From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
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@xxxxxxxxxx>
---
Documentation/ABI/stable/sysfs-bus-nvmem | 2 +
drivers/nvmem/Kconfig | 9 +
drivers/nvmem/Makefile | 3 +
drivers/nvmem/core.c | 264 +----------------------
drivers/nvmem/nvmem-sysfs.c | 256 ++++++++++++++++++++++
drivers/nvmem/nvmem.h | 62 ++++++
6 files changed, 336 insertions(+), 260 deletions(-)
create mode 100644 drivers/nvmem/nvmem-sysfs.c
create mode 100644 drivers/nvmem/nvmem.h
diff --git a/Documentation/ABI/stable/sysfs-bus-nvmem b/Documentation/ABI/stable/sysfs-bus-nvmem
index 5923ab4620c5..9ffba8576f7b 100644
--- a/Documentation/ABI/stable/sysfs-bus-nvmem
+++ b/Documentation/ABI/stable/sysfs-bus-nvmem
@@ -6,6 +6,8 @@ Description:
This file allows user to read/write the raw NVMEM contents.
Permissions for write to this file depends on the nvmem
provider configuration.
+ Note: This file is only present if CONFIG_NVMEM_SYSFS
+ is enabled
ex:
hexdump /sys/bus/nvmem/devices/qfprom0/nvmem
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index a90e9a1ebe55..e316811e9c04 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -13,6 +13,15 @@ menuconfig NVMEM
if NVMEM
+config NVMEM_SYSFS
+ bool "/sys/bus/nvmem/devices/*/nvmem (sysfs interface)"
+ depends on SYSFS
+ help
+ Say Y here to add a sysfs interface for NVMEM.
+
+ This interface is mostly used by userspace applications to
+ read/write directly into nvmem.
+
config NVMEM_IMX_IIM
tristate "i.MX IC Identification Module support"
depends on ARCH_MXC || COMPILE_TEST
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 4c7ba12a7005..c1fe4768dfef 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -6,6 +6,9 @@
obj-$(CONFIG_NVMEM) += nvmem_core.o
nvmem_core-y := core.o
+obj-$(CONFIG_NVMEM_SYSFS) += nvmem_sysfs.o
+nvmem_sysfs-y := nvmem-sysfs.o
+
# Devices
obj-$(CONFIG_NVMEM_BCM_OCOTP) += nvmem-bcm-ocotp.o
nvmem-bcm-ocotp-y := bcm-ocotp.o
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 5abebf2128b8..c7892c3da91f 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -17,27 +17,7 @@
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/slab.h>
-
-struct nvmem_device {
- struct module *owner;
- struct device dev;
- int stride;
- int word_size;
- int id;
- struct kref refcnt;
- size_t size;
- bool read_only;
- int flags;
- enum nvmem_type type;
- struct bin_attribute eeprom;
- struct device *base_dev;
- struct list_head cells;
- nvmem_reg_read_t reg_read;
- nvmem_reg_write_t reg_write;
- void *priv;
-};
-
-#define FLAG_COMPAT BIT(0)
+#include "nvmem.h"
struct nvmem_cell {
const char *name;
@@ -61,18 +41,7 @@ static LIST_HEAD(nvmem_lookup_list);
static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
-static const char * const nvmem_type_str[] = {
- [NVMEM_TYPE_UNKNOWN] = "Unknown",
- [NVMEM_TYPE_EEPROM] = "EEPROM",
- [NVMEM_TYPE_OTP] = "OTP",
- [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
-};
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-static struct lock_class_key eeprom_lock_key;
-#endif
-#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
@@ -91,187 +60,6 @@ static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
return -EINVAL;
}
-static ssize_t type_show(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct nvmem_device *nvmem = to_nvmem_device(dev);
-
- return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
-}
-
-static DEVICE_ATTR_RO(type);
-
-static struct attribute *nvmem_attrs[] = {
- &dev_attr_type.attr,
- NULL,
-};
-
-static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
- struct bin_attribute *attr,
- char *buf, loff_t pos, size_t count)
-{
- struct device *dev;
- struct nvmem_device *nvmem;
- int rc;
-
- if (attr->private)
- dev = attr->private;
- else
- dev = container_of(kobj, struct device, kobj);
- nvmem = to_nvmem_device(dev);
-
- /* Stop the user from reading */
- if (pos >= nvmem->size)
- return 0;
-
- if (count < nvmem->word_size)
- return -EINVAL;
-
- if (pos + count > nvmem->size)
- count = nvmem->size - pos;
-
- count = round_down(count, nvmem->word_size);
-
- rc = nvmem_reg_read(nvmem, pos, buf, count);
-
- if (rc)
- return rc;
-
- return count;
-}
-
-static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
- struct bin_attribute *attr,
- char *buf, loff_t pos, size_t count)
-{
- struct device *dev;
- struct nvmem_device *nvmem;
- int rc;
-
- if (attr->private)
- dev = attr->private;
- else
- dev = container_of(kobj, struct device, kobj);
- nvmem = to_nvmem_device(dev);
-
- /* Stop the user from writing */
- if (pos >= nvmem->size)
- return -EFBIG;
-
- if (count < nvmem->word_size)
- return -EINVAL;
-
- if (pos + count > nvmem->size)
- count = nvmem->size - pos;
-
- count = round_down(count, nvmem->word_size);
-
- rc = nvmem_reg_write(nvmem, pos, buf, count);
-
- if (rc)
- return rc;
-
- return count;
-}
-
-/* default read/write permissions */
-static struct bin_attribute bin_attr_rw_nvmem = {
- .attr = {
- .name = "nvmem",
- .mode = 0644,
- },
- .read = bin_attr_nvmem_read,
- .write = bin_attr_nvmem_write,
-};
-
-static struct bin_attribute *nvmem_bin_rw_attributes[] = {
- &bin_attr_rw_nvmem,
- NULL,
-};
-
-static const struct attribute_group nvmem_bin_rw_group = {
- .bin_attrs = nvmem_bin_rw_attributes,
- .attrs = nvmem_attrs,
-};
-
-static const struct attribute_group *nvmem_rw_dev_groups[] = {
- &nvmem_bin_rw_group,
- NULL,
-};
-
-/* read only permission */
-static struct bin_attribute bin_attr_ro_nvmem = {
- .attr = {
- .name = "nvmem",
- .mode = 0444,
- },
- .read = bin_attr_nvmem_read,
-};
-
-static struct bin_attribute *nvmem_bin_ro_attributes[] = {
- &bin_attr_ro_nvmem,
- NULL,
-};
-
-static const struct attribute_group nvmem_bin_ro_group = {
- .bin_attrs = nvmem_bin_ro_attributes,
- .attrs = nvmem_attrs,
-};
-
-static const struct attribute_group *nvmem_ro_dev_groups[] = {
- &nvmem_bin_ro_group,
- NULL,
-};
-
-/* default read/write permissions, root only */
-static struct bin_attribute bin_attr_rw_root_nvmem = {
- .attr = {
- .name = "nvmem",
- .mode = 0600,
- },
- .read = bin_attr_nvmem_read,
- .write = bin_attr_nvmem_write,
-};
-
-static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
- &bin_attr_rw_root_nvmem,
- NULL,
-};
-
-static const struct attribute_group nvmem_bin_rw_root_group = {
- .bin_attrs = nvmem_bin_rw_root_attributes,
- .attrs = nvmem_attrs,
-};
-
-static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
- &nvmem_bin_rw_root_group,
- NULL,
-};
-
-/* read only permission, root only */
-static struct bin_attribute bin_attr_ro_root_nvmem = {
- .attr = {
- .name = "nvmem",
- .mode = 0400,
- },
- .read = bin_attr_nvmem_read,
-};
-
-static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
- &bin_attr_ro_root_nvmem,
- NULL,
-};
-
-static const struct attribute_group nvmem_bin_ro_root_group = {
- .bin_attrs = nvmem_bin_ro_root_attributes,
- .attrs = nvmem_attrs,
-};
-
-static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
- &nvmem_bin_ro_root_group,
- NULL,
-};
-
static void nvmem_release(struct device *dev)
{
struct nvmem_device *nvmem = to_nvmem_device(dev);
@@ -422,43 +210,6 @@ static int nvmem_add_cells(struct nvmem_device *nvmem,
return rval;
}
-/*
- * nvmem_setup_compat() - Create an additional binary entry in
- * drivers sys directory, to be backwards compatible with the older
- * drivers/misc/eeprom drivers.
- */
-static int nvmem_setup_compat(struct nvmem_device *nvmem,
- const struct nvmem_config *config)
-{
- int rval;
-
- if (!config->base_dev)
- return -EINVAL;
-
- if (nvmem->read_only)
- nvmem->eeprom = bin_attr_ro_root_nvmem;
- else
- nvmem->eeprom = bin_attr_rw_root_nvmem;
- nvmem->eeprom.attr.name = "eeprom";
- nvmem->eeprom.size = nvmem->size;
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- nvmem->eeprom.attr.key = &eeprom_lock_key;
-#endif
- nvmem->eeprom.private = &nvmem->dev;
- nvmem->base_dev = config->base_dev;
-
- rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
- if (rval) {
- dev_err(&nvmem->dev,
- "Failed to create eeprom binary file %d\n", rval);
- return rval;
- }
-
- nvmem->flags |= FLAG_COMPAT;
-
- return 0;
-}
-
/**
* nvmem_register_notifier() - Register a notifier block for nvmem events.
*
@@ -651,14 +402,7 @@ 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;
- if (config->root_only)
- nvmem->dev.groups = nvmem->read_only ?
- nvmem_ro_root_dev_groups :
- nvmem_rw_root_dev_groups;
- else
- nvmem->dev.groups = nvmem->read_only ?
- nvmem_ro_dev_groups :
- nvmem_rw_dev_groups;
+ nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config);
device_initialize(&nvmem->dev);
@@ -669,7 +413,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
goto err_put_device;
if (config->compat) {
- rval = nvmem_setup_compat(nvmem, config);
+ rval = nvmem_sysfs_setup_compat(nvmem, config);
if (rval)
goto err_device_del;
}
@@ -696,7 +440,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem_device_remove_all_cells(nvmem);
err_teardown_compat:
if (config->compat)
- device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
+ nvmem_sysfs_remove_compat(nvmem, config);
err_device_del:
device_del(&nvmem->dev);
err_put_device:
diff --git a/drivers/nvmem/nvmem-sysfs.c b/drivers/nvmem/nvmem-sysfs.c
new file mode 100644
index 000000000000..6f303b91f6e7
--- /dev/null
+++ b/drivers/nvmem/nvmem-sysfs.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Linaro Limited
+ */
+#include "nvmem.h"
+
+static const char * const nvmem_type_str[] = {
+ [NVMEM_TYPE_UNKNOWN] = "Unknown",
+ [NVMEM_TYPE_EEPROM] = "EEPROM",
+ [NVMEM_TYPE_OTP] = "OTP",
+ [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
+};
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key eeprom_lock_key;
+#endif
+
+static ssize_t type_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct nvmem_device *nvmem = to_nvmem_device(dev);
+
+ return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
+}
+
+static DEVICE_ATTR_RO(type);
+
+static struct attribute *nvmem_attrs[] = {
+ &dev_attr_type.attr,
+ NULL,
+};
+
+static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t pos, size_t count)
+{
+ struct device *dev;
+ struct nvmem_device *nvmem;
+ int rc;
+
+ if (attr->private)
+ dev = attr->private;
+ else
+ dev = container_of(kobj, struct device, kobj);
+ nvmem = to_nvmem_device(dev);
+
+ /* Stop the user from reading */
+ if (pos >= nvmem->size)
+ return 0;
+
+ if (count < nvmem->word_size)
+ return -EINVAL;
+
+ if (pos + count > nvmem->size)
+ count = nvmem->size - pos;
+
+ count = round_down(count, nvmem->word_size);
+
+ rc = nvmem->reg_read(nvmem->priv, pos, buf, count);
+
+ if (rc)
+ return rc;
+
+ return count;
+}
+
+static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *attr,
+ char *buf, loff_t pos, size_t count)
+{
+ struct device *dev;
+ struct nvmem_device *nvmem;
+ int rc;
+
+ if (attr->private)
+ dev = attr->private;
+ else
+ dev = container_of(kobj, struct device, kobj);
+ nvmem = to_nvmem_device(dev);
+
+ /* Stop the user from writing */
+ if (pos >= nvmem->size)
+ return -EFBIG;
+
+ if (count < nvmem->word_size)
+ return -EINVAL;
+
+ if (pos + count > nvmem->size)
+ count = nvmem->size - pos;
+
+ count = round_down(count, nvmem->word_size);
+
+ rc = nvmem->reg_write(nvmem->priv, pos, buf, count);
+
+ if (rc)
+ return rc;
+
+ return count;
+}
+
+/* default read/write permissions */
+static struct bin_attribute bin_attr_rw_nvmem = {
+ .attr = {
+ .name = "nvmem",
+ .mode = 0644,
+ },
+ .read = bin_attr_nvmem_read,
+ .write = bin_attr_nvmem_write,
+};
+
+static struct bin_attribute *nvmem_bin_rw_attributes[] = {
+ &bin_attr_rw_nvmem,
+ NULL,
+};
+
+static const struct attribute_group nvmem_bin_rw_group = {
+ .bin_attrs = nvmem_bin_rw_attributes,
+ .attrs = nvmem_attrs,
+};
+
+static const struct attribute_group *nvmem_rw_dev_groups[] = {
+ &nvmem_bin_rw_group,
+ NULL,
+};
+
+/* read only permission */
+static struct bin_attribute bin_attr_ro_nvmem = {
+ .attr = {
+ .name = "nvmem",
+ .mode = 0444,
+ },
+ .read = bin_attr_nvmem_read,
+};
+
+static struct bin_attribute *nvmem_bin_ro_attributes[] = {
+ &bin_attr_ro_nvmem,
+ NULL,
+};
+
+static const struct attribute_group nvmem_bin_ro_group = {
+ .bin_attrs = nvmem_bin_ro_attributes,
+ .attrs = nvmem_attrs,
+};
+
+static const struct attribute_group *nvmem_ro_dev_groups[] = {
+ &nvmem_bin_ro_group,
+ NULL,
+};
+
+/* default read/write permissions, root only */
+static struct bin_attribute bin_attr_rw_root_nvmem = {
+ .attr = {
+ .name = "nvmem",
+ .mode = 0600,
+ },
+ .read = bin_attr_nvmem_read,
+ .write = bin_attr_nvmem_write,
+};
+
+static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
+ &bin_attr_rw_root_nvmem,
+ NULL,
+};
+
+static const struct attribute_group nvmem_bin_rw_root_group = {
+ .bin_attrs = nvmem_bin_rw_root_attributes,
+ .attrs = nvmem_attrs,
+};
+
+static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
+ &nvmem_bin_rw_root_group,
+ NULL,
+};
+
+/* read only permission, root only */
+static struct bin_attribute bin_attr_ro_root_nvmem = {
+ .attr = {
+ .name = "nvmem",
+ .mode = 0400,
+ },
+ .read = bin_attr_nvmem_read,
+};
+
+static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
+ &bin_attr_ro_root_nvmem,
+ NULL,
+};
+
+static const struct attribute_group nvmem_bin_ro_root_group = {
+ .bin_attrs = nvmem_bin_ro_root_attributes,
+ .attrs = nvmem_attrs,
+};
+
+static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
+ &nvmem_bin_ro_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;
+
+ return nvmem->read_only ? nvmem_ro_dev_groups : nvmem_rw_dev_groups;
+}
+
+/*
+ * nvmem_setup_compat() - Create an additional binary entry in
+ * drivers sys directory, to be backwards compatible with the older
+ * drivers/misc/eeprom drivers.
+ */
+int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
+ const struct nvmem_config *config)
+{
+ int rval;
+
+ if (!config->compat)
+ return 0;
+
+ if (!config->base_dev)
+ return -EINVAL;
+
+ if (nvmem->read_only)
+ nvmem->eeprom = bin_attr_ro_root_nvmem;
+ else
+ nvmem->eeprom = bin_attr_rw_root_nvmem;
+ nvmem->eeprom.attr.name = "eeprom";
+ nvmem->eeprom.size = nvmem->size;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ nvmem->eeprom.attr.key = &eeprom_lock_key;
+#endif
+ nvmem->eeprom.private = &nvmem->dev;
+ nvmem->base_dev = config->base_dev;
+
+ rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
+ if (rval) {
+ dev_err(&nvmem->dev,
+ "Failed to create eeprom binary file %d\n", rval);
+ return rval;
+ }
+
+ nvmem->flags |= FLAG_COMPAT;
+
+ return 0;
+}
+
+void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
+ const struct nvmem_config *config)
+{
+ if (config->compat)
+ device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
+}
diff --git a/drivers/nvmem/nvmem.h b/drivers/nvmem/nvmem.h
new file mode 100644
index 000000000000..eb8ed7121fa3
--- /dev/null
+++ b/drivers/nvmem/nvmem.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _DRIVERS_NVMEM_H
+#define _DRIVERS_NVMEM_H
+
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+
+struct nvmem_device {
+ struct module *owner;
+ struct device dev;
+ int stride;
+ int word_size;
+ int id;
+ struct kref refcnt;
+ size_t size;
+ bool read_only;
+ int flags;
+ enum nvmem_type type;
+ struct bin_attribute eeprom;
+ struct device *base_dev;
+ struct list_head cells;
+ nvmem_reg_read_t reg_read;
+ nvmem_reg_write_t reg_write;
+ void *priv;
+};
+
+#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
+#define FLAG_COMPAT BIT(0)
+
+#ifdef CONFIG_NVMEM_SYSFS
+const struct attribute_group **nvmem_sysfs_get_groups(
+ struct nvmem_device *nvmem,
+ const struct nvmem_config *config);
+int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
+ const struct nvmem_config *config);
+void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
+ const struct nvmem_config *config);
+#else
+static inline const struct attribute_group **nvmem_sysfs_get_groups(
+ struct nvmem_device *nvmem,
+ const struct nvmem_config *config)
+{
+ return NULL;
+}
+
+static inline int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
+ const struct nvmem_config *config)
+{
+ return -ENOSYS;
+}
+static inline void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
+ const struct nvmem_config *config)
+{
+}
+#endif /* CONFIG_NVMEM_SYSFS */
+
+#endif /* _DRIVERS_NVMEM_H */
