nvmem: core: add NVMEM_SYSFS Kconfig

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>

1 files changed, 62 insertions, 0 deletions

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 */