Messages in this thread | | | Subject | Re: [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2) | From | Pantelis Antoniou <> | Date | Tue, 6 Nov 2012 20:41:00 +0100 |
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Hi Russ,
On Nov 6, 2012, at 8:29 PM, Russ Dill wrote:
> On Tue, Nov 6, 2012 at 10:35 AM, Tony Lindgren <tony@atomide.com> wrote: >> * Grant Likely <grant.likely@secretlab.ca> [121106 03:16]: >>> On Tue, Nov 6, 2012 at 10:30 AM, Pantelis Antoniou >>> <panto@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.
This is our case on the bone. We don't enable the peripheral until a cape that references it is enabled.
I don't think that very big changes are going to be needed TBH.
So now we use:
am3358_pinmux: pinmux@44e10800 { .... bone_dvi_cape_led_pins: pinmux_bone_dvi_cape_led_pins { pinctrl-single,pins = < 0x48 0x07 /* gpmc_a2.gpio1_18, OUTPUT | MODE7 */ 0x4c 0x07 /* gpmc_a3.gpio1_19, OUTPUT | MODE7 */ >; }; .... };
And in the cape definition:
pinctrl-0 = <&bone_geiger_cape_pins>;
Ideally if we could do this in the cape definition:
cape_pinmux { parent = <&am3358_pinmux>;
bone_dvi_cape_led_pins: pinmux_bone_dvi_cape_led_pins { pinctrl-single,pins = < 0x48 0x07 /* gpmc_a2.gpio1_18, OUTPUT | MODE7 */ 0x4c 0x07 /* gpmc_a3.gpio1_19, OUTPUT | MODE7 */ >; };
pinctrl-0 = <&bone_geiger_cape_pins>; It would be just fine.
Regards
-- Pantelis
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