On Tue, Nov 6, 2012 at 10:35 AM, Tony Lindgren <t...@atomide.com> wrote: > * Grant Likely <grant.lik...@secretlab.ca> [121106 03:16]: >> On Tue, Nov 6, 2012 at 10:30 AM, Pantelis Antoniou >> <pa...@antoniou-consulting.com> wrote: >> > >> > Another can of worms is the pinctrl nodes. >> >> Yes... new pinctrl data would need to trigger adding new data to >> pinctrl. I don't know if the pinctrl api supports that. > > The actual pins stay the same, just their configuration > changes. AFAIK all that is already supported using the > pinctrl framework. > > For example, considering hotplugging capes on the beaglebone: > > 1. You need to map all the sensible modes for the pins exposed > to the capes in the board specific .dts file. This will > add roughly 4 x nr_capbus_pins named modes in the .dts file > so not too bad. > > 2. Claim all the capebus pins during the capbus driver probe > and set them to some safe mode. > > 3. Try to detect the connected cape(s) over i2c. > > 4. Use pinctr_select_state to set the desired modes for > the pins used by the cape(s). > > 5. Enable capebus regulators and clocks etc. > > 6. Load the driver modules for whatever omap internal > devices the cape supports. > > You could also claim the pin for the omap internal > devices instead of claiming them in the capebus, but then > things can get messy with binding and unbinding the > drivers. So just claiming all the pins in the capebus > probably keeps things simpler.
That assumes that for a particular external bus, certain pins aren't already shared with functions already on the board, for instance if an I²C bus brought out to the external bus already has a chip connected to it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
