linux-kernel - Re: [PATCH v2 05/22] fpga: mgr: add status for fpga-mgr

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Date:   Wed, 12 Jul 2017 10:22:17 -0500
From:   Alan Tull <atull@...nel.org>
To:     Wu Hao <hao.wu@...el.com>
Cc:     Moritz Fischer <mdf@...nel.org>, linux-fpga@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-api@...r.kernel.org, "Kang, Luwei" <luwei.kang@...el.com>,
        "Zhang, Yi Z" <yi.z.zhang@...el.com>
Subject: Re: [PATCH v2 05/22] fpga: mgr: add status for fpga-mgr

On Sun, Jun 25, 2017 at 8:52 PM, Wu Hao <hao.wu@...el.com> wrote:

Hi Hao,

> This patch adds status to fpga-manager data structure, to allow
> driver to store full/partial reconfiguration errors and other
> status information.
>
> one sysfs interface created for user space application to read
> fpga-manager status.
>
> Signed-off-by: Wu Hao <hao.wu@...el.com>
> ---
>  Documentation/ABI/testing/sysfs-class-fpga-manager | 10 +++++++++
>  drivers/fpga/fpga-mgr.c                            | 24 ++++++++++++++++++++++
>  include/linux/fpga/fpga-mgr.h                      |  9 ++++++++
>  3 files changed, 43 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-fpga-manager b/Documentation/ABI/testing/sysfs-class-fpga-manager
> index 23056c5..71b083e 100644
> --- a/Documentation/ABI/testing/sysfs-class-fpga-manager
> +++ b/Documentation/ABI/testing/sysfs-class-fpga-manager
> @@ -35,3 +35,13 @@ Description: Read fpga manager state as a string.
>                 * write complete        = Doing post programming steps
>                 * write complete error  = Error while doing post programming
>                 * operating             = FPGA is programmed and operating
> +
> +What:          /sys/class/fpga_manager/<fpga>/status
> +Date:          June 2017
> +KernelVersion: 4.12
> +Contact:       Wu Hao <hao.wu@...el.com>
> +Description:   Read fpga manager status as a string.
> +               If FPGA programming operation fails, it could be due to crc
> +               error or incompatible bitstream image. The intent of this
> +               interface is to provide more detailed information for FPGA
> +               programming errors to userspace.
> diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
> index be13cce..2485658 100644
> --- a/drivers/fpga/fpga-mgr.c
> +++ b/drivers/fpga/fpga-mgr.c
> @@ -388,12 +388,36 @@ static ssize_t state_show(struct device *dev,
>         return sprintf(buf, "%s\n", state_str[mgr->state]);
>  }
>
> +static ssize_t status_show(struct device *dev,
> +                          struct device_attribute *attr, char *buf)
> +{
> +       struct fpga_manager *mgr = to_fpga_manager(dev);
> +       int len = 0;
> +
> +       if (mgr->status & FPGA_MGR_STATUS_OPERATION_ERR)
> +               len += sprintf(buf + len, "reconfig operation error\n");
> +       if (mgr->status & FPGA_MGR_STATUS_CRC_ERR)
> +               len += sprintf(buf + len, "reconfig crc error\n");
> +       if (mgr->status & FPGA_MGR_STATUS_INCOMPATIBLE_BS_ERR)
> +               len += sprintf(buf + len, "reconfig incompatible BS error\n");
> +       if (mgr->status & FPGA_MGR_STATUS_IP_PROTOCOL_ERR)
> +               len += sprintf(buf + len, "reconfig IP protocol error\n");
> +       if (mgr->status & FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR)
> +               len += sprintf(buf + len, "reconfig fifo overflow error\n");
> +       if (mgr->status & FPGA_MGR_STATUS_SECURE_LOAD_ERR)
> +               len += sprintf(buf + len, "reconfig secure load error\n");
> +
> +       return len;
> +}
> +
>  static DEVICE_ATTR_RO(name);
>  static DEVICE_ATTR_RO(state);
> +static DEVICE_ATTR_RO(status);
>
>  static struct attribute *fpga_mgr_attrs[] = {
>         &dev_attr_name.attr,
>         &dev_attr_state.attr,
> +       &dev_attr_status.attr,
>         NULL,
>  };
>  ATTRIBUTE_GROUPS(fpga_mgr);
> diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
> index b222a57..8cb42ac 100644
> --- a/include/linux/fpga/fpga-mgr.h
> +++ b/include/linux/fpga/fpga-mgr.h
> @@ -128,6 +128,14 @@ struct fpga_manager_ops {
>         void (*fpga_remove)(struct fpga_manager *mgr);
>  };
>
> +/* FPGA manager status: Partial/Full Reconfiguration errors */
> +#define FPGA_MGR_STATUS_OPERATION_ERR          BIT(0)
> +#define FPGA_MGR_STATUS_CRC_ERR                        BIT(1)
> +#define FPGA_MGR_STATUS_INCOMPATIBLE_BS_ERR    BIT(2)

How about ..._INCOMPATIBLE_IMAGE_ERR? :)

> +#define FPGA_MGR_STATUS_IP_PROTOCOL_ERR                BIT(3)
> +#define FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR      BIT(4)
> +#define FPGA_MGR_STATUS_SECURE_LOAD_ERR                BIT(5)
> +
>  /**
>   * struct fpga_manager - fpga manager structure
>   * @name: name of low level fpga manager
> @@ -142,6 +150,7 @@ struct fpga_manager {
>         struct device dev;
>         struct mutex ref_mutex;
>         enum fpga_mgr_states state;
> +       u64 status;

With this implementation, the low level driver sets ops->status and
that could be stale by the time the framework looks at it.  I suggest
adding a function to fpga_manager_ops that returns the status.  That
way whenever the status is requested, the low level driver will have
the opportunity to read status registers.

Besides this, this new sysfs looks helpful.

Alan

>         const struct fpga_manager_ops *mops;
>         void *priv;
>  };
> --
> 1.8.3.1
>