diff options
Diffstat (limited to 'drivers/usb/dwc2/core.h')
| -rw-r--r-- | drivers/usb/dwc2/core.h | 85 |
1 files changed, 83 insertions, 2 deletions
diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h index 52cbea28d0e9..115925909390 100644 --- a/drivers/usb/dwc2/core.h +++ b/drivers/usb/dwc2/core.h @@ -592,6 +592,84 @@ struct dwc2_hregs_backup { bool valid; }; +/* + * Constants related to high speed periodic scheduling + * + * We have a periodic schedule that is DWC2_HS_SCHEDULE_UFRAMES long. From a + * reservation point of view it's assumed that the schedule goes right back to + * the beginning after the end of the schedule. + * + * What does that mean for scheduling things with a long interval? It means + * we'll reserve time for them in every possible microframe that they could + * ever be scheduled in. ...but we'll still only actually schedule them as + * often as they were requested. + * + * We keep our schedule in a "bitmap" structure. This simplifies having + * to keep track of and merge intervals: we just let the bitmap code do most + * of the heavy lifting. In a way scheduling is much like memory allocation. + * + * We schedule 100us per uframe or 80% of 125us (the maximum amount you're + * supposed to schedule for periodic transfers). That's according to spec. + * + * Note that though we only schedule 80% of each microframe, the bitmap that we + * keep the schedule in is tightly packed (AKA it doesn't have 100us worth of + * space for each uFrame). + * + * Requirements: + * - DWC2_HS_SCHEDULE_UFRAMES must even divide 0x4000 (HFNUM_MAX_FRNUM + 1) + * - DWC2_HS_SCHEDULE_UFRAMES must be 8 times DWC2_LS_SCHEDULE_FRAMES (probably + * could be any multiple of 8 times DWC2_LS_SCHEDULE_FRAMES, but there might + * be bugs). The 8 comes from the USB spec: number of microframes per frame. + */ +#define DWC2_US_PER_UFRAME 125 +#define DWC2_HS_PERIODIC_US_PER_UFRAME 100 + +#define DWC2_HS_SCHEDULE_UFRAMES 8 +#define DWC2_HS_SCHEDULE_US (DWC2_HS_SCHEDULE_UFRAMES * \ + DWC2_HS_PERIODIC_US_PER_UFRAME) + +/* + * Constants related to low speed scheduling + * + * For high speed we schedule every 1us. For low speed that's a bit overkill, + * so we make up a unit called a "slice" that's worth 25us. There are 40 + * slices in a full frame and we can schedule 36 of those (90%) for periodic + * transfers. + * + * Our low speed schedule can be as short as 1 frame or could be longer. When + * we only schedule 1 frame it means that we'll need to reserve a time every + * frame even for things that only transfer very rarely, so something that runs + * every 2048 frames will get time reserved in every frame. Our low speed + * schedule can be longer and we'll be able to handle more overlap, but that + * will come at increased memory cost and increased time to schedule. + * + * Note: one other advantage of a short low speed schedule is that if we mess + * up and miss scheduling we can jump in and use any of the slots that we + * happened to reserve. + * + * With 25 us per slice and 1 frame in the schedule, we only need 4 bytes for + * the schedule. There will be one schedule per TT. + * + * Requirements: + * - DWC2_US_PER_SLICE must evenly divide DWC2_LS_PERIODIC_US_PER_FRAME. + */ +#define DWC2_US_PER_SLICE 25 +#define DWC2_SLICES_PER_UFRAME (DWC2_US_PER_UFRAME / DWC2_US_PER_SLICE) + +#define DWC2_ROUND_US_TO_SLICE(us) \ + (DIV_ROUND_UP((us), DWC2_US_PER_SLICE) * \ + DWC2_US_PER_SLICE) + +#define DWC2_LS_PERIODIC_US_PER_FRAME \ + 900 +#define DWC2_LS_PERIODIC_SLICES_PER_FRAME \ + (DWC2_LS_PERIODIC_US_PER_FRAME / \ + DWC2_US_PER_SLICE) + +#define DWC2_LS_SCHEDULE_FRAMES 1 +#define DWC2_LS_SCHEDULE_SLICES (DWC2_LS_SCHEDULE_FRAMES * \ + DWC2_LS_PERIODIC_SLICES_PER_FRAME) + /** * struct dwc2_hsotg - Holds the state of the driver, including the non-periodic * and periodic schedules @@ -682,7 +760,9 @@ struct dwc2_hregs_backup { * This value is in microseconds per (micro)frame. The * assumption is that all periodic transfers may occur in * the same (micro)frame. - * @frame_usecs: Internal variable used by the microframe scheduler + * @hs_periodic_bitmap: Bitmap used by the microframe scheduler any time the + * host is in high speed mode; low speed schedules are + * stored elsewhere since we need one per TT. * @frame_number: Frame number read from the core at SOF. The value ranges * from 0 to HFNUM_MAX_FRNUM. * @periodic_qh_count: Count of periodic QHs, if using several eps. Used for @@ -803,7 +883,8 @@ struct dwc2_hsotg { struct list_head periodic_sched_queued; struct list_head split_order; u16 periodic_usecs; - u16 frame_usecs[8]; + unsigned long hs_periodic_bitmap[ + DIV_ROUND_UP(DWC2_HS_SCHEDULE_US, BITS_PER_LONG)]; u16 frame_number; u16 periodic_qh_count; bool bus_suspended; |
