On Tue, Jul 3, 2018 at 3:44 AM, Appana Durga Kedareswara rao <appana.durga....@xilinx.com> wrote:
Hi Appana, > 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/readback Two things here: I'd prefer calling the attribute "image" rather than "readback" This should be an entry per fpga manager, not one entry for the whole framework, so cat /sys/kernel/debug/fpga/fpga0/image > > Signed-off-by: Appana Durga Kedareswara rao <appana.durga....@xilinx.com> > --- > drivers/fpga/fpga-mgr.c | 52 > +++++++++++++++++++++++++++++++++++++++++++ > include/linux/fpga/fpga-mgr.h | 6 +++++ > 2 files changed, 58 insertions(+) > > diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c > index 9939d2c..7a9fd7c 100644 > --- a/drivers/fpga/fpga-mgr.c > +++ b/drivers/fpga/fpga-mgr.c > @@ -484,6 +484,39 @@ void fpga_mgr_put(struct fpga_manager *mgr) > } > EXPORT_SYMBOL_GPL(fpga_mgr_put); > > +#ifdef CONFIG_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; Here you should return an error for mgr's that don't support read function: if (!mgr->mops->read) return -ENOENT; Then you probably should lock the mgr so that nobody tries to write it while you are reading. If you can't lock it, return -EBUSY. > + > + if (mgr->state != FPGA_MGR_STATE_OPERATING) > + return -EBUSY; If the FPGA isn't programmed, I'm not sure that EBUSY would be the correct error. > + > + /* 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"); > + return ret; Don't need this return here since we return right afterwards anyway. > + } > + > + 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_debugops = { Suggest including the name of the debugfs file in the name since more debugfs files will be added over time, so s/fpga_mgr_debugops/fpga_mgr_ops_image/ or something. > + .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 +614,21 @@ int fpga_mgr_register(struct device *dev, const char > *name, > if (ret) > goto error_device; > > +#ifdef CONFIG_DEBUG_FS I'd prefer an added config such as CONFIG_FPGA_MGR_DEBUG_FS. > + mgr->dir = debugfs_create_dir("fpga", NULL); > + if (!mgr->dir) > + goto error_device; > + > + mgr->parent = mgr->dir; > + mgr->dir = debugfs_create_file("readback", 0644, mgr->parent, mgr, > + &fpga_mgr_debugops); > + if (!mgr->dir) { > + debugfs_remove_recursive(mgr->parent); > + mgr->parent = NULL; > + goto error_device; > + } > +#endif > + > dev_info(&mgr->dev, "%s registered\n", mgr->name); > > return 0; > @@ -604,6 +652,10 @@ void fpga_mgr_unregister(struct device *dev) > > dev_info(&mgr->dev, "%s %s\n", __func__, mgr->name); > > +#ifdef CONFIG_DEBUG_FS > + debugfs_remove_recursive(mgr->parent); > + mgr->parent = NULL; > +#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..6013809 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: read FPGA configuration information Please add note that the read ops is optional similar to below. > * @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 +153,10 @@ struct fpga_manager { > enum fpga_mgr_states state; > const struct fpga_manager_ops *mops; > void *priv; > +#ifdef CONFIG_DEBUG_FS > + struct dentry *dir; > + struct dentry *parent; > +#endif > }; > > #define to_fpga_manager(d) container_of(d, struct fpga_manager, dev) > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fpga" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Thanks, Alan