Messages in this thread Patch in this message | | | From | Nicholas Johnson <> | Subject | [PATCH v5 1/1] nvmem: Add support for write-only instances | Date | Wed, 18 Mar 2020 15:20:14 +0000 |
| |
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> --- 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 77d890d36..ddc7be514 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 9e0c429cd..4ceac8680 100644 --- a/drivers/nvmem/nvmem-sysfs.c +++ b/drivers/nvmem/nvmem-sysfs.c @@ -196,16 +196,49 @@ 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, +}; + +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; - return nvmem->read_only ? nvmem_ro_dev_groups : nvmem_rw_dev_groups; + return NULL; } /* @@ -224,17 +257,24 @@ int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem, if (!config->base_dev) return -EINVAL; - if (nvmem->read_only) { + if (nvmem->reg_read && (!nvmem->reg_write || nvmem->read_only)) { if (config->root_only) nvmem->eeprom = bin_attr_ro_root_nvmem; else nvmem->eeprom = bin_attr_ro_nvmem; - } else { + } else if (!nvmem->reg_read && nvmem->reg_write && !nvmem->read_only) { + if (config->root_only) + nvmem->eeprom = bin_attr_wo_root_nvmem; + else + return -EINVAL; + } else if (nvmem->reg_read && nvmem->reg_write && !nvmem->read_only) { if (config->root_only) nvmem->eeprom = bin_attr_rw_root_nvmem; else nvmem->eeprom = bin_attr_rw_nvmem; - } + } else + return -EINVAL; + nvmem->eeprom.attr.name = "eeprom"; nvmem->eeprom.size = nvmem->size; #ifdef CONFIG_DEBUG_LOCK_ALLOC -- 2.25.1
| |