/* * In order to do lockless preemption we use a simple state machine to progress * through the process. * * PREEMPT_NONE - no preemption in progress. Next state START. * PREEMPT_START - The trigger is evaluating if preemption is possible. Next * states: TRIGGERED, NONE * PREEMPT_FINISH - An intermediate state before moving back to NONE. Next * state: NONE. * PREEMPT_TRIGGERED: A preemption has been executed on the hardware. Next * states: FAULTED, PENDING * PREEMPT_FAULTED: A preemption timed out (never completed). This will trigger * recovery. Next state: N/A * PREEMPT_PENDING: Preemption complete interrupt fired - the callback is * checking the success of the operation. Next state: FAULTED, NONE.
*/
/* * struct a6xx_preempt_record is a shared buffer between the microcode and the * CPU to store the state for preemption. The record itself is much larger * (2112k) but most of that is used by the CP for storage. * * There is a preemption record assigned per ringbuffer. When the CPU triggers a * preemption, it fills out the record with the useful information (wptr, ring * base, etc) and the microcode uses that information to set up the CP following * the preemption. When a ring is switched out, the CP will save the ringbuffer * state back to the record. In this way, once the records are properly set up * the CPU can quickly switch back and forth between ringbuffers by only * updating a few registers (often only the wptr). * * These are the CPU aware registers in the record: * @magic: Must always be 0xAE399D6EUL * @info: Type of the record - written 0 by the CPU, updated by the CP * @errno: preemption error record * @data: Data field in YIELD and SET_MARKER packets, Written and used by CP * @cntl: Value of RB_CNTL written by CPU, save/restored by CP * @rptr: Value of RB_RPTR written by CPU, save/restored by CP * @wptr: Value of RB_WPTR written by CPU, save/restored by CP * @_pad: Reserved/padding * @rptr_addr: Value of RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP * @rbase: Value of RB_BASE written by CPU, save/restored by CP * @counter: GPU address of the storage area for the preemption counters * @bv_rptr_addr: Value of BV_RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP
*/ struct a6xx_preempt_record {
u32 magic;
u32 info;
u32 errno;
u32 data;
u32 cntl;
u32 rptr;
u32 wptr;
u32 _pad;
u64 rptr_addr;
u64 rbase;
u64 counter;
u64 bv_rptr_addr;
};
/* * The preemption counter block is a storage area for the value of the * preemption counters that are saved immediately before context switch. We * append it on to the end of the allocation for the preemption record.
*/ #define A6XX_PREEMPT_COUNTER_SIZE (16 * 4)
/* * Given a register and a count, return a value to program into * REG_CP_PROTECT_REG(n) - this will block both reads and writes for * _len + 1 registers starting at _reg.
*/ #define A6XX_PROTECT_NORDWR(_reg, _len) \
((1 << 31) | \
(((_len) & 0x3FFF) << 18) | ((_reg) & 0x3FFFF))
/* * Same as above, but allow reads over the range. For areas of mixed use (such * as performance counters) this allows us to protect a much larger range with a * single register
*/ #define A6XX_PROTECT_RDONLY(_reg, _len) \
((((_len) & 0x3FFF) << 18) | ((_reg) & 0x3FFFF))
/* Return true if we are in a preempt state */ staticinlinebool a6xx_in_preempt(struct a6xx_gpu *a6xx_gpu)
{ /* * Make sure the read to preempt_state is ordered with respect to reads * of other variables before ...
*/
smp_rmb();
int preempt_state = atomic_read(&a6xx_gpu->preempt_state);
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