linux-kernel - [PATCH] PCI: cadence: Fix next function value in case of ARI

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Date:   Wed, 18 Jan 2023 12:50:35 +0530
From:   Achal Verma <a-verma1@...com>
To:     Tom Joseph <tjoseph@...ence.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczy_ski <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Vignesh Raghavendra <vigneshr@...com>
CC:     <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Achal Verma <a-verma1@...com>,
        Milind Parab <mparab@...ence.com>, Jian Wang <jian-wang@...com>
Subject: [PATCH] PCI: cadence: Fix next function value in case of ARI

From: Jasko-EXT Wojciech <wojciech.jasko-EXT@...tinental-corporation.com>

Next function field in ARI_CAP_AND_CTR field register for last
function should be zero but thats not the case, so this patch
programs the next function field for last function as zero.

Signed-off-by: Jasko-EXT Wojciech <wojciech.jasko-EXT@...tinental-corporation.com>
Signed-off-by: Achal Verma <a-verma1@...com>
---
 drivers/pci/controller/cadence/pcie-cadence-ep.c | 15 ++++++++++++++-
 drivers/pci/controller/cadence/pcie-cadence.h    |  6 ++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
index b8b655d4047e..6b6904cf0123 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
@@ -565,7 +565,8 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
 	struct cdns_pcie *pcie = &ep->pcie;
 	struct device *dev = pcie->dev;
 	int max_epfs = sizeof(epc->function_num_map) * 8;
-	int ret, value, epf;
+	int ret, epf, last_fn;
+	u32 reg, value;
 
 	/*
 	 * BIT(0) is hardwired to 1, hence function 0 is always enabled
@@ -573,6 +574,18 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
 	 */
 	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, epc->function_num_map);
 
+	/* Setup ARI Next Function Number.
+	 * This field should point to the next physical Function and 0 for
+	 * last Function.
+	 */
+	last_fn = find_last_bit(&epc->function_num_map, BITS_PER_LONG);
+	reg     = CDNS_PCIE_CORE_PF_I_ARI_CAP_AND_CTRL(last_fn);
+
+	// Clear Next Function Number for the last function used.
+	value  = cdns_pcie_readl(pcie, reg);
+	value &= ~CDNS_PCIE_ARI_CAP_NFN_MASK;
+	cdns_pcie_writel(pcie, reg, value);
+
 	if (ep->quirk_disable_flr) {
 		for (epf = 0; epf < max_epfs; epf++) {
 			if (!(epc->function_num_map & BIT(epf)))
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 190786e47df9..68c4c7878111 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -130,6 +130,12 @@
 #define CDNS_PCIE_EP_FUNC_DEV_CAP_OFFSET	0xc0
 #define CDNS_PCIE_EP_FUNC_SRIOV_CAP_OFFSET	0x200
 
+/*
+ * Endpoint PF Registers
+ */
+#define CDNS_PCIE_CORE_PF_I_ARI_CAP_AND_CTRL(fn)	(0x144 + (fn) * 0x1000)
+#define CDNS_PCIE_ARI_CAP_NFN_MASK	GENMASK(15, 8)
+
 /*
  * Root Port Registers (PCI configuration space for the root port function)
  */
-- 
2.25.1