On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:

On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:

quoted

Patch adding support for specifying trickle charger setup from device
tree. Patch is based on linux-next tree.


Some DS13XX devices have "trickle chargers". Introduce a device tree binding
for specifying the setup and register values.

Signed-off-by: Matti Vaittinen <redacted>
---
 .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
 .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
 drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
 3 files changed, 59 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index 6af570e..e9206a4 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt

@@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
 cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
 dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
 dallas,ds1338		I2C RTC with 56-Byte NV RAM
-dallas,ds1339		I2C Serial Real-Time Clock
 dallas,ds1340		I2C RTC with Trickle Charger
 dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
 dallas,ds1631		High-Precision Digital Thermometer

diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
new file mode 100644
index 0000000..9faf40e
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt

@@ -0,0 +1,19 @@
+* Dallas DS1339		I2C Serial Real-Time Clock
+
+Required properties:
+- compatible: Should contain "dallas,ds1339".
+- reg: I2C address for chip
+
+Optional properties:
+- trickle_setup : Used Trickle Charger configuration,
+        corresponding to 5 lowest bits in trickle charger register.

The value is provided via platform data, so it is platform specific
and presumably needs to be configurable. I did, however, not find
a single in-kernel driver which is actually setting it.
So this is a good question.

s/_/-/ in property names please.

What do these bits do? is there any documentation available?

Why do they need to be in the DT?

Why do we not have a higher-level description?

quoted

+- trickle_reg   : Trickle charger register address. Defaults to 0x10 for ds1339.

Is this expected to change? Why does this need to be in the DT?

A quick look into the code suggests that this is a chip specific register,
and the register address is set by the driver depending on the chip type.
I don't think it should be configurable via dt.

Guenter
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