Re: [PATCH] i2c-designware: add OF binding support

[Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>]

On Thu, Aug 4, 2011 at 10:52 PM, Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> On 08/04/2011 10:45 AM, Rob Herring wrote:
>> Ben,
>>
>> On 08/04/2011 04:12 AM, Ben Dooks wrote:
>>> On Wed, Aug 03, 2011 at 03:04:23PM -0500, Rob Herring wrote:
>>>> From: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
>>>>
>>>> Add of_match_table and DT style i2c registration to designware i2c
>>>> driver.
>>>>
>>>> Signed-off-by: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
>>>> Cc: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
>>>> Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
>>>> Cc: Ben Dooks <ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>
>>>> Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>>> ---
>>>>  Documentation/devicetree/bindings/i2c/dw-i2c.txt |   23 ++++++++++++++++++++++
>>>>  drivers/i2c/busses/i2c-designware.c              |   13 ++++++++++++
>>>>  2 files changed, 36 insertions(+), 0 deletions(-)
>>>>  create mode 100644 Documentation/devicetree/bindings/i2c/dw-i2c.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/i2c/dw-i2c.txt b/Documentation/devicetree/bindings/i2c/dw-i2c.txt
>>>> new file mode 100644
>>>> index 0000000..cbcb404
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/i2c/dw-i2c.txt
>>>> @@ -0,0 +1,23 @@
>>>> +* Synopsys DesignWare I2C
>>>> +
>>>> +Required properties :
>>>> +
>>>> + - compatible : should be "snps,designware-i2c"
>>>> + - reg : Offset and length of the register set for the device
>>>> + - interrupts : <IRQ> where IRQ is the interrupt number.
>>>> +
>>>> +Recommended properties :
>>>> +
>>>> + - clock-frequency : desired I2C bus clock frequency in Hz.
>>>> +
>>>> +Example :
>>>> +
>>>> +   i2c@f0000 {
>>>> +           #address-cells = <1>;
>>>> +           #size-cells = <0>;
>>>> +           compatible = "snps,designware-i2c";
>>>> +           reg = <0xf0000 0x1000>;
>>>> +           interrupts = <11>;
>>>> +           clock-frequency = <400000>;
>>>> +   };
>>>> +
>>>
>>> looks good to me.
>>>
>>>> diff --git a/drivers/i2c/busses/i2c-designware.c b/drivers/i2c/busses/i2c-designware.c
>>>> index b7a51c4..2911a49 100644
>>>> --- a/drivers/i2c/busses/i2c-designware.c
>>>> +++ b/drivers/i2c/busses/i2c-designware.c
>>>> @@ -37,6 +37,7 @@
>>>>  #include <linux/platform_device.h>
>>>>  #include <linux/io.h>
>>>>  #include <linux/slab.h>
>>>> +#include <linux/of_i2c.h>
>>>>
>>>>  /*
>>>>   * Registers offset
>>>> @@ -770,12 +771,17 @@ static int __devinit dw_i2c_probe(struct platform_device *pdev)
>>>>     adap->algo = &i2c_dw_algo;
>>>>     adap->dev.parent = &pdev->dev;
>>>>
>>>> +#ifdef CONFIG_OF
>>>> +   r = i2c_add_adapter(adap);
>>>> +#else
>>>>     adap->nr = pdev->id;
>>>>     r = i2c_add_numbered_adapter(adap);
>>>> +#endif
>>>
>>> I would say that doing the #ifdef CONFIG_OF is dangerous here when we
>>> are in a mixed OF/platform enviromnent as we're depending on compile
>>> time selection.
>>>
>>> I'm also wondering whether we have an of helper macro which takes
>>> a pdev and gives you an adapter number either given on pdev->id or
>>> -1 for the case when we're using the OF bindings.
>>>
>>> It might be worth talking to Grant about setting pdev->id to -1 if we
>>> are using an OF device.
>>>
>>
>> As Grant said, that's already done and this hunk is not needed.
>>
>>>>     if (r) {
>>>>             dev_err(&pdev->dev, "failure adding adapter\n");
>>>>             goto err_free_irq;
>>>>     }
>>>> +   of_i2c_register_devices(adap);
>>>
>>> If we did that, we could add a of_i2c_register_adapter() call which
>>> would take the platform device and then do the of_i2c_register_devices()
>>> and do these steps.
>>>
>>
>> Better yet, how about putting of_i2c_register_devices into
>> i2c_register_adapter? Everywhere that calls of_i2c_register_devices is
>> preceded by a call to i2c_add_numbered_adapter or i2c_add_adapter. It
>> seems logical to put it with i2c_scan_static_board_info. I'll prepare a
>> patch to add that and remove all the other callers unless you think
>> that's a bad idea.
>>
>
> Nevermind. That would be undoing this commit:
>
>    of/i2c: Fix module load order issue caused by of_i2c.c

The other alternative would be to move the i2c dt parsing code into
drivers/i2c.  I'm already planning to do that for spi and gpio dt
parsing code.

g.