diff options
| author | Trent Piepho <tpiepho@kymetacorp.com> | 2016-05-19 23:39:32 +0000 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2016-05-30 07:12:19 +0200 |
| commit | 24fcf5fceec8a3af9fab21f2ba702da08ba7c430 (patch) | |
| tree | b83db8ef00cb564dc26e720fd11ae725212c9de5 /Documentation/devicetree | |
| parent | 61ddbd35207af8dbd9b1a0c17619148179235203 (diff) | |
| download | barebox-24fcf5fceec8a3af9fab21f2ba702da08ba7c430.tar.gz barebox-24fcf5fceec8a3af9fab21f2ba702da08ba7c430.tar.xz | |
rtc: ds1307: Add support for configuring external clock pin
The DS1307 has a square wave output pin, which can be used to output a
clock signal from the DS1307. Additionally, the DS1308 supports
configuring this pin as an input from an external clock source to
which it should sync itself.
Add support with OF device tree properties to configure these
settings. Supported features are using the clock pin as an output, an
input, the rate of the pin, and if it should be enabled on battery
backup power.
The driver does not check that the selected features are supported by
the clock chip being used. It is the designer's responsibility to
create a valid device tree node; the bootloader does not attempt to be
a device tree validator.
Signed-off-by: Trent Piepho <tpiepho@kymetacorp.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'Documentation/devicetree')
| -rw-r--r-- | Documentation/devicetree/bindings/rtc/dallas,ds1307.rst | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst b/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst new file mode 100644 index 0000000000..602f74b4dc --- /dev/null +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1307.rst @@ -0,0 +1,33 @@ +Dallas DS1307 I2C Serial Real-Time Clock +======================================== + +Required properties: +* ``compatible``: ``dallas,ds1307``, ``dallas,ds1308``, ``dallas,ds1338`` + "maxim" can be used in place of "dallas" + +* ``reg``: I2C address for chip + +Optional properties: +* ``ext-clock-input``: Enable external clock input pin +* ``ext-clock-output``: Enable square wave output. The above two + properties are mutually exclusive +* ``ext-clock-bb``: Enable external clock on battery power +* ``ext-clock-rate``: Expected/Generated rate on external clock pin + in Hz. Allowable values are 1, 50, 60, 4096, 8192, and 32768 Hz. + Not all values are valid for all configurations. + +The default is ext-clock-input, ext-clock-output, and ext-clock-bb +disabled and ext-clock-rate of 1 Hz. + +Example:: + ds1307: rtc@68 { + compatible = "dallas,ds1307"; + reg = <0x68>; + }; + + ds1308: rtc@68 { + compatible = "maxim,ds1308"; + reg = <0x68>; + ext-clock-output; + ext-clock-rate = <32768>; + }; |