smmu學習筆記之streamtable 2

2019-11-06 09:38:02

字體：大中小

來源：轉載

供稿：網友

streamtable的另一種組織方式是linear，調用的是static int arm_smmu_init_strtab_linear(struct arm_smmu_device *smmu){ void *strtab; u64 reg; u32 size; struct arm_smmu_strtab_cfg *cfg = &smmu->strtab_cfg; #計算size size = (1 << smmu->sid_bits) * (STRTAB_STE_DWordS << 3); #申請memory strtab = dmam_alloc_coherent(smmu->dev, size, &cfg->strtab_dma, GFP_KERNEL | __GFP_ZERO); if (!strtab) { dev_err(smmu->dev, "failed to allocate linear stream table (%u bytes)/n", size); return -ENOMEM; } cfg->strtab = strtab; cfg->num_l1_ents = 1 << smmu->sid_bits; /* Configure strtab_base_cfg for a linear table covering all SIDs */ reg = STRTAB_BASE_CFG_FMT_LINEAR; reg |= (smmu->sid_bits & STRTAB_BASE_CFG_LOG2SIZE_MASK) << STRTAB_BASE_CFG_LOG2SIZE_SHIFT; cfg->strtab_base_cfg = reg; arm_smmu_init_bypass_stes(strtab, cfg->num_l1_ents); return 0;}在arm_smmu_init_bypass_stes中會根據cfg->num_l1_ents 為最大值來逐一調用arm_smmu_write_strtab_ent而這里的ste定義如下：可見valid和bypass都是true struct arm_smmu_strtab_ent ste = { .valid = true, .bypass = true, };在arm_smmu_write_strtab_ent中主要是給strtab 賦值。最終調用arm_smmu_cmdq_issue_cmd 來發送CMDQ_OP_CFGI_STE 和 CMDQ_OP_PREFETCH_CFG命令。static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu, struct arm_smmu_cmdq_ent *ent){ u64 cmd[CMDQ_ENT_DWORDS]; unsigned long flags; bool wfe = !!(smmu->features & ARM_SMMU_FEAT_SEV); struct arm_smmu_queue *q = &smmu->cmdq.q; if (arm_smmu_cmdq_build_cmd(cmd, ent)) { dev_warn(smmu->dev, "ignoring unknown CMDQ opcode 0x%x/n", ent->opcode); return; } spin_lock_irqsave(&smmu->cmdq.lock, flags); while (queue_insert_raw(q, cmd) == -ENOSPC) { if (queue_poll_cons(q, false, wfe)) dev_err_ratelimited(smmu->dev, "CMDQ timeout/n"); } if (ent->opcode == CMDQ_OP_CMD_SYNC && queue_poll_cons(q, true, wfe)) dev_err_ratelimited(smmu->dev, "CMD_SYNC timeout/n"); spin_unlock_irqrestore(&smmu->cmdq.lock, flags);}從arm_smmu_cmdq_issue_cmd 中可以看到線根據arm_smmu_cmdq_ent->opcode的不同，bycase來對cmd賦值然后將cmd插入到queue中，并通過queue_poll_cons 來查詢是否執行插入成功 while (queue_insert_raw(q, cmd) == -ENOSPC) { if (queue_poll_cons(q, false, wfe)) dev_err_ratelimited(smmu->dev, "CMDQ timeout/n"); }特別的是如果ent->opcode == CMDQ_OP_CMD_SYNC的話，還要查詢queue是否為null。 if (ent->opcode == CMDQ_OP_CMD_SYNC && queue_poll_cons(q, true, wfe)) dev_err_ratelimited(smmu->dev, "CMD_SYNC timeout/n");

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