Messages in this thread Patch in this message | | | Date | Mon, 23 Mar 2020 20:05:05 +0100 | From | Greg KH <> | Subject | Re: [PATCH 5/5] nvmem: Add support for write-only instances |
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On Mon, Mar 23, 2020 at 03:00:07PM +0000, Srinivas Kandagatla wrote: > From: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au> > > There is at least one real-world use-case for write-only nvmem > instances. Refer to 03cd45d2e219 ("thunderbolt: Prevent crash if > non-active NVMem file is read"). > > Add support for write-only nvmem instances by adding attrs for 0200. > > Change nvmem_register() to abort if NULL group is returned from > nvmem_sysfs_get_groups(). > > Return NULL from nvmem_sysfs_get_groups() in invalid cases. > > Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au> > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> > --- > drivers/nvmem/core.c | 10 +++++-- > drivers/nvmem/nvmem-sysfs.c | 56 +++++++++++++++++++++++++++++++------ > 2 files changed, 56 insertions(+), 10 deletions(-) > > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c > index 77d890d3623d..ddc7be5149d5 100644 > --- a/drivers/nvmem/core.c > +++ b/drivers/nvmem/core.c > @@ -381,6 +381,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > nvmem->type = config->type; > nvmem->reg_read = config->reg_read; > nvmem->reg_write = config->reg_write; > + nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config); > + if (!nvmem->dev.groups) { > + ida_simple_remove(&nvmem_ida, nvmem->id); > + gpiod_put(nvmem->wp_gpio); > + kfree(nvmem); > + return ERR_PTR(-EINVAL); > + } > + > if (!config->no_of_node) > nvmem->dev.of_node = config->dev->of_node; > > @@ -395,8 +403,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > nvmem->read_only = device_property_present(config->dev, "read-only") || > config->read_only || !nvmem->reg_write; > > - nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config); > - > device_initialize(&nvmem->dev); > > dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); > diff --git a/drivers/nvmem/nvmem-sysfs.c b/drivers/nvmem/nvmem-sysfs.c > index 8759c4470012..9728da948988 100644 > --- a/drivers/nvmem/nvmem-sysfs.c > +++ b/drivers/nvmem/nvmem-sysfs.c > @@ -202,16 +202,49 @@ static const struct attribute_group *nvmem_ro_root_dev_groups[] = { > NULL, > }; > > +/* write only permission, root only */ > +static struct bin_attribute bin_attr_wo_root_nvmem = { > + .attr = { > + .name = "nvmem", > + .mode = 0200, > + }, > + .write = bin_attr_nvmem_write, > +};
You are adding a new sysfs file without a Documentation/ABI/ new entry as well?
> + > +static struct bin_attribute *nvmem_bin_wo_root_attributes[] = { > + &bin_attr_wo_root_nvmem, > + NULL, > +}; > + > +static const struct attribute_group nvmem_bin_wo_root_group = { > + .bin_attrs = nvmem_bin_wo_root_attributes, > + .attrs = nvmem_attrs, > +}; > + > +static const struct attribute_group *nvmem_wo_root_dev_groups[] = { > + &nvmem_bin_wo_root_group, > + NULL, > +}; > + > const struct attribute_group **nvmem_sysfs_get_groups( > struct nvmem_device *nvmem, > const struct nvmem_config *config) > { > - if (config->root_only) > - return nvmem->read_only ? > - nvmem_ro_root_dev_groups : > - nvmem_rw_root_dev_groups; > + /* Read-only */ > + if (nvmem->reg_read && (!nvmem->reg_write || nvmem->read_only)) > + return config->root_only ? > + nvmem_ro_root_dev_groups : nvmem_ro_dev_groups; > + > + /* Read-write */ > + if (nvmem->reg_read && nvmem->reg_write && !nvmem->read_only) > + return config->root_only ? > + nvmem_rw_root_dev_groups : nvmem_rw_dev_groups; > + > + /* Write-only, do not honour request for global writable entry */ > + if (!nvmem->reg_read && nvmem->reg_write && !nvmem->read_only) > + return config->root_only ? nvmem_wo_root_dev_groups : NULL;
What is this supposed to be doing, I am totally lost.
greg k-h
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