mpc8270 : i2c support

mpc8270 : i2c support

[jfaslist]

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Hi,
We have designed a system using a mpc8270 cpu. The firmware we 
use is u-boot and we can access all our i2c devices from u-boot.

But when we try to access i2c devices from under linux 2.6 using 
the /dev/i2c-0 special file we get an ENODEV on opening that 
file. I think it is because we lack an adapter driver.

If I look in the official kernel, it looks like the adapter 
driver for the mpc8270 i2c system is 
./drivers/i2c/busses/i2c-mpc.c. Is this correct?

Why is this driver registering as a platform driver and not as a 
i2c bus driver?

In DENX ELDK there is also a i2c-mpc8260.c, but we couldn't get 
that to work either.

What should I do to be able to access i2c devices using the 
/dev/i2c-0 file? I feel I need to modify the i2c adapter driver 
to follow the driver model, but in what ways?

Thx for any help,
-jf simon

	

	
		
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Re: mpc8270 : i2c support

[Heiko Schocher]

Hello jfaslist,

on Wed, 03 May 2006 14:33:37 jfaslist wrote:
> But when we try to access i2c devices from under linux 2.6 using 
> the /dev/i2c-0 special file we get an ENODEV on opening that 
> file. I think it is because we lack an adapter driver.
> 
> If I look in the official kernel, it looks like the adapter 
> driver for the mpc8270 i2c system is 
> ./drivers/i2c/busses/i2c-mpc.c. Is this correct?

No. It is for:
MODULE_DESCRIPTION
("I2C-Bus adapter for MPC107 bridge and MPC824x/85xx/52xx processors");

> In DENX ELDK there is also a i2c-mpc8260.c, but we couldn't get 
> that to work either.

OK, this was the right driver ... but it was tested on a MPC826x
Processor.

Hmmm.... I think there are differences in the memory map between
MPC826x and MPC827x ... can you try following Hack in
include/asm-ppc/cpm_8260.h?

-#define PROFF_I2C       ((16 * 1024) - 64)
+#define PROFF_I2C       ((8 * 1024) - 64)

[If it solves the problem, we must do this on a better way ;-)]

I think i had the same problem with a 2.4er Kernel ... Yes,
this is in my queue, but not merged in our official 2.4er Tree ...

Maybe you have to set other Portsettings in
drivers/i2c/busses/i2c-cpm2.c cpm2_iic_init() ... ?

> What should I do to be able to access i2c devices using the 
> /dev/i2c-0 file? I feel I need to modify the i2c adapter driver 
> to follow the driver model, but in what ways?

Bring up the driver running, and then read:
Documentation/i2c/dev-interface.

Best regards
Heiko

Re: mpc8270 : i2c support

[Heiko Schocher]

Hello jean-francois,

on Wed, 03 May 2006 22:56 jean-francois simon wrote:
> > Maybe you have to set other Portsettings in
> > drivers/i2c/busses/i2c-cpm2.c cpm2_iic_init() ... ?
> 
> Sorry, but where can i find this file? 

Sorry, I meant:
drivers/i2c/busses/i2c-mpc8260.c mpc8260_iic_init()

Best regards
Heiko

mpc8270 : i2c support

[Heiko Schocher]

Hello,

on Thu May 4 06:11:17 2006 i wrote:
> Hmmm.... I think there are differences in the memory map between
> MPC826x and MPC827x ... can you try following Hack in
> include/asm-ppc/cpm_8260.h?
> 
> -#define PROFF_I2C       ((16 * 1024) - 64)
> +#define PROFF_I2C       ((8 * 1024) - 64)
> 
> [If it solves the problem, we must do this on a better way ;-)]

I don t know, if this was necessary to solve the problem, but i think
the follwing patch is useful, but I have no Hardware to try it out.

Any comments?

Best regards
Heiko

diff --git a/include/asm-ppc/cpm2.h b/include/asm-ppc/cpm2.h
index 6197986..738259c 100644
--- a/include/asm-ppc/cpm2.h
+++ b/include/asm-ppc/cpm2.h
@@ -181,7 +181,11 @@ #define PROFF_IDMA4_BASE	((uint)0x8afe)
  */
 #define PROFF_SMC1	(0)
 #define PROFF_SMC2	(64)
+#if defined(CONFIG_8272) || defined(CONFIG_MPC8555)
+#define PROFF_I2C	((8 * 1024) - 64)
+#else
 #define PROFF_I2C	((16 * 1024) - 64)
+#endif
 
 /* Define enough so I can at least use the serial port as a UART.
  */