path: root/Documentation
diff options
authorNiklas Söderlund <>2016-05-14 14:17:08 +0200
committerWolfram Sang <>2016-05-15 08:52:49 +0200
commit73e8b0528346e88a0624f2d9821f382cd6256677 (patch)
treee6dcfd5eefeee9ac5e5b77645e52f71dc10a516a /Documentation
parent40027b2fffc2dcef20080847b0913d210ef3ced0 (diff)
i2c: rcar: add DMA support
Make it possible to transfer i2c message buffers via DMA. Start/Stop/Sending_Slave_Address and some data is still handled using the old state machine, it is sending the bulk of the data that is done via DMA. The first byte of a transmission and the last two bytes of reception are sent/received using PIO. This is needed for the HW to have access to the first byte before DMA transmit and to be able to set the STOP condition for DMA reception. Signed-off-by: Niklas Söderlund <> Acked-by: Rob Herring <> Tested-by: Wolfram Sang <> [wsa: fixed a checkpatch warning] Signed-off-by: Wolfram Sang <>
Diffstat (limited to 'Documentation')
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-rcar.txt b/Documentation/devicetree/bindings/i2c/i2c-rcar.txt
index cf8bfc956cdc..5f0cb502b1db 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-rcar.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-rcar.txt
@@ -19,6 +19,9 @@ Optional properties:
- clock-frequency: desired I2C bus clock frequency in Hz. The absence of this
property indicates the default frequency 100 kHz.
- clocks: clock specifier.
+- dmas: Must contain a list of two references to DMA specifiers, one for
+ transmission, and one for reception.
+- dma-names: Must contain a list of two DMA names, "tx" and "rx".
- i2c-scl-falling-time-ns: see i2c.txt
- i2c-scl-internal-delay-ns: see i2c.txt