i2c: add a message flag for DMA safe buffers

I2C has no requirement that the buffer of a message needs to be DMA
safe. In case it is, it can now be flagged, so drivers wishing to
do DMA can use the buffer directly.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/uapi/linux/i2c.h b/include/uapi/linux/i2c.h
index fe648032d6b9..f71a1751cacf 100644
--- a/include/uapi/linux/i2c.h
+++ b/include/uapi/linux/i2c.h
@@ -72,6 +72,9 @@ struct i2c_msg {
 #define I2C_M_RD                0x0001  /* read data, from slave to master */
                                         /* I2C_M_RD is guaranteed to be 0x0001! */
 #define I2C_M_TEN               0x0010  /* this is a ten bit chip address */
+#define I2C_M_DMA_SAFE          0x0200  /* the buffer of this message is DMA safe */
+                                        /* makes only sense in kernelspace */
+                                        /* userspace buffers are copied anyway */
 #define I2C_M_RECV_LEN          0x0400  /* length will be first received byte */
 #define I2C_M_NO_RD_ACK         0x0800  /* if I2C_FUNC_PROTOCOL_MANGLING */
 #define I2C_M_IGNORE_NAK        0x1000  /* if I2C_FUNC_PROTOCOL_MANGLING */