[PATCH v6 5/9] i2c: add i2c_master_{send|recv}_dmasafe

Wolfram Sang
2017-11-04T20:20:05Z

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>
---
include/linux/i2c.h | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index ef1a8791c1ae24..8c144e3cbfb261 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -81,6 +81,22 @@ static inline int i2c_master_recv(const struct i2c_client *client,
};

/**
+ * 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
* @buf: Data that will be written to the slave
@@ -93,6 +109,21 @@ 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.
*/
--
2.11.0