On Mon, 08 Jun 2020, Michael Walle wrote: > Am 2020-06-08 20:56, schrieb Lee Jones: > > On Mon, 08 Jun 2020, Michael Walle wrote: > > > > > Am 2020-06-08 12:02, schrieb Andy Shevchenko: > > > > +Cc: some Intel people WRT our internal discussion about similar > > > > problem and solutions. > > > > > > > > On Mon, Jun 8, 2020 at 11:30 AM Lee Jones <lee.jones@xxxxxxxxxx> wrote: > > > > > On Sat, 06 Jun 2020, Michael Walle wrote: > > > > > > Am 2020-06-06 13:46, schrieb Mark Brown: > > > > > > > On Fri, Jun 05, 2020 at 10:07:36PM +0200, Michael Walle wrote: > > > > > > > > Am 2020-06-05 12:50, schrieb Mark Brown: > > > > > > > > ... > > > > > > > > > Right. I'm suggesting a means to extrapolate complex shared and > > > > > sometimes intertwined batches of register sets to be consumed by > > > > > multiple (sub-)devices spanning different subsystems. > > > > > > > > > > Actually scrap that. The most common case I see is a single Regmap > > > > > covering all child-devices. > > > > > > > > Yes, because often we need a synchronization across the entire address > > > > space of the (parent) device in question. > > > > > > > > > It would be great if there was a way in > > > > > which we could make an assumption that the entire register address > > > > > space for a 'tagged' (MFD) device is to be shared (via Regmap) between > > > > > each of the devices described by its child-nodes. Probably by picking > > > > > up on the 'simple-mfd' compatible string in the first instance. > > > > > > > > > > Rob, is the above something you would contemplate? > > > > > > > > > > Michael, do your register addresses overlap i.e. are they intermingled > > > > > with one another? Do multiple child devices need access to the same > > > > > registers i.e. are they shared? > > > > > > No they don't overlap, expect for maybe the version register, which is > > > just there once and not per function block. > > > > Then what's stopping you having each device Regmap their own space? > > Because its just one I2C device, AFAIK thats not possible, right? Not sure what (if any) the restrictions are. I can't think of any reasons why not, off the top of my head. Does Regmap only deal with shared accesses from multiple devices accessing a single register map, or can it also handle multiple devices communicating over a single I2C channel? One for Mark perhaps. > > The issues I wish to resolve using 'simple-mfd' are when sub-devices > > register maps overlap and intertwine. [...] > > > > > What do these bits configure? > > > > > > - hardware strappings which have to be there before the board powers > > > up, > > > like clocking mode for different SerDes settings > > > - "keep-in-reset" bits for onboard peripherals if you want to save > > > power > > > - disable watchdog bits (there is a watchdog which is active right > > > from > > > the start and supervises the bootloader start and switches to > > > failsafe > > > mode if it wasn't successfully started) > > > - special boot modes, like eMMC, etc. > > > > > > Think of it as a 16bit configuration word. > > > > And you wish for users to be able to view these at run-time? > > And esp. change them. > > > Can they adapt any of them on-the-fly or will the be RO? > > They are R/W but only will only affect the board behavior after a reset. I see. Makes sense. This is board controller territory. Perhaps suitable for inclusion into drivers/soc or drivers/platform. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
