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    SubjectRe: GPIO-Ports on VIA EPIA-SN
    Date
    On Monday 09 June 2008, Bart Van Assche wrote:
    > On Mon, Jun 9, 2008 at 8:00 PM, Stefan Hellermann <stefan@the2masters.de> wrote:
    > > I have a VIA Epia-SN embedded-board with 8 GPIO-connectors. I got the
    > > attached documentation from VIA after I asked how to use the
    > > GPIO-connectors with Linux.
    >
    > Are you already familiar with the LDD book
    > (http://lwn.net/Kernel/LDD3/ +
    > http://lwn.net/Articles/2.6-kernel-api/) ? That book is a good
    > starting point, together with the file Documentation/gpio.txt in the
    > Linux kernel tree.

    So in short: you'll want to add a Kconfig option for your board,
    and when it's selected you'll want to link in some EPIA-specific
    int logic. That logic will register a gpio_chip, and then you'll
    be able to use the standard GPIO calls (and whatever uses them).

    You will also want something like the appended patch ... but do
    the "select" commands when your board is selected.

    Of course an entirely roll-your-own approach could work too, but
    I won't recommend that here.

    - Dave


    ===== CUT HERE
    DEBUG ONLY -- make X86_PC use gpiolib.

    It's not clear to me how the various x86-ish platforms should
    be made to work here, since there seems to be no convention
    that each platform type has its own <asm/arch/...> subdir.

    ---
    arch/x86/Kconfig | 2 ++
    include/asm-x86/gpio.h | 20 +++++++++++++++++++-
    2 files changed, 21 insertions(+), 1 deletion(-)

    --- g26.orig/arch/x86/Kconfig 2008-06-03 19:43:53.000000000 -0700
    +++ g26/arch/x86/Kconfig 2008-06-03 20:03:25.000000000 -0700
    @@ -236,6 +236,8 @@ choice

    config X86_PC
    bool "PC-compatible"
    + select GENERIC_GPIO
    + select HAVE_GPIO_LIB
    help
    Choose this option if your computer is a standard PC or compatible.

    --- g26.orig/include/asm-x86/gpio.h 2008-06-03 19:43:53.000000000 -0700
    +++ g26/include/asm-x86/gpio.h 2008-06-03 20:03:25.000000000 -0700
    @@ -1,6 +1,24 @@
    #ifndef _ASM_I386_GPIO_H
    #define _ASM_I386_GPIO_H

    -#include <gpio.h>
    +// #include <gpio.h>
    +
    +#include <linux/errno.h>
    +#include <asm-generic/gpio.h> /* cansleep wrappers */
    +
    +#define gpio_get_value __gpio_get_value
    +#define gpio_set_value __gpio_set_value
    +#define gpio_cansleep __gpio_cansleep
    +
    +static inline int gpio_to_irq(unsigned gpio)
    +{
    + return -ENOSYS;
    +}
    +
    +static inline int irq_to_gpio(unsigned irq)
    +{
    + return -EINVAL;
    +}
    +

    #endif /* _ASM_I386_GPIO_H */



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