +		break;
> +	default:
> +		xrt_err(xdev, "unknown IOCTL cmd %d", cmd);
> +		rc = -EINVAL;
> +		break;
> +	}
> +	return rc;
> +}
> +
> +static struct xrt_driver xrt_group_driver = {
> +	.driver	= {
> +		.name    = XRT_GRP,
> +	},
> +	.subdev_id = XRT_SUBDEV_GRP,
> +	.probe = xrt_grp_probe,
> +	.remove = xrt_grp_remove,
> +	.leaf_call = xrt_grp_leaf_call,
> +};
> +
> +XRT_LEAF_INIT_FINI_FUNC(group);

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