[U-Boot] [PATCH] 7/12 Multiadapter/multibus I2C, drivers part 4

[Heiko Schocher]

Hello ksi,

ksi at koi8.net wrote:
> On Fri, 13 Feb 2009, Heiko Schocher wrote:
>> ksi at koi8.net wrote:
>>> Signed-off-by: Sergey Kubushyn <ksi at koi8.net>
>>> ---
>>> diff -purN u-boot-i2c.orig/drivers/i2c/soft_i2c.c u-boot-i2c/drivers/i2c/soft_i2c.c
>>> --- u-boot-i2c.orig/drivers/i2c/soft_i2c.c	2009-02-12 10:43:41.000000000 -0800
>>> +++ u-boot-i2c/drivers/i2c/soft_i2c.c	2009-02-12 10:46:00.000000000 -0800
>>> @@ -1,4 +1,8 @@
>>>  /*
>>> + * Copyright (c) 2009 Sergey Kubushyn <ksi at koi8.net>
>>> + *
>>> + * Changes for multibus/multiadapter I2C support.
>>> + *
>>>   * (C) Copyright 2001, 2002
>>>   * Wolfgang Denk, DENX Software Engineering, wd at denx.de.
>> [...]
>>
>> The following patch is based on your patches without 7/12 and
>> adds multibus support for the soft_i2c driver without doing such
>> a big change as you did. Maybe it is not yet perfect, because
>> it is just a fast try, but I think we should go this way. What
>> do you/others think?
> 
> The reason behind this patch is making SEVERAL different SOFT_I2C ADAPTERS
> available. Not BUSSES but separate PHYSICAL I2C ADAPTERS made of different
> pin pairs from different chips.

This you can also do with "my" suggestion ...

> OK, please explain how are you going to make different functions for
> different adapters? Let's say you want to use 2 on-SoC GPIO pins for

You can do now the following for example in your
include/configs/MPC8548CDS.h example:

you only have to define

#define I2C_SDA(bit)   (printf("hwadap: %d sda1: %d", cur_adap_nr->hwadapnr, bit))

if this is a real driver you can make a function in your board code
say (just a fast thought):

void i2c_soft_sda (int bit)
{
	switch(cur_adap_nr->hwadapnr) {
		case 0:
			/* adapter specfic code 0 */
			break;
		case 1:
			/* adapter specfic code 1 */
			break;
		[...]
	}
}

and define in config file

#define I2C_SDA(bit)   i2c_soft_sda (bit)

> adapter #0, 2 GPIOs from a PCI-PCI bridge for adapter #1, and 2 pins from
> some chip sitting behind that bridge for adapter #2 if all those pin sets
> are accessed totally different. I won't even start about using pins from
> different chips for SDA and SCL (let's say you only have one GPIO available
> on your SoC and another one on PCI Bridge.)
> 
> What your patch creates is just aliases to the SAME physical adapter.

No, it is not! I only use the same functions, but in the board
specific code it is possible to made a switch and access
the Pins where ever they are.

bye
Heiko
-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany