Hi Joan, On Fri, 17 Dec 2010 18:21:57 +0100, Joan Pau Beltran wrote: > We are also working with an Advantech PCM3362 board in an underwater > vehicle, and want to use the GPIO port to monitor the battery charge (a > battery board is connected to the GPIO port and sets a pin to 1 when > voltage goes below 20V). > > We need to use Ubuntu, currently 10.04 with kernel > linux-image-2.6-32-26-generic. > > As Giampolo says, out of the box there aren't any chips under > /sys/class/gpio (only import/export files). > After checking that i2c-gpio and pca953x are shipped with the kernel but > no loaded by default, I tried to modprobe them and they load > successfully, but the chip does not appear in /sys/class/gpio. > i2cdetect does not list any bus. When you load the i2c-gpio driver, it looks for support devices. So your platform initialization code must instantiate a platform device with name "i2c-gpio" and proper platform data (GPIO pin descriptions). There are several examples under arch/blackfin and arch/arm you can look at. If done properly, after loading i2c-dev, i2cdetect should see your I2C bus. Until you manage to get there, there is no point in using driver pca953x, it simply can't work. > The battery board is not connected to the GPIO now. Actually nothing is > connected to it. I suppose that the chip should be detected even if > there is nothing attached to it. But just to be sure, do I need to > connect it to some device to get the chip appear under /sys/class/gpio? > > Giampolo (ore anyone on the list), did you success using the GPIO port > on that board? In that case, could you point me what steps have you > done? It's the first time I use a GPIO port and I read the Documentation > and both examples pointed out by Jean but still can not figure out why > the chip is not recognized under /sys/class/gpio or how to access it. > > Thanks Jean for pointing out about the address alignment difference in > Linux. For sure I won't even thought about it reading the Advantech manual. -- Jean Delvare -- 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
