1436: rp: Clock configuration r=CBJamo a=CBJamo
Draft of a more complete clock config for the 2040.
I also extended and made public the clk_<name>_freq functions. I know at least the ws2812 pio example would like to get the sys clock at runtime rather than just using a constant. I suspect most pio-based peripherals will want access to the clocks.
Open questions:
1. Best way to handle the 3 external clock frequencies. I think the XIN (aka crystal) freq should just be set by the init function then never changed, though if it's an external clock that could change? I'm not sure anyone would ever want to do that but maybe it should be handled just in case? The other two should probably be set by the application.
2. Better estimation of ROSC frequency. Right now it's really just a lookup table of the speed from the single sample I did this testing on, and only uses the frequency range and div, drive strength is ignored.
3. Probably some kind of warning should be generated if the random bit from the rosc won't be useful, not sure how to do that.
4. Should clocks only be allowed to be configured at init, or should they be modifiable at runtime? For example, switching the RTC to a clock in pin when a pps source is available.
Bonus feature to support clock output. I only implemented the bare minimum, and only for gpout0. I'm sure there's a clean way with macros to impl all 4 without just copy/paste, but I haven't learned macros yet.
Co-authored-by: Caleb Jamison <caleb@cbjamo.com>
1439: rp: use rp2040-boot2 to provide the boot2 blob r=Dirbaio a=pennae
we're currently shipping an old boot2 that runs the flash at half speed. use the more recent version instead, and allow user to choose between the different supported boot2 versions for different flash chips if they need that.
Co-authored-by: pennae <github@quasiparticle.net>
we're currently shipping an old boot2 that runs the flash at half speed.
use the more recent version instead, and allow user to choose between
the different supported boot2 versions for different flash chips if they
need that.
1434: rp pio IV (the voyage home) r=Dirbaio a=pennae
this should hopefully be the last entry in this series. after this we'll have a reasonably safe interface to pio, both for configuration and at runtime. pio now looks very much like the other peripherals (though not exactly, seeing how state machines can't be constructed from a config but only have it applied to them later). the generated code for `StateMachine::set_config` is still larger than we'd like (almost 300 bytes at Oz), but it's a great step up in safety from the previous interface at approximately the same code space cost.
Co-authored-by: pennae <github@quasiparticle.net>
execution wraps around after the end of instruction memory and wrapping
works with this, so we may as well allow program loading across this
boundary. could be useful for reusing chunks of instruction memory.
sometimes state machines need to be started, restarted, or synchronized
at exactly the same time. the current interface does not allow this but
the hardware does, so let's expose that.
the many individual sets aren't very efficient, and almost no checks
were done to ensure that the configuration written to the hardware was
actually valid. this adresses both of these.
none of these are safe. the x/y functions mangle the fifos, the set
functions require the state machine to be stopped to be in any way safe,
the out functions do both of those things at once. only the jump
instruction is marginally safe, but running this on an active program is
bound to cause problems.
programs contain information we could pull from them directly and use to
validate other configuration of the state machine instead of asking the
user to pull them out and hand them to us bit by bit. unfortunately
programs do not specify how many in or out bits they use, so we can only
handle side-set and wrapping jumps like this. it's still something though.
there's nothing this critical section protects against. both read and
write-to-clear are atomic and don't interfere with other irq futures,
only potentially with setting/clearing an irq flag from an arm core.
neither have ever been synchronized, and both have the same observable
effects under atomic writes and critical sections. (for both setting and
clearing an irq flag observable differences could only happen if the
set/clear happened after the poll read, but before the write. if it's a
clear we observe the same effects as sequencing the clear entirely after
the poll, and if it's a set we observe the same effects as sequencing
the set entirely before the poll)
it's only any good for PioPin because there it follows a pattern of gpio
pin alternate functions being named like that, everything else can just
as well be referred to as `pio::Thing`
