eeprom: at24: extend driver to plug into the NVMEM framework

Add a regmap for accessing the EEPROM, and then use that with the
NVMEM framework. Set the NVMEM config structure to enable backward, so
that the 'eeprom' file in sys is provided by the framework.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/eeprom/Kconfig

@@ -3,6 +3,8 @@ menu "EEPROM support"
 config EEPROM_AT24
 	tristate "I2C EEPROMs / RAMs / ROMs from most vendors"
 	depends on I2C && SYSFS
+	select REGMAP
+	select NVMEM
 	help
 	  Enable this driver to get read/write support to most I2C EEPROMs
 	  and compatible devices like FRAMs, SRAMs, ROMs etc. After you

drivers/misc/eeprom/at24.c

@@ -15,7 +15,6 @@
 #include <linux/slab.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
-#include <linux/sysfs.h>
 #include <linux/mod_devicetable.h>
 #include <linux/log2.h>
 #include <linux/bitops.h>
@@ -23,6 +22,8 @@
 #include <linux/of.h>
 #include <linux/acpi.h>
 #include <linux/i2c.h>
+#include <linux/nvmem-provider.h>
+#include <linux/regmap.h>
 #include <linux/platform_data/at24.h>
 
 /*
@@ -64,12 +65,15 @@ struct at24_data {
 	 * but not from changes by other I2C masters.
 	 */
 	struct mutex lock;
-	struct bin_attribute bin;
 
 	u8 *writebuf;
 	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.
@@ -283,17 +287,6 @@ static ssize_t at24_read(struct at24_data *at24,
 	return retval;
 }
 
-static ssize_t at24_bin_read(struct file *filp, struct kobject *kobj,
-		struct bin_attribute *attr,
-		char *buf, loff_t off, size_t count)
-{
-	struct at24_data *at24;
-
-	at24 = dev_get_drvdata(kobj_to_dev(kobj));
-	return at24_read(at24, buf, off, count);
-}
-
-
 /*
  * Note that if the hardware write-protect pin is pulled high, the whole
  * chip is normally write protected. But there are plenty of product
@@ -414,16 +407,6 @@ static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
 	return retval;
 }
 
-static ssize_t at24_bin_write(struct file *filp, struct kobject *kobj,
-		struct bin_attribute *attr,
-		char *buf, loff_t off, size_t count)
-{
-	struct at24_data *at24;
-
-	at24 = dev_get_drvdata(kobj_to_dev(kobj));
-	return at24_write(at24, buf, off, count);
-}
-
 /*-------------------------------------------------------------------------*/
 
 /*
@@ -450,6 +433,49 @@ 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;
+	int err;
+
+	err = at24_read(at24, val, offset, val_size);
+	if (err)
+		return err;
+	return 0;
+}
+
+static int at24_regmap_write(void *context, const void *data, size_t count)
+{
+	struct at24_data *at24 = context;
+	const char *buf;
+	u32 offset;
+	size_t len;
+	int err;
+
+	memcpy(&offset, data, sizeof(offset));
+	buf = (const char *)data + sizeof(offset);
+	len = count - sizeof(offset);
+
+	err = at24_write(at24, buf, offset, len);
+	if (err)
+		return err;
+	return 0;
+}
+
+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)
@@ -481,6 +507,7 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	struct at24_data *at24;
 	int err;
 	unsigned i, num_addresses;
+	struct regmap *regmap;
 
 	if (client->dev.platform_data) {
 		chip = *(struct at24_platform_data *)client->dev.platform_data;
@@ -573,16 +600,6 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	at24->chip = chip;
 	at24->num_addresses = num_addresses;
 
-	/*
-	 * Export the EEPROM bytes through sysfs, since that's convenient.
-	 * By default, only root should see the data (maybe passwords etc)
-	 */
-	sysfs_bin_attr_init(&at24->bin);
-	at24->bin.attr.name = "eeprom";
-	at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
-	at24->bin.read = at24_bin_read;
-	at24->bin.size = chip.byte_len;
-
 	at24->macc.read = at24_macc_read;
 
 	writable = !(chip.flags & AT24_FLAG_READONLY);
@@ -593,9 +610,6 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 			at24->macc.write = at24_macc_write;
 
-			at24->bin.write = at24_bin_write;
-			at24->bin.attr.mode |= S_IWUSR;
-
 			if (write_max > io_limit)
 				write_max = io_limit;
 			if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
@@ -627,14 +641,38 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		}
 	}
 
-	err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
-	if (err)
+	at24->regmap_config.reg_bits = 32;
+	at24->regmap_config.val_bits = 8;
+	at24->regmap_config.reg_stride = 1;
+	at24->regmap_config.max_register = chip.byte_len - 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_clients;
+	}
+
+	at24->nvmem_config.name = dev_name(&client->dev);
+	at24->nvmem_config.dev = &client->dev;
+	at24->nvmem_config.read_only = !writable;
+	at24->nvmem_config.root_only = true;
+	at24->nvmem_config.owner = THIS_MODULE;
+	at24->nvmem_config.compat = true;
+	at24->nvmem_config.base_dev = &client->dev;
+
+	at24->nvmem = nvmem_register(&at24->nvmem_config);
+
+	if (IS_ERR(at24->nvmem)) {
+		err = PTR_ERR(at24->nvmem);
+		goto err_clients;
+	}
 
 	i2c_set_clientdata(client, at24);
 
-	dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
-		at24->bin.size, client->name,
+	dev_info(&client->dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
+		chip.byte_len, client->name,
 		writable ? "writable" : "read-only", at24->write_max);
 	if (use_smbus == I2C_SMBUS_WORD_DATA ||
 	    use_smbus == I2C_SMBUS_BYTE_DATA) {
@@ -663,7 +701,8 @@ static int at24_remove(struct i2c_client *client)
 	int i;
 
 	at24 = i2c_get_clientdata(client);
-	sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
+
+	nvmem_unregister(at24->nvmem);
 
 	for (i = 1; i < at24->num_addresses; i++)
 		i2c_unregister_device(at24->client[i]);