crypto: octeontx2 - CN10K CPT to RNM workaround

When software sets CPT_AF_CTL[RNM_REQ_EN]=1 and RNM in not producing
entropy(i.e., RNM_ENTROPY_STATUS[NORMAL_CNT] < 0x40), the first cycle of
the response may be lost due to a conditional clocking issue. Due to
this, the subsequent random number stream will be corrupted. So, this
patch adds support to ensure RNM_ENTROPY_STATUS[NORMAL_CNT] = 0x40
before writing CPT_AF_CTL[RNM_REQ_EN] = 1, as a workaround.

Signed-off-by: Srujana Challa <schalla@marvell.com>
Signed-off-by: Shijith Thotton <sthotton@marvell.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c

@@ -1076,6 +1076,39 @@ static void delete_engine_grps(struct pci_dev *pdev,
 		delete_engine_group(&pdev->dev, &eng_grps->grp[i]);
 }
 
+#define PCI_DEVID_CN10K_RNM 0xA098
+#define RNM_ENTROPY_STATUS  0x8
+
+static void rnm_to_cpt_errata_fixup(struct device *dev)
+{
+	struct pci_dev *pdev;
+	void __iomem *base;
+	int timeout = 5000;
+
+	pdev = pci_get_device(PCI_VENDOR_ID_CAVIUM, PCI_DEVID_CN10K_RNM, NULL);
+	if (!pdev)
+		return;
+
+	base = pci_ioremap_bar(pdev, 0);
+	if (!base)
+		goto put_pdev;
+
+	while ((readq(base + RNM_ENTROPY_STATUS) & 0x7F) != 0x40) {
+		cpu_relax();
+		udelay(1);
+		timeout--;
+		if (!timeout) {
+			dev_warn(dev, "RNM is not producing entropy\n");
+			break;
+		}
+	}
+
+	iounmap(base);
+
+put_pdev:
+	pci_dev_put(pdev);
+}
+
 int otx2_cpt_get_eng_grp(struct otx2_cpt_eng_grps *eng_grps, int eng_type)
 {
 
@@ -1189,9 +1222,17 @@ int otx2_cpt_create_eng_grps(struct otx2_cptpf_dev *cptpf,
 
 	if (is_dev_otx2(pdev))
 		goto unlock;
+
+	/*
+	 * Ensure RNM_ENTROPY_STATUS[NORMAL_CNT] = 0x40 before writing
+	 * CPT_AF_CTL[RNM_REQ_EN] = 1 as a workaround for HW errata.
+	 */
+	rnm_to_cpt_errata_fixup(&pdev->dev);
+
 	/*
 	 * Configure engine group mask to allow context prefetching
-	 * for the groups.
+	 * for the groups and enable random number request, to enable
+	 * CPT to request random numbers from RNM.
 	 */
 	otx2_cpt_write_af_reg(&cptpf->afpf_mbox, pdev, CPT_AF_CTL,
 			      OTX2_CPT_ALL_ENG_GRPS_MASK << 3 | BIT_ULL(16),