Re: [PATCH] I2C: ocores can add I2C devices to the bus

["Richard R?öjfors" <richard.rojfors.ext-l7gf1WXxx3uGw+nKnLezzg@public.gmane.org>]

Ben Dooks wrote:
> On Tue, Jun 02, 2009 at 07:52:40PM +0200, Richard R????jfors wrote:
>> There is sometimes a need for the ocores driver to add devices to the bus when installed.
> 
> please wrap to 72 characters per line.
>  
>> i2c_register_board_info can not always be used, because the I2C devices are not known at an early state,
>> they could for instance be connected on a I2C bus on a PCI device which has the Open Cores IP.
> 
> Maybe i2c_register_board_info() needs to check if the bus is extant
> or not. Anyone else have any feedback on this suggestion?
>  
>> i2c_new_device can not be used in all cases either since the resulting bus nummer might be unknown.
>>
>> The solution is the pass a list of I2C devices in the platform data to the Open Cores driver. Is
>> useful for MFD drivers for instance.
> 
> Possibly, but most systems I see know what devices they have before
> instantiation so can hard-fix the bus numbering when supplying the MFD
> drivers with their data.

I agree, but we have a case here where PCI device(s) are plugged in to a
standard system so we really don't know the bus numbering.

>  
>> Signed-off-by: Richard R??jfors <richard.rojfors.ext-l7gf1WXxx3uGw+nKnLezzg@public.gmane.org>
>> ---
>> Index: linux-2.6.30-rc7/drivers/i2c/busses/i2c-ocores.c
>> ===================================================================
>> --- linux-2.6.30-rc7/drivers/i2c/busses/i2c-ocores.c	(revision 861)
>> +++ linux-2.6.30-rc7/drivers/i2c/busses/i2c-ocores.c	(revision 862)
>> @@ -216,6 +216,7 @@
>>  	struct ocores_i2c_platform_data *pdata;
>>  	struct resource *res, *res2;
>>  	int ret;
>> +	u8 i;
> 
> really, an int will do here, you might find compilers on !x86 archs
> will spend time contracting this variable to an u8.

Agreed.

>  
>>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>  	if (!res)
>> @@ -271,6 +272,10 @@
>>  		goto add_adapter_failed;
>>  	}
>>
>> +	/* add in known devices to the bus */
>> +	for (i = 0; i < pdata->num_devices; i++)
>> +		i2c_new_device(&i2c->adap, pdata->devices + i);
>> +
>>  	return 0;
>>
>>  add_adapter_failed:
>> Index: linux-2.6.30-rc7/include/linux/i2c-ocores.h
>> ===================================================================
>> --- linux-2.6.30-rc7/include/linux/i2c-ocores.h	(revision 861)
>> +++ linux-2.6.30-rc7/include/linux/i2c-ocores.h	(revision 862)
>> @@ -14,6 +14,8 @@
>>  struct ocores_i2c_platform_data {
>>  	u32 regstep;   /* distance between registers */
>>  	u32 clock_khz; /* input clock in kHz */
>> +	u8 num_devices; /* number of devices in the devices list */
>> +	struct i2c_board_info const *devices; /* devices connected to the bus */
>>  };
> 
> anyone want to kerneldoc this?

If you accept the patch, I will send an updated one with updated docs.

>  
>>  #endif /* _LINUX_I2C_OCORES_H */
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>