linux-kernel - [PATCH v4 2/3] PCI: qcom-ep: Enable cache coherency for SA8775P EP

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Message-Id: <1700577493-18538-3-git-send-email-quic_msarkar@quicinc.com>
Date:   Tue, 21 Nov 2023 20:08:12 +0530
From:   Mrinmay Sarkar <quic_msarkar@...cinc.com>
To:     agross@...nel.org, andersson@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        konrad.dybcio@...aro.org, mani@...nel.org, robh+dt@...nel.org
Cc:     quic_shazhuss@...cinc.com, quic_nitegupt@...cinc.com,
        quic_ramkri@...cinc.com, quic_nayiluri@...cinc.com,
        dmitry.baryshkov@...aro.org, robh@...nel.org,
        quic_krichai@...cinc.com, quic_vbadigan@...cinc.com,
        quic_parass@...cinc.com, quic_schintav@...cinc.com,
        quic_shijjose@...cinc.com,
        Mrinmay Sarkar <quic_msarkar@...cinc.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: [PATCH v4 2/3] PCI: qcom-ep: Enable cache coherency for SA8775P EP

In a multiprocessor system cache snooping maintains the consistency
of caches. Snooping logic is disabled from HW on this platform.
Cache coherency doesn’t work without enabling this logic.

8775 has IP version 1.34.0 so intruduce a new cfg(cfg_1_34_0) for
this platform. Add struct qcom_pcie_ep_cfg as match data. Assign
no_snoop_override flag into struct qcom_pcie_ep_cfg and set it true
in cfg_1_34_0 and enable cache snooping if this particular flag is
true.

Signed-off-by: Mrinmay Sarkar <quic_msarkar@...cinc.com>
---
 drivers/pci/controller/dwc/pcie-qcom-ep.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 3a53d97..2cf9a24 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -47,6 +47,7 @@
 #define PARF_DBI_BASE_ADDR_HI			0x354
 #define PARF_SLV_ADDR_SPACE_SIZE		0x358
 #define PARF_SLV_ADDR_SPACE_SIZE_HI		0x35c
+#define PCIE_PARF_NO_SNOOP_OVERIDE		0x3d4
 #define PARF_ATU_BASE_ADDR			0x634
 #define PARF_ATU_BASE_ADDR_HI			0x638
 #define PARF_SRIS_MODE				0x644
@@ -86,6 +87,10 @@
 #define PARF_DEBUG_INT_CFG_BUS_MASTER_EN	BIT(2)
 #define PARF_DEBUG_INT_RADM_PM_TURNOFF		BIT(3)
 
+/* PARF_NO_SNOOP_OVERIDE register fields */
+#define WR_NO_SNOOP_OVERIDE_EN                 BIT(1)
+#define RD_NO_SNOOP_OVERIDE_EN                 BIT(3)
+
 /* PARF_DEVICE_TYPE register fields */
 #define PARF_DEVICE_TYPE_EP			0x0
 
@@ -149,6 +154,10 @@ enum qcom_pcie_ep_link_status {
 	QCOM_PCIE_EP_LINK_DOWN,
 };
 
+struct qcom_pcie_ep_cfg {
+	bool no_snoop_overide;
+};
+
 /**
  * struct qcom_pcie_ep - Qualcomm PCIe Endpoint Controller
  * @pci: Designware PCIe controller struct
@@ -167,6 +176,7 @@ enum qcom_pcie_ep_link_status {
  * @num_clks: PCIe clocks count
  * @perst_en: Flag for PERST enable
  * @perst_sep_en: Flag for PERST separation enable
+ * @cfg: PCIe EP config struct
  * @link_status: PCIe Link status
  * @global_irq: Qualcomm PCIe specific Global IRQ
  * @perst_irq: PERST# IRQ
@@ -194,6 +204,7 @@ struct qcom_pcie_ep {
 	u32 perst_en;
 	u32 perst_sep_en;
 
+	const struct qcom_pcie_ep_cfg *cfg;
 	enum qcom_pcie_ep_link_status link_status;
 	int global_irq;
 	int perst_irq;
@@ -489,6 +500,11 @@ static int qcom_pcie_perst_deassert(struct dw_pcie *pci)
 	val |= BIT(8);
 	writel_relaxed(val, pcie_ep->parf + PARF_LTSSM);
 
+	/* Enable cache snooping for SA8775P */
+	if (pcie_ep->cfg && pcie_ep->cfg->no_snoop_overide)
+		writel_relaxed(WR_NO_SNOOP_OVERIDE_EN | RD_NO_SNOOP_OVERIDE_EN,
+				pcie_ep->parf + PCIE_PARF_NO_SNOOP_OVERIDE);
+
 	return 0;
 
 err_disable_resources:
@@ -511,6 +527,10 @@ static void qcom_pcie_perst_assert(struct dw_pcie *pci)
 	pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED;
 }
 
+static const struct qcom_pcie_ep_cfg cfg_1_34_0 = {
+	.no_snoop_overide = true,
+};
+
 /* Common DWC controller ops */
 static const struct dw_pcie_ops pci_ops = {
 	.link_up = qcom_pcie_dw_link_up,
@@ -817,6 +837,7 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
 	pcie_ep->pci.ep.ops = &pci_ep_ops;
 	pcie_ep->pci.edma.nr_irqs = 1;
 	platform_set_drvdata(pdev, pcie_ep);
+	pcie_ep->cfg = of_device_get_match_data(dev);
 
 	ret = qcom_pcie_ep_get_resources(pdev, pcie_ep);
 	if (ret)
@@ -875,7 +896,7 @@ static void qcom_pcie_ep_remove(struct platform_device *pdev)
 }
 
 static const struct of_device_id qcom_pcie_ep_match[] = {
-	{ .compatible = "qcom,sa8775p-pcie-ep", },
+	{ .compatible = "qcom,sa8775p-pcie-ep", .data = &cfg_1_34_0},
 	{ .compatible = "qcom,sdx55-pcie-ep", },
 	{ .compatible = "qcom,sm8450-pcie-ep", },
 	{ }
-- 
2.7.4