On 28/02/2025 00:52:34+0900, William Breathitt Gray wrote: > On Fri, Feb 28, 2025 at 12:13:00AM +0900, William Breathitt Gray wrote: > > On Thu, Feb 27, 2025 at 03:37:28PM +0100, Alexandre Belloni wrote: > > > On 27/02/2025 23:22:36+0900, William Breathitt Gray wrote: > > > > Skimming through the driver, it looks like what we'll need is for > > > > mchp_tc_counts[] to have all three TCCs defined, then have > > > > mchp_tc_probe() match on a TCB node and configure each TCC. Once that's > > > > setup, then whenever we need to identify which TCC a callback is > > > > exposing, we can get it from count->id. > > > > > > > > So for example, the TC_CV register offset is calculated as 0x00 + > > > > channel * 0x40 + 0x10. In the count_read() callback we can leverage > > > > count->id to identify the TCC and thus get the respective TC_CV register > > > > at offset + count->id * 0x40 + 0x10. > > > > > > > > > > We can't do that because the TCC of a single TCB can have a mix of > > > different features. I struggled with the breakage to move away from the > > > one TCB, one feature state we had. > > > Be fore this, it was not possible to mix features on a single TCB, now, > > > we can have e.g. the clocksource on TCC 0 and 1 of TCB0 and a PWM on > > > TCC 2. mchp_tc_probe must not match on a TCB node... > > > > Okay I see what you mean, if we match on a TCB mode then we wouldn't be > > able to define the cases where one TCC is different from the next in the > > same TCB. > > > > The goal however isn't to support all functionality (i.e. PWM-related > > settings, etc.) in the counter driver, but just expose the TCB > > configuration options that affect the TCCs when configured for counter > > mode. For example, the sysfs attributes can be created, but they don't > > have to be available until the TCC is in the appropriate mode (e.g. > > return -EBUSY until they are in a counter mode). > > > > Is there a way to achieve that? Maybe there's a way we can populate the > > sysfs tree on the first encountered TCC, and then somehow indicate when > > additional TCCs match. Attributes can become available then dynamically > > based on the TCCs that match. > > > > William Breathitt Gray > > Sorry, let me step back for a moment because maybe I'm trying to solve > a problem that might not actually be a problem. > > I see functionality settings available in the TC Block Mode Register > (BMR) that can affect multiple TCCs at a time. Are these BMR settings > exposed already to users in someway? If not, do we have a way to > introduce these settings if someone wants them; e.g. would the > AutoCorrection function enable bit be exposed as a sysfs attribute, or > configured in the devicetree? BMR is already available and used by the individual drivers. The current microchip-tcb-capture already uses it to enable qdec mode. timer-atmel-tcb uses it to chain timers. Note that we already have a driver for the pwm function too in drivers/pwm/pwm-atmel-tcb.c. In fact all the other TCB drivers predate the microchip-tcb-capture driver. -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
