Re: [PATCH V3 XRT Alveo 16/18] fpga: xrt: DDR calibration platform driver

Tom Rix
2021-03-06T15:35:56Z

On 2/17/21 10:40 PM, Lizhi Hou wrote:
> Add DDR calibration driver. DDR calibration is a hardware function
> discovered by walking firmware metadata. A platform device node will
> be created for it. Hardware provides DDR calibration status through
> this function.
>
> 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/include/xleaf/calib.h | 30 ++++
> drivers/fpga/xrt/lib/xleaf/calib.c | 226 +++++++++++++++++++++++++
> 2 files changed, 256 insertions(+)
> create mode 100644 drivers/fpga/xrt/include/xleaf/calib.h
> create mode 100644 drivers/fpga/xrt/lib/xleaf/calib.c
calib is not descriptive, change filename to ddr_calibration
>
> diff --git a/drivers/fpga/xrt/include/xleaf/calib.h b/drivers/fpga/xrt/include/xleaf/calib.h
> new file mode 100644
> index 000000000000..f8aba4594c58
> --- /dev/null
> +++ b/drivers/fpga/xrt/include/xleaf/calib.h
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Header file for XRT DDR Calibration Leaf Driver
> + *
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * Authors:
> + * Cheng Zhen <maxz@xilinx.com>
> + */
> +
> +#ifndef _XRT_CALIB_H_
> +#define _XRT_CALIB_H_
> +
> +#include "xleaf.h"
> +#include <linux/xrt/xclbin.h>
> +
> +/*
> + * Memory calibration driver IOCTL calls.
> + */
> +enum xrt_calib_results {
> + XRT_CALIB_UNKNOWN,
Initialize ?
> + XRT_CALIB_SUCCEEDED,
> + XRT_CALIB_FAILED,
> +};
> +
> +enum xrt_calib_ioctl_cmd {
> + XRT_CALIB_RESULT = XRT_XLEAF_CUSTOM_BASE, /* See comments in xleaf.h */
> +};
> +
> +#endif /* _XRT_CALIB_H_ */
> diff --git a/drivers/fpga/xrt/lib/xleaf/calib.c b/drivers/fpga/xrt/lib/xleaf/calib.c
> new file mode 100644
> index 000000000000..fbb813636e76
> --- /dev/null
> +++ b/drivers/fpga/xrt/lib/xleaf/calib.c
> @@ -0,0 +1,226 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Xilinx Alveo FPGA memory calibration driver
> + *
> + * Copyright (C) 2020-2021 Xilinx, Inc.
> + *
> + * memory calibration
> + *
> + * Authors:
> + * Lizhi Hou<Lizhi.Hou@xilinx.com>
> + */
> +#include <linux/delay.h>
> +#include "xclbin-helper.h"
> +#include "metadata.h"
> +#include "xleaf/calib.h"
> +
> +#define XRT_CALIB "xrt_calib"
> +
> +struct calib_cache {
> + struct list_head link;
> + const char *ep_name;
> + char *data;
> + u32 data_size;
> +};
> +
> +struct calib {
> + struct platform_device *pdev;
> + void *calib_base;
> + struct mutex lock; /* calibration dev lock */
> + struct list_head cache_list;
> + u32 cache_num;
> + enum xrt_calib_results result;
> +};
> +
> +#define CALIB_DONE(calib) \
> + (ioread32((calib)->calib_base) & BIT(0))
> +
> +static void calib_cache_clean_nolock(struct calib *calib)
> +{
> + struct calib_cache *cache, *temp;
> +
> + list_for_each_entry_safe(cache, temp, &calib->cache_list, link) {
> + vfree(cache->data);
> + list_del(&cache->link);
> + vfree(cache);
> + }
> + calib->cache_num = 0;
> +}
> +
> +static void calib_cache_clean(struct calib *calib)
> +{
> + mutex_lock(&calib->lock);
> + calib_cache_clean_nolock(calib);
No lock functions (i believe) should be prefixed with '__'
> + mutex_unlock(&calib->lock);
> +}
> +
> +static int calib_srsr(struct calib *calib, struct platform_device *srsr_leaf)

what is srsr ?

Why a noop function ?

> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static int calib_calibration(struct calib *calib)
> +{
> + int i;
> +
> + for (i = 0; i < 20; i++) {

20 is a config parameter so should have a #define

There a couple of busy wait blocks in xrt/ some count up, some count down.

It would be good if they were consistent.

> + if (CALIB_DONE(calib))
> + break;
> + msleep(500);

500 is another config

Tom

> + }
> +
> + if (i == 20) {
> + xrt_err(calib->pdev,
> + "MIG calibration timeout after bitstream download");
> + return -ETIMEDOUT;
> + }
> +
> + xrt_info(calib->pdev, "took %dms", i * 500);
> + return 0;
> +}
> +
> +static void xrt_calib_event_cb(struct platform_device *pdev, void *arg)
> +{
> + struct calib *calib = platform_get_drvdata(pdev);
> + struct xrt_event *evt = (struct xrt_event *)arg;
> + enum xrt_events e = evt->xe_evt;
> + enum xrt_subdev_id id = evt->xe_subdev.xevt_subdev_id;
> + int instance = evt->xe_subdev.xevt_subdev_instance;
> + struct platform_device *leaf;
> + int ret;
> +
> + switch (e) {
> + case XRT_EVENT_POST_CREATION: {
> + if (id == XRT_SUBDEV_SRSR) {
> + leaf = xleaf_get_leaf_by_id(pdev,
> + XRT_SUBDEV_SRSR,
> + instance);
> + if (!leaf) {
> + xrt_err(pdev, "does not get SRSR subdev");
> + return;
> + }
> + ret = calib_srsr(calib, leaf);
> + xleaf_put_leaf(pdev, leaf);
> + calib->result =
> + ret ? XRT_CALIB_FAILED : XRT_CALIB_SUCCEEDED;
> + } else if (id == XRT_SUBDEV_UCS) {
> + ret = calib_calibration(calib);
> + calib->result =
> + ret ? XRT_CALIB_FAILED : XRT_CALIB_SUCCEEDED;
> + }
> + break;
> + }
> + default:
> + break;
> + }
> +}
> +
> +static int xrt_calib_remove(struct platform_device *pdev)
> +{
> + struct calib *calib = platform_get_drvdata(pdev);
> +
> + calib_cache_clean(calib);
> +
> + if (calib->calib_base)
> + iounmap(calib->calib_base);
> +
> + platform_set_drvdata(pdev, NULL);
> + devm_kfree(&pdev->dev, calib);
> +
> + return 0;
> +}
> +
> +static int xrt_calib_probe(struct platform_device *pdev)
> +{
> + struct calib *calib;
> + struct resource *res;
> + int err = 0;
> +
> + calib = devm_kzalloc(&pdev->dev, sizeof(*calib), GFP_KERNEL);
> + if (!calib)
> + return -ENOMEM;
> +
> + calib->pdev = pdev;
> + platform_set_drvdata(pdev, calib);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + goto failed;
> +
> + calib->calib_base = ioremap(res->start, res->end - res->start + 1);
> + if (!calib->calib_base) {
> + err = -EIO;
> + xrt_err(pdev, "Map iomem failed");
> + goto failed;
> + }
> +
> + mutex_init(&calib->lock);
> + INIT_LIST_HEAD(&calib->cache_list);
> +
> + return 0;
> +
> +failed:
> + xrt_calib_remove(pdev);
> + return err;
> +}
> +
> +static int
> +xrt_calib_leaf_ioctl(struct platform_device *pdev, u32 cmd, void *arg)
> +{
> + struct calib *calib = platform_get_drvdata(pdev);
> + int ret = 0;
> +
> + switch (cmd) {
> + case XRT_XLEAF_EVENT:
> + xrt_calib_event_cb(pdev, arg);
> + break;
> + case XRT_CALIB_RESULT: {
> + enum xrt_calib_results *r = (enum xrt_calib_results *)arg;
> + *r = calib->result;
> + break;
> + }
> + default:
> + xrt_err(pdev, "unsupported cmd %d", cmd);
> + ret = -EINVAL;
> + }
> + return ret;
> +}
> +
> +static struct xrt_subdev_endpoints xrt_calib_endpoints[] = {
> + {
> + .xse_names = (struct xrt_subdev_ep_names[]) {
> + { .ep_name = XRT_MD_NODE_DDR_CALIB },
> + { NULL },
> + },
> + .xse_min_ep = 1,
> + },
> + { 0 },
> +};
> +
> +static struct xrt_subdev_drvdata xrt_calib_data = {
> + .xsd_dev_ops = {
> + .xsd_ioctl = xrt_calib_leaf_ioctl,
> + },
> +};
> +
> +static const struct platform_device_id xrt_calib_table[] = {
> + { XRT_CALIB, (kernel_ulong_t)&xrt_calib_data },
> + { },
> +};
> +
> +static struct platform_driver xrt_calib_driver = {
> + .driver = {
> + .name = XRT_CALIB,
> + },
> + .probe = xrt_calib_probe,
> + .remove = xrt_calib_remove,
> + .id_table = xrt_calib_table,
> +};
> +
> +void calib_leaf_init_fini(bool init)
> +{
> + if (init)
> + xleaf_register_driver(XRT_SUBDEV_CALIB, &xrt_calib_driver, xrt_calib_endpoints);
> + else
> + xleaf_unregister_driver(XRT_SUBDEV_CALIB);
> +}