Hi Giampaolo, On Wed, 23 Jun 2010 14:02:04 +0200, Giampaolo Bellini wrote: > Hi all... > > I'm new to I2c and I'm in trouble trying to get GPIO works on an > Advantech PCM-3362 motherboard. > > manufacturer says that GPIO controller is an NXP PCA9555PW chip, > attached to the i2c BUS; the chip has the addresses 40 (read) and 41 > (write) but, if I'm not wrong, in his linux libsusi library This means they refer to left-aligned addresses. Linux uses right-aligned addresses, so your device lives at 0x20 as far as Linux is concerned. > manufacturer access GPIO via BIOS calls and not via linux i2c. > > CPU is an intel Atom N450 with ICH8M chipset and it seems that SMBUS > controller is correctly recognized by the kernel as dmegs reports > something like: > i801_smbus 0000:00:1f.3: PCI INT C -> GSI 17 (level, low) -> IRQ 17 > > actually I've configured the latest 2.6.34 kernel with i2c and pca953x > drivers, but /sys/class/gpio reports only import / export entries, > with no GPIO chips at all... > > I've read Documents/gpio.txt but still don't understand if I have to > do something more to enable GPIO: as I want to access it from kernel > space, I think I'll need to write my own driver (calling > gpio_request() etc) but still miss info about GPIO numbers... and I'm > not even sure GPIO is currently detected. Check arch/arm/mach-ks8695/board-acs5k.c and arch/arm/mach-pxa/cm-x300.c for examples. > Ive try also registering a new GPIO device using generic gpiolib & > sysfs support (eg: echo GPIO-RD 0x40 > > /sys/bus/i2c/devices/i2c-0/new_device) but with no success. Wrong name and wrong address, no surprise it didn't work. Try instead: echo pca9555 0x20 > /sys/bus/i2c/devices/i2c-0/new_device (Assuming i2c-0 is the bus on which the chip actually lives - you can check with i2cdetect). That being said, I doubt that a GPIO chip can really be instantiated from user-space, as it needs configuration settings which you can't provide that way. -- Jean Delvare http://khali.linux-fr.org/wishlist.html -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
