Re: [PATCH v12 7/7] nvmem: core: Expose cells through sysfs

Miquel Raynal
2023-10-11T07:15:37Z

Hi Srinivas,

> > +{
> > + struct bin_attribute **cells_attrs, *attrs;
> > + struct nvmem_cell_entry *entry;
> > + unsigned int ncells = 0, i = 0;
> > + int ret = 0;
> > +
> > + mutex_lock(&nvmem_mutex);
> > +
> > + if (list_empty(&nvmem->cells) || nvmem->sysfs_cells_populated) {
> > + nvmem_cells_group.bin_attrs = NULL;
> > + goto unlock_mutex;
> > + }
> > +
> > + /* Allocate an array of attributes with a sentinel */
> > + ncells = list_count_nodes(&nvmem->cells);
> > + cells_attrs = devm_kcalloc(&nvmem->dev, ncells + 1,
> > + sizeof(struct bin_attribute *), GFP_KERNEL);
> > + if (!cells_attrs) {
> > + ret = -ENOMEM;
> > + goto unlock_mutex;
> > + }
> > +
> > + attrs = devm_kcalloc(&nvmem->dev, ncells, sizeof(struct bin_attribute), GFP_KERNEL);
> > + if (!attrs) {
> > + ret = -ENOMEM;
> > + goto unlock_mutex;
> > + }
> > +
> > + /* Initialize each attribute to take the name and size of the cell */
> > + list_for_each_entry(entry, &nvmem->cells, node) {
> > + sysfs_bin_attr_init(&attrs[i]);
> > + attrs[i].attr.name = devm_kasprintf(&nvmem->dev, GFP_KERNEL,
> > + "%s@%x", entry->name,
> > + entry->offset);
> > + attrs[i].attr.mode = 0444;
> > + attrs[i].size = entry->bytes;
> > + attrs[i].read = &nvmem_cell_attr_read;
> > + attrs[i].private = entry;
> > + if (!attrs[i].attr.name) {
> > + ret = -ENOMEM;
> > + goto unlock_mutex;
> > + }
> > +
> > + cells_attrs[i] = &attrs[i];
> > + i++;
> > + }
> > +
> > + nvmem_cells_group.bin_attrs = cells_attrs;
> > +
> > + ret = devm_device_add_groups(&nvmem->dev, nvmem_cells_groups);
> > + if (ret)
> > + goto unlock_mutex;
>
> This is going to create groups after the nvmem device is added, isn't this going to be problem with user space notifications?

Greg said it was not. I hope I understood correctly :-)

And anyway, cells have never been available to userspace, so there is
nothing userspace might expect yet?

Thanks,
Miquèl