On Mon, 26 Feb 2018 21:40:32 +0100 Boris Brezillon <boris.brezillon@xxxxxxxxxxx> wrote: > On Mon, 26 Feb 2018 21:36:07 +0100 > Boris Brezillon <boris.brezillon@xxxxxxxxxxx> wrote: > > > > >>> + > > > >>> +/** > > > >>> + * struct i3c_master_controller_ops - I3C master methods > > > >>> + * @bus_init: hook responsible for the I3C bus initialization. This > > > >>> + * initialization should follow the steps described in the I3C > > > >>> + * specification. This hook is called with the bus lock held in > > > >>> + * write mode, which means all _locked() helpers can safely be > > > >>> + * called from there > > > >>> + * @bus_cleanup: cleanup everything done in > > > >>> + * &i3c_master_controller_ops->bus_init(). This function is > > > >>> + * optional and should only be implemented if > > > >>> + * &i3c_master_controller_ops->bus_init() attached private data > > > >>> + * to I3C/I2C devices. This hook is called with the bus lock > > > >>> + * held in write mode, which means all _locked() helpers can > > > >>> + * safely be called from there > > > >>> + * @supports_ccc_cmd: should return true if the CCC command is supported, false > > > >>> + * otherwise > > > >>> + * @send_ccc_cmd: send a CCC command > > > >>> + * @send_hdr_cmds: send one or several HDR commands. If there is more than one > > > >>> + * command, they should ideally be sent in the same HDR > > > >>> + * transaction > > > >>> + * @priv_xfers: do one or several private I3C SDR transfers > > > >>> + * @i2c_xfers: do one or several I2C transfers > > > >>> + * @request_ibi: attach an IBI handler to an I3C device. This implies defining > > > >>> + * an IBI handler and the constraints of the IBI (maximum payload > > > >>> + * length and number of pre-allocated slots). > > > >>> + * Some controllers support less IBI-capable devices than regular > > > >>> + * devices, so this method might return -%EBUSY if there's no > > > >>> + * more space for an extra IBI registration > > > >>> + * @free_ibi: free an IBI previously requested with ->request_ibi(). The IBI > > > >>> + * should have been disabled with ->disable_irq() prior to that > > > >>> + * @enable_ibi: enable the IBI. Only valid if ->request_ibi() has been called > > > >>> + * prior to ->enable_ibi(). The controller should first enable > > > >>> + * the IBI on the controller end (for example, unmask the hardware > > > >>> + * IRQ) and then send the ENEC CCC command (with the IBI flag set) > > > >>> + * to the I3C device > > > >>> + * @disable_ibi: disable an IBI. First send the DISEC CCC command with the IBI > > > >>> + * flag set and then deactivate the hardware IRQ on the > > > >>> + * controller end > > > >>> + * @recycle_ibi_slot: recycle an IBI slot. Called every time an IBI has been > > > >>> + * processed by its handler. The IBI slot should be put back > > > >>> + * in the IBI slot pool so that the controller can re-use it > > > >>> + * for a future IBI > > > >>> + * > > > >>> + * One of the most important hooks in these ops is > > > >>> + * &i3c_master_controller_ops->bus_init(). Here is a non-exhaustive list of > > > >>> + * things that should be done in &i3c_master_controller_ops->bus_init(): > > > >>> + * > > > >>> + * 1) call i3c_master_set_info() with all information describing the master > > > >>> + * 2) ask all slaves to drop their dynamic address by sending the RSTDAA CCC > > > >>> + * with i3c_master_rstdaa_locked() > > > >>> + * 3) ask all slaves to disable IBIs using i3c_master_disec_locked() > > > >>> + * 4) start a DDA procedure by sending the ENTDAA CCC with > > > >>> + * i3c_master_entdaa_locked(), or using the internal DAA logic provided by > > > >>> + * your controller > > > >> You mean SETDASA CCC command? > > > > No, I really mean ENTDAA and DAA. By internal DAA logic I mean that > > > > some controllers are probably automating the whole DAA procedure, while > > > > others may let the SW control every step. > > > My understanding is that i3c_master_entdaa_locked() will trigger the DAA process > > > and DAA can be done by SETDASA, ENTDAA and later after the bus initialization > > > with SETNEWDA. > > > > No. Only ENTDAA can trigger a DAA procedure. SETDASA is here to assign > > a single dynamic address to a device that already has a static address > > but no dynamic address yet, and SETNEWDA is here to modify the dynamic > > address of a device that already has one. > > > > > > > > I think the DAA process should be more generic, right now is only made through > > > the ENTDAA command with (cmd.ndests = 1). > > > I mean, shouldn't this be made by the core? First doing DAA for the devices > > > declared and them try do discover the rest of devices on the bus. > > > > Can you detail a bit more? If the only part you're complaining about is > > pre-assignment of dynamic addresses with SETDASA when a device is > > declared in the DT with a reg and dynamic-address property, then yes, I > > think I can provide an helper for that. But this helper would still have > > to be called from the master controller driver (from ->bus_init() or > > after a Hot-Join). > > > > Now, if the question is, is there a way we can automate things even more > > and completely implement DAA from the core? I doubt it, because the way > > the core will trigger DAA, expose discovered devices or allow you to > > declare manually assigned addresses is likely to be > > controller-dependent. > > When I designed the framework I took the decision to base my work on the > > spec rather than focusing on the I3C master controller I had to support > > (Cadence). This is the reason I decided to keep the interface as simple > > as possible at the risk of encouraging code-duplication (at first) > > rather than coming up with an interface that is designed with a single > > controller in mind and having to break things every time a new > > controller comes out. > > > > Thank you for you comments, but I'd like to know if some of my design > > choices are blocking you to support your controller. What I've seen so > > far is a collection of things that might be relevant to fix (though > > most of them are subject to interpretation and/or a matter of taste), > > but nothing that should really block you. > > Well, that's not entirely true: I agree that something is missing in > ->priv_xfers() to let the controller know about the device limitations, > and this could be a blocking aspect. > And I2C functionalities might differ between I3C master controllers, so that's also something we should transfer to the I3C master driver instead of imposing it in the core. -- Boris Brezillon, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
