nvmem: Add backwards compatibility support for older EEPROM drivers.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 76 insertions, 8 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);