[PATCH v4 1/2] fpga: fpga-mgr: Add readback support

[appanad@xilinx.com (Appana Durga Kedareswara Rao)]

Hi Alan,

	Thanks for the review... 

<Snip>
> On Fri, Jul 27, 2018 at 1:22 AM, Appana Durga Kedareswara rao
> <appana.durga.rao@xilinx.com> wrote:
> 
> Hi Appana,
> 
> There should be some documentation for the debugfs added under
> Documentation/driver-api/fpga/
> 
> Also there are a lot of #ifdefs that were added due to the
> CONFIG_FPGA_MGR_DEBUG_FS.  This has caused a kernel robot complaint.
> The way to fix that is to have a separate c file for the debugfs
> implementation.  I see a lot of other kernel drivers have done it this way.  I
> have an implementation that I haven't submitted yet, it exposes different
> functionality (exposing the image firmware file name and writing to the
> image file).  It's on the downstream github.com/altera-opensource repo [1].
> I'll clean this up and submit it to the mailing list, it may take a minute for me
> to get to that.
> Once that's done, your added functionality can be a patch on top of that.

Sounds good...
Let me know if you need any help on testing this will do.

Regards,
Kedar.
> 
> Alan
> 
> [1] https://github.com/altera-opensource/linux-socfpga/blob/socfpga-
> 4.17/drivers/fpga/fpga-mgr-debugfs.c
> https://github.com/altera-opensource/linux-socfpga/blob/socfpga-
> 4.17/drivers/fpga/fpga-mgr-debugfs.h
> 
> 
> > Inorder to debug issues with fpga's users would like to read the fpga
> > configuration information.
> > This patch adds readback support for fpga configuration data in the
> > framework through debugfs interface.
> >
> > Usage:
> >         cat /sys/kernel/debug/fpga/fpga0/image
> >
> > Signed-off-by: Appana Durga Kedareswara rao
> > <appana.durga.rao@xilinx.com>
> > ---
> > Changes for v4:
> > --> None.
> > Changes for v3:
> > --> None.
> > Changes for v2:
> > --> Fixed debug attribute path and name as suggested by Alan Add
> > --> config entry for DEBUG as suggested by Alan Fixed trival coding
> > --> style issues.
> >
> >  drivers/fpga/Kconfig          |  7 +++++
> >  drivers/fpga/fpga-mgr.c       | 68
> +++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/fpga/fpga-mgr.h |  5 ++++
> >  3 files changed, 80 insertions(+)
> >
> > diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig index
> > 53d3f55..838ad4e 100644
> > --- a/drivers/fpga/Kconfig
> > +++ b/drivers/fpga/Kconfig
> > @@ -11,6 +11,13 @@ menuconfig FPGA
> >
> >  if FPGA
> >
> > +config FPGA_MGR_DEBUG_FS
> > +       tristate "FPGA Debug fs"
> > +       select DEBUG_FS
> > +       help
> > +         FPGA manager debug provides support for reading fpga
> configuration
> > +         information.
> > +
> >  config FPGA_MGR_SOCFPGA
> >         tristate "Altera SOCFPGA FPGA Manager"
> >         depends on ARCH_SOCFPGA || COMPILE_TEST diff --git
> > a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c index
> > 9939d2c..4bea860 100644
> > --- a/drivers/fpga/fpga-mgr.c
> > +++ b/drivers/fpga/fpga-mgr.c
> > @@ -484,6 +484,48 @@ void fpga_mgr_put(struct fpga_manager *mgr)  }
> > EXPORT_SYMBOL_GPL(fpga_mgr_put);
> >
> > +#ifdef CONFIG_FPGA_MGR_DEBUG_FS
> > +#include <linux/debugfs.h>
> > +
> > +static int fpga_mgr_read(struct seq_file *s, void *data) {
> > +       struct fpga_manager *mgr = (struct fpga_manager *)s->private;
> > +       int ret = 0;
> > +
> > +       if (!mgr->mops->read)
> > +               return -ENOENT;
> > +
> > +       if (!mutex_trylock(&mgr->ref_mutex))
> > +               return -EBUSY;
> > +
> > +       if (mgr->state != FPGA_MGR_STATE_OPERATING) {
> > +               ret = -EPERM;
> > +               goto err_unlock;
> > +       }
> > +
> > +       /* Read the FPGA configuration data from the fabric */
> > +       ret = mgr->mops->read(mgr, s);
> > +       if (ret)
> > +               dev_err(&mgr->dev, "Error while reading configuration
> > + data from FPGA\n");
> > +
> > +err_unlock:
> > +       mutex_unlock(&mgr->ref_mutex);
> > +
> > +       return ret;
> > +}
> > +
> > +static int fpga_mgr_read_open(struct inode *inode, struct file *file)
> > +{
> > +       return single_open(file, fpga_mgr_read, inode->i_private); }
> > +
> > +static const struct file_operations fpga_mgr_ops_image = {
> > +       .owner = THIS_MODULE,
> > +       .open = fpga_mgr_read_open,
> > +       .read = seq_read,
> > +};
> > +#endif
> > +
> >  /**
> >   * fpga_mgr_lock - Lock FPGA manager for exclusive use
> >   * @mgr:       fpga manager
> > @@ -581,6 +623,29 @@ int fpga_mgr_register(struct device *dev, const
> char *name,
> >         if (ret)
> >                 goto error_device;
> >
> > +#ifdef CONFIG_FPGA_MGR_DEBUG_FS
> > +       struct dentry *d, *parent;
> > +
> > +       mgr->dir = debugfs_create_dir("fpga", NULL);
> > +       if (!mgr->dir)
> > +               goto error_device;
> > +
> > +       parent = mgr->dir;
> > +       d = debugfs_create_dir(mgr->dev.kobj.name, parent);
> > +       if (!d) {
> > +               debugfs_remove_recursive(parent);
> > +               goto error_device;
> > +       }
> > +
> > +       parent = d;
> > +       d = debugfs_create_file("image", 0644, parent, mgr,
> > +                               &fpga_mgr_ops_image);
> > +       if (!d) {
> > +               debugfs_remove_recursive(mgr->dir);
> > +               goto error_device;
> > +       }
> > +#endif
> > +
> >         dev_info(&mgr->dev, "%s registered\n", mgr->name);
> >
> >         return 0;
> > @@ -604,6 +669,9 @@ void fpga_mgr_unregister(struct device *dev)
> >
> >         dev_info(&mgr->dev, "%s %s\n", __func__, mgr->name);
> >
> > +#ifdef CONFIG_FPGA_MGR_DEBUG_FS
> > +       debugfs_remove_recursive(mgr->dir);
> > +#endif
> >         /*
> >          * If the low level driver provides a method for putting fpga into
> >          * a desired state upon unregister, do it.
> > diff --git a/include/linux/fpga/fpga-mgr.h
> > b/include/linux/fpga/fpga-mgr.h index 3c6de23..e9e17a9 100644
> > --- a/include/linux/fpga/fpga-mgr.h
> > +++ b/include/linux/fpga/fpga-mgr.h
> > @@ -114,6 +114,7 @@ struct fpga_image_info {
> >   * @write: write count bytes of configuration data to the FPGA
> >   * @write_sg: write the scatter list of configuration data to the FPGA
> >   * @write_complete: set FPGA to operating state after writing is done
> > + * @read: optional: read FPGA configuration information
> >   * @fpga_remove: optional: Set FPGA into a specific state during driver
> remove
> >   * @groups: optional attribute groups.
> >   *
> > @@ -131,6 +132,7 @@ struct fpga_manager_ops {
> >         int (*write_sg)(struct fpga_manager *mgr, struct sg_table *sgt);
> >         int (*write_complete)(struct fpga_manager *mgr,
> >                               struct fpga_image_info *info);
> > +       int (*read)(struct fpga_manager *mgr, struct seq_file *s);
> >         void (*fpga_remove)(struct fpga_manager *mgr);
> >         const struct attribute_group **groups;  }; @@ -151,6 +153,9 @@
> > struct fpga_manager {
> >         enum fpga_mgr_states state;
> >         const struct fpga_manager_ops *mops;
> >         void *priv;
> > +#ifdef CONFIG_FPGA_MGR_DEBUG_FS
> > +       struct dentry *dir;
> > +#endif
> >  };
> >
> >  #define to_fpga_manager(d) container_of(d, struct fpga_manager, dev)
> > --
> > 2.7.4
> >
> > --
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