Hi Andrew,

Thanks for the patch, few comments other than Stefan's comments.

On 16/08/15 03:54, Andrew Lunn wrote:
Add a read only regmap for accessing the EEPROM, and then use that
with the NVMEM framework.

Signed-off-by: Andrew Lunn <and...@lunn.ch>
---
  drivers/misc/eeprom/at24.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 65 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2d3db81be099..0e80c0c09d4e 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -22,6 +22,8 @@
  #include <linux/jiffies.h>
  #include <linux/of.h>
  #include <linux/i2c.h>
+#include <linux/nvmem-provider.h>
+#include <linux/regmap.h>
  #include <linux/platform_data/at24.h>

  /*
@@ -69,6 +71,10 @@ struct at24_data {
        unsigned write_max;
        unsigned num_addresses;

+       struct regmap_config regmap_config;
+       struct nvmem_config nvmem_config;
+       struct nvmem_device *nvmem;
+
        /*
         * Some chips tie up multiple I2C addresses; dummy devices reserve
         * them for us, and we'll use them with SMBus calls.
@@ -471,6 +477,34 @@ static ssize_t at24_macc_write(struct memory_accessor 
*macc, const char *buf,

  /*-------------------------------------------------------------------------*/

+/*
+ * Provide a regmap interface, which is registered with the NVMEM
+ * framework
+*/
+static int at24_regmap_read(void *context, const void *reg, size_t reg_size,
+                           void *val, size_t val_size)
+{
+       struct at24_data *at24 = context;
+       off_t offset = *(u32 *)reg;
+
+       return at24_read(at24, val, offset, val_size);
+}
+
+static int at24_regmap_write(void *context, const void *data, size_t count)
+{
+       struct at24_data *at24 = context;
+
+       return at24_write(at24, data, 0, count);
+}
+
+static const struct regmap_bus at24_regmap_bus = {
+       .read = at24_regmap_read,
+       .write = at24_regmap_write,
+       .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+/*-------------------------------------------------------------------------*/
+
  #ifdef CONFIG_OF
  static void at24_get_ofdata(struct i2c_client *client,
                struct at24_platform_data *chip)
@@ -502,6 +536,7 @@ static int at24_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
        int err;
        unsigned i, num_addresses;
        kernel_ulong_t magic;
+       struct regmap *regmap;

        if (client->dev.platform_data) {
                chip = *(struct at24_platform_data *)client->dev.platform_data;
@@ -644,6 +679,30 @@ static int at24_probe(struct i2c_client *client, const 
struct i2c_device_id *id)
        if (err)
                goto err_clients;

+       at24->regmap_config.reg_bits = 32;
+       at24->regmap_config.val_bits = 8;
+       at24->regmap_config.reg_stride = 1;
+       at24->regmap_config.max_register = at24->bin.size - 1;
+
+       regmap = devm_regmap_init(&client->dev, &at24_regmap_bus, at24,
+                                 &at24->regmap_config);
+       if (IS_ERR(regmap)) {
+               dev_err(&client->dev, "regmap init failed\n");
+               err = PTR_ERR(regmap);
+               goto err_sysfs;
+       }
+
+       at24->nvmem_config.name = dev_name(&client->dev);
+       at24->nvmem_config.dev = &client->dev;
+       at24->nvmem_config.read_only = !writable;
+       at24->nvmem_config.owner = THIS_MODULE;
+
+       at24->nvmem = nvmem_register(&at24->nvmem_config);
+       if (IS_ERR(at24->nvmem)) {
+               err = PTR_ERR(at24->nvmem);
+               goto err_sysfs;
+       }
+
        i2c_set_clientdata(client, at24);

        dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
@@ -662,6 +721,9 @@ static int at24_probe(struct i2c_client *client, const 
struct i2c_device_id *id)

        return 0;

+err_sysfs:
+       sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
+

?? Not sure Why this code is still needed. Can't we remove it?

Is this the the same binary file which is exposed by nvmem in /sys/bus/nvmem too?

--srini
  err_clients:
        for (i = 1; i < num_addresses; i++)
                if (at24->client[i])
@@ -676,6 +738,9 @@ static int at24_remove(struct i2c_client *client)
        int i;

        at24 = i2c_get_clientdata(client);
+
+       nvmem_unregister(at24->nvmem);
+
        sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);

        for (i = 1; i < at24->num_addresses; i++)

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