Re: [PATCH v5 20/28] fpga: dfl: add fpga bridge platform driver for FME

From: Wu Hao
Date: Wed May 23 2018 - 18:59:59 EST

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In reply to: Alan Tull: "Re: [PATCH v5 20/28] fpga: dfl: add fpga bridge platform driver for FME"
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On Wed, May 23, 2018 at 04:06:17PM -0500, Alan Tull wrote:
> On Wed, May 23, 2018 at 10:28 AM, Wu Hao <hao.wu@xxxxxxxxx> wrote:
> > On Wed, May 23, 2018 at 10:15:00AM -0500, Alan Tull wrote:
> >> On Tue, May 1, 2018 at 9:50 PM, Wu Hao <hao.wu@xxxxxxxxx> wrote:
> >>
> >> Hi Hao,
> >>
> >> > This patch adds fpga bridge platform driver for FPGA Management Engine.
> >> > It implements the enable_set callback for fpga bridge.
> >> >
> >> > Signed-off-by: Tim Whisonant <tim.whisonant@xxxxxxxxx>
> >> > Signed-off-by: Enno Luebbers <enno.luebbers@xxxxxxxxx>
> >> > Signed-off-by: Shiva Rao <shiva.rao@xxxxxxxxx>
> >> > Signed-off-by: Christopher Rauer <christopher.rauer@xxxxxxxxx>
> >> > Signed-off-by: Wu Hao <hao.wu@xxxxxxxxx>
> >> > Acked-by: Alan Tull <atull@xxxxxxxxxx>
> >> > Acked-by: Moritz Fischer <mdf@xxxxxxxxxx>
> >> > ---
> >> > v3: rename driver to fpga-dfl-fme-br
> >> > remove useless dev_dbg in probe function.
> >> > rebased due to fpga api change.
> >> > v4: rename to dfl-fme-br and fix SPDX license issue
> >> > include dfl-fme-pr.h instead of dfl-fme.h
> >> > add Acked-by from Alan and Moritz
> >> > v5: rebase due to API changes.
> >> > defer port and its ops finding when really need.
> >> > ---
> >> > drivers/fpga/Kconfig | 6 +++
> >> > drivers/fpga/Makefile | 1 +
> >> > drivers/fpga/dfl-fme-br.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++
> >> > 3 files changed, 121 insertions(+)
> >> > create mode 100644 drivers/fpga/dfl-fme-br.c
> >> >
> >> > diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> >> > index 89f76e8..a8f939a 100644
> >> > --- a/drivers/fpga/Kconfig
> >> > +++ b/drivers/fpga/Kconfig
> >> > @@ -156,6 +156,12 @@ config FPGA_DFL_FME_MGR
> >> > help
> >> > Say Y to enable FPGA Manager driver for FPGA Management Engine.
> >> >
> >> > +config FPGA_DFL_FME_BRIDGE
> >> > + tristate "FPGA DFL FME Bridge Driver"
> >> > + depends on FPGA_DFL_FME
> >> > + help
> >> > + Say Y to enable FPGA Bridge driver for FPGA Management Engine.
> >> > +
> >> > config FPGA_DFL_PCI
> >> > tristate "FPGA Device Feature List (DFL) PCIe Device Driver"
> >> > depends on PCI && FPGA_DFL
> >> > diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> >> > index f82814a..75096e9 100644
> >> > --- a/drivers/fpga/Makefile
> >> > +++ b/drivers/fpga/Makefile
> >> > @@ -32,6 +32,7 @@ obj-$(CONFIG_OF_FPGA_REGION) += of-fpga-region.o
> >> > obj-$(CONFIG_FPGA_DFL) += dfl.o
> >> > obj-$(CONFIG_FPGA_DFL_FME) += dfl-fme.o
> >> > obj-$(CONFIG_FPGA_DFL_FME_MGR) += dfl-fme-mgr.o
> >> > +obj-$(CONFIG_FPGA_DFL_FME_BRIDGE) += dfl-fme-br.o
> >> >
> >> > dfl-fme-objs := dfl-fme-main.o dfl-fme-pr.o
> >> >
> >> > diff --git a/drivers/fpga/dfl-fme-br.c b/drivers/fpga/dfl-fme-br.c
> >> > new file mode 100644
> >> > index 0000000..5c51b08
> >> > --- /dev/null
> >> > +++ b/drivers/fpga/dfl-fme-br.c
> >> > @@ -0,0 +1,114 @@
> >> > +// SPDX-License-Identifier: GPL-2.0
> >> > +/*
> >> > + * FPGA Bridge Driver for FPGA Management Engine (FME)
> >> > + *
> >> > + * Copyright (C) 2017 Intel Corporation, Inc.
> >> > + *
> >> > + * Authors:
> >> > + * Wu Hao <hao.wu@xxxxxxxxx>
> >> > + * Joseph Grecco <joe.grecco@xxxxxxxxx>
> >> > + * Enno Luebbers <enno.luebbers@xxxxxxxxx>
> >> > + * Tim Whisonant <tim.whisonant@xxxxxxxxx>
> >> > + * Ananda Ravuri <ananda.ravuri@xxxxxxxxx>
> >> > + * Henry Mitchel <henry.mitchel@xxxxxxxxx>
> >> > + */
> >> > +
> >> > +#include <linux/module.h>
> >> > +#include <linux/fpga/fpga-bridge.h>
> >> > +
> >> > +#include "dfl.h"
> >> > +#include "dfl-fme-pr.h"
> >> > +
> >> > +struct fme_br_priv {
> >> > + struct dfl_fme_br_pdata *pdata;
> >> > + struct dfl_fpga_port_ops *port_ops;
> >> > + struct platform_device *port_pdev;
> >> > +};
> >> > +
> >> > +static int fme_bridge_enable_set(struct fpga_bridge *bridge, bool enable)
> >> > +{
> >> > + struct fme_br_priv *priv = bridge->priv;
> >> > + struct platform_device *port_pdev;
> >> > + struct dfl_fpga_port_ops *ops;
> >> > +
> >> > + if (!priv->port_pdev) {
> >> > + port_pdev = dfl_fpga_cdev_find_port(priv->pdata->cdev,
> >> > + &priv->pdata->port_id,
> >> > + dfl_fpga_check_port_id);
> >> > + if (!port_pdev)
> >> > + return -ENODEV;
> >> > +
> >> > + priv->port_pdev = port_pdev;
> >> > + }
> >> > +
> >> > + if (priv->port_pdev && !priv->port_ops) {
> >> > + ops = dfl_fpga_get_port_ops(priv->port_pdev);
> >> > + if (!ops || !ops->enable_set)
> >> > + return -ENOENT;
> >> > +
> >> > + priv->port_ops = ops;
> >> > + }
> >>
> >> This is saving some pointers. Is it possible that the port_pdev or
> >> port_ops could go away?
> >
> > Hi Alan
> >
> > Thanks for the comments.
> >
> > The find_port function will get the port device to prevent that.
> > You can see put device in remove function. And it's similar for the
> > port ops. In dfl_fpga_get_port_ops function, it will prevent unexpected
> > port ops removing by try module get.
>
> OK, good, and I see the find_port function documents that put_device
> is needed, so that's good too.
>
> When we previously discussed this [1] you described a procedure of
> hot-unplugging the VF AFU from the VM and turning it back to PF before
> doing the FPGA programming. Some comments on that would be helpful,
> maybe located with the port_ops functions.
>

Hi Alan

Actually I plan to add those descriptions about virtualization in the
documenation/fpga/dfl.txt, together with the patch which enables the
virtualization support for Intel FPGA device (e.g Intel PAC card). I
think dfl.txt is a better place to have that procedure documented.
How do you think?

> [1] https://lkml.org/lkml/2018/4/6/180
>
> >
> >>
> >> Also, the port ops routines probably should be named
> >> dfl_fpga_port_ops_get/find_port/etc
> >>
> >
> > Hm.. as I see there are functions named as get_device(), put_device(), so
> > I just name it as ..._get_port_ops and ..._put_port_ops in similar way. :)
> > If you think that could be a better name, it's fine for me to change them.
>
> Yes, I've seen that too. I think keeping the prefix the same helps to
> organize the namespace. Plus :) if I'm grepping through the code, I
> can be lazy and not have to use a regex to find the port ops
> functions.

so we good with current naming?

some places we find it's get_device() and put_device(), but other functions
like device_add(), device_del(). actually it's not a big problem I think, :)
currently port_ops has a unified style ..._add/del/get/put_port_ops. I am
fine with both kind of naming, if you prefer ...port_ops_add/del/get/put
style, please let me know, I can change them in the next version.

Thanks
Hao

>
> Alan
>
> >
> > Thanks
> > Hao
> >
> >> Alan
> >>
> >> > +
> >> > + return priv->port_ops->enable_set(priv->port_pdev, enable);
> >> > +}
> >> > +
> >> > +static const struct fpga_bridge_ops fme_bridge_ops = {
> >> > + .enable_set = fme_bridge_enable_set,
> >> > +};
> >> > +
> >> > +static int fme_br_probe(struct platform_device *pdev)
> >> > +{
> >> > + struct device *dev = &pdev->dev;
> >> > + struct fme_br_priv *priv;
> >> > + struct fpga_bridge *br;
> >> > + int ret;
> >> > +
> >> > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> >> > + if (!priv)
> >> > + return -ENOMEM;
> >> > +
> >> > + priv->pdata = dev_get_platdata(dev);
> >> > +
> >> > + br = fpga_bridge_create(dev, "DFL FPGA FME Bridge",
> >> > + &fme_bridge_ops, priv);
> >> > + if (!br)
> >> > + return -ENOMEM;
> >> > +
> >> > + platform_set_drvdata(pdev, br);
> >> > +
> >> > + ret = fpga_bridge_register(br);
> >> > + if (ret)
> >> > + fpga_bridge_free(br);
> >> > +
> >> > + return ret;
> >> > +}
> >> > +
> >> > +static int fme_br_remove(struct platform_device *pdev)
> >> > +{
> >> > + struct fpga_bridge *br = platform_get_drvdata(pdev);
> >> > + struct fme_br_priv *priv = br->priv;
> >> > +
> >> > + fpga_bridge_unregister(br);
> >> > +
> >> > + if (priv->port_pdev)
> >> > + put_device(&priv->port_pdev->dev);
> >> > + if (priv->port_ops)
> >> > + dfl_fpga_put_port_ops(priv->port_ops);
> >> > +
> >> > + return 0;
> >> > +}
> >> > +
> >> > +static struct platform_driver fme_br_driver = {
> >> > + .driver = {
> >> > + .name = DFL_FPGA_FME_BRIDGE,
> >> > + },
> >> > + .probe = fme_br_probe,
> >> > + .remove = fme_br_remove,
> >> > +};
> >> > +
> >> > +module_platform_driver(fme_br_driver);
> >> > +
> >> > +MODULE_DESCRIPTION("FPGA Bridge for DFL FPGA Management Engine");
> >> > +MODULE_AUTHOR("Intel Corporation");
> >> > +MODULE_LICENSE("GPL v2");
> >> > +MODULE_ALIAS("platform:dfl-fme-bridge");
> >> > --
> >> > 1.8.3.1
> >> >
> --
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Next message: Kent Overstreet: "Notes on locking for pagacache consistency (was: [PATCH 01/10] mm: pagecache add lock)"
Previous message: Ray Jui: "Re: [PATCH v2 2/6] Documentation: DT: Add optional 'timeout-sec' property for sp805"
In reply to: Alan Tull: "Re: [PATCH v5 20/28] fpga: dfl: add fpga bridge platform driver for FME"
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