I managed to get a chance to test a ds1307 today. Once you connect it and make the kernel and device tree changes it works perfectly.
1) Connect the hardware. You need to connect 5V power and ground. The I2C signals SCL and SDA need to go through a level shifter.
2) Modify the device tree. in the file arch/arm64/boot/dts/qcom/msm8916.dtsi add the following under blsp_i2c0
compatible = "maxim,ds1307";
reg = <0x68>;
status = "okay";
3) Modify the kernel. After you build the .config file (make defconfig distro.config) you need to run "make menuconfig" and turn on the DS1307 drivers. Then complete building the kernel, the dts, and install the new kernel on the board.
Once you do all of this the kernel will read the time from the clock at power-up time. If you are connected to the network, the kernel will write the current time into the DS1307.