linux-kernel - [PATCH v2] PCI: cadence: Enable Controller to respond to received PTM Requests

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Date:   Tue, 22 Feb 2022 17:26:05 +0100
From:   Christian Gmeiner <christian.gmeiner@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     kishon@...com, Christian Gmeiner <christian.gmeiner@...il.com>,
        Tom Joseph <tjoseph@...ence.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org
Subject: [PATCH v2] PCI: cadence: Enable Controller to respond to received PTM Requests

This enables the Controller [RP] to automatically respond with
Response/ResponseD messages if CDNS_PCIE_LM_TPM_CTRL_PTMRSEN
and PCI_PTM_CTRL_ENABLE bits are both set.

Signed-off-by: Christian Gmeiner <christian.gmeiner@...il.com>
---
 drivers/pci/controller/cadence/pcie-cadence-host.c | 10 ++++++++++
 drivers/pci/controller/cadence/pcie-cadence.h      |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index fb96d37a135c..940c7dd701d6 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -123,6 +123,14 @@ static int cdns_pcie_retrain(struct cdns_pcie *pcie)
 	return ret;
 }
 
+static void cdns_pcie_host_enable_ptm_response(struct cdns_pcie *pcie)
+{
+	u32 val;
+
+	val = cdns_pcie_readl(pcie, CDNS_PCIE_LM_PTM_CTRL);
+	cdns_pcie_writel(pcie, CDNS_PCIE_LM_PTM_CTRL, val | CDNS_PCIE_LM_TPM_CTRL_PTMRSEN);
+}
+
 static int cdns_pcie_host_start_link(struct cdns_pcie_rc *rc)
 {
 	struct cdns_pcie *pcie = &rc->pcie;
@@ -501,6 +509,8 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
 	if (rc->quirk_detect_quiet_flag)
 		cdns_pcie_detect_quiet_min_delay_set(&rc->pcie);
 
+	cdns_pcie_host_enable_ptm_response(pcie);
+
 	ret = cdns_pcie_start_link(pcie);
 	if (ret) {
 		dev_err(dev, "Failed to start link\n");
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index c8a27b6290ce..1ffa8fa77a8a 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -116,6 +116,10 @@
 #define LM_RC_BAR_CFG_APERTURE(bar, aperture)		\
 					(((aperture) - 2) << ((bar) * 8))
 
+/* PTM Control Register */
+#define CDNS_PCIE_LM_PTM_CTRL 	(CDNS_PCIE_LM_BASE + 0x0da8)
+#define CDNS_PCIE_LM_TPM_CTRL_PTMRSEN 	BIT(17)
+
 /*
  * Endpoint Function Registers (PCI configuration space for endpoint functions)
  */
-- 
2.35.1