Re: i2c core: issue in of_i2c_register_devices()

[Alexandre Belloni <alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

Take 2 of my nice ascii-art:

    +----------------+
    |                |<------+ i2c0
    |                |
    | gpio i2c muxer |
    |                |<------+ gpios
    |                |
    +----+-----------+
         |            +--------------+
         |            |              |<-------+ V1
         |        +---+ nau7802      |
         |        |   |              +---IRQ--------------+
         |        |   +--------------+                    |
         |        |                                       |
         +--i2c---+   +--------------+                    |
                  |   |              |<-------+ V2        |
                  +---+ nau7802      |                    |
                  |   |              +---IRQ----------+   |
                  |   +--------------+                |   |
                  |                                   |   |
                  |   +--------------+                |   |
                  |   |              |<-------+ V3    |   |
                  +---+ nau7802      |                |   |
                  |   |              +---IRQ-------+  |   |
                  |   +--------------+             |  |   |
                  |                                |  |   |
                  |   +--------------+             |  |   |
                  |   |              |<------------+  |   |
                  +---|              |                |   |
                      | pca9555      |<---------------+   |
 IRQ   <--------------+              |                    |
                      |              |<-------------------+
                      +--------------+


On 18/06/2013 16:52, Alexandre Belloni wrote:
> Hi,
>
> I think I have a corner case and I don't immediately see how to solve
> the issue.
>
> On the cfa-10049, we have 3 nau7802 ADCs. As they are sharing the same
> address,  they are behind a gpio based i2c muxer.
>
> Those ADCs are able to send interrupts. So, the interrupts lines are
> connected to a pca9555 which is behind the same i2c muxer.
>
>
>                                            +--------------+
>                                            |              |<-------+ V1
>                                        +---+ nau7802      |
>             +-----------------+        |   |             
> +---IRQ--------------+
>      i2c0+--+                 |        |  
> +--------------+                    |
>             |                 |       
> |                                       |
>             |  gpio i2c muxer +--i2c---+  
> +--------------+                    |
>      gpios+-+                 |        |   |              |<-------+
> V2        |
>             |                 |        +---+ nau7802     
> |                    |
>             +-----------------+        |   |             
> +---IRQ----------+   |
>                                        |  
> +--------------+                |   |
>                                       
> |                                   |   |
>                                        |  
> +--------------+                |   |
>                                        |   |              |<-------+
> V3    |   |
>                                        +---+ nau7802     
> |                |   |
>                                        |   |             
> +---IRQ-------+  |   |
>                                        |   +--------------+            
> |  |   |
>                                        |                               
> |  |   |
>                                        |   +--------------+            
> |  |   |
>                                        |   |             
> |<------------+  |   |
>                                        +---|             
> |                |   |
>                                            | pca9555     
> |<---------------+   |
>                  IRQ   <-------------------+             
> |                    |
>                                            |             
> |<-------------------+
>                                            +--------------+
>
>
> So, the relevant bits of the DT are:
>
> i2cmux {
>         compatible = "i2c-mux-gpio";
>         #address-cells = <1>;
>         #size-cells = <0>;
>         mux-gpios = <&gpio1 22 0 &gpio1 23 0>;
>         i2c-parent = <&i2c1gpio>;
>
>         i2c@0 {
>             reg = <0>;
>             #address-cells = <1>;
>             #size-cells = <0>;
>
>             adc0: nau7802@2a {
>                 compatible = "nuvoton,nau7802";
>                 reg = <0x2a>;
>                 nuvoton,vldo = <3000>;
>                 interrupt-parent = <&pca9555>;
>                 interrupts = <8 0x2>;
>             };
>         };
>
> [...]
>
>         i2c@3 {
>             reg = <3>;
>             #address-cells = <1>;
>             #size-cells = <0>;
>
>             pca9555: pca9555@20 {
>                 compatible = "nxp,pca9555";
>                 interrupt-parent = <&gpio2>;
>                 interrupts = <19 0x2>;
>                 gpio-controller;
>                 #gpio-cells = <2>;
>                 interrupt-controller;
>                 #interrupt-cells = <2>;
>                 reg = <0x20>;
>             };
>         };
>     };
>
> Now, for the issue, at the time we are registering the ADCs in
> of_i2c_register_devices(), using info.irq = irq_of_parse_and_map(node,
> 0) results in :
>
> irq: no irq domain found for /i2cmux/i2c@3/pca9555@20 !
>
> as the pca9555 is not yet registered. But, it is not possible to move
> the pca9555 definition upper in the DT be cause the order seems to be
> significant for i2c-mux-gpio. Obviously, if I use irq_of_parse_and_map()
> in the probe of the nau7802 driver, it is working fine but that is not a
> future proof solution.
>
> How would you suggest to solve that ?
>
> regards,
>


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com