i2c: add i2c_master_{send|recv}_dmasafe

Use the new helper to create variants of i2c_master_{send|recv} which
mark their buffers as DMA safe.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

include/linux/i2c.h

@@ -80,6 +80,22 @@ static inline int i2c_master_recv(const struct i2c_client *client,
 	return i2c_transfer_buffer_flags(client, buf, count, I2C_M_RD);
 };
 
+/**
+ * i2c_master_recv_dmasafe - issue a single I2C message in master receive mode
+ *			     using a DMA safe buffer
+ * @client: Handle to slave device
+ * @buf: Where to store data read from slave, must be safe to use with DMA
+ * @count: How many bytes to read, must be less than 64k since msg.len is u16
+ *
+ * Returns negative errno, or else the number of bytes read.
+ */
+static inline int i2c_master_recv_dmasafe(const struct i2c_client *client,
+					  char *buf, int count)
+{
+	return i2c_transfer_buffer_flags(client, buf, count,
+					 I2C_M_RD | I2C_M_DMA_SAFE);
+};
+
 /**
  * i2c_master_send - issue a single I2C message in master transmit mode
  * @client: Handle to slave device
@@ -94,6 +110,22 @@ static inline int i2c_master_send(const struct i2c_client *client,
 	return i2c_transfer_buffer_flags(client, (char *)buf, count, 0);
 };
 
+/**
+ * i2c_master_send_dmasafe - issue a single I2C message in master transmit mode
+ *			     using a DMA safe buffer
+ * @client: Handle to slave device
+ * @buf: Data that will be written to the slave, must be safe to use with DMA
+ * @count: How many bytes to write, must be less than 64k since msg.len is u16
+ *
+ * Returns negative errno, or else the number of bytes written.
+ */
+static inline int i2c_master_send_dmasafe(const struct i2c_client *client,
+					  const char *buf, int count)
+{
+	return i2c_transfer_buffer_flags(client, (char *)buf, count,
+					 I2C_M_DMA_SAFE);
+};
+
 /* Transfer num messages.
  */
 extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,