On Fri, Nov 20, 2009 at 03:21:31PM -0700, Grant Likely wrote: > On Tue, Nov 17, 2009 at 1:27 AM, David Brownell <david-b@xxxxxxxxxxx> wrote: > > Since *everything* boils down to one or more signal lines, > > your argument leads directly to Linux having no native > > hardware interface except GPIOs. ?Not ... practical. ;) > I think you've missed my point and taken it to an illogical extreme to > counter it. I agree that PWMs are not GPIOs and visa versa. However, > *some* devices are both GPIOs and PWMs. Also what is needed to manage > GPIO and PWM pins is pretty much identical. On most of the ARM SoCs PWM and GPIO aren't particularly special here - most of the on-SoC functionality is multiplexed onto pins through the same hardware interface. A very large proportion of the pins of the SoC will have muxes to bring out the signals from the internal IP blocks, and pretty much all of those will have GPIO as one of those functions. For many SoCs there will be multiple pin options for bringing out each of the internal signals which complicates matters further. > But that *isn't* the primary purpose of the GPIO subsystem. All that > stuff is layered on top of the GPIO pin management code and doesn't > really play into this debate. The GPIO subsystem isn't doing pin management in that way for most systems, it's just controlling the GPIO functionality and relies on separate configuration to ensure that the relevant pins are in GPIO mode. -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
