![Srinivas Kandagatla](/assets/img/avatar_default.png)
Many nvmem providers are not very keen on having default sysfs nvmem entry, as most of the usecases for them are inside kernel itself. And in some cases read/writes to some areas in nvmem are restricted and trapped at secure monitor level, so accessing them from userspace would result in board reboots. This patch adds new NVMEM_SYSFS Kconfig to make binary sysfs entry an optional one. This provision will give more flexibility to users. This patch also moves existing sysfs code to a new file so that its not compiled in when its not really required. Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Reviewed-by: Gaurav Kohli <gkohli@codeaurora.org> Tested-by: Gaurav Kohli <gkohli@codeaurora.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
257 lines
5.4 KiB
C
257 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2019, Linaro Limited
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*/
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#include "nvmem.h"
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static const char * const nvmem_type_str[] = {
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[NVMEM_TYPE_UNKNOWN] = "Unknown",
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[NVMEM_TYPE_EEPROM] = "EEPROM",
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[NVMEM_TYPE_OTP] = "OTP",
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[NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
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};
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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static struct lock_class_key eeprom_lock_key;
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#endif
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static ssize_t type_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct nvmem_device *nvmem = to_nvmem_device(dev);
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return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
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}
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static DEVICE_ATTR_RO(type);
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static struct attribute *nvmem_attrs[] = {
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&dev_attr_type.attr,
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NULL,
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};
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static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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char *buf, loff_t pos, size_t count)
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{
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struct device *dev;
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struct nvmem_device *nvmem;
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int rc;
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if (attr->private)
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dev = attr->private;
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else
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dev = container_of(kobj, struct device, kobj);
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nvmem = to_nvmem_device(dev);
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/* Stop the user from reading */
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if (pos >= nvmem->size)
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return 0;
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if (count < nvmem->word_size)
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return -EINVAL;
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if (pos + count > nvmem->size)
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count = nvmem->size - pos;
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count = round_down(count, nvmem->word_size);
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rc = nvmem->reg_read(nvmem->priv, pos, buf, count);
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if (rc)
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return rc;
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return count;
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}
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static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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char *buf, loff_t pos, size_t count)
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{
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struct device *dev;
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struct nvmem_device *nvmem;
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int rc;
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if (attr->private)
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dev = attr->private;
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else
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dev = container_of(kobj, struct device, kobj);
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nvmem = to_nvmem_device(dev);
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/* Stop the user from writing */
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if (pos >= nvmem->size)
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return -EFBIG;
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if (count < nvmem->word_size)
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return -EINVAL;
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if (pos + count > nvmem->size)
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count = nvmem->size - pos;
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count = round_down(count, nvmem->word_size);
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rc = nvmem->reg_write(nvmem->priv, pos, buf, count);
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if (rc)
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return rc;
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return count;
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}
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/* default read/write permissions */
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static struct bin_attribute bin_attr_rw_nvmem = {
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.attr = {
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.name = "nvmem",
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.mode = 0644,
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},
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.read = bin_attr_nvmem_read,
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.write = bin_attr_nvmem_write,
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};
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static struct bin_attribute *nvmem_bin_rw_attributes[] = {
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&bin_attr_rw_nvmem,
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NULL,
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};
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static const struct attribute_group nvmem_bin_rw_group = {
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.bin_attrs = nvmem_bin_rw_attributes,
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.attrs = nvmem_attrs,
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};
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static const struct attribute_group *nvmem_rw_dev_groups[] = {
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&nvmem_bin_rw_group,
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NULL,
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};
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/* read only permission */
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static struct bin_attribute bin_attr_ro_nvmem = {
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.attr = {
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.name = "nvmem",
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.mode = 0444,
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},
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.read = bin_attr_nvmem_read,
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};
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static struct bin_attribute *nvmem_bin_ro_attributes[] = {
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&bin_attr_ro_nvmem,
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NULL,
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};
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static const struct attribute_group nvmem_bin_ro_group = {
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.bin_attrs = nvmem_bin_ro_attributes,
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.attrs = nvmem_attrs,
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};
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static const struct attribute_group *nvmem_ro_dev_groups[] = {
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&nvmem_bin_ro_group,
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NULL,
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};
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/* default read/write permissions, root only */
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static struct bin_attribute bin_attr_rw_root_nvmem = {
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.attr = {
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.name = "nvmem",
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.mode = 0600,
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},
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.read = bin_attr_nvmem_read,
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.write = bin_attr_nvmem_write,
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};
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static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
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&bin_attr_rw_root_nvmem,
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NULL,
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};
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static const struct attribute_group nvmem_bin_rw_root_group = {
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.bin_attrs = nvmem_bin_rw_root_attributes,
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.attrs = nvmem_attrs,
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};
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static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
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&nvmem_bin_rw_root_group,
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NULL,
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};
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/* read only permission, root only */
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static struct bin_attribute bin_attr_ro_root_nvmem = {
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.attr = {
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.name = "nvmem",
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.mode = 0400,
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},
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.read = bin_attr_nvmem_read,
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};
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static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
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&bin_attr_ro_root_nvmem,
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NULL,
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};
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static const struct attribute_group nvmem_bin_ro_root_group = {
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.bin_attrs = nvmem_bin_ro_root_attributes,
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.attrs = nvmem_attrs,
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};
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static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
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&nvmem_bin_ro_root_group,
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NULL,
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};
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const struct attribute_group **nvmem_sysfs_get_groups(
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struct nvmem_device *nvmem,
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const struct nvmem_config *config)
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{
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if (config->root_only)
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return nvmem->read_only ?
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nvmem_ro_root_dev_groups :
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nvmem_rw_root_dev_groups;
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return nvmem->read_only ? nvmem_ro_dev_groups : nvmem_rw_dev_groups;
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}
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/*
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* nvmem_setup_compat() - Create an additional binary entry in
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* drivers sys directory, to be backwards compatible with the older
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* drivers/misc/eeprom drivers.
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*/
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int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
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const struct nvmem_config *config)
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{
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int rval;
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if (!config->compat)
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return 0;
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if (!config->base_dev)
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return -EINVAL;
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if (nvmem->read_only)
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nvmem->eeprom = bin_attr_ro_root_nvmem;
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else
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nvmem->eeprom = bin_attr_rw_root_nvmem;
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nvmem->eeprom.attr.name = "eeprom";
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nvmem->eeprom.size = nvmem->size;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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nvmem->eeprom.attr.key = &eeprom_lock_key;
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#endif
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nvmem->eeprom.private = &nvmem->dev;
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nvmem->base_dev = config->base_dev;
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rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
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if (rval) {
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dev_err(&nvmem->dev,
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"Failed to create eeprom binary file %d\n", rval);
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return rval;
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}
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nvmem->flags |= FLAG_COMPAT;
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return 0;
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}
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void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
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const struct nvmem_config *config)
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{
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if (config->compat)
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device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
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}
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