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Problem with linaro and i2c devices

Former Member

Hi,
I'm facing some problems trying to work with a i2c camera and linaro on a zedboard.
For first I tested the system with the bare metal OS and everything works smooth thanks to all the support file created in the sdk, then I tried to switch to linaro, but I don't understand how to use the device properly.
Using /dev/mem for a quick test I was able to send a reset signal to the device in order to verify that it was properly mapped, then I tried to add to the device tree this:

=========================================
ps7_i2c_0: ps7-i2c@e0004000 {
clock-frequency = <400000>;
clocks = <&clkc 38>;
compatible = "cdns,i2c-r1p10";
interrupt-parent = <&ps7_scugic_0>;
interrupts = <0 25 4>;
reg = <0xe0004000 0x1000>;
xlnx,has-interrupt = <0x0>;
xlnx,i2c-reset = "";
} ;
=========================================

As far as I have understand of the device tree "cdns,i2c-r1p10" should be the name of the driver associated with the peripheal, is this right?
The result was that under "/sys/devices/..." I now have "ps7-i2c@e0004000", how I'm supposed to used it now?
I have tried googling for it but with not good results... Have you some good guide, advice or tutorial on this specific argument?
Thank you in advance and sorry for the dumb question, but I think that I'm missing some crucial part here!

  • 0

    What are you trying to do on I2C?  For example, I installed a PMOD real-time-clock.  I did the following for my setup using a microZed 7020.

    1) Create a new block design with I2C 0 mapped to MIO 14 & 15 with pullups enabled and no interrupt.
    2) Generate a new bit file, fsbl, boot.bin, etc
    3) Update my device tree as follow:
    -------------------
    ttps7_i2c_0: ps7-i2c@e0004000 {
    tttbus-id = <0>;
    tttclock-frequency = <100000>;
    tttclocks = <&clkc 38>;
    tttcompatible = "cdns,i2c-r1p10";
    tttinterrupt-parent = <&ps7_scugic_0>;
    tttinterrupts = <0 25 4>;
    tttreg = <0xe0004000 0x1000>;
    tttxlnx,has-interrupt = <0x0>;
    ttt#address-cells = <1>;
    ttt#size-cells = <0>;
    tttrtc@6F {
    ttt       compatible = "dallas,ds1337";
    ttt       reg = <0x6F>;
    ttt       };
    tt} ;
    -----------------
    Things to note:
    a) I reduced the clock from 400kHz to 100kHz
    b) I added a section rtc@6F to tell Linux my real-time-clock is at address 0x6F, and also what specific clock device I have.
    4) Now in linux if I type:
    i2cdetect -y -r 0
         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- --
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    50: -- -- -- -- -- -- -- 57 -- -- -- -- -- -- -- --
    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- UU
    70: -- -- -- -- -- -- -- --

    This shows my RTC is active at 6F (hence the UU).  The device also has something at 57 that I haven't looked at yet.
    5) Since I have the RTC compiled into the kernel, in conjunction with the device tree, I get a /dev/rtc0 and a link to at at /dev/rtc.

    I don't have it working 100% at the moment, but it does somewhat work.  There are other examples out there on how to configure different I2C devices via the device tree.  Just make sure your kernel also supports the device.

    Hope this helps.