[PATCHv7 2/7] nvmem: Add backwards compatibility support for older EEPROM drivers.

Andrew Lunn
2016-02-26T19:59:59Z

Older drivers made an 'eeprom' file available in the /sys device
directory. Have the NVMEM core provide this to retain backwards
compatibility.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
v4: Add lockdep support
---
drivers/nvmem/core.c | 84 ++++++++++++++++++++++++++++++++++++++----
include/linux/nvmem-provider.h | 4 +-
2 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index b03690bc8f09..0de3d878c439 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -38,8 +38,13 @@ struct nvmem_device {
int users;
size_t size;
bool read_only;
+ int flags;
+ struct bin_attribute eeprom;
+ struct device *base_dev;
};

+#define FLAG_COMPAT BIT(0)
+
struct nvmem_cell {
const char *name;
int offset;
@@ -56,16 +61,26 @@ static DEFINE_IDA(nvmem_ida);
static LIST_HEAD(nvmem_cells);
static DEFINE_MUTEX(nvmem_cells_mutex);

+#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 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 = container_of(kobj, struct device, kobj);
- struct nvmem_device *nvmem = to_nvmem_device(dev);
+ 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;
@@ -90,10 +105,16 @@ 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 = container_of(kobj, struct device, kobj);
- struct nvmem_device *nvmem = to_nvmem_device(dev);
+ 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 0;
@@ -349,6 +370,43 @@ err:
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() - Register a nvmem device for given nvmem_config.
* Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
@@ -416,16 +474,23 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);

rval = device_add(&nvmem->dev);
- if (rval) {
- ida_simple_remove(&nvmem_ida, nvmem->id);
- kfree(nvmem);
- return ERR_PTR(rval);
+ if (rval)
+ goto out;
+
+ if (config->compat) {
+ rval = nvmem_setup_compat(nvmem, config);
+ if (rval)
+ goto out;
}

if (config->cells)
nvmem_add_cells(nvmem, config);

return nvmem;
+out:
+ ida_simple_remove(&nvmem_ida, nvmem->id);
+ kfree(nvmem);
+ return ERR_PTR(rval);
}
EXPORT_SYMBOL_GPL(nvmem_register);

@@ -445,6 +510,9 @@ int nvmem_unregister(struct nvmem_device *nvmem)
}
mutex_unlock(&nvmem_mutex);

+ if (nvmem->flags & FLAG_COMPAT)
+ device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
+
nvmem_device_remove_all_cells(nvmem);
device_del(&nvmem->dev);

diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index d24fefa0c11d..a4fcc90b0f20 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -24,6 +24,9 @@ struct nvmem_config {
int ncells;
bool read_only;
bool root_only;
+ /* To be only used by old driver/misc/eeprom drivers */
+ bool compat;
+ struct device *base_dev;
};

#if IS_ENABLED(CONFIG_NVMEM)
@@ -44,5 +47,4 @@ static inline int nvmem_unregister(struct nvmem_device *nvmem)
}

#endif /* CONFIG_NVMEM */
-
#endif /* ifndef _LINUX_NVMEM_PROVIDER_H */
--
2.7.0