+#define BLOCK_DATA_MAX_TRIES 10
+
+static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
+ u8 length, u8 *values)
+{
+ s32 i, data;
+
+ for (i = 0; i < length; i++) {
+ data = i2c_smbus_read_byte_data(client, command + i);
+ if (data < 0)
+ return data;
+ values[i] = data;
+ }
+ return i;
+}
+
+static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
+ u8 length, u8 *values)
+{
+ u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
+ s32 ret;
+ int tries = 0;
+
+ dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
+ ret = ds1307_read_block_data_once(client, command, length, values);
+ if (ret < 0)
+ return ret;
+ do {
+ if (++tries > BLOCK_DATA_MAX_TRIES) {
+ dev_err(&client->dev,
+ "ds1307_read_block_data failed\n");
+ return -EIO;
+ }
+ memcpy(oldvalues, values, length);
+ ret = ds1307_read_block_data_once(client, command, length,
+ values);
+ if (ret < 0)
+ return ret;
+ } while (memcmp(oldvalues, values, length));
+ return length;
+}
+
+static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
+ u8 length, const u8 *values)
+{
+ u8 currvalues[I2C_SMBUS_BLOCK_MAX];
+ int tries = 0;
+
+ dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
+ do {
+ s32 i, ret;
+
+ if (++tries > BLOCK_DATA_MAX_TRIES) {
+ dev_err(&client->dev,
+ "ds1307_write_block_data failed\n");
+ return -EIO;
+ }
+ for (i = 0; i < length; i++) {
+ ret = i2c_smbus_write_byte_data(client, command + i,
+ values[i]);
+ if (ret < 0)
+ return ret;
+ }
+ ret = ds1307_read_block_data_once(client, command, length,
+ currvalues);
+ if (ret < 0)
+ return ret;
+ } while (memcmp(currvalues, values, length));
+ return length;
+}
+
+/*----------------------------------------------------------------------*/
+