understanding GPIO registers

understanding GPIO registers

[OrazioPirataDelloSpazio (Lorenzo)]

Hi there,
I have a motherbord (VIA EPIA LT) with a digital I/O port composed by 4
GPI and 4 GPO (chip: SMSC SCH3114).

I want to provide voltage to GPO and read the input value of GPI with a
software.

Using the generic gpio kernel module, I tried to export pins without
success :

echo N > /sys/class/gpio/export
write error : invalid argument

I tried for several values of N (from 1 to 1000 !) then I gave up
thinking I would have needed some information from the hardware producer.
Now I have got this information that is the following offsets and addresses.

How can I use these registers to fix the export problem or alternatively
how to write a simple userspace C program to read and write these GPIO?

I read gpio.txt but I'm still confused on how to pass from GPIO numbers
to registers.

Thanks


Lorenzo


#define sGPIOBaseAddr	0A00
#define GPI1_CTRL_REG	0x6E
#define GPI2_CTRL_REG	0x6F
#define GPI3_CTRL_REG	0x72
#define GPI4_CTRL_REG	0x73
#define GPO1_CTRL_REG	0x2C
#define GPO2_CTRL_REG	0x2D
#define GPO3_CTRL_REG	0x35
#define GPO4_CTRL_REG	0x36

understanding GPIO registers

[vichy]

hi:

2011/8/26 OrazioPirataDelloSpazio (Lorenzo) <ziducaixao@autistici.org>:
> Hi there,
> I have a motherbord (VIA EPIA LT) with a digital I/O port composed by 4
> GPI and 4 GPO (chip: SMSC SCH3114).
>
> I want to provide voltage to GPO and read the input value of GPI with a
> software.
>
> Using the generic gpio kernel module, I tried to export pins without
> success :
>
> echo N > /sys/class/gpio/export
> write error : invalid argument
>
> I tried for several values of N (from 1 to 1000 !) then I gave up
> thinking I would have needed some information from the hardware producer.
> Now I have got this information that is the following offsets and addresses.
>
> How can I use these registers to fix the export problem or alternatively
> how to write a simple userspace C program to read and write these GPIO?
>
> I read gpio.txt but I'm still confused on how to pass from GPIO numbers
> to registers.
>
> Thanks
>
>
> Lorenzo
>
>
> #define sGPIOBaseAddr ? 0A00
> #define GPI1_CTRL_REG ? 0x6E
> #define GPI2_CTRL_REG ? 0x6F
> #define GPI3_CTRL_REG ? 0x72
> #define GPI4_CTRL_REG ? 0x73
> #define GPO1_CTRL_REG ? 0x2C
> #define GPO2_CTRL_REG ? 0x2D
> #define GPO3_CTRL_REG ? 0x35
> #define GPO4_CTRL_REG ? 0x36
>
does the base address of gpio in kernel you use is the same or you
have modified for your board?
BR

understanding GPIO registers

[OrazioPirataDelloSpazio (Lorenzo)]

On 8/28/11 8:59 AM, vichy wrote:
> does the base address of gpio in kernel you use is the same or you
> have modified for your board?
I didn't modify the kernel.
VIA EPIA LT BIOS set SCH3114 PME BASE ADDRESS at 0A00H

How do you suggest to proceed?

Thanks,

Lorenzo

understanding GPIO registers

[vichy]

hi:

2011/8/28 OrazioPirataDelloSpazio (Lorenzo) <ziducaixao@autistici.org>:
> On 8/28/11 8:59 AM, vichy wrote:
>> does the base address of gpio in kernel you use is the same or you
>> have modified for your board?
> I didn't modify the kernel.
> VIA EPIA LT BIOS set SCH3114 PME BASE ADDRESS at 0A00H
>
> How do you suggest to proceed?
>
> Thanks,

How about adding debug messages in the driver?
If that is a PCI device, you may use mmap to map the memory for programming.

BR,