Re: [PATCH 2/6] nvmem: Add backwards compatibility support for older EEPROM drivers.
From: Srinivas Kandagatla
Date: Tue Dec 15 2015 - 05:05:19 EST
Below are few comments.
On 08/12/15 14:05, Andrew Lunn wrote:
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@xxxxxxx>
---
drivers/nvmem/Kconfig | 7 ++++
drivers/nvmem/core.c | 75 +++++++++++++++++++++++++++++++++++++++---
include/linux/nvmem-provider.h | 10 ++++++
3 files changed, 88 insertions(+), 4 deletions(-)
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index bc4ea585b42e..b4e79ba7d502 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -13,6 +13,13 @@ menuconfig NVMEM
If unsure, say no.
if NVMEM
+config NVMEM_COMPAT
+ bool "Enable /sys compatibility with old eeprom drivers"
+ help
+ Older EEPROM drivers, such as AT24, AT25, provide access to
+ the eeprom via a file called "eeprom" in /sys under the
+ device node. Enabling this option makes the NVMEM core
+ provide this file to retain backwards compatibility
Lets get rid of this Kconfig as Wolfram suggested.
We are already adding NVMEM_COMPAT in the nvmem_device structrure lets
move the flags into the struct nvmem_config and use the nvmem_register
api as it is.
nvmem_register() can decide what do do with that from there.
I would also prefer a warning if this flag is set, this is to deter any
new users.
Let me know your thoughts?
config NVMEM_IMX_OCOTP
tristate "i.MX6 On-Chip OTP Controller support"
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 4ccf03da6467..75a498f5e139 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;
@@ -62,10 +67,16 @@ 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;
@@ -87,10 +98,16 @@ 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;
@@ -421,6 +438,53 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
}
EXPORT_SYMBOL_GPL(nvmem_register);
+#if IS_ENABLED(CONFIG_NVMEM_COMPAT)
+/**
+ * nvmem_register_compat() - Register a nvmem device for given nvmem_config.
+ * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem and
+ * an eeprom file in the drivers sys directory.
+ *
+ * @config: nvmem device configuration with which nvmem device is created.
+ * @dev: device structure of underlying device
+ *
+ * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
+ * on success.
+ */
+
+struct nvmem_device *nvmem_register_compat(const struct nvmem_config *config,
+ struct device *base_dev)
+{
Possibly move most of it or some of it a local static function which
will be called from nvmem_register depending on the NVMEM_FLAG_COMPAT.
+ struct nvmem_device *nvmem;
+ int rval;
+
+ nvmem = nvmem_register(config);
+ if (IS_ERR(nvmem))
+ return nvmem;
+
+ 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;
+ nvmem->eeprom.private = &nvmem->dev;
+ nvmem->base_dev = 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);
+ nvmem_unregister(nvmem);
+ return ERR_PTR(rval);
+ }
+
+ nvmem->flags |= FLAG_COMPAT;
+
+ return nvmem;
+}
+EXPORT_SYMBOL_GPL(nvmem_register_compat);
+#endif /* CONFIG_NVMEM_COMPAT */
+
/**
* nvmem_unregister() - Unregister previously registered nvmem device
*
@@ -437,6 +501,9 @@ 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..012030bd4495 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -45,4 +45,14 @@ static inline int nvmem_unregister(struct nvmem_device *nvmem)
#endif /* CONFIG_NVMEM */
+#if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_NVMEM_COMPAT)
+struct nvmem_device *nvmem_register_compat(const struct nvmem_config *config,
+ struct device *base_dev);
+#else
+static inline struct nvmem_device *
+nvmem_register_compat(const struct nvmem_config *c, struct device *base_dev)
+{
+ return ERR_PTR(-ENOSYS);
+}
+#endif /* CONFIG_NVMEM && CONFIG_NVMEM_COMPAT */
#endif /* ifndef _LINUX_NVMEM_PROVIDER_H */
--
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